This receiver for a modulated light intercom was found in a 90s Elektor. The audio amplifier can be replaced by an equivalent. The sensor can be any phototransistor.
This circuit generates very high voltages using an old TV flyback. The transformer has a secondary of...
This fraction watt amplifier uses transistors that are still quite common in our market. The power...
This circuit was obtained in documentation on medical applications from 1966. The circuit is used in...