The Night-Light

Do you want to find things in the dark? This circuit turns on an LED when it gets dark.

You can use it to light up things that you might want to find in the dark. Place it by the keyhole of your front door, or by a glass of water for when you wake up in the middle of the night.

The Circuit Diagram

Find the components used in the table below. Click here to buy the complete kit.

Part Value Note
LDR ~200kΩ Light-dependent resistor (photoresistor) with around 5-10kΩ resistance in light and around 200kΩ or more in dark
Q1 BC547 Any general purpose NPN transistor will work
R1 100 kΩ Standard resistor
R3 470 Ω Standard resistor
LED Standard output light-emitting diode

Are You Stuck?

Let me know your questions and comments in the comment field below

Comments on The Night-Light

  1. Gord says:

    I hate to admit I’m stumped, but at this early stage I still can’t fully comprehend and interpret a circuit diagram, so I’m stumped on this project. Can you show a better photograph of the breadboard so I can see the proper layout? Thanks.

  2. Oyvind says:

    Hi Gord,

    Here’s a quick drawing of the breadboard connections:
    https://ohmify.com/wp-content/uploads/2020/04/The-Night-Light.jpg

    Best Regards,
    Oyvind @ Ohmify

  3. Gord says:

    Thank you.

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