My first instructable! This is something I originally made for a friend who's still using it. It works very nicely at adding a nice ambient light to a dark room. I made this instructable because I decided to make one to stick in the bathroom at my house.

It's a small easy to build circuit that will, as the title says, turn an LED on when it's dark and turn it off when there's light, making it a perfect night light. It runs on a 12v wall adapter, so you won't need to worry about replacing a battery.

Step 1: What you need

So here's what you need for this project:

[Soldering iron, of course... and solder]

- 100k Resistor
- 1K Resistor
- NPN Switching transistor (2N4401)
- Photo Cell
- 3v LED
- 12v wall adapter (look around... I'm sure you've got one somewhere!)


- Small circuit board (makes it easier!)
- SPDT Switch (for complete disconnection)

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