Using a capacitor as a sensor, this circuit was found in the 1989 Radio Electronics Experimenter magazine. The circuit must be assembled in a shielded box.
This circuit is from a 60's documentation. The circuit uses components from the era and serves to...
This oscillator for the practice of telegraphy provides a good sound in a loudspeaker, with only...
Found in a Philips documentation from 1968, this circuit detects the trimpot set input voltage....