Found in the American 73 magazine for radio amateurs, this circuit can test common quartz crystals. The circuit includes the power supply.
This circuit is from a 1995 publication. The components are all common and the number of LEDs may...
This circuit, found in a 1995 documentation, is intended for switching composite RGB video signals...
This circuit is from Motorola's Linear Interface ICs of 1993. The integrated circuit is not common...