This circuit was obtained from an American 1980s documentation. The frequency depends on the crystal and the circuit may be a PNP that reaches the generated frequency.
This simple bridge unbalances according to the resistance variation in the electrodes. The circuit is...
This circuit was found in an Electronics World magazine from 1990. The circuit can be mounted...
Bike speedometer (CB20497E) This circuit can be powered by a solar cell. The circuit is from a...