Blog Electronics

First Drum Synth Build

The drum runs from 5v but for project completeness sake I put it in a box with a 9v battery. The leftmost two pots control sound parameters with the third controlling volume. The piezo picks up finger impacts from the outside so you can play the drum by tapping the tin. From left to right the circuit goes: 9v to 5v regulator, ATTINY45 synth (with a header around chip for in-circuit programming), filtering & pre-amp, power amp.

Circuits always seem to end up denser when I actually build them – it was a cram getting all this onto protoboard.  The actual circuit is pretty neat but the rats’ nest of cables is from hooking everything up to switches.  I also had to shoehorn more caps in than expected.  It would have been wiser to choose a bigger box and measure/mark out all the controls rather than faff around with files and a hole-borer, but I  learned a lot for the next build in the process.  Notably: I’ve never experienced dry solder joints before but the analogue stage of this circuit really highlighted them, I’m used to using strip board and not this sort of protoboard so I need a bit of practice here; the piezo does all manner of weird stuff when the metal side is against the inside of the tin, grounding issues; the whole circuit could be shuffled to the right – squeezing the battery in was a relatively last-minute decision.

Paint job required. I’m still running this with the original software from my rhythm piano and I want to add more range to the sounds. The next post will have the first ‘official’ code release in which I’d like to include some lovely abrasive glitchcore modes I discovered whilst this circuit was playing up.

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