Found in an 80's Elektor, this circuit can use any equivalent optical coupler. The buzzer is of the Sonalert type with included oscillator.
The SCR MCR1000 MOS is a rare component today. It is an SCR with MOS field trip, requiring a...
This circuit was found in a Radio Electrnics of the 90s. The SCR can be any of the 106 series...
This circuit transmits to an FM receiver placed nearby telephone conversations. The coil consists of 4...