We found this circuit in the Encyclopedia of Electronic Circuits Volume 5 from 1995. It uses a 3-terminal transducer from the time. The circuit is triggered by light.
This follower, found in a 1982 documentation, has only one amplification step, but it helps in the...
This circuit can use any comparator or even an operational amplifier. We can use the LM339 and the...
This transistorized oscillator, a modification of the Colpitts oscillator, was found in the...