Capacitive Relay (T1527E)

Found in Popular Electronics from August 1956 this sensitive two-tube relay is powered directly from the mains power supply.

Solar radio (CB22277E)
This simple 60's receiver is powered by solar cells of the time. The transistor is made of...
Voltage Controlled Oscillator (CB22373E)
This circuit has a duty cycle of 50%. We found it in old English documentation. The center...
Power Wien Bridge Oscillator LM377 (CB13245E)
The National Semiconductor LM377 integrated circuit consists of a low power audio amplifier. This...