Found in an Electronic Design from the 90's, this circuit measures the equivalent resistance in series of a resistor. The circuit operates at 50 kHz producing a rectangular signal.
This commercial circuit is from a Japanese magazine from 1967. It uses germanium transistors, and...
This circuit can be used to drive relays, solenoids, motors and other loads according the...
This circuit is based on the small keychain that responded to the sound of a whistle and were...