With the configuration shown in the figure, we have the relay being activated when the microphone picks up a sound and shutdown when the X1 reset sensor is activated.
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...