Making an interactive pen

In this section, we look at how we can create a interactive pen.
There are many helpful hints about this at www.wiimoteproject.com/ . We modified some of the ideas there and came up with our own keychain light pen, which works very well. Because we had no soldering iron and had no understanding of technical electronic terms, we looked for a simple process of connecting a battery to a bulb.

Our first working attempt was using a syringe from our science equipment, a battery and an infrared bulb. This worked well but was too difficult to manipulate.

We had many other attempts using biros with lights on the end but the most successful attempt was when we used the keychain light and removed the LED light and replaced it with our IR bulb.

We bought the keychain lights in Archway Stores, Castlebar, Co. Mayo and bought some similar ones in Westport.

We bought our infrared light bulbs on eBay. These were the specific details:
10 of SFH415 U IR-LED
maximum of emission 950nm (infrared)

UF 1,3V
IF 100mA
>40mW/sr
manufacturer SIEMENS

We then unscrewed the back of the light and removed the LED bulb. We replaced it with the IR bulb.

NB
It is important to remember that IR light cannot be seen with the naked eye and has to be viewed through a digital camera or mobile phone camera.

It is also important to remember that the bulb must not be recessed in the holder; it needs to protrude to pick the connection with the wiimote.

This new light was to become our interactive pen for the whiteboard.