Keyboards, MIDI and sampling

MIDI Prober
A device for probing MIDI signals with an oscilloscope

Minimalist MIDI-enabled sample player software

Expression pedal meter
A hardware position indicator for expression pedals

DIY microphones

Electret phantom power supply
Plug electet microphone capsules into phantom-powered XLR inputs

Electret battery box
9V power supply for electret capsules with switchable high-pass filter