>>Building IR Pens
Below are two different pen constructions;
Building a pen:
The biggest challenge is finding the right infrared LED emitter. After visiting several electronics stores, the best results were achieved using infrared LEDs from The Source. part # 2760142. The kit contains a detector and an emitter. You only need the emitter. (In the United States you can buy just the emitter part # 2760143 at Radio Shack).
* I have since found that ABRA Electronics in Montreal sells individual emitters. I have tested them and they work. They are $1.49 each. part number IRB 5-23C-B
http://www.abra-electronics.com
I looked for the smallest contact switch I could find and found some at an electornic surplus store (15 cents a piece). I also bought an AA battery case. I used an old felt tip marker as the holder for all the parts.
Carefully take apart the pen (non-permanent are better as the ink is water soluble) and clean out the old ink.
Trim the battery case so that it will slide inside the pen casing. I used a band saw to cut the corners and then a file to do the fine tuning. An AAA battery will fit into the holder and slide inside the pen.
Hold the pen as you would to draw or write with it and check where your index finger would go. Drill 2 small holes in the pen that will take the leads from the switch. Carefully bend the side clips of the switch so that it can lie flat on the pen. Bend the two contacts down 90 degrees so they can slide into the 2 holes in the pen.
Feed a wire through the pen casing and attach one end to the LED (the longer lead +) to + end of the battery casing. Run a wire from the other lead of the battery case (-) through one of the small switch holes and solder it to one of the switch contacts. Run another wire from the second switch contact back up to the free LED lead (the shorter one -).
TEST the pen before you close it up. The LED does not emit visible light to the naked eye. Hold it in front of a webcam and view the image. The webcam will detect the IR and you will see if the connections are all working.
Carefully feed the switch wires and leads into the casing. Use a dab of silicone sealer to hold it in place. Slide the battery into the casing. I connected a small screw into the end of the battery case so that it would be easier to pull it out when it was time to change the battery.
Slide the LED into the pen being careful to not push it too far. I sealed the LED into place with a drop of crazy glue. (LEDs don’t wear out like light bulbs do).
The second type of pen requires no soldering. The main component is an ultraviolet secret code pen that can be purchased at most Dollar stores in Quebec.
You will need the same IR emitter LED as listed above (ABRA Electronics in Montreal They are $1.49 each. part number IRB 5-23C-B)
The top of the pen can be unscrewed.
The internal housing is pulled out.
Carefully remove the Ultra Violet LED being careful not to bend the lead too much. Take your IR LED and orient the flat side to the same possition as the UV one. Bend your leads to the same approximate shape, but start them about 3mm farther away from the base of the LED (you want it to stick out a bit farther than the UV one did). Carefully clip it back into place the way the UV one was.
Using a digital camera (it can see IR light) test the LED to see if it works. If all is OK, slide the housing back into the case and screw the cover back on. You should be good to go.
If you should find this to be too challenging, there is a site in the US where this exact item is sold via the web for 7$ plus shipping and handling.
That’s it.
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