Found in 1968 Mullard documentation, this circuit uses period components. The transistors are matched pairs and the sensor is an Indian photocell of the time.
Found in Electronics Today International in the 90s, this circuit turns an operational on and off...
At dusk this circuit triggers a relay switching lamps. The circuit can be powered from 6 to 12 V...
This second-order low-pass Salen-Key filter was obtained from an American 1980s documentation. Formulas...