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 causes an LED to flash at a frequency determined by the capacitor. The circuit is...
This simple 1-transistor receiver has speaker listening. We found it in an article published in...
The integrated circuit used is equivalent to the 555 and the transistor can be the BC558. R1 and...