A number of people have asked for more info on how I modded the Gakken SX-150 analog synthesizer for pushbutton usage. If you’d like to add a DIY keyboard youself, check out my recipe –
Parts – Feel free to experiment with other resistor/trimpot values and using more/less switches. The basic idea here is to divide up the resistance of the original control strip into sections which are then connected via the switches to the stylus wire.
- 7 x pushbutton switches (I picked up some cheap ones here)
- 7 x 4.7K resistors (I used 1% tolerance, but 5% is fine)
- 1 x 100K trimpot
- prototyping perfboard
Schematic –
(click for larger view)
I removed the control strip and cut a piece of ‘pad-per-hole’ perfboard about the same size – then built the keyboard circuit per the above schematic. I ran wires through the preexisting holes used for the strip and soldered them internally to the appropriate board connections. After testing it out, I secured the board in place using a bit of hot glue.
I find the pushbutton/keyboard setup to be a lot more fun than the control strip, but still have that stylus hanging about. Hmm, perhaps the strip could be mounted additionally in another area … until then, you can see the finished product at work in the original video I posted –
Once you experiment a bit with your own design, you’ll likely notice how simple and versatile it can be. I picked up the basic concept a while back from Ray Wilson’s excellent Music From Outer Space. Drop a line in the comments if I’ve left anything out/etc – and most importantly, Have fun!
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