This stage was found in a 1964 Electronic Design. The transistors are of the time and the shape of the signal obtained is shown in the diagram.
We found this circuit in a Popular Electronics of the 80s. Used integrated circuits are uncommon...
The idea of this circuit is a resistance meter or continuity test with a common microammeter or...
This 1968 Mullard circuit detects fire by smoke using LDR-type sensors. The circuit makes use of...