Capacitive Relay (T1527E)

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

Alarm with the 555 (CB6777E)
Found in an old Popular Electronics this circuit is still current. The SCR can be of the 106...
Analog Multiplier (CB7930E)
Found in a 1968 EEE, this circuit accepts frequencies from 1 to 1000 Hz and control voltages from 0.1 to...
VCO PLL 4046 CIR24988S CB25025E (CB25025E)
This is the basic configuration of a voltage-controlled oscillator using the PLL 4046. The circuit...