Reverse engineering a Stylophone

The Stylophone – a musical toy from the 60s – is a surprisingly simple piece of engineering. With a simple metallic keyboard played with a stylus and just a handful of transistors, the Stylophone was able to produce a few marvelous for their time sounds, and is the equivalent of a pre-[Stradivarius] violin for the electronic music scene. [Simon] tore apart an original Stylophone, and did a complete teardown of the circuit, going over the ins and outs of why this ancient noise box is so cool.

There have been quite a few DIY Stylophone clones, but all of them suffered from the same raspy sound made by a 555 timer chip slightly misguided makers used instead of the relaxation oscillator (in the pic seen above) used in the original. Aside from the oscillator connect to the RC circuit of the metallic keyboard, [Simon] also looked into the vibrato circuit. This is just a simple oscillator producing an 8 Hz sine-ish wave. The keyboard, of course, is connected to the circuit with an array of resistors which [Simon] happily provided the values for.

[Simon] put up a schematic of his reverse engineered Stylophone, allowing you to clone this ancient electronic instrument. If you can source the transistors, that is.

Comments

  1. nes says:

    You can get those unijunction transistors new in packs of four on ebay. For authenticity you really want the ones in metal cans I suppose but even they’re not scarce.

  2. karl says:

    You can find both transistors by using “www.findchips.com”

  3. Galane says:

    Korg is making an updated version called the Monotron. http://www.gizmag.com/korg-monotron-analog-synthesizer/14612/

  4. QW says:

    The 2N6027 isn’t even rare or expensive. It can be bought for less than $2 from by local electronics shop (Jaycar). BC337 and 1N4001 are pretty basic and everything else is just passives.

  5. gleen close says:

    @above: Agreed. And who used a 555 to build the buzzy sweetness of a transistor sound lol?

    Galene the monotron has been out for a while and is awesome. Not really so much a stylophone as it is a fun lil basic synth. Their new one with the sequencer and delay comes on the heels of me getting the envelope trigger on my ghetto midi/cv control for it. Fun piece of kit and glad ya brought it up :)
    The real funny part of it all is that you can still find transistor organs in some very cheap Chinese keyboards, complete with metal tab and resistor array keyboard. I’ve seen them often retrofitted with a COB to play straight musical tunes that are sine, opposed to the triangle wave main keyboard. They often smell quite toxic and the sheer amount of human effort involved with making the junky keyboard (with non-functioning buttons and switches)and I wonder what Mordor looking factory produces these things. Sad and horrifying to find.

    Oh and kudos to the reverse engineer in this project :)

  6. Mr Sheesh says:

    2N6027 can be replaced by an NTE6402 if you cannot get any of those. Also a quick search on findchips gives MANY sources; http://www.findchips.com/avail?part=2n6027

  7. Simon Inns says:

    The PUT that I used is easy to source (which is why I used it). Now if someone knows the part number for the original (my Stylophone had an unmarked PUT) then I would love to know it so I could update the information. This project was the precursor to my stylophone studio 5 (which was featured on HaD a while back):

    http://www.waitingforfriday.com/index.php/Stylophone_Studio_5

  8. o4tuna says:

    For some strange reason, I read that entire article in the voice of Rolf Harris…

  9. matt_the_bat says:

    Sweet. I think mine needs a cleaning.

    Now, how do you get the box open without harming it?

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