5-tube commercial radio (T1619E)

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

High Sensitivity Fan Control (CB15521E)
Another way to increase the sensitivity of the circuit with the amplification of the sensor...
Astable with crystal (CB24937E)
We found this circuit in the Radio Electronics magazine of January 1986. The frequency is given by the...
Pulsating Buzzer (CB24836E)
This circuit was found in the September 1984 issue of Radio Electronics magazine. The circuit is...