1940s commercial receiver (T1618E)

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

Relay Drive AC Stage (CB12182E)
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
Visually Impaired Electronic Guide (CB18123E)
With this circuit the visually impaired can easily locate important places inside the house, such...
Schmitt trigger (CB21475E)
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...