We found this circuit in the September 1971 issue of Radio Electronics magazine. The sensor is an LDR and R1 adjusts the sensitivity. A relay with the appropriate voltage can be used instead of a buzzer.
September 2017 - The new LDOs of STMIcroelectrinics LDLN025 for currents up to 250 mA and 1.5 to...
We found this circuit, which should only be used with incandescent lamps. In the Motorola Linear...
This version operates in the opposite way to the previous one, triggering when light falls on the...