Thank's to the Instructables Build Night sponsored by http://www.jameco.com/, hosted at http://archreactor.org/, I bring you a 555 timer based project that blinks an LED at a rate that's affected by the intensity of the light in the room!
Things you need:
- 9V battery
- couple of resistors
- Photo-resistor, or LDR
- many jumper wires
Step 1: Connect All the Things!
Wire up the circuit on a breadboard. There's some leeway in the resistor values. Changing the 10K will change the blink speed, and the 3.3K you should change based on the LED you use.
Step 2: Move Around to Different Lighted Areas!
It should blink faster with more light!
Thins to do:
- add an inverter circuit so that it'll blink faster in darkness!
- try different LED's! the big yellow one was in Jameco's grab bag, it has 6 LED's inside it, all 5V forward voltage which is why I took the resistor off.
- replace the LED with a buzzer! place in your refrigerator to see if the light stays on when the door is closed!
- replace LED with a transistor and drive a big high power led!
- replace photo-resistor with a trim pot and set your own blink rate!