1940s commercial receiver (T1618E)

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

Simple RF wattmeter (CB3892E)
This circuit, found in US documentation, can measure the power of transmitters up to 10 W, given...
Flasher with Transistors (CB5210E)
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...
4 input mixer (CB6309E)
This setting appears with variations at various points on this site. This is from a Motorola...