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.
| 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
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.
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
Thank you.