FET pre-amplifier
- page last update March 2013- (página en catellano)

Because of their high impedance, piezo transducers have the disadvantage of being very sensitiv to external noise. Furthermore, because of their limitted bandwith, the sound reproduced from any object is enevitably poor and with little body.

The FET preamplifier which I am using for this project has been designed by J. Donald Tillman. I found his article by accident on the internet. This surprisingly simple circuit is very efficient at reducing the tranducers sensitivity to external noise, by converting the impedance from 10M to approx. 6K. The sound quality was significantly improved. From a ciucuit designed originally for a 6,3mm Jack socket, I have made a small PCB which includes a trimmer to adjust for optimum BIAS current.


PCB with FET BF245 and piezo transducer

Piezo Transducer used to trigger drums
fotos Holger Strauss


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Martin Hug