Piezo for use one SurfXX board

[dime196604]

I thought that I've seen here on geotech that you need to put a resistor across the speaker input in order to use a piezo on the surf pi. I can not find any post about it when searching. Do i need a resistor or no? If so what value would be recommended?

[kt315]

yes you do. 1kOhm. maybe better use inductor if it gives effect. effect of resonanse. piezo is capacitor,
so plus the cap you get LC circuit ie you can tune the resonanse.

[dime196604]

Thanks for the fast response.

[dime196604]

Pulled a pizeo from a microwave board. its not very loud at all, would changing the resistor value make it louder?

[kt315]

piezo is a cap. if you tune L+C on resonanse you get max loud. so... choice L.

[kt315]

[dime196604]

piezo is a cap. if you tune L+C on resonanse you get max loud. so... choice L.

Is there a way to tune L without having to keep winding different coil each time? Any tips were to start