On Mon, Aug 25, 2014 at 09:47:31AM +0100, Will Godfrey wrote: > On Mon, 25 Aug 2014 08:13:28 +0000 > Fons Adriaensen <[email protected]> wrote: > > ... or a charge amplifier. > > Interesting you mention that. I was wondering if that sort of thing would > work, although I didn't know the name - I had to look it up :)
The output produced by a piezo is an electric charge proportional to the mechanical input, so a charge amp is the right way to capture it, and the standard one for scientific or technical use. Basically what a charge amp does is to short-circuit the piezo and integrate the resulting current. And since current * time = charge, this produces the right output. What happens with a high-Z input instead is that the capacitance of the piezo itself plus that of the cable acts as the integrator. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
