Simple Automatic Night Light using LDR and BC547 Transistor
Simple Automatic Night Light using LDR and BC547 Transistor This circuit is a great way to save energy on your electricity bill and provide a low-light illumination source at night. It is relatively inexpensive to build and uses common electronic components. Components Required LDR (light-dependent resistor) BC547 transistor 4.7kΩ resistor LED USB Male connector Breadboard Jumper wires How it Works The LDR is a resistor that changes resistance based on the amount of light it is exposed to. In brighter light, the resistance of the LDR decreases. When it is dark, the resistance increases. The BC547 transistor acts as a switch that is controlled by the LDR. When there is light, the LDR allows current to flow through the base of the transistor, turning it on and allowing current to flow to the LED, which lights up. When it is dark, the LDR blocks current to the base of the transistor, which turns it off and the LED does not light. S chematic ...