The piezoelectric element of a kitchen gas lighter is used in this simple, yet effective seismic detector.
A 3 core shielded cable brings the signal to the rest of the circuit and to the power supply (+/- 15V). The SB140 diodes are Schottky type and pin 8 (substrate) of the IC should be connected to ground.
Article from Electronics Lab at http://www.electronics-lab.com
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