Super Simple Automatic Night Light

The automatic night light is an easy, beginner friendly, circuit that requires no coding and consists of simple components. The circuit's purpose is to turn on an LED when the room it is in is dark. When it is bright then the LED will stay off. It is great for a quick and easy build, and it is useful. Visit my Tinkercad design of this circuit at https://www.tinkercad.com/things/ijfNUYjGIdI-automatic-night-light

The supplies include the following:

1. 1 (or more) LED(s)
2. 100k ohm resistor
3. NPN transistor
4. LDR (light-dependent resistor, sometimes called a photoresistor)
5. 3V Battery Supply (such as battery pack or coil cell battery)
6. Switch (optional)
7. Breadboard
8. Jumper wires

Insert your LED(s) into the breadboard in parallel. Be mindful of the anodes and cathodes.

Connect the cathode(s) of the LED(s) to the collector of the NPN transistor. I'm using a 2N2222 transistor. Connect the emitter to ground.

Insert the LDR into the breadboard between the base and collector or the transistor.

Connect the resistor from the anode(s) of the LED(s) to the base of the transistor.

Connect the anode(s) of the LED(s) to VCC.

Connect your 3V power supply to the + and - rails of the breadboard.

Turn on your power supply to see your automatic night light in action! It should be off in the dark and off in the light. If preferred, you can vary the resistance of the resistor to change at what darkness the LED(s) turn on.

Circuit not working? Try these steps.

1. Make sure your LED(s) were inserted correctly (anode on the left, cathode on the right)
2. Make sure your transistor is NPN and that the transistor wasn't inserted backwards.
3. Check the resistance of your resistor
4. Check your connections and the power supply