Test circuit with bridge (CB22530E)

This bridge-biased transistor test circuit measures gain in the range 0 to 300. Circuit is from Radio Electronics June 1952.

Oscillator with AGC (CB6321E)
This circuit was found in a 1964 documentation. It shows how to achieve automatic gain control for...
Transmission line driver (CB6927E)
Using transistors at the time, this circuit was found in a 1967 Ferranti documentation. The...
Dual temperature and level control (CB9474E)
This circuit, which controls both the temperature and the level of a liquid in a reservoir, was...