Please also see this one by H4ZZ498
It's the same thing, he made it first thogh.
Step 1: Materials
Any NPN transistor
10k resistor ( Or trimpot for variable sensivity)
A LED ( You choose the color)
2X AA battery pack or any 3v battery
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.