This circuit was found in a General Electric documentation from 1970. Equivalent transistors can be used. The maximum signal frequency for the indicated components is 250 kHz.
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...