We found this circuit in a Radio Electronics from February 1966. The transistor is from the time and so are the transformers. The circuit is battery powered. Observe the impedances.
Based on an integrated circuit CA31062 which consists of a photosensor, this circuit was obtained from...
This ultra-simple meter uses an output transformer and a small speaker as a microphone. The...
The frequency of this oscillator depends on the crystal used and the transistors. The circuit was...