Dark sensor using transistor, phototransistor and photodiode - BuildCircuit.COM
LDR Darkness sensor circuit - Electric DIY Lab
Building a Simple Darkness Detector Circuit using LDR
I'm making a simple dark sensor project with a light dependent resistor (LDR) and I want to replace the LED with a buzzer but it doesn't work - Electrical Engineering Stack Exchange
How to Make LDR Darkness Sensor Circuit Simple DIY : 7 Steps - Instructables