Infrared Pen MkI

So, this evening, not wanting to spend more time on the computer (having been on it all day for day 2 of DB’s Rails course) I spent my time honing my long-unused soldering skills and constructing the first revision of my infrared marker pen for the JCL-special Wiimote Whiteboard.

The raw materials
Close-up of the LEDs Im removing
The finished article
Close-up of the switch detail
Activated under the IR-sensitive digital camera

I must say it’s turned out ok. I didn’t have any spare small switches so went for a bit of wire with enough springiness in it. On the opposite side of the makeshift switch is a retaining screw for holding the batteries in. I’m using two old AAA batteries (actually running about 2.4V according to the meter) and no resistor in series. The LED hasn’t burnt out yet!

To stop the pen switching on when not in use I slip a bit of electrical tape between the contacts. Obviously you can’t tell when it’s on unless you put in another, perhaps miniature, indicator visible LED.

It all fits together quite nicely though the retaining screw is too close for the batteries and has forced the back end out a bit – that’s easy to fix.

As I’m of course after multitouch I’ll be building the MkII pen soon with the other recovered LED!