This Instructable is a simple Arduino-powered night light. This project is great for beginners with Arduino and is a good introduction to programming with analog circuits.
Step 1: Supplies
For this project, only a few electronic components are needed. All of these components are easy to get a hold of and usually come in an Arduino starter kit.
1. Arduino board and IDE (I used a Micro, but the Uno or any other board will work as well)
2. Jumper Wires
5. 10K Resistor
Step 2: Building the Circuit
When building the circuit, be sure to place the LED at a decent distance from the photo-resistor. This will reduce interference of the LED's light from the actual light reading in the area. An additional resistor may also be used for the LED depending on how bright you want it.
Step 3: Writing the Program
Attached below is the .ino file and a screenshot of the program that you can copy. As I noted in the program, you will probably have to change the light sensor value at which the LED turns on. To test this, it is easiest to remove the the LED from the circuit and then run the program with the desired room lighting and see what the sensor reads. I would then take that value and round up to the nearest tenth for safe measure. Just play around with it a bit, and I'm sure you'll get it.
Step 4: The Final Product
I hope you found this to be a fun Arduino Project. Enjoy!