It’s amazing what a little disk can do … when it’s layered with piezoelectric crystals. Piezo disks are impressively sensitive to vibration and can easily be adapted to work as a contact microphones. The trick is the preamp – a basic circuit used to match the piezo’s signal to levels compatible with modern audio gear inputs. The resulting piezo/preamp combo can be used for electrifying an acoustic guitar or simply exploring the lesser-heard world of small sound around us.
The preamp I built is a variation of James T. Hawes’ design. In order to simplify construction, I reversed the MPF102’s source & drain connections from their usual orientation – which works fine in this case.
This thing really is an awful lot of fun to play with – you’ll likely here it used in some of my upcoming video soundtracks!
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