Archive for the 'Stylophones' Category

08
Aug
18

Stylophones 6 – The Soviet Stylophone

With the help of a correspondent to my blog I was lucky enough to get hold of an early 80’s ‘Stylophone’ from the Soviet Union.

Entitled the ‘Gamma’, I’m told it was made in the city of Chernivtsi, a part of the Soviet Union now in western Ukraine.

Larger than a Dübreq Stylophone, it came in a neat plastic box measuring about 25x20x5cm.

Inside, the Gamma Stylophone itself has a 20-note keyboard at the front, a stylus – more complicated than a Dübreq Stylophone stylus – on a twin lead, a volume control on the left-hand side, and a speaker in the top left-hand corner.  A coloured label indicates the notes of the scale represented by each section of the keyboard.

There are also 3 strange slots above the keyboard, which are slightly wider than the keyboard and just deep enough to be accessed by the stylus.  This close up of the keyboard shows the middle of two of these slots:

The stylus, as mentioned above, is more complicated than the Dübreq Stylophone stylus in that it includes a combined press and slide switch.  It turned out that the press switch had to be pushed for the stylus to work; the slide switch turned the vibrato on or off.

Helpfully, my correspondent had cleaned the instrument before sending it, so there wasn’t a lot for me to do!  I opened the case – just 4 slot-headed screws underneath – and examined the insides.  The circuit board was attached to 4 mounts on the base; the speaker had 4 mounts on the front.

Turning the circuit board over, I could see the components and the layout.  Everything seemed neat and well made, with a good solid loudspeaker.

The components on the circuit board weren’t quite the same as their Western equivalents, but quite recognisable, nonetheless:

I removed a little more of the disintegrating foam – and replaced a speaker wire, which I had inadvertently detached – and then turned to the power cables.  The battery fittings had been removed, but I could see from the booklet which came with the instrument, that these had been designed for a pair of Soviet-style 4.5v batteries: my correspondent explained to me that these were similar to a group of three 1.5v batteries – not unlike the kind of thing we used to have inside cordless phones – but which were, in any case, now uncommon.

I just added a PP3 battery clip, similar to the type one would find in an old-style Dübreq Stylophone, which worked fine.  I hadn’t intended to ‘circuit-bend’ this device, but I pondered on adding an on/off switch, as there isn’t one in the original design.

I attached the battery and tried it out.  The push switch needed a bit of attention – a few squirts of contact cleaner helped – but all the notes sounded perfectly, and the vibrato turned on and off.  I wasn’t able to check that the notes were in tune, and there’s no fine tuning control, which you would find on a Dübreq Stylophone, but I’ll look into that later.

The booklet that came with the Gamma Stylophone was delightful – the paper and printing quality weren’t high, but the illustrations were beautiful and the colourful instructions on how to play the many songs were attractively set out.

Read the Gamma Stylophone Booklet.

I’m told that Chernivtsi is in the region of Bukovina, which lies partly in the Ukraine and partly in Romania, and that the costume of the dancer in the picture is from this region.

The serial number in the booklet and on the back of the instrument is ‘304’.  It is normal, apparently, for these instruments to have 6-figure serial numbers, so this could be a very early example.

There is no circuit diagram in the booklet, but this is said to be unusual in the Soviet era when it was common for these to be included.

Here’s a short video of me testing the Gamma Stylophone.  You can see from this clip how the stylus switches function – and also what the 3 extra slots are for!

Continue reading ‘Stylophones 6 – The Soviet Stylophone’

26
May
16

Stylophones 5 – The Melophone

There are a number of different instruments called the ‘Melophone’ or ‘Mellophone’.  The one on the left in the picture below (by Kc8dis at the English language Wikipedia) is a brass instrument used in marching bands and the one on the right is ‘a cross between a guitar and a harmonium’, according to the Squeezytunes blog (at http://squeezyboy.blogs.com/squeezytunes/2008/02/melophone.html, from which the pictures came).

Mel(l)ophones

However, this Melophone which I recently acquired, is clearly a type of Stylophone – and a very stylish type of Stylophone at that!

Melophone2

Melophone1

I had never heard of this Melophone before, and found only a single reference to it on the internet.  A glance at the accompanying booklet – which, as you will see below, follows exactly the same style and format as the booklet from a 1960s/70s Stylophone – shows that it was not written by a native English speaker.  The company that manufactured it is (according to this website: http://www.pewc.com.tw/eng/) or was (according to this Wikipedia entry: https://en.wikipedia.org/wiki/Taiwan_Mobile) founded in Taiwan in the 1950s and acquired the name ‘Pacific Electric Wire and Cable Company’ on December 30th 1957.

The company would, therefore, have been in place to manufacture the Stylophone after its invention in 1967.  It looks as though it may have done so for some years as the picture on the box shows a Melophone with the early Stylophone keyboard with the black non-playing sections; just as the Stylophone was updated with a new keyboard, so it seems was the Melophone.

Box

The flap has a sticker on it showing the colour as yellow, which this one is; but other colours were presumably available.

It is, incidentally, not ‘Colour’, but ‘Color’, which may be an indication of the market it was intended for: Asia or America.  There would be no reason why it should not be intended for the UK, as the legend ‘Made in Taiwan’ was commonly seen during that period – except that genuine, British-made Stylophones were available over here, and Dübreq would surely not want to allow or encourage competition.

*

The similarities with the Stylophone – its appearance as well as its booklet – are striking: particularly the distinctively-shaped keyboard with its recess above to hold the stylus.

Stylus01

As can be seen  in the above photograph, the size and method of connection to the stylus are also the same as the Stylophone, and a detailed comparison of the yellow Melophone stylus with a black Stylophone stylus, shows that their dimensions are more or less identical:

Stylus02

Nevertheless, there are significant differences – aside, of course, from its handsome ‘Grand Piano’ shape!

First of all, although apparently identical, the Melophone keyboard is longer.  With a standard Stylophone on top, this can be clearly seen:

Keyboards

There are 2 extra notes at the bottom end of the keyboard, G and G#, and 1 extra note at the top, F – that is, 23 notes in total, as opposed to the Stylophone’s 20.

You can also see in the above photograph that the Melophone lacks the traditional Power and Vibrato switches at the left-hand end of the keyboard.  Instead, the Power On/Off switch is incorporated into a volume control on the top of the Melophone, to the left:

On_Off_Volume

The Vibrato switch is found on the left side, together with a control the standard Stylophone never had – an Octave-change switch!

Side

Using this switch, the range of the Melophone can be extended by another 12 notes, giving the instrument an exceptionally wide range.

Turning the instrument over reveals the battery compartment – like the original Stylophone, the Melophone requires a 9v PP3 battery – and the three screws which need to be undone to access the inside.

Back

The circuit board inside is quite different from the standard Stylophone – and so is the circuit itself: no fewer than 6 transistors can be identified in the following pictures (These are 1 x ED1402A, 3 x ED1402D, 1 x ED1402E and 1 x ED1602E, which are all NPN General Purpose transistors – except the 1602E, which is a PNP):

Inside1

Inside3

Inside4

Inside2

It has no tuning control like the standard Stylophone; I wonder if the top has been removed from one of the potentiometers in the first internal picture in order to make some pitch adjustment.

*

Comparing the Melophone Booklet with a typical Stylophone booklet of the period, the close similarity is evident:

Two CoversRead the Melophone Booklet

Even the two pieces of music at the back of the booklet are the same: ‘Silent Night’ in the key of Bb and ‘The Londonderry Air’ in the key of C, although references to ‘Stylophone’ or ‘Dübreq’ are noticeably absent.

*

One website (http://www.miniorgan.com/lib/view.php?miniorgan=80&view=E&srch=&srch_type=&sortby=&output=14) pictures and describes as ‘another very cheap STYLOPHONE clone’ an obvious copy (which they date to 1976 – the year after production of the original Stylophone ceased, according to the Stylophone Collectors Information Site  at http://www.stylophone.ws/index.html).  ‘Sounds poor and very poor plastic’, they say; but this Grand Piano Melophone seems like a step up from that, in sound and construction.

Here’s a brief example of the tones made by the Pacific Melophone:

Sufficiently Stylophone-like, I’m sure you’ll agree!  The two low notes beneath the Stylophone’s normal lowest note don’t come out too well, though.  I’ll have to see if something can be done about that.

Describing a Hong Kong made Stylophone, the Stylophone Collectors Information Site says ‘Problems were experienced by the Dübreq company regarding patent infringments, but licences were apparently also granted, so it is very difficult to categorise this particular model.’  Perhaps the same can be said for the Melophone: it definitely isn’t a Stylophone, but it seems to me reasonably built and with some very close similarities – was it somehow produced under licence, or just a clever copy?  If anyone has any further information, please let me know.

15
Sep
13

The StyloSound

front_IMG_1497

The idea for the StyloSound came to me when, at about the same time, I acquired two small sound effect devices.  One was a ‘Sound Machine’, a small hand-held unit with 16 push-buttons, the other was a Sound effect kit with PCB, also with 16 different sounds.  I thought it would be a good idea to combine the two things into one unit and use the Stylophone stylus to trigger the sounds; plus I was also working on devices to interact with the ‘Bigfoot’ trigger/sequencer, so I decided to add the capability for the sounds to be triggered by the Bigfoot’s 4-bit binary output.

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There are several varieties of Sound Machine.  The one I got was the silver ‘SciFi’ version.  This has a number of interesting ‘spacey’ effects, some of which I recognised from Star Wars, Close Encounters and others; some I didn’t.

sound-machine-sci-fi-box2

These Sound Machines aren’t all exactly the same inside, apparently (this site gives a very good first-hand account of looking inside them: http://www.magicmess.co.uk/cb/sm.php)*, but I guess the sounds are all initiated the same way – a +V pulse into the appropriate input of the dedicated chip which stores the samples.

*[Edit: unfortunately, this site is no longer up; I saved some of it, which had this information in it: http-www-magicmess-co-ukcbsm-php.pdf].

Having opened the Sound Machine and taken the PCB out, it was easy to attach a wire to each of the 16 inputs.  These wires went to the middle 16 notes on a Stylophone keyboard, salvaged from a broken instrument – via 16 SPDT switches, as I wanted to be able to choose either the sound from the Sound Machine or the sound from the Sound effect kit individually in each of the 16 positions.  This picture shows how the switches were arranged on the front of the StyloSound:

StyloSound outside in prep IMG_1469

The Stylophone stylus was connected to +V, and the output from the Sound Machine PCB went to the Stylophone speaker, which was much better than the small speaker in the original.

The Sound Machine is powered by three small 1.5v button cells, so it was no problem to use the Stylophone’s own battery compartment, which takes three AA batteries.  With all the switches to the left, the Sound Machine PCB was selected, and it was possible to play all 16 sounds from the Stylophone keyboard.  It was clearer from this than using the original buttons that each sound has to play right through before a new one can be selected.

The next obvious step was to interfere with the playback speed of the sample.  This version of the Sound Machine has only four visible components, two resistors and two capacitors – all tiny SMD (surface-mount) type – with the main chip embedded in its plastic blob.  Using the wetted finger method, I found the resistor responsible for playback speed, which is marked ‘R2’.  I removed it and replaced it with a potentiometer, which slowed down and speeded up the playback.

In this photograph you can see the points at which wires are soldered to the Sound Machine PCB.  In the magnified area you can just about make out the resistor on the left marked ‘R1’, the removed resistor, ‘R2’ (detached but still lying beside the place it was removed from), the wires going to the potentiometer and the two SMD capacitors behind the wires:

SMachine PCB IMG_1473

Unusually in my experience, the chip reacted badly to both too low a resistance and too high, and a 1M potentiometer, my usual first choice, was too big for it, causing it to crash.  In the end, I settled on a 470K potentiometer with 100k trimmers either side.  When the trimmers had been adjusted, this seemed to keep the resistance within acceptable levels.

(Later, I read the website referenced above, and the writer had a different solution to this problem, but I didn’t have time to check it out).

*

The above is all you would need to do to bend a Sound Machine, but the next thing in my case was to unpack the Sound Effect kit, which contained the following components:

Kit unpacked IMG_1471

The two logic chips are a 4066 (quad analog SPST switch), and 4011, (quad 2-input NAND gate); the sound effect chip was on a separate board, inserted, strangely, at right angles to the main board in the slot on the right.  The 4 SPDT switches enable the sound to be selected manually – the input is 4 bit binary – as an alternative to the 4 inputs on the left-hand side of the board.  Output is  through what looked like a small piezo element (the round black component in the bottom left of the picture).

The small board which the sound effect chip itself sits on is one of a range in the 9561 series.  This one has the prefix ‘LX’, but there are others, such  as ‘CK’, ‘CL’, ‘CW’, ‘KD” and others: all have the same general purpose, finding use in alarms, doorbells, and simple toys, making noises such as police sirens, machine guns and so on.  Simple circuits such as this one can be found on the internet utilising very few external components to produce the required sound (generally only one or two in each application):

LX9561

In fact, the kit I bought in an eBay auction only cost about the same as the module itself, and took full advantage of the range of sounds available by using the two switching terminals (F1 and F2) and a more complex array of resistors in place of the single 200k resistor shown in the circuit above.  The full list of sounds available is as follows:

0000: Machine gun voice
0001: Fire truck voice
0010: Ambulance voice
0011: The police car voice
0100: Crickets sound
0101: Alarm
0110: Electronic signal sound
0111: Koh
1000: Insect song
1001: Whistle
1010: Telegraph sound
1011: Bird song
1100: ChongJi gunfire
1101: Car sirens
1110: Bass instruments sound
1111: Racing sound

Some of these interpretations are rather fanciful, but that was no problem as I was more interested in making noise than repeating recognisable sounds.

This chart – for a similar chip in the series – gives some idea of the variations in binary inputs, combinations of selection inputs and resistances that produce different sounds.  If you read Chinese, which I don’t, it probably tells you in the right-hand column what sounds these combinations make.

KD9561 selection chart2

The PCB was robustly constructed and I put it together omitting the four slide switches, as I intended to control it externally, and didn’t attach the piezo sounder, which wasn’t going to be used.

Several of the resistors, when tested, had an effect on the pitch and speed of the sounds – the main job of the 4066 and 4011 is to select different combinations of resistors to affect the sound produced, much as indicated in the chart above – so I picked the likeliest one and replaced it with a 1M potentiometer.  This seemed to do the trick – perhaps taking things slightly too far in the upper direction, so I added a preset in series to keep it from going to its maximum – although it had happily done this without any danger of crashing the chip.

I only had a log potentiometer available, and in the end this was quite fortunate.  I found that connecting it the opposite way round from what would be expected – i.e. turning it clockwise decreased the pitch and speed, rather than increasing it – exploited the logarithmic scale well, making a much slower and smoother transition through the higher pitches and speeds.  I could have bought an ‘anti-log’ pot, but additional time and expense didn’t seem worth it.

This was a timely reminder that a useful part of experimentation would be to compare lin and log pots in particular situations, and reversing the log ones to see what difference this produced. (Reversing the linear ones would, of course, do no good, as they progress evenly through the scale from top to bottom, whichever way round they are).

This part of the circuit (the kit PCB) now looked like this:

Sound Effect Kit circuit 3

The original circuit diagram was provided by the supplier, Chip_Partner_Store, a Chinese company with an eBay shop at http://stores.ebay.com/Chip-Partner-Store.  Places like this – and there are many of them on eBay – are great for browsing through: you can find great deals on bulk buys of common components, as well as somewhat more unusual ones at very reasonable prices, and odd chips and modules like this one, which could always come in handy.

I’ve indicated in the diagram where I added the 1M potentiometer and preset, plus four LEDs, connected, via 470Ω resistors, to the A B C D inputs, the other ends connected to ground.  These were not there for any reason, particularly, except as an indicator of the code being received – and on the principle established with Bigfoot that flashing lights are always good.  I was sceptical as to whether the circuit supplying the four inputs would be able to power these as well as operate the Sound effect module correctly, but it all seemed OK.

The greyed-out section at the output wasn’t used in the final circuit.

Actually, this unit begins sounding repeatedly as soon as power is connected to it, since the default input 0 0 0 0 has an associated output – ‘Machine gun voice’ – and I couldn’t find a way of stopping it, so I also added a power on/off switch to this board, which isn’t shown, in case this feature became annoying.

*

SInce the circuit has four binary inputs, and I wanted to control the unit with the Bigfoot, which has a 4-bit binary output, it would seem logical to connect the Bigfoot output directly to the A B C D inputs.

Unfortunately, this wouldn’t allow the Sound effect module to be operated by the Stylophone keyboard, or the Bigfoot to control the Sound Machine, so additional circuitry was needed to convert the binary input into 16 individual outputs, and then convert that back into binary . . .

. . . Fortunately, the first of those would be a duplicate of part of the Bigfoot circuitry, which I was familiar with, using a 4067 chip.  This part of the circuit looked like this:

StyloSound - 4050_4067_3

The input from the 5-pin DIN socket goes first to a 4050 hex buffer.  Four of the six buffers are used.  The reason for doing this is to exploit an unusual and very useful feature which the 4050 shares with its more common sibling, the 4049.

Both perform a similar function, but the 4049 inverts the input (high level voltage in = low level voltage out, low level voltage in = high level voltage out), and the 4050 doesn’t.

What both of them are able to do is accept an input voltage level higher than the supply voltage, a vital consideration here as the output from Bigfoot is at 9v, whereas the circuitry of the StyloSound is at only 4.5v.  The 4050 is able to acccept the 9v input from Bigfoot and safely reduce it to 4.5v for the other circuits.  9v isn’t a problem for CMOS chips, but the Sound Machine and the Sound effects module are both rated at 4.5 – maybe 5 or 6 maximum – volts.

The four outputs of the 4050 go into the A B C D inputs of the 4067.  Each of the 16 outputs of the 4067 goes to the pole of one of the SPDT switches described earlier.  According to the binary coding on the inputs, one of the 16 outputs of the 4067 is connected to +V, and this signal is sent in the direction either of the Sound Machine when the switch is to the left, or the Sound effect module when it’s to the right.

*

The Sound Machine has 16 separate inputs, so no further circuitry was required: each switch was connected to one of the 16 places on the Sound Machine PCB where there used to be buttons.

For this signal to operate the Sound effect module, however, it needed to be changed back into binary.

Fortunately, this change is not difficult to implement, using a pair of 4532 chips and a 4071.  The 4532 is essentially the opposite of the 4067: it takes individual inputs and converts them to binary.  Each one has only 8 individual inputs and outputs in 3-bit binary, but the datasheet showed this 16-input, 4-bit binary output circuit, which is the one I used:

16 input encoder w pin Nos

The 16 inputs marked ‘From Stylophone Keyboard’ were all connected to ground with 100k resistors so that each one would be at 0v if not receiving a +V signal from the keyboard or the 4067.  The outputs of the 4071 were connected to the Sound effects module where marked A B C D in the earlier diagram.

Here’s how the physical connections are made, and what the chips look like on the board:

StyloSound 4532_4071_3

inside_IMG_1472_2

I’m not entirely sure that the correct order of those 16 inputs is as implied in the datasheet circuit.  Since I had LEDs on the inputs of the Sound effects module – i.e. effectively at the outputs of the 4071, I was able to check the sequence, and I found myself swapping some of them around.  If you’re using this method of converting single outputs to binary, it would be advisable to check this as you go along.  In my case, the wiring to and from the SPST switches was such a bird’s nest, that it became too difficult to work this out.  If it becomes clearer when I use this system in future projects, I’ll make sure to record the correct sequence.

However, when tested with ‘Bigfoot’, the module was triggered accurately, and the LEDs on the input lit up with the correct numbers when the notes were tested with the stylus and keyboard.

*

So now I had two separate sound effect circuits which differed in several ways: the Sound Machine uses samples, which are played back in their entirety, and are particularly effective when slowed down; the Sound effects module produces electronic sounds from oscillators, which can be cut off and replaced at any time by another sound, and lend themselves to being sped up.

Both sections had separate pitch/speed controls; both could be controlled automatically by Bigfoot, or manually via the Stylophone keyboard.

*

I could have stopped there, but I had another idea which I thought could be included.  I believe this is known in the trade as ‘feature creep’ – just adding that one extra implementation, which then turns into two, then three . . . and eventually makes a simple circuit over-complicated.

But I had  just acquired a number of unwanted ‘Voice Recorder’ key rings – 100, in fact! – at a few pence each.  At this price, they weren’t guaranteed to work, but when I tested some, quite a few seemed OK, and they were powered by 3 little coin cells – i.e. 4.5v, the same as the rest of the circuits in the StyloSound, so I thought I could employ a couple of them here.

Here’s what they look like:

outside_inside

There’s a very small microphone, a Record/Play switch, a button to operate whichever of the two functions it’s switched to, and an LED to indicate that it’s recording, as opposed to playing back.  I thought it would be good to be able to record a small (up to 8.2 seconds, it said) burst of sound while the samples or effects were being manipulated, then be able to play it back precisely the same again, a primitive – but undeniably inexpensive – repeat/looping device.

So I added a couple of these, connected to the outputs of the Sound Machine and the Sound effect module.  Small tactile switches glued to the front of the instrument replaced the ‘Record/Play’ switch and button, and I also moved the small LED’s to the front panel as well.

*

Only one thing remained, as far as the circuit was concerned, which was the output stage.  This turned out to be . . . strange.

First of all, I needed to mix together the four outputs: the Sound Machine, the Sound Effects module and the two recording devices, as well as send the Sound Machine and Sound Effects module outputs to the inputs of the recorders.  I planned to do this  with a passive mixer – i.e. just join the outputs together with resistors.

The Sound Machine worked perfectly with the internal speaker, but the Sound Effects module would only work with the other speaker terminal connected to +V rather than 0v: otherwise, it was extremely quiet.  I got round this by taking the output directly from the output of the LX9561 board, as indicated in the circuit diagram above, and bypassing the output transistor.

The outputs of the recorders were much too quiet, too, and the only way I could make them loud enough was to give them a path to +V by means of a very low value resistor (22Ω).  The sound quality of these didn’t quite match that of the Sound Machine and Effects module – partly, no doubt, because of reduced bandwidth in the recorders – but they definitely added a useful function.

In fact, I had intended to add tone and volume controls at this point, but the device refused point-blank to make any sound if anything other than a very low value resistor was put in the output path, I don’t know why.

In the end, I used 22Ω resistors to join the 4 outputs (two in series for the Sound Machine, which was a little louder than the others) and ran this straight to the speaker and output socket.  So, the final stage looked like this:

StyloSound - Output_3

The resistors are all 22Ω, as opposed to some other equally low value, simply because I had a pile of them which were going spare.

So: strange, but when I plugged it into my mixer, it  sounded fine, and the volume could be adjusted there.

*

The only thing left to do was to finish the case.  There was so much internal wiring and circuitry that the case had to be made 2.5″ deeper.  I constructed sides from an offcut piece of white plastic and superglued them in place – not especially neatly, it has to be said – with a little internal bracing.

top_IMG_1498
rside2_IMG_1494
back_IMG_1493*
This is what the StyloSound sounds like, controlled by ‘Bigfoot’:
01
Jun
13

The Taurus

The Taurus wasn’t a major project, but a handy companion piece to the Gemini, an earlier Stylophone modification.

The problem with the Gemini is that it has two voices, output in stereo, but, typical of the Stylophone, it has only the one speaker.  This means that some of its effects are only available via the stereo line out.

As a result of much past experimentation, I have many Stylophone bits left over.  To make the Taurus, which was to be a very simple external amplifier, I used an empty case, some spare grille material, two amplifier circuit boards and two speakers, all from S1 reissue versions of the instrument.

The Stylophone grille isn’t glued down, and can be removed from the inside by pushing out half a dozen lugs which hold it in place.  I did this first, cut a hole in the top of the case for the second speaker – vaguely matching the hole through which the original sounds – and refixed the grille.

The picture shows the second speaker glued in place, and the two amplifier boards connected to a new stereo input socket, the battery box and the speakers:

Taurus Inside DSCF0002

I wasn’t using any of the original keyboard, switch and socket parts, so I glued some spare grille sections inside the switch and socket holes and outside over the hole through which the keyboard is normally accessed.

A small tripod was attached to the base to enable the speakers to be angled for better distribution of the sound.  Decoration consisted of astrological symbols, in the style of the Gemini, and matching black and white bulls, front and back.

Front DSCF0003Reverse DSCF0005

It works well with the Gemini, which has its own volume and mix controls, but is a very basic unit indeed – no volume control, no on/off switch and no external power socket: it uses three AA batteries like the Gemini itself, and could be useful with other instruments needing a slight volume boost and not connected via a line out socket.

Gemini-Taurus DSCF0001

 

[Edit: the Taurus now has a volume control, which I should have put into start with.  This makes it much more practical to use.

Taurus Volume IMG_1512

As it uses a pair of Stylophone amp boards, I’ve done exactly the same as the Stylophone, and put a 10k log potentiometer at the input – in this case a dual, one for each channel].

23
Nov
12

Stylophones 4 – The Stylophone 350S, Part 2: Simple mods

After opening my 350S and giving it a good clean, I decided to carry out a few simple mods before putting it back together again.

The first thing I did was to detach the external connections to the two circuit boards to make it easier to take everything apart and get at.  These connections were:

  • keyboard
  • speaker
  • power
  • styluses
  • pitch

I carefully desoldered the wires, and replaced them with 2 or 3-way Molex connectors, like these:

Molex connectors IMG_1230

*

At this stage I decided not to make any further modifications to the keyboard.  The keyboard PCB now plugs into the main circuit board and is much easier to remove for cleaning and for further potential modifications.

This picture shows the front and back of the keyboard PCB with a 2-way Molex socket fitted, connecting top and bottom of the chain of resistors which produce the different notes:

Keyboard PCB complete

*

In the case of the speaker wires, the Molex connector makes it easier to move the main circuit board around while working on it, as the wires are no longer than absolutely necessary and the speaker is firmly fixed to the top half of the Stylophone body.

The modification I made to this – which I’ve done with several of my instruments recently – was to add a switch to swap between the internal speaker and a larger external speaker (as described here).  I chose a large DPDT rocker switch, which seemed to be in keeping with the 350S’s style.  I don’t know how necessary it was, but as the internal speaker is 35Ω and the external speaker is 8Ω , I added a 3W 27Ω resistor in series with the output, which is a pair of 4mm banana plug sockets.

*

As far as power was concerned, I first wanted to replace the large PP9 batteries.  Not only are these heavy and expensive, but they take up a lot of room inside the Stylophone case, which might be needed to house extra circuitry.  So what I decided to do at this stage was to replace them with something more practical: rechargeable PP3’s.

I wasn’t sure these would be powerful enough to allow the 350S to function properly, but I exchanged the PP9 wiring for PP3-sized battery clips and everything seemed to be working.  I then looked for some PP3 holders that would provide a more permanent fixture for the batteries.  This type seemed to fit the bill:

There was just enough room to fit these side by side into one of the covers formerly used for access to the PP9’s, each one attached with 4 small nuts and bolts.  Although opened from the outside, these battery holders occupy the internal space originally taken up by one of the PP9’s.

Battery holder panel complete

Clips for the two PP3’s are connected to the power Molex connector via a 3.5mm mono socket with an integral switch, so that anything plugged into the socket automatically disconnects the internal batteries.

Battery clips IMG_1220

Later, the socket might be used for an 18v power supply, but for the time being I attached the discarded PP9 wiring and clips to a 3.5mm plug, so that PP9’s can still be used, but don’t have to be installed inside the body of the 350S.

*

Unlike the regular Stylophone, the 350S has two styluses: one for normal playing, sounding continuously for as long as the stylus is in contact with the keyboard; and one for ‘Reiteration’ mode – with the appropriate switch selected – producing a fast or slow series of pulses, in imitation of a banjo or mandolin, on which it’s common to pluck a single note repeatedly.

However, I had found while modifying normal stylophones, that it was sometimes handy to have two styluses, one in each hand, for playing quicker or more intricate passages; so I decided to rewire the two existing styluses as standard, and add two extra ones for Reiteration mode.

With the Molex connectors in place, it was easy to wire all four styluses up, but not so easy to find a way to secure the extra two to the Stylophone in such a way that they would be easy to reach.  In the end, I used a pair of clips like this, sold on eBay as penholders and meant, I think, to clip onto a pocket:

Pen holder

I had some spare white styluses, so the ‘normal’ styluses are black, and the ‘reiteration’ styluses are white.  I attached a holder each side of the Stylophone in which the white styluses sit.  The long wires attached to these can be pushed inside the body of the Stylophone when not in use.

I wasn’t able to find an exact match for the wire used by Dübreq for attaching the styluses.  It’s only just over 2mm in diameter, and very flexible; there are no more than 10 or 11 strands of wire inside quite a thick outer layer, and a non-conductive cord running along the length of it, on the inside – presumably for strengthening.  If I ever find out where to get it, I’ll add it as an Edit to this post: in the meantime I had to make do with a standard multi-stranded white ‘hook-up’ wire of about the same width.

*

Dealing with the pitch of the 350S didn’t involve detaching external wires, in fact, but I added a 3-way Molex connector to the tuning control to make it easier to experiment with.

Unlike some of my previous Stylophone mods, I wasn’t looking for extreme pitch changes this time, but something more along the lines of a synth modulation wheel.  Strangely, these seem to be very rare, but I found one produced by the German company Doepfer, described here.  It comes as a kit of parts, like this:

Doepfer Mod Wheel Kit

The pot supplied with it is a 10k, which has a knurled shaft fitting tightly inside the hole in the ‘half-wheel’.

I  wired the wheel in parallel with the existing tuning control, and its effectiveness depended on three things:

1.  The setting of the tuning control: the higher it was set, the less variation produced by the wheel.  Not much I could do about this, as the tuning control is used to set the 350S to the correct pitch, compared to other instruments.  If it proves a problem, it could perhaps be solved in the future by a slight adjustment to the keyboard resistor chain.

2.  The value of the pot.  I found that a 2.5k pot was the most effective, but couldn’t find one with a shaft compatible with the Doepfer wheel.  So I added some 10k resistors in parallel with the 10k pot.  Originally I added 3, which would have made the pot 2.5k, but 2 seemed to be enough (3.3k), and took up less space, so I left it at that.

3. The part of the potentiometer track covered by movement of the wheel.  The wheel wasn’t able to move the wiper of the potentiometer round the whole track – which is normal for mod wheels, joysticks, etc.  It took a bit of experimentation to find the right place, which essentially meant turning the potentiometer to exactly the right position before attaching the wheel.  It needed to be at zero when the wheel was deflected fully down, and eventually I found the right place, wired leads and a Molex plug to it and fixed it in place with small nuts and bolts.

The whole construction took the place previously occupied by the left-hand PP9, with the wheel appearing through a slot in the top of the 350S .  The Doepfer kit cost about £10, so it was a bit of an extravagance, and something like it could probably be rigged up more cheaply.  However, it adds an interesting feature to the 350S which it never had before.

This picture shows the pitch wheel assembly in place and also, in the background, the speaker switch and banana sockets.

Speaker switch & wheel IMG_1219

This picture shows the top half of the 350S body, with the new components and the Molex connectors in place, with the circuit boards removed:

Inside no PCBs IMG_1218

*

After fitting everything, it was time to put the 350S back together.

The first item to go back into place was the main PCB.  This picture shows the board in position, with the 6 fixing screws marked:

Main PCB in place IMG_1233

Next, the Keyboard PCB was installed.  The 4 fixing screws are marked:

Main & Keyboard PCBs in place IMG_1234

Before the bottom half of the 350S body was attached, the PP3 battery clips were fed into the battery holders:

Inserting battery clips IMG_1235

The two halves of the body were fitted together and batteries inserted:

Battery inserted IMG_1237

Finished and ready to go!  The underside of the 350S now looks like this:

Back with battery holders IMG_1221

and the front and back like this:

Front & Back finished IMG_1240

This gives a good view of the power socket on the back left, as you look at it; the speaker switch and sockets on the back right; the pitch wheel on the top on the right; and the white ‘reiteration’ styluses in their holders.

*

Finally, with the 350S back together and in operation, I looked at the suggested external addition, a volume pedal.  According to the 350S manual, this would replace the photo control, and adjust not only the volume, but also the waa filter and the vibrato depth.

The manual recommends a ‘standard Foot Pedal’: but what was a standard foot pedal in the 1970s is not what we might consider a standard foot pedal – or ‘expression’ pedal – these days.  What’s required here is a 50k-100k log pot, which plugs into the 350S via a 6.35mm (1/4″) mono jack plug.

I had an old volume pedal (probably dating almost from that era!) which I was able to adapt.  The original cable was crackly and the pot was scratchy, so I shortened the cable to remove the section that was obviously damaged inside, and replaced the pot.

I didn’t have a 47k or 50k to experiment with, so I used a 100k, but that seemed to be fine.  The only oddity is that the ‘waa’ works backwards, in that the filter is at the ‘high end’ with the heel down – as compared to, for example, a guitar wah pedal, where heel-down is the low end, and toe-down is the high end.  I tried putting a polarity change switch in the pedal, but that didn’t work, as the pedal mechanism – just the same as the pitch wheel described earlier – is set to reach its minimum when the heel is fully down, and doesn’t cover the full travel of the pot, so when the two ends of the pot were swapped, the pedal wasn’t reaching zero, which it needed to do to produce the full ‘waa’ effect.  I’ll just have to get used to it.

After playing the instrument for a while, I noticed that one of the switches was a bit crackly, so this is something I might tackle later on, together with a couple more mods I have in mind.

12
Oct
12

Bigfoot – automatic/remote stylophone control, Part 2

As described in Bigfoot, Part 1, I was  constructing a device to play a modified stylophone remotely and automatically.  Using a 16 way analogue switch, the 24-pin 4067 chip, I designed a device where any one of 15 intervals on a 2-octave tonic sol-fa scale would be triggered by changing the chip’s 4-bit binary input.

First of all, I had used a physical control, a 16 position binary or hexadecimal rotary controller; what  I needed next to find was chips that could be made to output sequences of 4-bit binary numbers.

There are several of these, and I went for the 4516, which is a pre-settable binary counter.  It can, if left alone, repeatedly count upwards from 0 – 15, outputting numbers in binary form (‘0 0 0 0’ to ‘1 1 1 1’) on the pins marked ‘Q1’ to ‘Q4’ in the diagram below at the speed of a pulse connected to its clock input (Pin 15); or downwards from 15 – 0.  But by pre-setting a certain number, in binary form, on 4 extra binary inputs, marked ‘P1’ – ‘P4’ in the diagram, it can also be made to count upwards from this number to 15; or downwards from this number to 0.

This is how the 4516 is usually represented in circuits:

Q1 – Q4, as mentioned above, are the outputs, and P1 – P4 are the inputs for the number the count starts from, both in the form of a binary number.  The ‘Preset Enable’, pin 1, is usually held low (0v): when it’s taken high (+v) the number on the inputs P1 – P4 is loaded in and the next count starts from that number.  ‘Preset Enable’ is sometimes referred to as ‘Load’ for this reason.  The ‘Carry Out’ is normally high, but goes low when the count ends.

The ability to count downwards from a set number would be useful for an arpeggiator, which could be set to repeat a sequence with a length of 2 – 16 notes, using the rotary encoder, described in Part 1, connected to the 4 binary inputs to preset the sequence length.

The circuit for this device was extremely simple, requiring only the rotary encoder, a momentary switch to tell the 4516 to load the sequence length number, an on/off switch and two inverters from a 40106 (which has 6 in it altogether) .  One of the inverters was connected as an oscillator, which was connected to the 4516’s Clock input: this determines the speed at which notes sound; the other inverter was connected between the ‘Carry Out’ and ‘Preset Enable’ pins: the ‘Carry Out’ is normally high, so the inverter keeps the ‘Preset Enable’ low; when the count ends the ‘Carry Out’ goes low and the inverter sends a ‘high’ pulse to the Preset Enable, reloading the start number.

Encoder_4516

Pin 10 is connected to 0v in this circuit, which tells the 4516 to count down, not up: this was the easiest way to make sure it counted the right number of notes in the sequence.

In fact, counting up or down would result  only in a scale or part of a scale being played, so I made the output a bit more interesting by reversing the 4 outputs.  Instead of connecting the A output of the 4516 to the A input of the 4067, the B output to the B input, etc., I connected it so that A B C D were connected D C B A.  In essence this meant that consecutive notes in the sequence would not be consecutive notes in the scale, which I thought would be more interesting.

This produced method 2 of controlling the Stylophone: automatic arpeggiation.

*

The third method of controlling the Stylophone automatically used 3 more of the inverters in the 40106 which had been used for the 4516 clock and ‘Carry Out’ inverter.  The inverters were wired as oscillators.

This was the idea that came from the ‘Slacker Melody Generator’, described at http://electro-music.com/forum/viewtopic.php?t=27239&postorder=asc&start=50.  Each of the 4 oscillators is connected to one of the 4 inputs of the 4067; each runs at a different speed, changing the value on that input from low to high, or 0 to 1.  The different successive combinations of 0s and 1s produces a random melody, which can be changed by adjusting the speed of the oscillators, increasing or decreasing the rate at which each particular input changes from ‘1’ to ‘0’.

40106

The reason the four oscillators have two capacitors each is simply because the original circuit I used suggested values of 220n; I soldered these in place, but the oscillators seemed to run too fast for my liking, and it was easier to add new ones in parallel than take the old ones out and replace them.  The result of putting capacitors in parallel is the opposite of putting resistors in parallel – instead of the overall value decreasing, it increases; the capacitance is larger and the oscillators run slower.

Having put the 4067 and the five DPDT switches in place, I then had to connect the relevant input/outputs to 24 different resistors, in a chain (or ladder) like the original one inside the stylophone.  I suppose it would have been possible to calculate the exact resistances, but I had some time ago obtained a hundred 10k presets for about 7p each, for exactly this kind of situation, so decided to use those and tune it by ear.

This took some time, but at the end of it I had a substitute resistor chain for the SoftPot Stylophone and some methods of controlling it automatically.

*

It then occurred to me that with this arrangement, all this extravagance could only control one stylophone at a time, so I had a think about how to connect more instruments (and possibly instruments other than stylophones!).

The way to do it, it seemed to me, was to use the binary inputs to the 4067 as an output: any device could then be controlled, just by installing the 4067 and the five ‘major/minor’ switches in it – or perhaps some other suitable arrangement.

So I added two 5-pin DIN sockets as outputs, the five terminals being A, B, C, D and 0v.  Each of the four A, B, C, D outputs was buffered, using four of the six buffers in a 4050.  The 4050 is similar to its sister chip, the more well-known 4049; but whereas the 4049 inverts its outputs, the 4050 doesn’t.  This chip has even cleverer properties, which I will be using in a later project, but here I used it to ensure the binary outputs were of sufficient strength to make their way through a connecting cable and satisfactorily operate external circuitry.

I also added at this stage Clock In and Clock Out sockets, which would enable Bigfoot to set the tempo of a piece involving different instruments, or follow the tempo set elsewhere.  These two input/outputs passed through the remaining two buffers on the 4050.

The final thing was to add two more 5-pin DIN sockets, this time as inputs.  This would enable external circuitry to control the 4067s.  I had several more ideas of suitable external devices which could be used to do this, and I hope to be able to get around to making these quite soon.

The only other unusual component needed to get all this to work was a suitable master switch, to select the various external and internal inputs to the 4067s.  This had to have 4 poles – the A, B, C, D binary inputs – and 5 positions.  4 pole, 3 way rotary switches are easy to come by, but 4 pole, 4 or 5 way are not.  Fortunately, I was able to source a 4 pole, 5 way switch on eBay from a supplier in Hong Kong for just a couple of quid, so everything was in place.

With a circuit like this – just a handful of chips and a few external components – you either get a neatly laid out PCB or a rats’ nest of wiring.  I ended up with a rats’ nest of wiring . . . however, it worked, even when crammed into the case, with the addition of an extra section underneath the ‘big foot’ I had selected.

This picture shows the two binary input sockets on the left.  The 5 way switch is the knob on the front of the Bigfoot, just the right of centre in this picture.

Bigfoot Left DSCF0002

Due to a certain amount of experimentation along the way, some changes of mind about the functions, and some difficulties in getting all the switches and sockets to fit, there were some extraneous holes which I had drilled in the case.  The plastic frogs are there to hide the holes.  I also added a square of velcro on the back where I could attach a battery holder, as I had done with a number of previous projects.

DSCF0004*

This is what Bigfoot sounds like, controlling the SoftPot Stylophone and the StyloSound at the same time:

 [Edit: there is now a link to a short video of the Bigfoot in action at the bottom of this page].

12
Oct
12

Bigfoot – automatic/remote stylophone control, Part 1

I’d made enough instruments for the time being, and it was time to construct some automatic controllers – sequencers, arpeggiators and the like – as an alternative to playing them by hand.

When I made the SoftPot Stylophone, I had added a socket which allowed external circuitry to replace the chain of resistors which govern the pitch of the instrument.  This project was to make a device which would be able to use this feature to operate the SoftPot Stylophone remotely, and this rather blurry photograph shows the result – Bigfoot:

DSCF0005

I got the inspiration from several places: the arpeggiator and sequencer from Fun with Sea-Mosshttp://milkcrate.com.au/_other/sea-moss/; the melodygenerator by Slacker described on the electro-music.com forum: http://electro-music.com/forum/viewtopic.php?t=27239&postorder=asc&start=50; and the Intro to Lunetta Synths at https://docs.google.com/document/edit?id=1V9qerry_PsXTZqt_UDx7C-wcuMe_6_gyy6M_MyAgQoA&pli=1,  All these sites are full of great ideas and practical examples.

The main chip used in the circuits described above is a 4051, which is basically a single-pole 8-way switch.  It’s usually depicted in circuits like this:

The way it works is like this: it’s an analogue switch, not a digital switch, meaning you can connect anything you like to the pole (pin 3, marked Z in the diagram) and the 8 switch input/outputs (on the right-hand side, marked Y0 – Y7).  It doesn’t have to be logic high or logic low (i.e. +v or 0v) , it can be any voltage, an audio signal, anything – just like a physical switch.  Any one of the 8 input/outputs can be connected – one at a time – to the pole, not by turning a physical switch, but by the logic high or logic low status of the 3 ‘Select’ inputs (pins 9, 10 and 11, marked S1 – S3).

You can have every combination of logic high and logic low on the three Select inputs, ranging from 0v on all of them, 0v on one of the three and +v on two of them, +v on two of them and 0v on one, or +v on all of them.   There are eight possible variations, starting with 0v on all of them, which you could represent as ‘0 0 0’ or the binary equivalent of the number zero, to +v on all them, which could be represented as ‘1 1 1’ or the binary equivalent of the number 7.

If you feed 0v to all three of the Select inputs, or ‘0 0 0’, this is lowest possible binary number, so the lowest or first input/output is connected to the pole (Y0, pin 13); if you connect, say the one on pin 9 (S3) to +v and the other two to 0v, this would be the binary number ‘1 0 0’, the equivalent of the number 4.  Because the sequence starts with ‘0 0 0’ , or zero, feeding in ‘1 0 0’  connects the 5th rather than 4th input/output to the pole (Y4, pin 1).  By connecting all the Select inputs to +v, or ‘1 1 1’ (the number 7), the 8th input/output is connected to the pole (Y7, pin 4).

In the circuits I looked at, a common type of connection would be to have the pole connected to the part of an oscillator circuit that determines the pitch, and 8 input/outputs connected to different value resistors.  This would mean that a different resistance would be connected to the oscillator and a different pitch would be sounded when each of the 8 input/outputs was connected to the pole.

You could determine whether each of the Select inputs was a ‘1’ or a ‘0’  with  three 2 way switches, +v one way, 0v the other way, and change the notes by moving different switches up and down.  But this would be rather tedious.  By adding a circuit that automatically changed the ‘1’s and ‘0’s, you have a melody generator, arpeggiator or sequencer.

This was the kind of circuit I was after.

However, 8 notes was bit restricted.  Not restricted because there are 12 notes in one octave, though: I reasoned that you could make life easier for yourself by only allowing notes in a single scale – the ‘do’, ‘re’, ‘mi’ approach so succinctly captured in the Rodgers and Hammerstein song from The Sound of Music (‘Do a deer, a female deer/Re, a drop of golden sun’, etc.).  There are only 8 notes in a  ‘do’, ‘re’, ‘mi’ scale, including the next ‘do’ up from the one you started from.  If you just use those, you’ll never get an ‘out of tune’ note in your arpeggio or sequence.

The proper name for the ‘do’, ‘re’, ‘mi’ system, by the way, is ‘tonic sol-fa’, and was invented here in East Anglia by Sarah Ann Glover of Norwich, who lived from 1785 to 1867.  This 1868 woodcut shows Sarah Ann teaching ‘do’, ‘re’, ‘mi’ to the musical children of Norfolk:

(Why this public domain picture  is held by Music Department of the Bibliothèque National de France is not adequately explained by the Wikipedia, where I found it.  I suppose the fame of ‘do’, ‘re’, ‘mi’ is international).

No, it was restricted instead because the SoftPot Stylophone has 12 ‘do’, ‘re’, ‘mi’ steps from the bottom of the keyboard to the top – and in any case could be made to produce notes outside the range of the built-in keyboard.

So I decided I needed 16 steps (2 octaves, including ‘do’ two octaves up from the start), and found a chip, the 4067, to do the job.  The 4067 is a single-pole switch like the 4051, but with 16 switches instead of 8.  The only way it differs in operation from the 4051 is that it requires 4 Select inputs in order to go all the way from ‘0 0 0 0’ (zero, meaning the first input/output is connected) to ‘1 1 1 1’ (15, meaning the 16th input/output is connected).

The 4067 usually appears in circuits like this:

It’s very similar to the 4051: there’s a Pole (pin 1, marked Z); 16, instead of 8, input/outputs (right-hand side, marked Y0 – Y15); and 4, instead of 3, Select inputs (pins 10. 11, 13 and 14, marked S0 – S3).

I also decided to make things slightly more complicated by considering alternative scales.  If you follow the ‘do’, ‘re’, ‘mi’ scale of the Rogers and Hammerstein song, this is a major scale.  If, on the other hand, you wanted to play, for example, a minor scale, you would find that ‘mi’, sometimes ‘la’ and sometimes ‘ti’ have to be changed to be a semitone lower.  And occasionally you might feel like making ‘re’ and ‘so’ lower as well.  (‘Do’ and ‘fa’ can be left alone!).

I’ll explain in a minute exactly what scales I had in mind when doing this, and where I got the idea from, but adding the ability to sharpen or flatten certain notes of  the scale meant that I needed 25 notes instead of 15, so the 4067 was wired up like this:

4067 1 Edit

The notes depicted are the notes that would be used in the key of A.  Since the SoftPot Stylophone has a tuning control (in fact two tuning controls!) on it, it can be made to play in any key, not just A; the circuit here doesn’t need to be changed, only the tuning on the SoftPot Stylophone itself.

Each of the 16 outputs of the 4067 is connected to a resistor in a chain.  The top of the chain is connected to the tip of a 3 way (‘stereo’) 3.5mm socket; the bottom of the chain is connected to the ring, and the sleeve is connected to pin 1 of the 4067 – the pole of the 16-way switch.  When plugged in, it takes the place of the Stylophone’s own resistor chain.

Note that switches allow you to choose between 1) major and minor 2nd (‘re’); 2) major and minor 3rd (‘mi’); 3) major and minor 5th (‘so’); 4) major and minor 6th (‘la’); and 5) major and minor 7th (‘ti’), as you see fit.  C1/C#1 and C2/C#2, D#1/E1 and D#2/E2 etc. use the same switch, so there are 5 of these switches, not 10.

The reason I chose to do it this way is because of an extremely interesting article – series of articles, actually – which I read on The Tonal Centre website, written by Andrew Milne.  I’m not in the slightest bit concerned that the theory described there is ‘unconventional and some of the concepts . . . quite novel’, as it seems to me to make perfect sense, and presents a coherent view of scales and chords which I’ve found quite easy to understand, and useful to use.  Furthermore, Milne’s motives for writing the articles are ones with which I would hope none of my readers could disagree: ‘not for theory to be an intellectual straight-jacket which smothers spontaneity, but as a springboard for creativity and, even more importantly, as a foundation for exploration’.

Essentially, the articles do precisely as the author says in his introduction: ‘convince you that there is a lot more for the tonal composer to experiment with . . . than just the major and the minor scale.’

I can’t explain everything in the articles because a) there is too much, and b) I don’t understand it all; but essentially, the points I want to draw attention to are these:

1. What constitutes a useful and versatile scale?

A scale should constitute ‘a unified collection of notes – a selection which is in some sense complete and to which any addition is heard to be extraneous’.

2.  What makes a scale useful as a melodic resource?

A scale should be ‘reasonably smooth and even, without sudden gaps which sound as if a note has been omitted, or sudden concentrations of notes which sound as if an extraneous note has been added’.

3.  What makes a scale useful as a harmonic resource?

Because three-note major and minor chords are the basis of our kind of western music (like C-E-G and C-Eb-G), a scale shouldn’t have any notes which aren’t part of a three-note major or minor chord.

Of all possible scales there are only five prime scales which satisfy Milne’s criteria, as above. (These are the main criteria, but see the full article for a couple of others).

All of these scales contain, as it happens, seven notes, and these are clearly the most useful and versatile scales to use.  This was good news for me, as the Bigfoot would inevitably use 7-note scales.

There are 8 different scales altogether in Milne’s system, not just 5, because of  differences between major and minor, and so on, and these 8 variations of the 5 ‘prime scales’ (in the key of C) are:

1.  The diatonic scale, major and ‘aeolian’:

C-D-E-F-G-A-B

C-D-Eb-F-G-Ab-Bb

2.  The harmonic minor scale:

C-D-Eb-F-G-Ab-B

3. The harmonic major scale:

C-D-E-F-G-Ab-B

4.  The melodic scale, major and minor:

C-D-E-F-G-Ab-Bb

C-D-Eb-F-G-A-B

5.  The double harmonic scale, major and minor:

C-Db-E-F-G-Ab-B

C-D-Eb-F#-G-Ab-B

So, there are 8 different scales you can use, which all allow you to make interesting melodies and chords.  Each one has its own ‘character’, and some are much more commonly used than others.

This series of articles seemed to me when I came across it to be an extremely good guide to useful scales, and could be a help to anyone: you could use the description above to work out what scale or scales you commonly use, and then try writing a composition or improvising a solo using a completely different one.  There’s bound to be at least one you’ve never thought of using before!

Bigfoot allows the 2nd, 3rd, 5th, 6th and 7th (D, E, G, A, B in the above examples) to be individually adjusted, so arpeggios and sequences in all – well, almost all! – of these scales are possible.  The double harmonic minor isn’t possible because Bigfoot can’t produce F# and G at the same time; but 7 out of 8 isn’t bad!

So, 16 individual intervals are available  from the Bigfoot, spread over two octaves; the tonic is repeated 3 times, at 3 octaves; the 4th is repeated twice, at two different octaves; the other 10 notes are switchable between a ‘normal’ or ‘flattened’ version, which is semitone lower.

Hang on, that’s only 15 intervals . . . Well, since all 16 Select input combinations from ‘0 0 0 0’ to ‘1 1 1 1’ could be used to produce notes, there might in some circumstances be no way of stopping the Stylophone from sounding; so what I did was to start with ‘0 0 0 1’ (the second output) and make that the lowest note, reserving ‘0 0 0 0’ (the first output) for a rest where no note would sound.  I added a switch so that the first and second inputs could be connected together for those situations when this would be better.

I also added a START/STOP switch, which is what pin 15 of the 4067 does: if connected to +v it stops, and all the switches are disconnected, regardless of the state of the Select inputs; if pin 15 is connected to 0v the switches start to work.  (The 4051 also has this feature).

In practice, I actually installed a second 4067, with the two 4067’s being connected only at the 4 Select inputs (pins 10, 11, 13 and 14).  I wanted to have an LED indication of which switch was connected, and had to separate this function from the resistor chain that produced the notes.

So the pole pin of the second 4067 was connected to +9v via two 1k resistors [not one, as shown in the diagram], and each of the 16 outputs was connected to a green LED (matching the green case the circuit was built into).

4067 2

In order to test the LEDs – and later to test the notes which were being produced – I needed some way of connecting exactly the right input/output to the pole of the switch, so I would know I was adjusting the right preset.  This meant feeding exactly the right combination of  +v (‘1’s) and 0v (‘0’s) to the Select inputs, to get exactly the right output.

I considered four 2-way switches, +v one way, 0v the other way, and changing the notes by moving different switches up and down, as I described before – but it turns out there is a device which does this job very simply, just like turning a rotary switch: a 4 bit binary (sometimes called hex) rotary encoder.  I wouldn’t say these are extremely easy to come by, but this is the one I got:  http://uk.mouser.com/ProductDetail/Alpha-Taiwan/RE2001F-40E2-20F-4B/?qs=yA6kp8fx8Y4fjZ7sDt2l6A%3d%3d.

rotary encoder2

(The above picture shows a typical rotary encoder made by Alpha Electronics.  RS online sell a couple, but looking at the product details, I don’t think the connections of the ‘Code 033’ version they sell is right.  There are lots of 2 bit encoders, and lots of encoders which are not binary or hex.  They won’t work – it has to be 4 bit binary with 16 positions, starting with ‘0 0 0 0’ at position 1 and stepping through the binary numbers 1 – 15, ending up at ‘1 1 1 1’ at position 16. These are referred to as ‘hex’ because the hexadecimal system has 16 numbers in it [usually written as ‘0 1 2 3 4 5 6 7 8 9 A B C D E F’ – a more user-friendly way of depicting ‘0 0 0 0’ to ‘1 1 1 1’]).

I needed to use the encoder for another part of the circuit, which I’ll come to later, but for the time being its 4 outputs were connected directly to the 4 Select inputs, ‘A B C D’, of the 4067s.  Its other connection, ‘Common’, was connected to + volts.  To test it, I used  4 LEDs, and could see that turning it from position 1 to position 16, it automatically output the binary numbers in order from ‘0 0 0 0’ to ‘1 1 1 1’.

It’s worth mentioning an important point, to avoid later confusion, which is that ‘D’ is actually the bit on the left in a binary number such as ‘1 1 0 0’, and ‘A’ is the bit on the right.  You might sometimes see ‘D’ referred to as the ‘Most Significant Bit’ (or ‘MSB’) and ‘A’ as the ‘Least Significant Bit’ (‘LSB’).  That means the number sequence goes like this:

D  C  B  A

0  0  0  0

0  0  0  1

0  0  1  0

0  0  1  1

0  1  0  0

etc.

The other thing about rotary encoders is that they don’t usually have a stop, they just go round and round.  This is fairly useless if you need to know where ‘1’ is, or where ’16’ is, and this is the main reason why I decided to incorporate the LEDs as a visual indication.  The other reason is that sequencers and so forth really ought to have flashing lights on them.

The rotary encoder is the knob on the right-hand side of the Bigfoot, just to the right of centre in this picture:

DSCF0003

I glued the LEDs in place on the top and connected up the rotary switch.  Sure enough, with each turn the LEDs lit up one by one, one at a time, and now it was possible to tell which was position 1, which was position 2, etc.

Not only that, with the lack of a stop at 1 and 16 – which you would expect with a normal rotary switch – if nothing else I had Method 1 of controlling the Stylophone remotely: a manual method of arpeggiation by spinning the encoder backwards and forwards! . . .

. . . Entertaining, but not the automatic method I was looking for, however, so I moved on to Part 2 of the construction.

23
Aug
12

BigBoy BeatBox

You’ve got a Stylophone, you’ve got a Stylophone Beatbox – but don’t you sometimes wish the two could be combined into one instrument? . . .

Well, now that wish has become reality, with the ‘BigBoy BeatBox’: two great Stylophone products in one!

New Front IMG_1128

As the picture suggests, the BigBoy BeatBox is, in fact, two great Stylophone products literally glued and bolted together, with some of their internal circuitry combined.  The way it was created was like this:

1.  The Stylophone

The Stylophone half of the instrument is, in fact, a recreation of the original ‘Big Boy’ – a regular Stylophone S1 inside a Beatbox case.  As mentioned in an edit to the original post here, I managed to inflict terminal damage on the ‘Big Boy’ by reckless experimentation.  I normally do this before finishing an instrument, this time I contrived to do it afterwards . . . so the first thing I had to do was remove and replace the electronics with a new donor Stylophone I had lying around.

The actual process closely followed the construction of the original, but was made easier because of the sockets and wiring still remaining in the Beatbox case.  First of all, the end had to be sawn off the Stylophone circuit board, which is too long to fit in a Beatbox case; then the lowest 12 notes of the keyboard were connected to the 12 outside pads of the round Beatbox keyboard.  Fortunately, the wires attached to the Beatbox keyboard remained in the case, and just needed connecting to the appropriate Stylophone keys.  The Beatbox’s amp circuit board was taken out, but the Stylophone’s was kept and connected to the Beatbox’s speaker.  A power socket was connected to the Beatbox’s on/off switch, and the Stylophone’s on/off and vibrato switch circuit board disconnected.

I decided to replace the ‘Big Boy’s troublesome original 3-way octave switch with a simple  pitch potentiometer.  I used a 100k for  coarse tuning, in series with a 10k for fine tuning and a 100k variable preset to fix the highest pitch available.  Previous experimentation with Stylophones had taught me they have no objection to going down to very low pitches, but they cease to function – usually temporarily – if the pitch is taken up too high: on resetting, when this happens – by switching the power off and on – sometimes they will begin to work again, sometimes they won’t.

That’s what I did to the original ‘Big Boy’, and there’s no cure apart from throwing the circuit board away and starting again.  The likelihood of this happening is increased because I don’t just replace the tuning potentiometer pin-for-pin – the range of voltages available between the two pins the Stylophone uses isn’t wide enough for very large pitch variations, so I use only one of the pins that the original tuning potentiometer was connected to – the left-hand one – but connect the other one to +v.

The two new pitch controls were fixed to the front (the rounded end) of the Beatbox case, as was a replacement 10k log volume control.  The problem with the Stylophone’s original volume control was not that it wouldn’t work perfectly well, but that it would have had to be on the side of the case which I was intending to fix permanently to  the other Beatbox.

The original ‘Big Boy’ had no vibrato, but I decided the recreation should have a variable control, as fitted to the ‘Alien’, my first Stylophone modification project.  All this involved was connecting a 1M potentiometer instead of an on/of switch between the two vibrato connections next to the power connection on the main Stylophone circuit board.

Apart from an output socket and a switch to cut out the internal speaker, that half of the BigBoy BeatBox was done.

Stylophone half IMG_1132

2.  The Beatbox

The other half of the instrument was a plain Beatbox, with very little in the way of modifications.

(I don’t seem to have written specifically about the Beatbox in the blog, by the way.  Read the user guide here!)

The first thing I did to it was to replace the tuning potentiometer with a larger one of 100k (a direct pin-for-pin replacement this time), allowing for considerable slowing down and lowering of the pitch of the drums and other sounds.

I also followed an excellent example in this YouTube video: http://www.youtube.com/watch?v=xXdelnxXF7A to add buttons in parallel with the ‘Record’ and ‘Play’ pads normally operated by the stylus.  The trouble with the stylus-operated method is the delay in time between activating ‘Record’ with the stylus, and then using the same stylus to stop recording and begin playing the pattern you want to  be looped, as the loop begins the moment ‘Rec’ is selected.  With a small normally-open tactile switch as an alternative method of beginning and ending the recording period, you can be much more accurate as regards timing.

It’s worth mentioning at this point that, like the original Stylophone itself, the Beatbox comes in more than one variety, as far as circuitry is concerned.  I noticed two significant variations between the Beatbox I used in my ‘test to destruction’ phase, and the one that eventually found its way into the finished instrument: in one case, there was a tap from the battery compartment at 3v, which fed into the circuit (via the 3-way tone control) as well as the full 4.5v; and the layout of the circuit board was different.  As it happens, spots on the board marked ‘Rec’ and ‘Play’ were easily accessed in one case – the test unit – but not in the other – the one I was eventually to use.

In my experience, the Beatbox is a very delicate circuit, and it doesn’t take much to do something to it that will cause Record or Play to malfunction, or the output quality of the sound samples to degrade; so, proceed with caution, I’d say.

A third new button I added to this unit was ‘Reset’.  The Beatbox’s method of erasing an old loop and re-recording a new one is to switch the power off and on again.  The original power switch had to be removed as it was on the side of the case which was going to be fixed to the other Beatbox case – and there would, anyway, be a single power switch for both units: so the third button is a direct replacement for the Beatbox power switch, but now a normally-on, push-to-break, supplying power to the Beatbox side only.  To reset and re-record just takes a quick press and release of this button.

Finally, a new 10k log output volume pot was fixed to the front of the unit.

Beatbox controls IMG_1131

Beatbox halfIMG_1131

3  Joining the two halves

Superglue and two bolts was all that was required to physically join the two Beatbox cases, plus a couple of holes through which wires could pass from one side to the other.

The easiest way to connect the power seemed to be to detach the +v and 0v wires from the battery compartment on the Beatbox side and attach these to the original ‘Big Boy’ Stylophone side, which had a power input socket.

In the end I decided that whereas the battery compartment of the Big Boy Stylophone had to be removed – there was no room for batteries as well as the Stylophone circuitry – the one in the Beatbox could be used.  So I wired in a power cable which ran out of the back and was just long enough to reach the power socket in the other half.  In this way the instrument could be powered from an external source, or from internal batteries, and there was no need for a switch to change from one to the other.

The two 10k volume controls were taken to two individual tone controls.  I just wanted something fairly rudimentary, so I used a circuit from http://www.muzique.com/lab/swtc.htm called the ‘Stupidly Wonderful Tone Control’.  The component values I used were quite different – and I have no idea why – but the format of the circuit was more or less the same, and gave a little bit of variation to the tone.

After the tone controls, the two outputs were joined with 10k resistors to the original Beatbox volume control, and then the ‘Big Boy’ Stylophone amp circuit board.  This meant that the sound from both units was going to the ‘Big Boy’ half , and the volume and tone of each unit could be independently varied.  The input to the Beatbox amplifier was disconnected, and the speaker removed.

Now I had an instrument in a single conjoined case, with a single power supply and output through a single speaker or output socket.  There were two styluses and two keyboards, and – as I had hoped, but not expected with any confidence – both styluses work on both keyboards!  This means that both units can be played with a stylus in each hand, and quicker and more rhythmic patterns can be played.  I extended the wires to the styluses slightly to make sure they could reach right across both keyboards.

When using two styluses on the ‘Stylophone’ side of the unit, the ‘Beatbox’ side needs to be set to ‘Play’, otherwise that stylus will only work for a very short period and then not sound any more.  I haven’t timed the ‘very short period’, which might give a clue, but this is probably to do with the circuitry which regulates the maximum of 8 seconds (at ‘normal’ tempo) for which the Beatbox can record.

The complete circuit looks something like this:

BigBoy Beatbox circuit 2 Corrected sm

The following pictures show the inside of the instrument shortly before it was finished:

Inside Stylophone half with numbers 6 in IMG_1127

This is the ‘Big Boy’ stylophone half.

1 = speaker cutout switch

2 = socket for external 4.5v power source

3 = 3.5mm sound output socket

4 = Stylophone S1 circuit board with permanently soldered connections to first 12 keys

5 = socket for extra stylus, remaining from original ‘Big Boy’ design – not really needed now

6 = fine tune pitch control

7 = variable preset to prevent the Stylophone’s highest note from being too high and causing the circuit to malfunction

8 = coarse pitch control

9 = Stylophone volume control

Beatbox half with numbers 7 in IMG_1126

This the Beatbox half.

1 = the original Beatbox output and ‘mp3’ input sockets, no longer used

2 = Stylophone tone control

3 = Beatbox tone control

4 = Original Beatbox volume control, now master volume

5 = ‘Reset’, push to break switch

6 = wires going to ‘Play’ and ‘Record’ push to make switches mounted on top surface of Beatbox

7 = original Beatbox tempo switch, still in-circuit, but no longer used

8 = Beatbox pitch control

9 = Beatbox volume control

The features visible on the outside were these:

Front DSCF0003 3

Before finishing I gave the speaker grilles a coat of blackboard paint.  The reason I used blackboard paint was a) it was the only black paint I found in my garage not in a spray can, and 2) it gives a pleasing matt finish, but is more durable than water-based matt emulsion.

The rear of the instrument was sprayed black and the holes masked with painted material.

New Back IMG_1130Front & Rear View IMG_1129_30

22
Aug
12

Stylophones 3 – The Stylophone 350S, Part 1

A series on the Stylophone can only reach a climax with the mighty 350S!

The question of why the original Stylophone sold in its millions and became a world-wide success story, and the 350S didn’t, has long been debated.

According to http://stylophonica.com (‘The official home of the Stylophone’), it was ‘too costly, and lost the key uniqueness of the Stylophone itself, which was its small size and mass-market appeal’ – but it certainly wasn’t through of a lack of features.

You may be familiar with the Stylophone, but not the 350S: if so, then to start with, a run-down of its capabilities is required:

First of all, it’s certainly true to say that it’s much larger than the regular Stylophone – which is, after all, about the size of an inch-and-a-half thick postcard.  Here’s my 350S together with the regular-sized ‘New Sound’ Stylophone with which it shares many of its design cues:

350s + New Sound IMG_1050

The 350S is a souped-up Stylophone in every way: instead of the Stylophone’s 20 notes – an octave and a half – the 350S has 44.  That’s three and a half octaves, and you can see in the picture the difference in length between the two keyboards.

Not only that, the 350S has eight voices, as opposed to one (or even the S1’s three), and some of these are themselves in different octaves.

The voices are designated ‘woodwind’, ‘brass’ and ‘strings’.  In these days of sample-based synths, none of these sound terribly much like what they say they are, but they have the general qualities of these instruments – and, despite what you may read, one or two of them are quite like the distinctive tone of the regular Stylophone that we all know and love!

These voices are:

four ‘Woodwind’ voices pitched at four different octaves, and described (like organ stops) as 16′, 8′, 4′ and 2′;

two ‘Brass’ voices at 16′ and 8′; and

two ‘Strings’ voices at 4′ and 2′.

Because these voices are pitched at different octaves, from 2′ to 16′, in all no less than six and half octaves are available from the bottom of the keyboard to the top.  This is almost as large as a ‘professional’ 88-note synthesizer keyboard.  Up to two of the voices can be combined at any time, one each of the four octaves.

As well as this wide range of voices, the 350S has a variety of built-in effects.  Like the regular Stylophone, one of these is Vibrato – and two speeds are available, rather than one.

There is also a two-speed ‘Decay’ facility: as well as the usual Stylophone ability to hold a note as long as the stylus is in contact with the keyboard, when the Long or Short (actually, ‘short’ or ‘very short’) Decay button is pressed, the note will fade out while the stylus is still in contact.  According to the nicely-produced, LP-sized User’s Guide that comes with it, this enables the player to obtain ‘a percussive effect rather like  piano.’

350s rocker switches IMG_1053 sm

However, as can be seen from the above picture, this is only the beginning of the 350S’s abilities.

The fast or slow ‘Reiteration’ button (second from the left) can be used to imitate the sound of a banjo or mandolin, and the 350S even has a second stylus which is used to produce these effects.

Normally, whichever stylus is being used, the ‘regular’ or ‘reiteration’, it’s held in the right hand; but it’s possible to play two notes at once in reiteration mode by using the reiteration stylus with the right hand, and playing lower notes with the regular stylus in the left hand.  It doesn’t work the other way round, and it doesn’t work in ‘normal’ mode, i.e. without either the fast or slow reiteration switch pressed.

The white tuning control can also be seen in the above picture – handily placed on the front of the instrument, unlike its counterpart in the regular Stylophone, which is always hidden underneath.

The most unusual effect, though, has got to be this:

350s Photo control IMG_1052

Above the volume control is the 350S’s secret weapon – the ‘Photo Control’.  This device, operated with the player’s left hand while the stylus is wielded in the right, can be set to control the volume, amount of vibrato or low-pass filter cut-off point – acting as a ‘waa waa’.

On the side of the 350S, next to the Photo Control, are three 1/4″ mono jack sockets.:

350s sockets IMG_1051

While one of these is ‘sound in’ and another ‘sound out’, the middle one is a socket for a foot pedal that replaces the Photo Control – either because the player would prefer to control volume, vibrato or waa with their foot, or because the ambient light level is too low for the Photo Control to be effective.  A 50k – 100k potentiometer does the job, according to the User Guide.

My experience of light-dependent controls like this – and I’ve made a number of them – is that they are really only fully effective when quite a bright light is shining on them, which is not always the situation when you sit down to play.

Unsurprisingly, this magnificent machine requires a fair amount of juice, so it’s powered by not one, but two weighty PP9 batteries, connected in series to provide 18v of power to the 350S.  [Edit: but see notes below about powering the 350S].  The batteries are housed underneath the rear of the instrument:

350s back IMG_1056

The battery covers look as if they’re held in place by screws, but these aren’t really screws: they click into place when pushed, and just require a slight turn with a screwdriver or a thin object to loosen them.  (The User Guide suggests a coin, but in my experience modern coins are too thick to perform this function.  Maybe a 5p would do it).

This is the User Guide that came with the 350S:

p1

350sBooklet

Reliable information on when the 350S first came on the market, how many were sold, etc. seems hard to come by.  http://stylophonica.com says: ‘No more than a few thousand 350S’s were ever sold’; http://stylophone350s.com/ says ‘Dubreq, the manufacturer of the original Stylophone created and produced the Stylophone 350S beginning in 1971 . . . fewer than 3000 were ever produced’ and quotes a Ben Jarvis (son of Stylophone inventor Brian Jarvis and re-founder of Dübreq in 2003) estimate that only 200-300 working units are probably still available worldwide.

I’d be surprised if the numbers were quite this low, but they’re certainly not common, and those that appear on eBay in the UK frequently command in excess of £100, rarely less than £70. Stylophone350S.com in the States have access to a recently discovered cache of mint condition boxed examples, which are now on sale.  Their website tells the story of this amazing find.  [Edit: this site is now defunct, unfortunately.  I don’t know what happened to the mint condition 350S’s that were for sale there].

The back of the 350S is removed by undoing 4 large screws in the corners and two very small screws under the front, and reveals two printed circuit boards: a thin, narrow one at the front containing the keyboard and the resistor chain – not discrete resistors, but what I’ve previously called ‘resistor modules’, since I can’t remember what the proper name for them is – and a large, rectangular one with everything else on it, including potentiometers, sockets and switches:

Just opened IMG_1068

The circuit boards themselves come away quite easily: there are 4 screws, clearly visible in the above photograph, which hold the keyboard in place, and 6 similar ones for the larger board.  The volume control knob doesn’t need to be taken off – it fits through the hole surrounding it – but the plastic nuts on the three sockets need to be removed.

This is what the other sides of the boards look like:

Component side IMG_1070

Here we see the larger items across the middle of the board, from left to right: the three sockets, the volume control, the eight voice and effect switches, the pitch control and the on/off switch.  If I was an electronics expert, I could tell you what the rest of the components do; but I can’t.  I can only surmise that the round inductor next to the left-hand switch is to do with the waa circuit; the LDR (light-dependent resistor) to the left of that is the ‘Photo Control’.

LDR & Ind New IMG_1144

The black ‘hood’ that partly surrounds the LDR was slightly damaged when I came to look at it, and it’s quite possible that I did this myself when I opened the case.  It was easily repairable with a spot of superglue, but watch out for this if you’re looking inside yours.

The ferrite core inductor is a Mullard FX2236.  In this close-up you can see that mine looks a bit broken.  I don’t know enough about these things to know if this means it isn’t working properly, but, while by no means common, they can be found – perhaps more easily in the UK than elsewhere – so I shall certainly consider replacing it.

According to the experts at www.stylophone.com, under the heading ‘VITAL INFORMATION WHEN BUYING A 350S… PLEASE READ CAREFULLY!’, one of the components you can see here – which they describe as the ‘Amp-ic’ – is highly prone to failure.

The related website, the Stylophone Information Centre at www.stylophone.fsnet.co.uk says: ‘The circuit board carries an IC which controls sound output, and this component (long since obsolete) is the single- most likely cause of the 350S to break down. If this happens . . . the unit will only be heard if played through a separate amplifier, if at all.’

The symptoms to look out for are: ‘when the stylus is applied to the keyboard, only a very faint sound is heard (if even audible at all), which fades away rapidly . . . Even with the volume control turned up to max, the sound will still be very low – then quickly fall away. The user will then be left with a ‘dead’ 350S.’

The chip in question is this one – the black one with six legs in the middle of the picture:

MFC6070 New IMG_1145

It’s a Motorola MFC 6070, 1-watt power amplifier  – ‘designed primarily for low-cost audio amplifiers in phonograph, TV and radio applications’, according to the datasheet.

If you don’t know what a phonograph is, ask your grandad, he’ll remember them!  The use of this antiquated vocabulary confirms what is said above.  If you find the datasheet for this chip, it says ‘Device discontinued – consult factory’; if you try to buy one on the Net, you’ll mostly find specialist sites, dedicated to sourcing obsolete parts.

As a matter of fact, you can, at the time of writing, get one on eBay for about £20, but you aren’t going to want to do that: the problem doesn’t arise, apparently, just because 350S’s are now all old – it even used to happen to quite new ones.

Stylophone.com told me that ‘the original chips as fitted . . . were working very close to their breakdown point voltage-wise. Although theoretically all the chips supplied to them should have worked, Dübreq actually had to batch-test the chips to find those with an acceptable working voltage range, especially the maximum voltage’ (which is meant to be 20v). ‘We’ve seen some of these chips.’ they said, ‘ running extremely hot (basically too hot to touch) by simply switching the instrument on, before even playing a note.’

That’s not to say the MFC6070 was a particularly unusual part at the time – they were used all over the place, and even the venerable VCS3 synthesiser used one as a driver for its spring reverb circuit.  However, as the site offering VCS3 spares, http://www.synthi.com, says: ‘The Achilles heel of the VCS3/Synthi AKS are the now obsolete and ultra rare semiconductors that it uses’ . . .

This made me think twice about powering the 350S with a mains-powered adapter: the increased risk of overdoing the voltage and blowing the chip might not be worth it.  Dübreq themselves did apparently produce some 350S’s with an ‘adaptor socket factory-fitted’, but ‘this led to many of them blowing the chip.’

I’m not quite as worried as I was, however, as stylophone.com are now marketing a new module, the ‘Stylophone ACM’, which can be retro-fitted to an ailing 350S – or even to a working one, as a precautionary measure – to get round this problem altogether.

The circuitry inside this unit is not operating close to its limits, and makes it much safer to run the 350S from an 18v adapter.  (And if you buy a reconditioned 350S from stylophone.com, it will already have one of these in it).

[Edit: see comments from Christian Oliver Windler below relating to powering the 350S.  He concludes from his tests that the 350S could – and should – be powered at less than 18v, and preferably less than 15v.  Some of the above problems and their expensive solutions can thus be avoided.

As with the original Stylophone, by the way, there appear to have been various upgrades during the course of production, and it’s interesting to note that some of the components inside Christian’s 350S differ from those in mine].

As a matter of fact, this is not the only ‘obsolete’ component in the 350S.  Although the resistors, capacitors and transistors that fill the circuit board are not commonly used in new designs nowadays, they’re still readily obtainable; the round silver integrated circuit over on the right-hand side, just above the tuning control, isn’t.

AY15051 New IMG_1142

It’s a General Instruments AY-1-5051, and what it does is frequency division (presumably for the 350S’s different octaves) – the kind of thing modern CMOS 4000-series chips do with the greatest of ease.  There’s a description on this website: http://www.divdev.fsnet.co.uk/repair2a.htm of how one might make such a replacement (using the example of a 1960s Elka electronic organ).  All I can say it, it looks feasible in theory, but not something I’d want  to be faced with in practice – let’s hope this isn’t a part which is going to fail!

Returning to my 350s, it looked badly in need of a clean up.  There was a lot of dust inside it, and over the years the keyboard had got very dirty:

Corroded keyboard IMG_1072Dust and corrosion IMG_1076

The switches sounded OK – no crackling or intermittent operation, so I left those, and just cleaned the circuit board and keyboard.  The keyboard in particular needed attention from, in order, a soft brush, switch cleaner, WD40 and Brasso.   This seemed to do the trick, and it began to look shiny again.

I cleaned everything, including the switch rockers, the case and the tips of the styluses, and put it back together again.  It now looked much better, and sounded clearly and reliably on every note.

Outside after cleaning IMG_1091

In my next post in this series, I’ll take a longer look under the bonnet of the 350S and see what there is to see.

21
Jul
12

Stylophones 2 – Variations

As I said in my first post on the Stylophone, there have been a number of variations in Stylophone design over the years, so I thought I would illustrate some of these from the examples in my collection.

The earliest Stylophone – in the days before Rolf Harris adorned the box – looked like this:

Original Stylophone + box IMG_1035

This early variation is distinguished by the non-playable black sections of the keyboard.  There were three types, distinguishable only by the body colour – the black one illustrated was the ‘standard’, but there was also a white one, the ‘treble’, and also a ‘bass’.  I don’t know what colour it was: I’ve only ever seen it in pictures, and it looks like a reddish-brown to me, but I’m colour-blind, so an unreliable witness . . . I hope in time to get hold of one, and somebody will tell me if it is indeed brown!

Here is the booklet that you see pictured above:

p1

Read the Original Booklet.

The black sections of the original keyboard had been a feature of Brian Jarvis’s prototype – which you can read about here: http://www.stylophone.com/Prototype.html – but the next generation of Stylophones dispensed with them.

There were still three types – the black ‘standard’, the white ‘treble’ and the (presumed) brown ‘bass’, and they looked like this:

2nd generation IMG_1057

Note the identical case design to the original, but the keyboard is now completely silver.  (Ignore the switches on the sides of these instruments – they’re a speaker cut-out modification I made to them many years ago).

The circuits in all these early Stylophones were quite similar, although not identical.  The instrument was subject to constant development, and there are versions with all discrete components, including the resistors which determine the pitch of the notes, and versions with different types of resistor modules – rows of resistors in a single unit.

It’s easy to peer into the inside of the original and ‘2nd generation’ Stylophones: the back is designed to be easily removable, in order to change the battery, and the component side of the circuit board is visible.  This is the inside of an original version (the one with the black sections on the keyboard):

Original inside IMG_1060

As you can see, in the middle, just above the piece of foam rubber which keeps the battery in place, there is a row of resistors connected to the keyboard, which determine the pitch.  This arrangement continued with the 2nd generation Stylophones.  This is a view inside the black ‘standard’ version pictured above:

2nd gen black inside IMG_1058

(Ignore the large resistor at the back right-hand side – this is attached to the speaker cut-out mod).

At some time during the production of the 2nd generation Stylophone, resistor ‘modules’ came into use.  This picture of the white version pictured above, shows two orange-coloured blocks in place of the row of separate resistors:

2nd gen white inside IMG_1059

Other slight changes were made to the component layout, and the style of the switches in the bottom right-hand corner is different.  (Once again, ignore the non-original large resistor next to the speaker).

This would be a typical version of the circuit from this period:

Stylophone schematic 2

A slightly different one is illustrated here:

http://www.waitingforfriday.com/index.php/Reverse_Engineering_the_Stylophone.

Also at some point during production of the 2nd Generation Stylophone, there was a major change on the outside.  The shape and colours didn’t alter, but the guide to the notes, printed on the white background piece stuck around the keyboard and switches changed from showing notes (‘A’, ‘A#/Bb’, ‘B’, etc.) to numbers (‘1’, ‘1 1/2’, ‘2’, etc.):

Letters & Numbers IMG_1057

(These are the same two black and white Stylophones shown above).

This was the beginning of the famous Stylophone song-teaching method, which continues until this day.  Whereas the songs you learned from the original booklet were shown with notes, like this:

Original Booklet p7

songs were now shown with numbers, like this:

p8

Edit: However, there is a photograph of an object from the collection of the Museum of Design in Plastic at http://www.modip.ac.uk/artefact/aibdc–002025 which shows an original issue Stylophone (the one with the black sections on the keyboard) in its packaging: and one of the items included is an overlay for the keyboard surround.  First of all, this is white lettering on a black background, rather than black lettering on a white background; secondly, it uses numbers, not letters for the notes.

*

The third distinctly different type of early Stylophone was the ‘New Sound’, which came out in around 1975.  The sound was ‘new’ because instead of the transistor in the original, the oscillator used a 555 integrated circuit.  Mine came in a box featuring Rolf Harris:

New Sound in box IMG_1048

This Stylophone featured, for the first time,a volume control, which can be seen on the left of the front panel, just above the on/off and vibrato switches.

The circuit for the ‘New Sound’ version looked like this:

555-based Stylophone circuit.LARGE

This view of the inside of the ‘New Sound’ shows the black, rectangular 555 chip just above the centre of the circuit board:

New sound inside IMG_1061

The Booklet that came with the ‘New Sound’ Stylophone was more extravagant than the original – although it was only printed in black and white, it was 16 pages long and the pages were about twice the size:

p1

Read the New Sound Booklet.

*

Edit: Not part of my collection, but of interest nonetheless, is a variation made in Hong Kong and sold mostly in the United States.  These are described in detail at http://www.stylophone.ws/hk.html, but a correspondent, ageing60hippy,  has sent me some very nice photos of one that he has.

It can’t be stated for certain if these stylophones were copies as a number were manufactured under licence at this time, but they have several features which differ significantly from the versions being made in the UK.  Note the ® symbol after the Stylophone logo on the front grille, the socket for an external 9v power supply, and the small battery compartment on the back.

Imgp3462Imgp3436Imgp3443Imgp3449

Inside, the circuit board design is different and the construction quality perhaps not quite the equal of the originals, but not bad for this period:

Imgp3458Imgp3450

*

All of these early series of Stylophones offer opportunities for modification and circuit-bending: the electronics aren’t complex, circuit diagrams are often available, and the components themselves are large and readily accessible.

I haven’t worked on these much, but my SoftPot Stylophone is a modified ‘2nd Generation’ treble version.  The ‘Hedgehog’ uses a Stylophone ‘New Sound’.

Production of the original Stylophones ceased in 1980 and the manufacturer, Dübreq, moved on to other things (‘Top Trumps’ playing cards!), but in 2006 the design was revived.

The new ‘Stylophone S1’ had different electronics inside, but a more or less identical case design.  Only by looking carefully can you see the tell-tale signs: the extra socket on the side – an ‘mp3’ input – a volume control on the right-hand side, and a three-way tone switch on the front, none of which is present on any of the 1960s and 1970s Stylophones:

Stylophone S1 2

Several colour variations – sometimes referred to as ‘Special editions’ were produced.  These were all-black (‘ebony’), silver and white:

4 S1s IMG_1044

Unlike the earlier Stylophones, the colour isn’t an indication of different sounds – as all S1’s have 3 tones, there was no longer any need to make three different types.  They’re all identical on the inside – although I did have the impression that a little more care was given to the assembly of the Special editions, compared to the standard version.

*

In Asia an even more completely black version, the ‘Stylophone Studio’ was marketed:

StylophoneSBE_package_Full lge

They’re very uncommon in Europe and I’ve never seen one.

[Edit: I’ve finally acquired one!  Here are some pictures:

IMG_0607aIMG_0612IMG_0613

As you can see, it’s VERY black!  I like the contrasting white switches].

*

This is the booklet that came with the Stylophone S1:

p1

Read the S1 Booklet.

The version that comes with the black ‘Stylophone Studio’ is mostly in Japanese (at least mine is, having been purchased from there; different languages may have been used if it was sold in other countries):

IMG_0609_10IMG_0611_12

*

Another rare variation of the S1 is the so-called ‘Raconteurs Tour edition’ – a special version made to be sold as part of the merchandising connected with The Raconteurs,  a band formed by Jack White after the dissolution of the White Stripes.

Both the colour scheme of the instrument and the package design were unique, with a distinctive black and gold colouring:

Raconteur + box IMG_1036

In addition, the contents of the booklet were customised for the band:

p1

Read the Raconteurs Booklet.

According to a concert-goer (at http://cousinsvinyl.com/2008/dude-check-out-the-merch-raconteurs-and-black-lips-play-the-fillmore-detroit/): ‘I was very curious to see what a Stylophone was.  The box read “The Original Pocket Electronic Organ”.  My friend said, “Dude, you’re going to want to get one of these,” as he opened the box.  It was $40, but worth the money: it’s a working instrument with the Raconteurs logo on it.  The next day, it was worth $200 online.’  Mine was a lucky find on eBay, but these can be very expensive when you come across them, usually more than the original $40 price tag.

[Edit: True at the time of writing, but less so now!]

As an added attraction for those who bought the Stylophone at Raconteurs’ gigs, the band held a competition, inviting fans to submit Stylophone versions of their songs.  The competition was announced on the band’s website:

Raconteurs competition

 The video made by the winner, Zach Herrmann, can be seen on YouTube at http://www.youtube.com/watch?v=2eK17MqWIo0. [link now dead]

The circuitry of the S1 is very different from the earlier Stylophones, being based on a tiny digital chip which you can’t even see as it’s covered in a blob of protective wax.  It has a separate amplifier circuit board.  It also runs on 4.5v, not 9v, so instead of a PP3 battery it takes three AA batteries.  These are not inserted by removing the back of the instrument like the earlier ones, but are held in a battery compartment accessed from outside.  For this reason, the S1 is glued shut and getting to the inside of it for the purpose of modification (or troubleshooting) is not a simple matter.

The only picture of the inside of an S1 I seem to have to hand is this one, which has points marked on it for a ‘feedback’ bend: but it clearly shows the components which are visible on the main circuit board – i.e. not very many! – and the amp board in the background:

Inside stylophone sm

The chip which does all the work is under the black blob; the resistors are tiny surface-mounted (SMD) type.

For this reason, modifications and circuit-bending opportunities are a little more limited than with the early series of Stylophones.  Elsewhere in the blog are one or two examples of my efforts: The ‘Alien’ was my first modification project; the ‘Gemini’ uses two S1 boards in a single case.

And finally, a word about the smallest ever Stylophone, the Stylophone mini:

stylophone-mini

This one really is miniature!  Measuring a mere 8cm x 4.5cm, this is an official Dübreq/re:creation product, and is a perfect reproduction of the regular Stylophone.  Powered by 3 AAA batteries, it has a working stylus and the full complement of 20 notes.  The only thing it lacks is the Stylophone’s traditional Vibrato.

Here is a Stylophone mini with a regular Stylophone S1:

Mini Stylophone IMG_1042

Inside, there seems to be very little indeed!:

Stylophone mini IMG_1094

It looks as though the keyboard is connected to a small piezo element acting a sounder, with very little in between!  I didn’t take the circuit board out on this occasion to look, but I suspect, like the S1, the chip which operates the Stylophone mini is very small and surface-mounted on the other side.  It certainly looks as though modification and bending possibilities are limited.

That’s an overview of the mini and regular Stylophones; my next post on the topic will deal with the amazing machine often described as the Stylophone’s ‘big brother’, the 44-note, 8-voice Stylophone 350S:

Outside angle after cleaning IMG_1089

16
May
12

The SoftPot Stylophone

Ever since I found out about the ‘SoftPot’, I wanted to use one to control a stylophone.

A SoftPot, if you’ve never come across one, is a type of slider potentiometer – but not a metal one with a knob, like a fader on a mixer: it’s a wafer-thin piece of flexible plastic, and you operate it by pressing on it with your finger, or an ‘actuator’ – something like a pen will do, but it’s better if it has a rounded end not a pointed one, as that won’t damage the thin plastic. It looks like this:

softpot1

(This is one which still has its backing sheet.  The SoftPot itself is transparent, and sticky on the back).

The normal SoftPot value is 10k. When I looked at stylophone circuits, I realised that in most cases 10k isn’t going to do much. The pitch pot I added to The Alien – a modern reissue stylophone – was 2.2M, and although that amount of variation in pitch wouldn’t really be necessary, 10k would only represent a few notes.

So I looked at one of the original 1970s stylophones, and saw more possibilities there, so I bought one from eBay with a slightly damaged keyboard.

The definitive guide to the sounds and circuitry of the original stylophone is at http://www.waitingforfriday.com/index.php/Reverse_Engineering_the_Stylophone, but the particular circuit variation of the one I had was not quite the same as the one they had. The circuit of mine was like this:

Original Stylophone circuit

The values of the resistors are a bit blurry in this scan, but you can see that 10k isn’t going to affect the pitch very much if connected to the resistor ladder on the left – along most of the scale, this would represent only about 2 or 3 semitones.

So I concentrated on the area where there is a tuning pot and a resistor to +v and resistor to ground. The tuning pot, which was 25k, allows the stylophone to be tuned, but doesn’t really cover more than about half an octave – still not enough to play tunes effectively.

At first, I tried varying the 470Ω resistor to +V and the 820Ω resistor to ground, but to little effect: adding a 1k variable resistor to the +V end, in series with the 470Ω, and turning it down a bit did seem to help, but in the end the effect I wanted to achieve – a variation between top and bottom of a couple of octaves – was achieved first of all by reducing the tuning pot value to 10k, the magic number, the same value as the SoftPot.

Secondly, the stylophone version I was working on had a resistor in parallel with the tuning pot – a very small one of about 270Ω. Replacing this with a resistance of 1k seemed to do the trick – and in fact I added a 1k potentiometer, as this would function as a narrow-to-wide control of the note range, in tandem with the 10k tuning pot.

A 3.5mm stereo switched socket on the side of the stylophone would allow the stylophone to function normally, when required, but anything plugged into the socket would replace the tuning potentiometer in the circuit. This is how the SoftPot would be attached.

That part of the circuit now looked like this:

SoftPot Stylophone 2

and the SoftPot Stylophone looked like this:

SoftPot Stylophone right high angle IMG_0906SoftPot stylophone back corner IMG_0907

The next thing was to make a unit for the SoftPot which could be plugged in when required. This was quite a minimalist design, and was put together like this:

SoftPot Stylophone 4

The SoftPot, as previously mentioned, is sticky on the back, so was stuck to a piece of 2mm acrylic sheet cut to fit on top of the keyboard, just clear of the power and vibrato switches, and nestling inside the lip on the right hand side. Underneath this was stuck a smaller piece of 2mm acrylic which fitted inside the keyboard cut-out, and stopped the whole thing from moving as it was played.  These three layers were stuck together, but weren’t stuck down to the keyboard.

The soft pot terminals came attached to a 3 pin socket, the same size as the ones you get for PCB headers. I had some of these, so made up a lead with a 3.5mm stereo plug on one end, and a 3-pin PCB header plug on the other.

SoftPot attachment 2 IMG_0903

You may be able to see from the back of the attachment how it was put together to fit firmly into the keyboard recess:

SoftPot Stylophone w back of attachment IMG_0908

The SoftPot assembly fitted in place, and was ready to go. All it needed was an actuator – like a pen, but with a rounded end. And, of course, the stylophone has one of these already: the stylus which gives it its name! So the SoftPot Stylophone can still be played with the stylus in the traditional manner, but moving up and down the SoftPot, like a ribbon controller.

SoftPot Stylophone Complete high angle IMG_0909

There was just one more change to make to the circuit before this could happen. The Stylophone sounds when the +V in the stylus contacts a key, which is in turn connected somewhere within the resistor ladder. Now that the keys had been covered up, there would be no sound without a connection between the resistor ladder and +V – the stylus only pushes the SoftPot together, and the connection is made internally.

As with The Alien and The Hedgehog, I simply made an internal connection between +V and one of the resistors in the ladder – the highest note – operated by closing a switch. Try as I might, I couldn’t arrive at a situation where the SoftPot Stylophone was silent until the Softpot was activated, but still gave a good note range.  So I added a volume control – a feature which any stylophone would benefit from – and when you play, you can turn the volume down when not sounding a note with the SoftPot.

Before finishing up, I added a socket to allow the SoftPot Stylophone to be operated from an external power source, a switch to cut out the internal speaker (this is not done automatically when the lineout socket is used), and a switch to cut out the low-pass filter in the line-out circuit.

These original stylophones are famous for having a simple resistor-capacitor tone control on the line-out circuit which is not in the circuit to the internal speaker. This is the main reason why stylophones sound so different when the line-out socket is used. When you see pop musicians who use the stylophone at live gigs holding their instrument up to the vocal mic as they play, this is not mere theatricality: it is theatricality, of course, but it’s also the only way to get an unmodified stylophone to sound the same to a stadium or festival audience as it does to you when you play it ‘unplugged’ at home.

The other end of the circuit now looked like this:

SoftPot Stylophone 1

Finally, I made a small modification for the benefit of a future project which I haven’t yet started on. I added another 3.5mm stereo socket configured in a similar way to the SoftPot input socket. In normal or SoftPot operation the resistor ladder is connected into the circuit; but anything plugged into this socket replaces the resistor ladder.

IMG_0912

13
Jan
12

Jack and the StyloSim

My next programming project was designed as an experiment to see if Pure Data could deal with QWERTY keyboard input, USB input and audio input all at the same time.

I planned to make an audio effects device, using a Stylophone for the audio input, plugged into the laptop’s 3.5mm (1/8″) stereo mic/line in socket; the laptop keyboard; and a nice twin-joystick device I found on eBay.

The joystick device was called ‘USB Simulator’ (‘For Airplan Heli’) and had the model number FS-SM020.  The two joysticks were quite good to use – not the kind you grip in the hand, but bigger than the thumb-operated joysticks you get on a game controller, plus each of the 4 axes had separate adjusters which you could use to fix the centre of the joystick’s range of control.  There were a couple of buttons on the front, which you can see on the bottom right and left, but these proved to be cosmetic only once I opened the case and looked inside.

StyloSim6sm

I couldn’t find out much about this device on the internet, except that it was, as its name implied, normally used for flight simulation – presumably to simulate a radio-control transmitter – and, in fact, it came with a CD, probably containing the simulation program.

The case was quite large, and there would be ample room inside for further circuitry.  I may look at this possibility later, but for the moment I made no alterations to the device, intending just to use the two joysticks: a bandpass (‘wah wah’-type) filter and volume for the left one, and a binaural panning control for the right one.

The first problem to be overcome was to make sure the audio input from the Stylophone couldn’t be heard, only the output from Pure Data, which would hopefully be the audio input modulated by the joystick effects.  This was achieved by the simple-to-use and very handy audio-routing program Jack.

Jack works by running an app called JackPilot.  When opened this presents a small window like this:

Actually, the top button on the left reads ‘Start’ when opened, but I took this screenshot after clicking it and starting the Jack server.  The normal procedure is to open Jack, start all the programs involved in your routing scheme, then click ‘Start’, and then, when it’s ready, ‘Routing’.  (Just occasionally, you may have to start some audio running through a program before Jack recognises it, but mostly that isn’t necessary).

The Routing window looks like this:

jack2

All the inputs are in the left-hand column, all the outputs on the right; it always shows the System audio in and out.  In this instance I was just practising, so I only used Pure Data, but I would frequently have Logic running, too.  To set the route, click on all the inputs and outputs in turn (they are shown in red when being edited), and click on the item(s) you want them to be connected to before moving on to the next one.

At the beginning of the Pure Data program I put the ‘Print’ and ‘Open’ instructions, as I did for the Theresynth and Cybersynth (see previous posts):

This configuration enabled me, once I’d plugged in the Stylophone (audio input) and Simulator (USB input),to check the Device number of the Simulator and open the Device so the ‘hid’ object would receive and deal with the output from the two joysticks.  When I clicked the ‘Print’ message box at the top, the following was printed in the Pure Data window, telling me that the Device Number was ‘0’:

StyloSim4

(It also gave the Device’s name ‘FS-SM020’, which it hadn’t done with the particular game controller I used for the Theresynth and Cybersynth).

As the Device number was 0, I amended the ‘Open’ box to show this number, and clicked it.  Then I clicked the ‘Print’ message box at the top again, and it showed me the controls it could recognise:

StyloSim5

The 4 axes of the joysticks can be seen (‘abs_x’, ‘abs_y’, ‘abs_z’ and abs_rx’, I think, and I can’t remember if any input was recognised from ‘abs_ry) – and also 3 buttons, but the button function hadn’t been implemented in this device.

I clicked the on/off toggle switch, applied the stylus to the Stylophone keyboard, and sounds issued forth – a very good sign!

The Pure Data StyloSim program had three inputs:

StyloSim3

On the left is the [key] object, which receives input from the laptop keyboard.  In the end, I added only the box with [== 114] in it: 114 is the ASCII code for the ‘r’ key, so the program only responds to the letter r, turning a reverb effect on or off.

[Edit: I later changed this to 119, the letter ‘W’, to avoid conflict with another program that used ‘R’ for a different function]

In the middle is the audio input, [adc~] (analogue-to-digital converter), which leads to the output stage.

On the right is the [hid] (Human Interface Device) object, receiving input from the 4 axes of the joysticks.  The [route] objects separate the 4 inputs and send them in different directions for their various functions (bandpass filter, volume and binaural panning).

All the effects worked – although the panning was less binaural than left-to-right; I’ve heard better.  This is the complete patch, showing the objects I used, and the mathematical calculations required to get it right.

StyloSim2

The patch can be downloaded from here.  (Click ‘Save Link As’).

This proved that Pure Data could combine information from the keyboard (or an external USB QWERTY keyboard) and [hid] to work on an audio signal entering simultaneously.   As  can be seen from the following picture of the set-up in action, I used ‘The Alien‘, my first Stylophone modification, as the audio source.

StyloSim1sm

This instrument has a ‘drone’ function, so it’s possible to put the stylus down and operate both joysticks on the Simulator at the same time.  Both the joysticks, incidentally, are centre-sprung, meaning that all values return to the central ones, except the y-axis of the left one – the bandpass filter.  This means the centre-frequency of the filter can be set and left while other parameters are adjusted.

Here’s a sound file illustrating the StyloSim:

It’s more of an example than an actual piece, just to show what the StyloSim does.

It’s slightly edited, but only to make it a bit shorter, otherwise it’s exactly as it sounded when played. There’s no post production effects on it, I just hit the ‘r’ button to turn on the StyloSim’s reverb before I started.

There are three parts: the first part is the Stylophone played with the stylus in the conventional manner; the second part uses The Alien’s ‘drone’ feature and variable pitch and vibrato controls; the third part is played with the ‘feedback’ switch on.

[Edit: more modifications have been made to the StyloSim joystick (although not for this particular use).  See this post].

31
Dec
11

Stylophones

I must say I’m very fond of Stylophones!

The Stylophone, if you’ve never encountered one, is a small, hand-held monophonic instrument played by touching a stylus to a row of metal pads – the edge of a large printed circuit board – laid out like the keys of a piano. It was invented and first marketed in the 1960s, and is sometimes described as the world’s first mass-produced synthesizer.

In my view the Stylophone is an indispensable element in the arsenal of the electronic musician – it’s simple, distinctive-sounding, and most types are available at a reasonable price, with patience, from charity shops or on eBay. It’s also possible to make a number of straightforward – and some not-so-straightforward – modifications to it. I have described elsewhere in the blog some of the ones I’ve done.

Although largely the brainchild of engineer Brian Jarvis, accounts of its genesis in 1967 suggest that the Stylophone would never have seen the light of day without the encouragement and input of brothers Burt and Ted Coleman who, together with Jarvis, ran a company called Dübreq. Dübreq produced equipment for the film and broadcasting industry and their name is said to derive from their specialities of DUBbing and RECording, with the umlaut and the ‘q’ added to give the firm more of an international air (or perhaps, like Motörhead or Mötley Crüe, just to look cool!)

The marketing masterstroke which ensured the eternal popularity of the Stylophone was the engagement of the multi-talented London-based, but Australian-born entertainer, Rolf Harris. Even before production began, the Stylophone was introduced to the world on Harris’s popular Saturday TV show on the BBC, and, it is said, became an instant hit – despite at first being available only by mail-order from Dübreq at the frightening cost of 8 pounds 18 shillings and sixpence, around ninety-five pounds in today’s money!

Over the following decade a number of different versions of the Stylophone were produced. I have a treble – which is all white – a standard black, and a bass – also black. This latter wasn’t a production model, but the circuit diagram that came with the standard showed different component values for all these three types, so I modified a standard to produce the bass register, an octave below. I’ve subsequently modified this to produce a further octave below that – I call it ‘The Double Bass’ – but this is not a modification suggested by Dübreq themselves.

This is a circuit diagram of an early Stylophone. Note the details of alternative components: resistors in the top left and capacitors in the bottom left.

Stylophone schematic 2

There is also a later 1970’s version (the ‘New Sound’) with a fake wood fascia in place of the familiar metal grille. This latter has a feature noticeably absent from the earlier models – a volume control, a useful feature in the days before the ubiquitous earphones. Here is the component layout and schematic/circuit diagram from the booklet which came with it.

Layout and Circuit Diagram

It was not long after this, in 1975 or thereabouts, when production of the original Stylophone ceased; and this might have been the end of the Stylophone story, had Brian Jarvis’s son Ben not had the idea in the early 2000s of bringing it back. By 2007 the new Stylophone S1 was on sale, sufficiently similar to the original to be instantly recognisable, but with some updated features, including built-in input and output sockets and a three-way tone control.

Stylophone S1 2sm

It’s possible to do modifications on all these variations on the Stylophone design, even the S1. Despite the fact that the chip that does all the work in the S1 is very tiny and inaccessible, parts of the pitch and vibrato circuits are available, and the output stage is on a separate PCB. I was able to do some mods on a couple of these.

The ‘New Sound’, based on the very common 555 chip is easier to deal with, and I was able to do a lot with mine (see http://wp.me/p25FoK-10). There are many circuits for 555-based oscillators in books and on the internet, and the 555 in the ‘New Sound’ is easily accessible for modding.

I haven’t done much with the original Stylophones – but these should be even easier, as the resistors which fix the pitches of the notes are exposed, and it should be possible to do things to these without too much trouble.

The biggest problem with the original and ‘New Sound’ Stylophones is likely to be the cost. Since these are sought after by collectors, they can fetch rather higher prices than you might want to pay for something which you intend to experiment on!

Many stars – other than Rolf Harris himself – have been publicly associated with the Stylophone. You can read about these on the Stylophone page in the Wikipedia at http://en.wikipedia.org/wiki/Stylophone, and see pictures of them on Stylophonica, ‘the official home of the Stylophone’ at www.stylophonica.com. You can also learn more of the history of the Stylophone at www.stylophone.ws (or www.stylophone.fsnet.co.uk), the Stylophone Collectors Information Site; buy a vintage Stylophone at www.stylophone.com, the Stylophone Sales Center; or even make your own Stylophone at www.instructables.com/id/A-Stylophone!

You will also find out about the mighty Stylophone 350S, much larger than the ordinary Stylophone, with two styluses (styli?), more notes, more tones and a cunning light-sensitive filter/vibrato control. This also went out of production in the 1970s and has not so far been revived.

Stylophone 350s

These machines – wonderful thought they are, as you can see – can be seriously expensive, and you would probably want to think twice about having a go at the electronics in it without knowing what you were doing. Having said that, like the conventional Stylophones of the period, the electronics will be relatively straightforward compared to modern devices. A bit like cars, really – in the old days it was much easier for the amateur home mechanic to sort out engine problems: nowadays, there’s very little you can do. The 350S has many different ‘voices’ and that intriguing photocell circuit . . . there’s got to be some scope there.

A new type of Stylophone that has appeared in recent years is the Stylophone Beatbox: a drum machine playable – of course! – by means of a stylus, including percussion, vocal percussion and bass sounds, and able to record and replay sequences. I have some functioning ones, which may also be good for circuit-bending, and some non-functioning ones from which the attractive circular playing surface should be useful for other projects.

stylophone_beatbox

I used the case and the keyboard PCB of one of these for a Stylophone project, but not the sound-producing electronics as there were faults with the ones I acquired which I couldn’t fix.

Dübreq’s website at www.dubreq.com suggests there are more Stylophone products in the pipeline, but none, at the time of writing have appeared. Some other websites have been advertising the imminent arrival of the ‘Stylophone Remixxer’, but I’m not aware of any genuine sighting of such an object.

29
Dec
11

The Superstylonanophone

I wasn’t intending to get into MIDI instruments at the time I started on this project, and construction of the Superstylonanophone came about by accident when I acquired an apparently non-working Korg Nanopad.

Superstylonanophone1

Essentially, what it is is a cut-down Nanopad attached to a Stylophone, so that the middle 12 keys of the stylophone operate what would, in the Nanopad, have been the 12 pads.  The touch sensitivity of the original pads seems to have all but gone, which is a big loss – but the pads didn’t work at all on the device I acquired, so the present arrangement is an improvement on that.

I have since learned that stuck pads is a common fault in Nanopads, and there is currently an instructional video on YouTube at www.youtube.com/watch?v=BuomrJNd0cM, uploaded by treilaux,*  telling you how to fix them.  If you have a Nanopad with stuck pads, you could do that instead of what I did; even if you don’t, you can see from that film how I took the Nanopad apart and detached the pad section from the electronics section.

*[Edit: this video disappeared for a while, but it’s back now.  While it was away, this note said try this one uploaded by TechinWorship, which details the same procedure, at: https://www.youtube.com/watch?v=spfYhzyjP6g.  As the intro to the video says, ‘Often times the trackpad will be responsive but the pads will not. This is due to normal wear and tear over time that causes the sensors to become jammed within the hardware. If this happens to just one of your pads, all will become unresponsive. Opening up your Nanopad and separating the sensors often returns your MIDI controller to like-new condition.’]

I continued by sawing off the large right-hand section of the Nanopad with the pads in it, and was left with just the circuit board, ‘Scene’, ‘Hold’, ‘Flam’ and ‘Roll’ buttons and the track pad.  I trimmed down the back as well, to fit the remaining piece of Nanopad front panel.

Nanopad 1

Everything was removed from inside the Stylophone (it was no longer working), except the PCB with the keyboard on it.

The difficult bit was connecting the Nanopad PCB to the Stylophone PCB.  This was not difficult in principle, but only in practice.  The Nanopad pads were operated by a plastic film connected to the PCB via a 14 way ZIF socket.  The connections on the PCB were too small for me to get at – just 1mm apart – so I was hoping to find a replacement 14 way jumper cable that would be long enough to go from the ZIF socket, out of the new Nanopad enclosure into the body of the Stylophone.

I couldn’t find one: it wasn’t a proper ribbon cable, but another thin plastic thing, and in the end I had to get a short one and solder a proper ribbon cable to another ZIF socket at the other end of it.  I managed to find a type with alternate pins pointing in opposite directions, giving me 2mm space between each one.

The other end of the ribbon cable attached to the backs of the 12 middle keys on the Stylophone PCB.  I chose C – B because these are the defaults for the Nanopad’s Scenes 2 – 4, which resemble a conventional keyboard.  You can change this with the Korg Kontrol Editor program, but there seemed no point.

The 14 lines from the Nanopad PCB to its pads were one connection for each pad, plus 2 control lines, one for the top row of pads and one for the bottom row.  I was gambling that these two control lines were, in fact the same, as the Stylophone’s stylus has only one wire going to it and I obviously wanted to be able to play all 12 notes.

Fortunately, I was right, so in the end only 13 connections were needed.  However, since the Nanopad is polyphonic, it seemed a bit of a waste not to take advantage of this, so I added a socket on the side for a second stylus.  This is connected to the same spot on the circuit board as the integral stylus.  After using the Stylonanophone for a short while, I realised that this is a great asset, especially for playing drums and percussion, even if only one note at a time is sounded.

Because foot controls would be more natural for some applications (e.g. bass drum and hi-hat, or bass pedals) I added an external socket for other input devices to connect to, giving access to all 12 notes.  I’ll be writing in more detail elsewhere about the switching systems I’ve devised, and later on in the blog about any of the input devices I’ve been working on, as and when they get finished.

Superstylonanophonerear

The Nanopad doesn’t have MIDI in and out connections: instead, it has a built-in MIDI interface, and requires only a USB cable.  To allow for the possibility of future expansion (for example, I also have a Nanokeys I plan to work on), I decided to add a USB hub.  I found a flat square one that fitted into the base, and didn’t interfere with the vast amount of wiring inside the Stylophone body.  I superglued this in place.  The Superstylonanophone connects to this hub with a very short mini-USB to USB A cable, and the hub connects to the computer with a longer one.  The hub has proved very useful when I’ve needed to plug in more USB devices.

The Superstylonanophone logo, by the way, is just printed on a slip of paper tucked into the edging of the Nanopad trackpad.  This is easily removable, but isn’t thick enough to prevent the trackpad operating properly.  This was something I also saw on YouTube, at www.youtube.com/watch?v=xNKFJZX4Na4, uploaded by meltdownband.*

*[Edit: oh, dear – this video isn’t available either.  The procedure for adding the logo is very simple, though: just draw or print it on a piece of paper slightly larger than the visible trackpad and push the edges under the white plastic trackpad edging.  An ordinary thickness paper, like a printer or copier paper shouldn’t prevent the trackpad being used in the normal way.]

Sounds

There are no sound files to go with this instrument, as it’s a MIDI controller, and can be used with any real or virtual MIDI instrument.

See this post for details of the foot controller I made to go with the Superstylonanophone.

29
Dec
11

The Big Boy – Mod 4

[Edit: the BigBoy, alas, is no more!  I irreparably damaged the  circuit . . . but now it lives on in the BigBoy Beatbox, which is described here].

Big Boy verticalsm

The creation of the Big Boy came about as the result of the blindingly simple, though ultimately pointless idea of transplanting the workings of a Stylophone into the body of a Stylophone Beatbox.

I had a number of broken donor Beatboxes, and proceeded to dismantle one of these.  There are 12 ‘keys’ on the circular board, laid out in a similar way to piano keys, or the keys of a Stylophone, so one octave was available.  I decided there should be three octaves, so had two challenges: one, to connect the Beatbox keyboard to the Stylophone keyboard; two, to add switches to change octaves.

Connecting the two boards together proved fairly simple.  FirstIy I had to saw off the end of the Stylophone board to make it fit into the Beatbox case, and although this made it impossible to use the higher notes, there were still at least 12 left.  So I used the lowest 12 keys, soldering one end of a wire to the middle of each key on the Stylophone board, and the other end of the wire to the connection on the edge of the Beatbox board for the appropriate key.  It was easy to see which key on the Beatbox board led to which connection on the edge.

There are also two built-in switches on the main Beatbox board, operated by depressing either side of a plastic ring around the keys.  I also made connections to these, for later use.

The existing on/off switch was used, with its associated LED, and the space taken by the 3 way slide switch used for selecting the drum, bass or vocal beatbox modes was used for the Stylophone 3 way tone switch.  The Beatbox stylus was attached to the place on the Stylophone output board where the Stylophone stylus had been attached.

I carefully removed the Stylophone tuning pot and used it to replace the Beatbox tuning pot on the small board which is attached to the inside of the base of the Beatbox.  One end terminal of the pot was attached by a wire to the place it was originally attached to on the Stylophone board; the centre terminal was connected to +V at the same place on the Stylophone output board as the stylus, via a series of preset potentiometers, as described below.

The preset potentiometers were designed to produce the three octaves.  If there had been room for a 3 way rotary switch in the body of the Beatbox, this would have been simple.  But there wasn’t.  There was room for a three way miniature toggle switch of the ON-OFF-ON type, so I decided to use one of these.

With a simple 3 way switch, it would just have required three presets, each adjusted to produce the same note in different octaves; but with the 3 way toggle it required the middle terminal to be permanently connected, and the other two pins – representing the switch in the ‘up’ or ‘down’ position – to be in parallel with the middle terminal resistor.  This proved quite complicated, and many adjustments were required before the 3 octaves became available.  The Stylophone functions in such a way that the lower the resistance, the higher the pitch.  As the rule about two resistors in parallel means that their combined resistance is always lower then the resistance of the lowest of the two, the middle position had to be the lowest octave, and the ‘up’ and ‘down’ positions had to be two octaves higher and one octave higher, respectively.

The integral switches on the board, operated by the plastic ring, duplicated the function of the toggle switch, allowing for momentary octave changes when either the left or right switch was depressed – this only really worked when the toggle switch was in the middle, ‘off’, position, but that was the most practical setting for most uses, I found.

An extra 10k resistor had to be placed in series with the stylus connection, to ensure that the correct pitch could be achieved with the tuning pot roughly in the centre of its travel.

Big Boy horizontal rearsm

29
Dec
11

The Gemini – 3rd Mod

I was apprehensive about my third project, my final Stylophone mod for the time being, since it involved major surgery to two individual Stylophones, and I wasn’t really sure at the outset whether it would work.  In the end, in an unpredictable way of its own, it did!

The concept was simple, to generate two notes at the same time, using two Stylophone circuit boards operated by one stylus.  The ability to tune the fundamental note had to be retained, as well as means of selecting any harmony note – and, of course, it had to be possible to play the Stylophone as originally intended.

This photograph shows the main pitch control of the Gemini, the dual concentric potentiometer at the back left, as well as the fine tune, volume and blend controls on the back.  It also shows its decoration with signs of the zodiac stickers – I think the sign of Cancer (not visible) is the wrong way round, but this is not my fault, it was like that when I bought them.

Gemini high angle standard knobs sm

The first extra control to be added would be a 3 way rotary switch, to select ‘Normal’, ‘Harmony’ and ‘Modulated’ outputs.  This is just visible on the right hand side of the picture above.  ‘Normal’ would switch only one of the boards in circuit, with a mono output available to the internal speaker or to the headphone output; ‘Harmony’ would switch both boards in circuit, with one board available to the internal speaker, but both boards available to left and right sides respectively of the headphone output; in ‘Modulated’ mode, the outputs of the two boards were connected by diodes to allow the tones to interact with one another.

A dual 10k lin pot was used as a ‘Blend’ control, ranging from Board One (Oscillator 1) only to the left, and Board Two (Oscillator 2) only to the right, with varying mixes in between of the two tones produced.  A dual 10k log pot controlled the overall volume.  These were located in the circuit in place of the existing volume controls and both original volume pots and associated circuit boards were removed.

Pitch was to be controlled by a dual 500k concentric pot, the inner control for correct tuning of the fundamental pitch, the outer control for the harmony note, the interval being set by ear.  As this pot would cover a wide range, and the fundamental note would be difficult to set precisely, I decided to add a 10k lin pot, normally in centre position, in series with the inner pot, as a ‘Fine Tune’ control.

The first problem was to test if removing one stylus and connecting the ‘keys’ on one board to the corresponding keys on the other board would successfully enable one stylus on one keyboard to create two distinct notes at the same time.  Connecting the keys was easy enough, as each one has a small point – presumably included for testing purposes at the factory – to which wires could be connected.  To my relief, this procedure worked, two notes were produced simultaneously, and the interval set remained steady along the length of the keyboard.

The Stylophone’s original 3-way tone switch, as I had discovered on my first modification project, is a two-pole type, with only one pole used; so it was easy to connect the three wires from the two boards to other side of the same switch, to ensure the same tone was used on both boards.

I hoped the same would be possible with the vibrato, and connected the main boards together at the 3 inputs to the small board containing the power and vibrato switches.  This worked, too, and enabled one power on/off and one vibrato on/off switch to be used for both main boards.

It was the ‘mp3’ input/headphone output that caused difficulty, and I didn’t fully resolve this problem, I just got round it in a not entirely satisfactory way.  I had hoped that the outputs of the two amplifier boards would simply appear separate and equal at the headphone socket, and that a stereo input would appear as a stereo output.  (A stereo input is normally reproduced in mono through the internal speaker and the headphone output, as an unmodified Stylophone has only one mono amplifier in it).

I disconnected one of the mp3 inputs and one of the headphone outputs from Board One and replaced them with an input and an output from Board Two, in order to make this happen, but it was clear that one of the channels was leaking into the other one somewhere and the output was still mono, even though using two amplifier boards.  I had removed the 3.5mm sockets from Board Two, in order to fit this in the original case on top of Board One – maybe this had some effect on the stereo image, I don’t know.  But I eventually created a slightly stereo output by putting a 1k preset into the output of one channel, so Oscillator 1 was slightly to the left in the headphones, and Oscillator 2 slightly to the right.  This was the effect I was after in the first place, it just wasn’t the way I anticipated achieving it.

However, this was close enough to what I set out to create, so I considered the job done.

The following diagrams might help illustrate what I did and how I did it:

Gemini  Board 1b smGemini Board 2 sm

As it turned out, the pitches of the two oscillators couldn’t be set independently – raising the pitch of one would automatically lower the pitch of the other, and vice versa!  Not only that, but as the 500k pots were logarithmic the pitches would vary at different rates.  This apparent disadvantage, I decided, would be turned to an advantage – and would, in fact, be the whole point of ‘The Gemini’: the careful adjustment of the three pots to obtain a suitable pair of notes would become its principal performance feature.

The stylus, of course, was still fully functional, so as soon as a suitable interval was stumbled upon, this was playable up and down the keyboard.

Fitting everything back into the case was not easy, and involved quite a bit of rewiring to reduce the tangle of leads inside.  I had hoped to be able to fit everything in the original Stylophone case, but it soon became apparent that this wouldn’t be possible, so I aimed to deepen the case, as I had with ‘The Hedgehog’ – although not so drastically, as there would be fewer extra controls to add.  In the end doubling the depth proved adequate to contain the extra boards and wiring without unduly squashing them.  The extra piece of bodywork added to the case proved an ideal base for the zodiac motif stickers I added.

In use, the basic pitch seemed somewhat lower than originally intended, but it turns out that ‘The Gemini’ is perfect for bass sounds, and some excellent tones are obtained, especially in ‘Modulation’ mode.

29
Dec
11

The Hedgehog – my 2nd modification

My second modification, and first variation on a classic theme, was initially described by its inventor, Forrest Mimms III, as a ‘Sound Synthesizer’, and later as a ‘Stepped Tone Generator’ before it acquired lasting fame as the ‘Atari Punk Console’, or APC for short.

The APC consists of a pair of oscillators, using the ubiquitous 555 timer i.c.: one ‘astable’, or continuous, the other ‘monostable’, triggered by the first.  The 556 is often used, as it contains two 555s in one chip.

The design is so famous, it even has its own page in the Wikipedia.

I remembered that one of the Stylophones in my collection, the 1970s ‘New Sound’, was based on a 555, so decided this could be adapted as the first oscillator in the circuit.

This is what the ‘New Sound’ Stylophone looks like:

Stylophone Parts sm

And this is the circuit diagram from the booklet that came with it:

New Sound Stylophone Circuit Diagram sm

Looking around at various implementations of the circuit, I decided an LFO would be a handy addition, so decided to add a 556, to give 3 oscillators altogether.

I designed the circuit in my usual way by drawing, photocopying, erasing, cutting, and sticking, and ending up in this case with a very large piece of paper that had to be laid out on the floor to be read.  This is a photograph of the finished design:

270111 002 med

The middle part of the diagram is part of the Stylophone circuit.  The other parts were mainly inspired by Forrest Mimms’ own description of the stepped tone generator at www.jameco.com/Jameco/PressRoom/punk.html?CID=punk, the ‘Blast Fed Disaster’ from www.thesquarewaveparade.com, and the article at www.getlofi.com/?page_id=1395, including the Datura Mod.

As far as I recall, the 680Ω resistor shown in the circuit diagram as R8, where the circuit was broken for SW1B, wasn’t actually there and was replaced by a wire link in my Stylophone.

In the end, there were very few components to add to the Stylophone, just lots and lots of pots and switches, and yards of connecting cable.  The 556 and one or two other components for decoupling were on a small piece of veroboard, and took up very little room, but the biggest problem I had was to find enough space inside to fit the extra circuit board and all the wires in, and enough space on the outside to attach all the switches and knobs.

It was clear from the start that the Stylophone case was far too small to contemplate this.  I didn’t want to add a break-out box, or disfigure the Stylophone too much by sticking extra boxes to the side of it, so I decided to extend the depth of the case to create more room.  I bought some small pieces of 2mm acrylic, to match the thickness of the original case material, sprayed it black, drilled holes and stuck it in place.

It was now more than twice the height of the original Stylophone.  Still not deep enough.  A couple more centimetres all round of brown acrylic vaguely the same colour as the original ‘natural wood’ finish on top, and it was as deep as it was wide, with switches and knobs poking out on all sides.  This is how it acquired its nickname, ‘The Hedgehog’.

This low-angle shot of the considerably enlarged case of the ‘New Sound’ Stylophone shows most of the controls added to it to create ‘The Hedgehog’.

Hedgehog low angle 1 sm

The three on/off switches and potentiometers on the left, controlling Oscillator 1, are duplicated on the right-hand side for Oscillator 2, as are the two small touch points above.

Hedgehog inside 1 sm

It took some days to connect all the wires, and jam everything into position, but when I finished, much to my surprise, most of the functions worked straight away!  First of all, with the 3-pole SW1 (‘Keyboard off’; upper switch, front left) and the double pole SW2 (‘Oscillator on’; lower switch, front left) switches both in the ‘up’ position, the Stylophone was able to function normally; with the ‘Oscillator on’ switch down, notes played with the stylus could interact with the second oscillator; with both switches down, the stylus is not used, and the instrument is ready for full ‘Punk Console’ mode.

Classic ‘stepped tone generator’ effects can be produced with the middle switches on each side down, putting VR1 and VR3 in circuit.

Using the other switches on the sides, VR4 and VR5 alter the pitch or timbre of Oscillator 1 (the Stylophone oscillator); VR2 and VR6 can be used to alter the pitch or timbre of Oscillator 2, and thus radically affect the overall nature of the output.  The pitch range of both oscillators can also be altered by selecting one of 6 capacitors for each.

The third oscillator is configured as an LFO, connected to the control voltage input of oscillator 2, and thus affecting its pitch.  There are two sets of 6 capacitors associated with the LFO, and a variable potentiometer, which control its speed and depth (visible in the first picture above).  These controls actually enable it to move up into a similar pitch range to oscillator 2, creating some frequency modulation-type effects.  The Stylophone’s original vibrato is still available to oscillator 1.

The LFO is particularly effective when used in conjunction with the two controls on the back of the instrument: ‘starve’ (right of the picture below) – reducing the supply voltage available to the oscillators – and a flashing LED, which produces a slow, steady fluctuation in pitch (centre of picture).  Both of the pots have integral on/off switches.  A steady LED indicates when the starve control is on, and dims as the voltage decreases.  The knob on the left of the picture controls the brightness of the flashing LED, and thus the amount of effect it has.

Hedgehog high angle back sm

Also visible in the picture is a 2.5mm power socket, installed many years ago before rechargeable batteries became common, and before this series of modifications was planned.

The three feedback controls on the front are ‘on-off-momentary’ switches, which are sprung to return to centre (off).  This makes it a little easier to apply a short burst of the effect by raising the switch and letting go, rather than flicking it down, then up again.

The Stylophone is intended to be tuned in the following way:

Tuning sm

The tuning control has been extended with a length of plastic tubing so it still protrudes through the casing underneath and can be used as originally intended.  This can be seen in the picture of the inside of ‘The Hedgehog’.

The original base of the Stylophone was replaced.  It was not glued in position as it has to be opened in order to replace the battery, a 9v PP3 type.  The battery leads were extended in length to reduce strain, due to the longer distance between the circuit board and the battery compartment.

Playing ‘The Hedgehog’ is always a delight.  Because of the wide variety of interactions between the oscillators, the amount of adjustment that can be made, and the lack of any labels to remind you what each of the controls does, successive sessions are rarely identical.

Playing the Stylophone

Here are links to the sound files for ‘The Hedgehog’.

The first one is an extract from a track on my forthcoming album, slightly remixed to feature The Hedgehog’s contribution:

For hard-core electronic noise fans, the others are a slightly edited 15-minute improvisation – one long piece, but divided into 5 sections to make the files shorter, and because the different parts have a different feel to them:

A:
B:
C:
D:
E:

The Hedgehog is a mono instrument, so I’ve added a stereo spread plug-in to the recordings (made in Logic) and some reverb.

29
Dec
11

The Alien – my first modification project

My first Modification project involved a Stylophone – the 2007 re-issue – which I modified as shown below:

Stylophone labelled

1.  Power on/off.  This is the original power switch, unchanged.

2.  Drone switch.  The original vibrato switch with different wiring connected to it.  This switch causes the Stylophone to sound without using the stylus – useful in conjunction with some of the other modifications for which you need free hands.

For anyone interested in the details, I didn’t manage to document the whole procedure, but I’ve got a couple of pictures of the inside.  This one shows the end of the main circuit board and the small board for the power on/off and vibrato switches.

pic1

The original wires to the vibrato switch were disconnected, but not the other wire to the small circuit board, which goes to the Power switch.  As it’s a three-way cable, it might be easier to disconnect all of them, bend the two vibrato wires out of the way, and then reconnect the other one.

The pole of this switch (the middle of the three tracks) was attached to the highest note on the keyboard.  Each note has a small round spot where a wire can be connected, and you can see the spot for this note nearby on the keyboard circuit board.  The ‘on’ end of this switch is attached to the point where the stylus wire is connected to the third circuit board inside.

(In the picture, where it says ‘connect the end one to the end of the stylus wire’, it means the end track on the circuit board, not the end of the wire itself, which is going to be used for something else later.  Note that both these switches are SPDT, but used as SPST, with one end not connected).

3.  Tone.  This is the original 3-way tone switch, unchanged.  It’s a double-pole switch, with only one side used, so there ought to be plenty of scope for adding functionality to it.  I tried adding momentary switches linking the three wires that go back to the circuit board, for brief tone bursts, but in the end didn’t leave them in as it was hard to find one that worked in each of the three tone settings.  Adding potentiometers didn’t seem to have any effect.

4.  Feedback loop.  This switch and potentiometer are wired to two places in the output circuit of the Stylophone.

The switch turns Feedback on, producing a continuous high-pitched sound, adjustable by means of a 220k Log potentiometer.  When using the stylus with this circuit on, very interesting tones are produced as the feedback tone modulates the note played with the stylus.  In Drone mode, a ‘double’ tone is produced, very rich in harmonics.

Once the feedback wires are attached to the circuit, even with the switch off, a hint of the high-pitch breaks through to the output, and there’s a hint of the modulation when notes are played with the stylus.  Apart from this one effect, ‘The Alien’, as it is known, can be used with all the switches off as a normal Stylophone, with variable rather than fixed vibrato.  Feedback is such an effective tonal modification, though, I didn’t want to leave it out.

5.  Wide-range pitch control.  This is a 2.2M Log potentiometer which allows the pitch to be changed from a very high note, to a very low note – so low, that it hardly seems a pitch at all, almost a beat.  Can be useful!

6.  Pitch Effects on/off.  This switches the Stylophone’s pitch control out of the circuit as well as switching on the modified pitch effects.

7.  Wide-range pitch control on/off switch.

These 3 controls were the most difficult to arrange, especially as I wanted the Stylophone’s original pitch control to be used as normal when it wasn’t switched out of the circuit by 6.  This meant breaking the original connections to the pitch potientiometer and putting in some new ones.

pic3

The other difficulty was that the Stylophone doesn’t mind going right down to a very low pitch, but doesn’t like going up too high.  If you try to make it go too high, it will cease sounding and you can only get it to work again by switching off and on, or in some cases switching off, removing the batteries, putting the batteries back in and switching on again.  This is a common phenomenon in circuit bending, but I didn’t install a battery cut-out switch, as is often done – there’s no need for this to happen, even with all the modifications working, so it could be designed out.

Accordingly, the wide-range pitch control doesn’t go all way from + v to 0v, but is connected to +v by a variable resistor, enabling you to set the highest note it will be able to produce and stop it from going silent.

This diagram shows how the rest of the connections to the switches are made and shows three preset variable potentiometers which are used.

Alien Switch connections2 sm

Note that I found it easier to connect the 3 presets to the TOP side of the circuit board, rather than the side in the picture, with the components on it.  The Stylophone’s pitch control does face this way, and it’s easy to find space on the tops of the two legs to solder the potentiometers.  You just have to make sure they’re out of the way when you put the back of the Stylophone on again.

Make sure when turning the circuit board over that you identify the correct two legs.

To adjust them, start by setting them to mid-position.  Switch on the part of the circuit connected to each one – e.g. the wide-range pitch control – turn it up to maximum pitch and adjust the preset upwards to the point just before it goes silent.  There’s a small area just before this where the tone starts to degrade, and you could turn the preset down a little so this is never reached in normal use.

The original pitch control is somewhere in mid-position in normal use, but don’t forget this may be working in some settings, and may have to be turned up when adjusting the presets.

Once this has been done once, it won’t need doing again.

9.  LDR (Light-dependent resistor, photoresistor or photocell) and LDR on/off switch.  The LDR is a NORPS-12, which has wide resistance range.  The less light that falls on it, the lower the pitch.  It depends very much on the ambient light how close you need to put your hand to it to achieve useful effects, but in many circumstances I’ve found very close – even to the point of touching it.  This is not a bad thing, as you don’t have to stand away from it to stop it working, and it almost resembles a touch switch in this way.

A handy accessory to have is a small torch, with which you can raise the ambient light level and increase the pitch by shining it on the LDR.  I have an LED-based cycle light – 99p from a supplier in Hong Kong – which is very bright, and also has a number of flashing modes, which produce LFO-type effects.

8.  Variable vibrato.  Connect a 1M Log potentiometer between the two wires you disconnected from the power/vibrato board. This gives a transition between full vibrato and no vibrato at all.  Only two of the connections on the potentiometer are used, and you might want to experiment with which of the end ones you use as the degree of control is different, and I can’t remember which way round I put them.

The Stylophone’s volume control (next to the LDR switch on the right hand side, not pictured) was left in place, and still functions as before.  It has no effect, however, when Feedback is on.  You must do as we did with the original Stylophone, which had no volume control, and put your hand over the speaker!  And watch out when using earphones!

General construction notes

1.  The first thing is that the top and bottom halves of these reissue Stylophones don’t come apart easily, like the old ones did.

The old ones were powered by a 9v battery which was on the inside, so you had to take them apart easily to replace the battery.  The reissue ones take 3 AA batteries in a battery compartment which is accessed from the outside with a cross-point screwdriver, so the top and bottom are superglued together.

The 4 main points where they’re glued are near the corners on the long sides, and there is no alternative but to insert a knife or screwdriver in the gap and prise it open.

2.  The black blob hides the main processor that does all the sound generation.  It seems a little sensitive, so avoid soldering near it for all but the briefest time, and don’t solder with batteries in.  I managed to ruin a couple, almost certainly by doing one of these two things.  In particular, be careful when connecting the drone switch to the keyboard circuit board.

3.  I also painted the base black and superglued a metal alien face to the front.  Neither of these things has in any way improved the sound, except insofar as the effect it has on the mind of the player.

The alien face, by the way, actually comes from Roswell, New Mexico in the USA, site of the original UFO flap in 1947.  How much more authentic can you get!

Acknowledgements

Some useful pointers came from a well illustrated article by TraceKaiser on the www.stylophonica.com forum; and from circuit-bender Freeform Delusion, www.facebook.com/pages/freeform-delusion/144587583120.

29
Dec
11

How I started

I’m writing this Blog to document some work I’ve been doing in the field of electronic music-making.

I wasn’t an expert in any of these things before I started – and I’m probably not an expert in any of them now, but I’ve learned a lot as I’ve gone on, and I hope if I can pass it on it’ll be a source of interest and in some small way an inspiration to others who are getting involved in this field

When I began thinking about this project I decided to do it in the following way:

a).  To avoid working with computers (until the very end).

I’d used computers extensively in my music before, from Logic for straightforward composed pieces to a variety of other programs for electronic composition or sound treatment.  I expected to return to using the computer in the end, but with the benefit – hopefully – of new knowledge and new sound devices.

b).  To incorporate where relevant some projects I’d started, and mostly not finished, many years ago.

I’d made some guitar effects with a degree of success that could be described as ‘mixed’ – some of them I use to this day, which work very well and can’t or don’t need to be replaced by anything new; some are still around, not quite working the way they were intended to; some never worked at all!

So I decided not to go back to guitar effects, but to concentrate on sound producing devices.

c).  To explore certain specific ‘movements’ in electronic sound-producing, such as ‘circuit bending’ and ‘Lunetta’ devices, and construct some of the ‘classic’ designs along the way.

d).  To explore alternative methods of music input – isomorphic keyboards, game controllers, and other home made devices.

One of the intentions behind this was to create music in more of an informal and  ‘live’ way than I had done using the computer; another was to explore the variety of music- and noise-producing devices now available – usually cheaply in sales, second-hand shops and on eBay.

I also wanted to pursue my obsession with the Stylophone, an early electronic synthesiser of the late 60’s and early 70’s, but recently reintroduced.

I’ve divided the different parts of the project into the following categories:

1.  Modification

In this first phase I would take existing devices and add new features, or expand existing ones.

My principle in doing this was understanding the circuits (to a certain degree) and making appropriate changes to produce specific effects.

2.  Construction

Phase 2 was to build a number of sound-producing devices from scratch, using circuit diagrams and descriptions from books and magazines (I had a number of these collected over the years, and hand-drawn circuits copied from publications in libraries) and from the internet.

Again, a certain amount of understanding of the principles of the circuits would be necessary.

3.  Circuit Bending

In this phase the idea was to take existing electronic instruments – children’s toys mostly – and make them produce sounds they were never intended to produce, mostly without worrying too much about the circuits that produced these sounds and how they were working, which I felt was more within the spirit of the enterprise.

4.  Freeform designs

The intention then was to extend the knowledge gained in previous phases to create new designs, partly modified, partly constructed, incorporating past ideas I had had, but never put into practice and new ideas discovered through experimentation.

5.  Software/MIDI

This phase was to be mainly computer-based, involving programming, which I had not done before.

As it turned out, I was overtaken by events, and parallel with the Modification and Construction, have got involved in some slightly different areas.  However, I’ll write about each of my projects in order, and put them in the appropriate category.




andymurkin

August 2020
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