Ultraviolet Light Pen

Step 2 Make the Joule thief

Ok so remember how I said we are using a single AAA batter holder? Well one AAA battery only supplies 1.5VDC, so how can an LED that uses 3VDC be powered using only one AAA battery? With something called a Joule Thief; a Joule Thief is a device that allows a 3VDC LED to be powered using only 1.5VDC. If you are not fimmiliar with the process of making a Joule Thief then you should pay 1up a visit, he has a great Instructable on how to make a Joule thief. If you aren't the building type than you can steal a Joule Thief from a solar garden light you will have to swap out the white LED for an ultraviolet one though.