/diy/ - Do It Yourself

>>1623641
piezos typically have a pretty high resonance frequency. If you thing about the sound vibrating back and forth across the panel, the resonant wavelength will be twice the diameter, and the speed of sound will be pretty high (up to 6000m/s), so getting a low resonance frequency would require a large piezo element. However, to use a piezo as a microphone, you don't have to be near the resonance frequency at all. You should be able to find piezo microphone datasheets that show a response curve that's somewhat linear below the resonant frequency.

To convert this signal into something usable, I'd throw it through a jfet op-amp non-inverting amplifier topology, perhaps with filter elements, probably with a gain knob. Then I'd feed this through a DC-blocking capacitor and into your microphone/trrs socket. The capacitor is to avoid feeding the microphone socket's phantom power back into your circuit. You could either use USB to power this, or an external battery like a 9V. If using USB, you could buy a cheapy USB-soundcard and use this as both your power source and audio input, such that you only need one plug into your computer.

Pic related, using the second op-amp to buffer the ground rail. The 1kΩ resistor is there to limit the maximum gain so you don't make a naughty when you accidentally bump the knob up to maximum.

>>1623649
>DC bias
>to a piezo
Lmao, though the protection diodes could be a good idea I guess.