This electronic defense generates a high voltage discharge capable of intimidating an attacker. The circuit was found in the Radio Electronics Experimenter magazine special edition of 1990.
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...
This circuit produces a strong tone of audio or ultrasound, depending on the values of components C1 and...
This alarm from an old 1978 publication uses PNP transistors and driver and output transformers that are...