This high sensitivity sensor was found in a 1967 General Electric SCR manual. The circuit admits equivalents by triggering a load according to the used SCR.
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...