FM Demodulator (CB21752E)

This circuit was found in documentation from 1977. The integrated circuit used is a PLL.

VCO (CB11518E)
This VCO or Voltage Controlled Oscillator was found in a Popular Electronics from 1991 but can be...
Humidity sensor (CB22467E)
This simple circuit was found in Popular Electronics from 1992. The transistor is a...
Automatic speed regulator for DC motors (CB23722E)
This type of circuit is widely used in old cassette recorders and tape players, regulating the...