Music and Synth DIY

Eurorack, Schematics, SMD, Synth DIY

One Shot (modulation source) – work in progress

Another module from an Electric Druid chip, this time a more unusual modulation generator…


 “(Oneshot) creates interesting unipolar modulation waveforms made from a single ”ping”. You can alter the shape and speed of the ping, and also add decaying echos to it, with separate Delay and Repeats controls. This lets you easily generate interesting and unusual one-off modulation waveforms. It makes things that sounds like a ball bouncing on the floor, or a single hit with echoes, or a stick being dragged across a washboard.

As such, it exists somewhere in the area between an envelope generator and an LFO.”

This is largely the schematic in the datasheet: all I’ve done is to add control voltage inputs with diode clamping, and an LED for the trigger input.


This is 6hp. Rather than the usual “sandwich” 2 PCB approach, I tried to keep this to one: a bit messy, but it should do the job. Largely 0603 SMD, but with DIP8 for the ONESHOT chip, a PIC 16F18313, to encourage anyone making one of these to buy an “OG” chip from Electric Druid and support them.


So…off to JLCPCB it goes for a prototype. Once I’ve built and tested it, the gerbers and KiCad files will be uploaded here as usual.

More info and datasheet here: