We find this oscillator in a 1980s documentation. The frequency depends on the crystal and the transistor used must be able to oscillate at the desired frequency.
This low frequency doubler requires a 50 mV signal at the input. The circuit is from an old...
This circuit can be used to drive relays, solenoids, motors and other loads according the...
This triac circuit was found in the July 1995 Electronics Now magazine. The triac is based on the...