We found this circuit in the July 1971 Radio Electronics magazine. The circuit activates a Sonalert or a relay for a higher power warning system.
Photoelectric cells can be used as sensitive light sensors. However, the low voltage they generate...
With the illustrated circuit we can run a DC motor in one direction or the other, depending on...
In this circuit the relay triggers on when light falls onto the sensor, a common LDR. Power supply...