Thrift Score Casio SK-1 and the Urge to Circuit-Bend again…

I managed to get out thriftin’ this weekend and scored an old Casio SK-1 Sampling Keyboard for $7, which is something of a Holy Grail among Circuit Bending enthusiasts for the sheer number of mods that can be done to wildly affect the sounds this little toy keyboard makes.

20160501_150406 20160501_150827Nice! No battery Acid Rot, clean inside – great shape!

For those who missed the 80’s, a Casio SK-1 was pretty much the first Digital Sampling keyboard that was available at the price range of your typical 1985 teenager. The one I bought back in the day was the later model – the SK-5 – which could hold a whopping 4 samples, but was otherwise similar to the SK-1. If you were at a party sampling fart noises and turning them into songs in the late 1980’s, it was probably a Casio SK that was your delightfully compact and fun instrument of bad taste.

For those who missed the 90’s, Circuit Bending is the hobby (or religious experience, depending on how you view it) of altering the electrical and logic pathways of the simple electronic circuitry of a battery-powered toy musical instrument to make it do things and make sounds that it was never designed to make or do. In most mods, one usually even provides contact points for introducing the electrical skin resistance of the musician into the circuits for even more control options.

Although there are schematics for many popular projects like “Speak-n-(Spell/Math/Etc)” units and many, many documented mods for the SK-1, the real fun of bendin’ is the experimentation involved in bending virgin – or altering an instrument that you have no map for, one that might never have been bent by anyone before. My last bending project in the early oughts was one such.

mzAUT_0020Monster Zero!

Monster Zero started off as some odd white plastic toy guitar synth about a foot and a half long, covered in brightly colored buttons. The neck buttons are notes, the body buttons are voices. Made probably in the early 80’s, it had a very simple circuit board with widely-spaced components and prominent solder points. Very easy to probe and find ways to alter the sounds, adding in my own circuitry when I discovered interesting results.

mzAUT_0015 mzAUT_0007What direction am I thinking for the SK-1? Well, the possibilities just in already mapped mods are endless. Just take a gander at what people have done to the humble Casio SK-1:

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But I’m thinking of taking mine in the direction of merging it with one of those old Rat Shack “150-In-One” Electronics kits. The possibilities for mashups are super-tasty! Exciting project, and now I have to dig up all my alligator clips. :D

Q.R. Ghazala’s “Circuit Bending, Build Your Own Alien Instruments” Part 1 & 2

Updated: October 25, 2018 — 10:10 pm


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  1. Back then I couldn’t afford these. I look forward to enjoying it vicariously here.

  2. Darn, I have one of those someplace. I recorded my dog’s bark, then used to plan tunes in his voice. Now I got to find it. I never throw away anything electronic.

  3. Fun! Can’t wait to see which direction you take this. Awesome Pimp My Casio examples.

  4. Can’t wait to see you merge it with the Green Hornet! :)

  5. Very tempting to add another project to my never ending list of electronics things I want to do when I get time. I passed up many of these on the used market over the years thinking there is not much that can be done with a tiny KB. I had a few Poly90s (if I remember the model number) that I loved. Analog all the way and easy to mod.

    Now you need to find a Theremin.

    1. Where’s the “like” button?

  6. I remember some circuit benders who used to attend the M.I.T. Flea about 15 or so years ago. Nice folks. They had this big blanket spread out with all these electronic toys for sale. Five dollars for your choice.

    Never circuit bent myself, but I’ve clipped my fair share of diodes on police scanners, may or may not have replaced an oscillator crystal on a Radio Shack tone dialer, and hooked up a 1N34A to a oatmeal box coil and 250 feet of fence wire.

    Bend that SK-1. You know you want to.


    1. yep, that’d be about the time I was doing my first bends, seems like the hobby was quite popular in the early ‘oughts. With these simple ~3v circuits, there’s not much you really *need* to know other than “don’t short capacitors unless you like tiny puffs of smoke and ugly smells”. :D

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