1940s commercial receiver (T1618E)

This receiver was found in a Radio Electronics from 1949. It is a superheterodyne of the time using 6 tubes.

Optical FM Transmitter (CB8864E)
This circuit was found in a 1970s General Electric documentation. This circuit already used an...
Capacítancemeter (CB3878E)
This circuit uses an oscillator that generates a signal of approximately 1450 kHz to test...
4 Levels Digital Voltmeter (CB4375E)
This circuit was found in an English magazine Radio & Electronics Constructor of February 1977....