Radio with amplifier (CB20486E)

We found this circuit in a publication of 1991. The audio amplifier is an operational that admits equivalent.

RMS to DC Converter (CB6105E)
This circuit was suggested by Signetics in 1980s documentation. The circuit makes use of the...
Sinusoidal Oscillator (MSB013E)
This circuit produces low frequency sinusoidal signals. The circuit is a phase shift oscillator...
Pulsing Tone Alarm (CB4878E)
This variation of the previous circuit produces a pulsating sound when the sensor is activated. The...