Posted: 9/20/2008 6:05:25 PM EDT
I was at Radio Shack today and was digging thru the parts bin shelves looking for battery holders for the flexible solar panel I keep in my BOB. I came across a bin labeled LED's and opened it to find a tray with Infrared LED's in it. They were the standard T20 type package, and at $2 I could afford to experiment.
The conversion is almost a drop-in, just have to cut the legs to match the length of the stock LED, bend one leg to match, and reassemble. Do all of this over a table with a white sheet of paper as the parts are tiny. The result is a keychain light that will light up a room discreetly, or act as a signalling beacon. The new digital Photon microlights have all kinds of strobe functions and whizbang shit that will do everything a Phoenix JR. will do, but only has one LED instead of 2 or 3-shouldn't matter on Gen3 NVD's.
A couple of things to point out up front:
1)you can't hurt the LED by getting the polarity (voltage direction) wrong. The job of a diode is to stop current flowing in a direction it isn't supposed to. Think of them as a one-way valve. It just happens that Light Emitting Diodes give off light when current is passed thru them in the proper direction.
2) LED's are nominally 3 volt components. Doesn't matter what type or kind, all LED's are meant to run on 3v. Yes, there are LED flashlights that run more than 3 volts, but they are regulated electronically to 3V.
3) If you have small fingers, this is a project you will need help with. The screws are small and the bends on the anode/cathode need to be done carefully.
4) don't bend the leads (anode and cathode) any more than you have to. While they are not fragile, they do not tolerate repeated bending cycles and will break off right at the base.
5) Exercise care that you do not short the LED leads across the battery where you have to bend the wire. It will make the light not work and you will wonder why the keychain light is getting warm... probably kill the battery and you'll have to replace it at the drug store, which will double the cost of your project.
5)Give it a shot!, took me 15min. to do mine
1 (one) keychain LED light/photon microlight (DealExtreme sells them for like... 10 for $6)
1 (one ) IR LED, Radio Shack PN#276-143, $2
and, either a:
Jeweler's screwdriver and wire cutters
A leatherman/multi tool
Take the case screws out. Light pressure, it's Chicom plastic now... Same when you reinstall them-this thing is never going to be waterproof, just tighten with finger pressure and go another 1/4 turn.
Gently lift the batteries out, taking note of which way up they are.
Look at the white visible LED and not how the leg opposite the switch side has a kink in it. Since they are already cut to length, you will have to find out what side is the Anode/cathode so you know which leg to bend on the IR LED. Or, you could just cheat like me and turn your NVG's on and shove them between the leads-one direction or the other it will work. Make a note to yourself of which one you will have to bend now. If you have good eyes, you will not need the NVD's to test this conversion because it goves off a red glow, average people will need to turn the light off and hold it up to their face to see it. Now you can bend the lead on the diode and cut them to length. Reassemble the light-just make sure the bent lead doesn't short against the battery body.
If I had three hands, I could take a pic of the results,.....suffice to say that it works and is pretty bright. Remeber what I said about 3V LED's? Well, this light has two batteries in it, making it more like 7.4 volts to the diode. Like the stock LED, it is being overdriven, but unlike the stock LED, this diode not only draws more current-it creates heat (IR radiation) too. The light gets noticeably warm after a minute or so, so I would use it more for a sqeeze light than switching it on and leaving it. I don't think the diode will suffer from being overdriven too much because the batteries lack the testicular fortitude to pump a whole lot of watts to the diode.