This circuit was obtained from a Linear Technology manual from the 90's. The integrated circuits are from the time and could possibly be tested as modern equivalents.
This circuit from a Radio Electronics from February 1966 uses an LDR as a sensor. The transistor is a...
The trigger signal for this circuit is an audio tone. Tones up to close to 100 kHz can be used. The...
This transistor tester configuration can be found on this website with many variations. The...