The humble piezo disc buzzer is much more than something that makes tinny beeps in retro electronic equipment, it can also be used as a sensor. Tapping a piezo buzzer gives an interesting waveform, with a voltage spike followed by an envelope, and then a negative rebound voltage. It’s something [Igor Brichkov] is using, to make a simple but effective electronic drum.
First of all, the output of the buzzer must be tamed, which he does by giving it a little impedance to dissipate any voltage spikes. There follows some simple signal conditioning with passive components, to arrive at an envelope for the final drum sound. How to turn a voltage into a sound? Using a voltage controlled amplifier working on a noise source. The result is recognizably the drum sound, entirely in electronics.
In a world of digital music it’s easy to forget the simpler end of sound synthesis, using circuits rather than software. If you hanker for the Good Old Days, we have an entire series on logic noise, doing the job with 4000 series CMOS logic.
Syntom lives again!
http://davethompson.co.nz/syntom.htm
If you disassemble e.g. an Alesis electronic drum, this is what you will find in it ;-) One for drum head and one for the hoop (or the whole drum case)
I love these kind of projects, back to basics.
No fancy 555 or overkill Pi (or less overkill Arduino), sure those could be lot’s of fun too, but this “old-skool” approach is very refreshing.
I remember having some of these hexagonal electronic drums back in the late 80s. I took them apart to find just a single piezo sensor glued in the center.
https://en.wikipedia.org/wiki/Simmons_(electronic_drum_company)