This printed circuit board (PCB) is based on the design created at Eaton Peabody Laboratories (Mass. Eye and Ear Infirmary), but redesigned to work at lower frequencies. It features:
- High-pass input filter with 96 Hz cutoff.
- Selectable 20 or 40 dB gain
- Low-pass amplification with a 72 kHz cutoff.
- Low-noise 1.5V supply for microphone with a low-pass filter cutoff of 0.33 Hz (ensuring that very little noise makes it into the microphone).
The board is 74mm x 48mm and the mounting holes, spaced 40mm x 40mm, are sized for a M3 screw. The board will fit in a Hammond enclosure that accomodates 75mm wide boards.
OSH Park will print and ship three of these boards for approximately $30.
Order the parts from the bill of materials.
Solder the parts using solder with water-soluble flux.
Wash the board with dH2O.