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Jacket cuff lights: Convenient Illumination

All > Tech > Inventions > Jacket cuff lights: Convenient Illumination by natetrue
The next generation of cuff lights is here! Check out Printable Jacket Cuff Lights - now easier to make and install, plus they're much more reliable - no wires to break!

We've all been there. Fumbling around in a dark parking lot, trying to find the keyhole on the car door or mailbox. Sure, you'd use a flashlight, but who has the room for those bulky outlines?

Granted, the cuff lights aren't the most practical of solutions but they're so cool. They're hidden in your jacket cuffs, invisible and perfectly comfortable, just waiting to be activated with a little sideways pressure.

Words don't do this little hack justice (though I do love the photos... thanks Jesse!). How about a video?

(this video appeared on the March 20 2006 Rocketboom episode)

Are you excited yet? Like I said in the video, I'm offering the cuff lights as a kit for you to build into your own jacket (jacket not included!). The cost is $20 plus shipping (and sales tax if you're in WA). Buy Now or read on for the parts list!

To make your cuff lights, you'll need:

- 10 White LEDs (I use 17000mcd 3mm LEDs, they're effing BRIGHT)
- 2 small PC boards on which to mount the LEDs (10 x 2 solder pads)
- 4 small tactile pushbuttons
- 1 3xAAA battery holder (or a 4xAAA battery holder with a jumpered 4th battery slot)
- 2 10-ohm resistors (not pictured)
- About 12 feet of hookup wire, preferably stranded, 26 gauge

That's what's included in the kit. In addition, you'll need some other stuff:

- A jacket with suitable cuffs (non-elastic)
- A soldering iron and solder
- Basic soldering skills (this kit makes a good learning kit too)
- Electrical tape or similar to cover up the electronics
- Needle and thread for permanent mounting

Let's start with the LED boards.
First off, note that the LEDs have a polarity - there is a longer lead on one side (the anode, positive (+) connection). On the head of the LED you can see that one side is bigger (on these it's the cathode, negative (-) connection). You'll also notice that the head has a flat side on the cathode as well.

When you install these LEDs on the boards, make sure they're all facing the same way. If they're not, only some of the LEDs will light up.
Insert the first LED into the board like this.
Bend the LED toward the front of the board so it lays flat and protrudes past the edge of the board. Bend the rest of the leads away as shown.
Repeat for the 4 other LEDs on that board. Note that they are all oriented the same way - anodes to the left, cathodes to the right.
Take an end lead and bend it across the others. This forms one half of the power bus that will power the LEDs.
Bend the four leads that it crosses over the lead, and up and over the board. This will make it very easy to solder them together.
Repeat for the opposite side of the bus.
Solder the leads where they cross.
Then bend the excess over and clip it. To avoid scratchy points on your wrist bend the cut bits inward like so.

Repeat for the other board!
Next, take your leather jacket or equivalent and put it on.
Hang your arms casually in the jacket.
Then draw your hand a little into the sleeve and spread your hand out. Mark where your thumb and pinky fingers touch the sleeve. This is where the buttons for each sleeve must go, and where the two wire runs per sleeve need to come out.
Most jackets have a seam on the sleeve, between the leather and the liner, with stitches far enough apart to slip a wire through. It might be a tight fit, but it's doable and doesn't damage the jacket at all.
Grab the wire and stuff it through. Then (this is a hard part) work the wire through the liner to run it all the way up the sleeve. You'll want to grab the wire through the liner, then bunch up the liner towards the top of the sleeve and grab the wire through that. Pull the wire up and repeat until you have it where you want it.
Route the wire toward a convenient inside pocket. Exiting the liner is a more difficult task. You can poke a hole with a very sharp pencil or similar large pointy object. If you do it right, you won't break any of the fibers in the liner.

Put the jacket back on and move around to be sure you have enough wire in the run, then cut and tape it down. Repeat for the other side of the sleeve and for the other sleeve.

Once you have that done, measure and cut two pieces of wire that go halfway around your sleeve (from one wire-run spot to the other), crossing the side that you want the LED board on (usually the palm side). Cut each wire in half, strip the ends, and tin them for soldering.
Take the LED board and solder the wires near the center, so that the original length of the wire is preserved.
Use some superglue to attach the insulation of the wires to the board. This will reduce wear on the solder joints.
Solder the other ends of the wires to the buttons. Take care that everything is oriented correctly - the LED board solder side should be against your sleeve, and the wires should run toward the far side of the buttons as shown.
Put a piece of electrical tape over the LEDs on the LED board, and use a knife to cut a slit in the tape for each LED.
Pull the tape back and the slits will let each LED through.
Use the tape to attach the LED board to the sleeve where you want it. We'll sew them on later.
Pull the wire a little bit out of the sleeve (take care that the other end doesn't get pulled back up the liner) and solder to the button like so. Make sure the insulation of the wire crosses; this is again to prevent stress on the solder joint. You can use superglue here too to connect the insulations together. Make sure, however, that no superglue gets on the buttons - superglue destroys buttons!
Draw or push the wire back into the sleeve and position the button in its final position. You can tape it down and test the position if you want.
Using your needle and thread, sew the crossing of the wires to the jacket. You don't have to go through to the other side of the sleeve - you can just push in and out of the inner layer of leather. Tighten the thread and fasten it with a knot or just use superglue again. I love superglue! Use more thread to tie the top pins of the button to the leather also.
Cover with tape to keep the button leads from scratching your wrist.
(crappy photo) Sew the wire near the LED boards or just sew through some free holes on the LED board.

That's all for the installation of the lights. Connect the inside wires to the battery pack (make sure THREE AAA batteries are used, not four, or the LEDs will burn out) and test the buttons to see if the LEDs light up. If they don't, reverse the wires and try again. Be sure that the 10-ohm resistors are in series with the line going to each cuff. Use the inside pocket to store the batteries.

If you're confused about wiring, here is a crappily drawn diagram:
Now go impress your friends with your new Trix T-shir... I mean, new jacket cufflights!
For best results have fog in the air - they make great photos!

Once again you can purchase a kit from me via this Buy Now link for $20 plus shipping (and tax in WA). Remember to give me your phone number if you're outside the USA (for shipping reasons).

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Posted by jesse 8 years ago ( 28-Feb-2007 00:08:05 )

You look like your some sort of magician or sorcerer in that thing! Its swwweeeet!

Posted by kamikasee 8 years ago ( 20-Mar-2007 19:50:46 )

I like it.

Just so you know, you would probably find an improvement if you put a current-limiting resistor in series with the LEDs. Without the current limiting resistor, the connection through the LEDs is basically a short-circuit, and the high current causes a lot of energy to be expended in the LED. Some of this goes as light, but most of it goes as heat, and when the semiconductor gets too hot, you "let the magic smoke out" (that's a technical term :). The larger the resistor you use, the less current flows. This reduces the brightness of the LEDs, but could also extend your battery life.

If you're not EE minded, this link might help:

Still, it's a very cool hack.

Posted by natetrue 8 years ago ( 20-Mar-2007 19:57:20 )

Hi kamikasee,

That's a good point. The lights do seem to heat up a bit (but nowhere near the smokeout point), and some of them have started flickering (which is perhaps the first step toward failure). I put a 10-ohm resistor in series with each cuff light and it seems to have stopped the flickering. Though the brightness is maybe 70% of what it used to be. I'm not sure whether I'm satistfied with that.

Posted by natetrue 8 years ago ( 20-Mar-2007 21:46:51 )

Looks like 5 ohms gets me what I want with my rechargeable Li-ion battery, but that's only 4.2 volts max. I think 10 ohms will work best for the 4.5v of alkaline batteries. That will be what's included in the kits.

This comment was edited at 2007-03-20 21:47:42

Posted by natetrue 8 years ago ( 26-Mar-2007 17:39:13 )

I should mention that if you put these lights in your jacket that you shouldn't try to get through airport security with it on. Put it in your checked baggage!

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