This simple sensitive circuit was suggested in a July 1992 Radio Electronics issue. The relay is a double-contact changeover relay. Sensitivity adjustment is made at R2.
This precision circuit was found in ancient American documentation. The most critical component is the...
Using an LDR, this Philips circuit directly activates a relay when light strikes the sensor. The...
This circuit can be used to obtain control signals from an infrared emitting source. The circuit is...