Making an LED T Shirt!

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

Hi guys!

New to the forums!

Im an old boy who still loves a good dance now and again! :wink:

I wanted to make an LED tshirt... Inspired by this:

http://web.media.mit.edu/~leah/grad_work/projects/LED_clothing/tank.html

http://web.media.mit.edu/~leah/grad_work/diy/diy_tank.html

I have a bit of experience with programming and a bit with electronics from my youth!

Im looking at this long term project! As im going to have to learn a bit as i go! Im not looking for all the answers here but hopfully I can be guided. Im quite looking forward to this as a project!

As you can see with the tshirt above I want LEDS all around the tshirt! Preferably quite a bit more than the one Leah made. I want to be able to run different states, like text, different patterns running across.

Like this but with more LED's and detail : http://web.media.mit.edu/~leah/grad_work/movies/shirt.mov

I dont know its possible to run that many LEDs with the lilypad or how detailed I can go into different states? Any other chips that would be better?

(If its too much maybe just the front or back with LEDs.)

Everything will have to be insulated, as I tend to sweat a bit when out clubbing. ;D

Id also like to try the temp sensor and vibration sensor maybe!

Is this too much to ask? Is it possible?

Like I said this is long(ish) term dependant on how much time I can put towards it but hopfully a couple of months. :sunglasses:

Any help greatly appriciated!

Thanks Very much!

Loz

2

The first thing that you need to figure out is how many LEDs you want to control. There are not near enough output pins on an Arduino to directly control more than a very few LEDs, so some sort of multiplexing is required. With multiplexing, the lights are on for short periods of time. If the period of time between off and on is short enough, a given light will appear to be always on. Because the light is not on all the time, though, it will not appear as bright as one that IS on all the time.

The next thing to figure out is how you will power all the LEDs. LEDs consume current. Lots of LEDs consume lots of current. Lots of current implies big batteries. How will you supply the necessary current?

3

Thanks for the quick reply!

Im not want to conrtol every individual LED. Bascialy... some flashing text as one state a maybe a chase and a pattern.

I think about surface mount 100 LEDS myabe more? If you have a look at the video link, her tank top is run off small batteries.

Maybe i should think about just cutting it down to text only and hav that flashing ect How many LEDS ca you run off one pin?

Any other suggestions? Hardware?

Thanks very much :smiley:

4

How many LEDS can you run off one pin?

You have a limit of about 30mA per pin so if you wire them up in parallel you can run 3 LEDs at 10mA each. However there is a total current limit of 200mA for the whole chip so you can't run each pin at 30mA.
If you use a transistor as a switch you can draw more current and so have more in parallel or you can use a higher voltage and have some in series. It depends on your voltage source and how much voltage your LED drops.
By using a shift register you can expand the number of output pins you have. These can be cascaded almost indefinitely, you get 8 output pins off each shift register.
Non of those links appear to work.

5

You can try to find some "intelligent LED strips". The are still rare at the moment, and generally include a controller unit. They consit of packs of three RGB LEDs dimmed by a 10 lead controller chip, and a voltage regulator
So e.g. 50 sections = 50 controllers + 50 voltage regulators + 150 RGB LEDs

A chip used for this is:
http://www.ydsco.com/english/info/SD600_DataSheet_EN.pdf