This circuit was obtained in a Hobbyst Handbook from 1990. The circuit can be easily assembled since the SCR can be a TIC106 and the transistor a 2N30555.
This circuit is from a 1995 technical documentation. The transistor can be a BC558 and the sensor...
Found in a Popular Electronics from the 90s, this circuit checks the presence of voltage on a...
The critical component of this amplifier is the output transformer. We found the circuit in an old...