Remote listening amplifier (CB21957E)

Today we can call this circuit a baby monitor. It is a microphone amplifier found in a publication by Hugo Gernsback from 1960.

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fet infrared Modulator (CB14681E)
The circuit shown is from the Texas Instruments optoelectronics manual, applying to low power...
High Impedance 2 W Amplifier (CB6163E)
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...
Twin-T Rejector Filter 741 (CB25603E)
This filter that rejects a frequency range determined by the double-T was found in the August 1993...