Piezo input

[TonyA]

Hi,

Could anyone refer me to schematics and code for adding a piezo input. Using it just like a switch. What I'm wondering is should there be a diode before the input pin?

Thanks,
Tony

[mister_e]

a few seconds on google may give you some help too
http://devices.sapp.org/circuit/piezo/

Probably i would forget the LowPass and impedance buffer stages. Never use it before.

Another idea, that 'could work', is to use a PIC with an internal Comparator. You just need to read the comparator output. I think! Using that, you may implement a software threshold as in some Musical Drums Pad (wich may use those sensor or not...)

Saying that, the sensor impedance may give you some problem.... or not without a 'preamp' or 'buffer' Some bench test will says you all.

Good luck!

PS about the diode... if you use a single rail OP-AMP you'll don't need it. If you use the internal PIC comparator, use a serie resistor and the internal PIC diode may do the job. 1N5817 are still cheap, and almost diode could do the job. It's not as this critical IMHO.

[mister_e]

I found an interesting application link so far :)
http://www.media.mit.edu/physics/pedagogy/fab/fab_2002/personal_pages/hayes/mit.edu/urinecontrol-photos2.html

Enjoy!

[TonyA]

Very interesting... Thanks again, I appreciate it.

Tony

[Jhdgkss]

Could you use a piezo sensor for a gyro?