These optical relays, which can act as a shield, were found in an American documentation from the 1980s. The circuit has a LDR sensor. It can be adapted for other types of sensors.
In this circuit, which uses only diodes, we have both simultaneous functions. The diodes are...
This logic tester circuit was published in the November 1980 issue of Radio Electronics magazine. The...
This circuit was found in a 90s Popular Electronics. The circuit uses 4 bicolor LEDs to indicate...