5-tube commercial radio (T1619E)

This commercial superheterodyne receiver was found in a 1949 Radio Electronics. The circuit uses battery.

Single transistor receiver (CB22568E)
This receiver was found in the Radio Electronics magazine of March 1953. It tunes to the medium wave...
Water Level Control (CB16953E)
This circuit was found in a 1990 publication. The sensors are electrodes placed in the water tank...
Rectangular to triangular converter (CB24194S)
The figure shows how to convert a rectangular signal into a triangular signal using an integrator. The...