This circuit activates a garage door by the car headlights car or a lantern. The circuit is from a 1967 documentation, making use of period components.
If the input voltage falls below 12 V the LED glows up. Other voltages can be monitored by...
This capacitive switch or approximation relay was found in a 1980s US publication. Power should...
Found in an Electronics World of 1968, this circuit is indicated for applications in photography...