This circuit was obtained from an 80's Electronic Engineering. The circuit detects ice formation by triggering a warning light. The operational amplifier is of the time.
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...