BMC25. FM Drum

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.


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 information on this module, download this PDF file.  

PCBs are available for $8.
Unfinished panels are for sale for $8 each. Please read this page on unfinished panels before ordering.
If you'd like to drill your own panel, here is the drill guide that I use to make these panels. It should be printed at 300dpi.