https://codeberg.org/mechatronicmagic/farseer

Farseer can be used as a fly wingbeat detector, or flight “tachometer”.

Farseer is a small electro-optical device that uses reflected infrared light from the fly’s wingbeats to generate an oscillating voltage signal. The oscillation frequency of the voltage signal matches, and thus allows one to measure, the tethered fly’s wingbeat frequency.

Farseer includes the main pcb, containing the sensor, amplifiers, and electrical filters, an aluminum enclosure, an optical light guide, an optical filter, a breakout pcb, containing power and bnc connectors, also with an aluminum enclosure, a USB cable connecting the two pcbs, and a USB power supply.