Found in Motorola documentation from the 1980s, this circuit employs an integrated device from that time, which is unusual today.
This capacitive sensor that operates with a high frequency oscillator was found in Radio...
This amplifier for the experimenter´s bench source 1 W and uses germanium transistors but can be...
This circuit was found in a Hands On Electronics from the 90s. The microphone is a small 75-ohm...