NEW PCB REVISION: DIP package LM13700s have been replaced with SMD LM13700s due to the DIP package chip going out of production. All other parts are still through hole. If you'd prefer a PCB for a DIP 13700, let me know when ordering, they're still available.
The FM Drum is a percussion module designed to make far-out and strange sounds. It features a manually controlled modulating oscillator and a voltage controlled oscillator. Each oscillator has both square and triangle waveshapes, selectable with toggle switches. It also accepts external CV for modulation. It is easy to patch, just input a trigger or gate source and out comes a new sound.E
The board features PC mounted pots for less wiring, and mounting holes for flexibility in panel layout. There are Eurorack and MOTM power connecters. It can be built in +/-12V or +/-15V systems.
This MP3 demonstrates the differences in adjusting just modulation depth and waveforms. The output of the unit is patched to the CV input for self modulation.
This MP3 has an increase of the modulating oscillator at the beginning and then some general tweaking.
For complete descriptions of the way the module is used, and how to build it, including schematics and parts list; download this PDF file.
Boards are available now. Price for 1 PCB is $8.
Unfinished eurorack
panels are available for this project, they are 8HP and cost $8 each.
There is
more information here about panels. If you're interested in drilling your own panel for
this project, feel free to use my
drill guide. That image should be printed at 300dpi for proper
scaling.
