Bioacoustics — open microphone front-end

An open electronics design to capture wildlife sound with low noise. The chain is simple and robust: a low-noise electret capsule (Primo EM272Z1) feeds a preamplifier (OPA2365) with jumper-selectable gain (+12/+22/+32 dB), whose line-level output is digitised by a standard USB audio class (UAC) converter.

Design characteristics: a usable band of roughly 48 Hz to 19.5 kHz, 3.3 V supply (~25 mW from USB) and line-level output. The project includes the full KiCad design with manufacturing gerbers, a bill of materials (BOM) with real supplier part numbers, and a SPICE simulation of the response.

An honest status: this is a reference design verified by simulation, not yet validated on the bench. Before manufacturing a batch it is worth measuring noise and response on the physical board.