My buddy and I have come up with a circuit which is working perfectly with my bass drum trigger and the ION Drumrocker. The input signal from the bass drum trigger is adjustable to avoid double kicks and there is a pass-thru USB connection which also powers the circuit. We have included a small potentiometer to adjust the pulse length of the 555 chip but this could probably be set at a fixed value of 5K.
My bass drum trigger is a Sound Percussion SPA08 (similiar to a Gibraltar GBDP) with a radio shack piezo mounted inside.
Bass Pad: http://www.guitarcenter.com/Sound-Pe...22-i1416020.gc
I have tried this with my bass drum trigger and an ion drum pad and found it works perfectly.
- 555 IC (converts analog input to digital: http://www.national.com/ds/LM/LM555.pdf)
- 386 IC (this is the amp we used: http://www.national.com/mpf/LM/LM386.html)
- 100K resistor
- 10K potentiometer or 5K resistor (controls pulse length of 555 output)
- 100K potentiometer (for adjusting the input sensitivity - mine is set at 3 if off is 0)
- 2N3904 NPN transistor
- .1uF cap
- 10 uF cap
- USB Male To Female extension (for powering circuit from USB)
- male mono phono plug (we hard-wired this output to the box)
- female mono phone plug (for the drum trigger input)
- an LED as a power indicator (I forgot to include this on the schematic)
EDIT: See post #9 for md95's cleaner schematic with a couple enhancements.