This circuit was found in a Radio Electronics from February 1966. The circuit operates with a common battery and the frequency is given by the resonant LC circuit.
This circuit allows 220 / 240V shavers to be used in the 110V network. The diodes can be general...
Used with telephones at the time, this circuit was found in Popular Electronics from the 90s. The...
This circuit was obtained from an American 80's documentation. It can be implemented with modern...