This circuit was found in the Electronics Experimenter Handbook from 1991. The circuit controls a simple relay for the purpose of turning circuits on or off or switching audio channels.
The assembly of this amplifier was described in an article in the magazine Radio Electronics from...
Mouser Electronics offers a vibration sensor which is considered the smallest in its class. This...
This circuit was found in a documentation by A. Fanzeres making use of a grounded metal housing...