I've been invited to go to a friends 40th birthday party and want to take a present that will be appreciated. He is a bit of a tech head and has also been known to get drunk and shout PANTS! a lot. So I've decided to make him a pair of flashing LED disco pants.

The idea is that the LEDs will be controlled by an Arduino so they can be flashed in sequence. To achieve this each LED on the pants will be separately addressable but to do this without a large number of unnecessary wires in the undergarment I will be using the Charlieplexing method to power them. There will be four strings of 12 charlieplexed LEDs
and each string of 12 LEDs will only need  4 wires. So a total of 12 wires will be needed to control the whole array of 48 LEDs.

The other advantage of multiplexing a Charliplexed array of LEDs is that only one LED per array will be ON at any one time. The down side to this is that they will have to be rapidly flashed or multiplexed to give the illusion that more than one is on at a time and that is more complex code on the arduino. However the big benefit is in power saving as there will be a potential of 4 LEDs on at any one time (one for each 12 LED string) which will lower battery consumption enough to get away with using a 9 volt battery.

Step 1: Materials

I only had this idea a week before the party so I had to use materials I had in my junk pile and 'left over bits' box. I'm glad I buy LEDs in bulk numbers.

Pants, Good old fashioned Y fronts are the best
LEDs Blue (36) and Red (12)
Resistors (Red 130 Ohm) (Blue 80 Ohm)
9V battery
Battery clip
Coloured wire
Heat shrink tubing.

Soldering iron
Computer and Arduino IDE
Pre-programmed arduino processor.
Big assed needles
Sewing machine (but you could probably sew by hand as an alternative)

Plus the usual small workshop tools.

Yes. Just yes.
<p>No schematics, huh?</p>
<p>No schematics, huh?</p>
<p>Hmmm... do you need to dry-clean the Y-fronts had it survived? I can't imagine it be thrown in the washing machine with all the wiring in place.</p>
<p>Okay I now I seen everything!!!!</p>
but why?!
A good point, very well made. <br>It took so long to solder up the LEDs that I simply didn't have time to make a up a bit of perf board to hold the micro. I even had a ATMEGA8 with a bootloader burnt on it ready to knock the cost down a few more points but the party date was fixed and as they say, Time and Tide Wait for no Man.
Why did you used a Arduino Duemilanove module? wouldn't it have been more reliable to use some perfboard and a simple bit of componets soldering it might have taken a extra day or 2 but would have been way more flexible because of lack of parts to be bent/snapped off, also those duemilanove boards are like $30 aren't they? Other than that this is a really nice project!
Nice, but was disappointed in the video...<br><br>I was hoping for some older bald guy (with a beer belly) doing the Saturday Night Fever dance with nothing on but these :(
Totally awesome.
Blinking undergarments, that's a brilliant idea! You know in case you're jogging at night.......in your underwear!
I thought you would have also wired up a disposable camera taser circuit to it for your friend. It's not going to hurt a bit.
That's a great idea!
The Flux Capacitor, now in underpants! Although running at 88 miles per hour could be troublesome..

About This Instructable




Bio: I'm a keen motorcyclist with a collection of post-apocalyptic looking bikes and sidecars. I enjoy touring about for my holidays with my dog who ... More »
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