Hey gang. I've been working on a new pen concept that would fix the traditional problems with the original IR LED design: forward facing LED, IR wavelength not optimal, one LED not powerful or large enough. I found a different kind of LED light at Mouser.com that is smaller and flatter then your traditional LED. (see mouser link below) You can fit three of these across a dime and when you lay them on the table the light would shine up towards you not to the side. Their wavelength is 870nm which I understand from this forum is right where the wiimote is most sensitive to IR light. The old Vishay TSAL6400's are 950nm which work but I wanted every advantage when trying to get my wiimote to pick up the IR light.
So I set out to get these and put them on a previously made pen. I used the online LED calculator and got my new resistors (10 ohm 1/8 watt). The little LEDs were difficult to solder because of their size, but the end result was brilliant. Too bad I'll have to wait till work tomorrow to try them out. I expect great things however because if the old style pen kinda worked, this pen has got to give the wiimote a definite light source to follow.
I'll return and report how it performed, meanwhile please link to my Picasa page to view photos and specifics on the pen and the new diodes. Look at the second half of the photos to see the new diodes.
One last thing. I planned to make two pens: one large format pen with four leds for presentation use with a projector, the other will be a very small slimline pen for use at my desktop monitor using only one of these diodes for Photoshop work.
http://www.mouser.com/Search/ProductDetail.aspx?qs=oNDV51lhjEMyspNOxDDOcA%3d%3dhttp://picasaweb.google.com/Micbridge/WiimoteWhiteboardProject