This circuit with TTL output was found in a 1968 EEE. The transistor can be of general use. The tunnel diode is an uncommon component today.
This stage circuitry for amplifying microphone signals makes use of germanium transistors as indicated...
This continuity tester for low resistances was found in an English magazine from 1978. The circuit...
This is a classic FM amplifier IF amplification stage configuration. The circuit is from a 1980s...