Light beam switch (CB21413E)

This circuit was obtained from a 1965 General Electric SCR manual. The components are from the period.

Precision Limiter (CB15883E)
The circuit in the figure is based on an LM101A; diodes can be replaced with equivalents. The...
Transistorized tachometer (CB9355E)
This circuit, with magnetic sensor, uses an operational amplifier of the time. The circuit is from...
Remote control analyzer (CB7812E)
Found in a 90s Popular Electronics, this circuit checks if a remote-control transmitter is...