This circuit was found in the August 1972 issue of Radio Electronics magazine. The circuit generates 4 types of signals as can be seen in the diagram. The maximum frequency is around 20 kHz.
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...