A light controlled switch can be made with a PNP Bipolar Junction Transistor (BJT) and Light Dependent Resistor (LDR) In the circuit shown to the right, the transistor and LED are on when little light falls on the light dependent resistor (LDR). A fair amount of light will turn the transistor and LED off. Here … Continue reading "LED on when it is dark circuit using PNP BJT LDR – 2N3906 and Light Dependent Resistor"
