Picture of LilyPad Wrist Band POV
Persistence of Vision (POV) is the illusion  that an image continues to persist even though the image has changed.   In essence, we are taking advantage of the limitations of the brain-eye processing time.  With a camera we can tune our eye for a longer exposure.  The Lilypad POV (row of LEDs) is a fun toy to build with minimal programming and electronic needs.
Remove these adsRemove these ads by Signing Up

Step 1: Supplies

Picture of Supplies
 You will need:
  1. 8 LEDs (though you can use more or less, probably not less than 6 for a clear image)
  2. Lilypad Arduino 
  3. Lilypad Power Supply 
  4. Conductive thread
  5. Velcro/fastener
  6. Elastic Band

Step 2: Layout of LEDs

Choose 8 LEDs.  I am using the Lilypad Bright White LED (  You can use other LEDs but keep in mind the LEDs required forward voltage and current consumption ratings; you may have to include a resistor and/or need additional power.   

I have chosen to use output pins 6-13 and 5 as ground.  (I will explain more in the next step)

Because I am inexperienced with sewing, I first stitched everything down on a piece of fabric to be transfered later to an elastic band 
(removed by author or community request)
quasiben (author)  brent.evjen.73 days ago

Wow -- not very elegant. This is a macro which produces the length of an array. It's being used to return the number of values (elements) in the array "lilypad". sizeof(x) returns the total number of bytes in the array and sizeof(*(x)) returns the number of bytes in a single element. So we have total bytes/(byte/element)= total number of elements. perhaps if would be more clear if we wrote: (sizeof(x)/sizeof(x[0]))

Thanks! I deleted my post after I figured it out. Thanks for the response!

I've modified your code to make it work with my 10 LED POV wand. It is much better than the crappy code I wrote before. I'm not very good at arrays! The way you did it made sense to me though!

Thanks again!

Zovits4 years ago
Why did you create the ledPin6-ledPin13 variables?
They don't seem to be used anywhere.
Or is it a way to tell the Lilypad that those outputs are used to power LEDs?
quasiben (author)  Zovits4 years ago
 You're right.  I was using those variable in a previous version of the code.  I will take them out and repost.  Thanks!  For what it's worth, I am telling the Lilypad to use pins 6-13 as output using the following code:
int ledPinArray[8] = {6,7,8,9,10,11,12,13};

for(int i = 0; i < 8; i++){

Thanks for posting such a great tutorial! I am using the LilyPad USB, which has a different numbering on the pins. I have succeeded at blinking all the lights, by changing the values in the array as such:

int ground = 2; // LED connected to digital 2 "ground"
int ledPinArray[8] = {A5, A4, A3, A2, 11, 10, 9, 3};

But when I run the rest of the program, I have only two leds blinking... I am working on understanding the loop, and I think the problem is that the ledPinArray variable isn't used in the digitalWrite command in the printWord function... and since my pins are not all numerals, this is failing for me. Can you help me get my head around how the PrintWord function should look using the ledPinArray variable?  Thanks!

ugly3 years ago
I know this is an old post but can I substitute a 3v button cell for the power supply?
quasiben (author)  ugly3 years ago
Yes. I hooked up a multimeter and measured a 3mA draw for a button cell (3V CR2032) a LilyPad LED and around a 3mA draw to power a LilyPad. As a large estimate: 8*3mA=24mA+3mA=27mA. The coin cell battery has between 200and 250mAh. So you should be able to power you POV wristband between 7 and 9 hrs continuously.

This is a pretty rough estimate. The current draw will actually change over time and you can't extract all the juice in a coin cell battery. For a great discussion check out:
I can't get any of my leds to flash. Everything else turns on except the leds. did I do something wrong?
quasiben (author)  monopoly_on_372124 years ago
Did you remember to set the last pin as LOW? Do the LEDs turn on at all?
yes, so sorry, I was able to figure it out. Thanks so much! this is a great instructable.
nedim1554 years ago
please could u test this for me

Nolava4 years ago
 Could this be modified to make "Pixel Poi"?

Alerick4 years ago
Where did you buy your LEDs?
quasiben (author)  Alerick4 years ago
The leds are from sparkfun (
SirMask4 years ago
Great tutorial.  I'm teaching my kids (homeschoolers) electronics, robotics, etc.  Lots of it is new to me, although I did teach MS office, Internet, etc at one point in a traditional school (duh K-12 jail lol).  Anyway, loving this site and your posts.   
bryanbrews4 years ago
extremely cool!  I like building circuits, but this might be over my head.
Kryptonite4 years ago
This is a very cool little project, awesome piece! 5/5.
Ward_Nox4 years ago
seems like a geeky and clever way to get a girls attention at a bar
DemonDomen4 years ago
It can't be seen with the naked eye, right? You would only see the flashing lights.
quasiben (author)  DemonDomen4 years ago
Actually, you can see this with the naked eye; you just have to move fairly fast.  It does get a bit more difficult the longer the word/image is.  For example, here are some 3D globes that are spinning really really fast!  And for a great electronics POV kit visit or
nevsmom4 years ago
Where was this when I was a teenager?! Very cool.
the_gella4 years ago
 I saw this on flickr the other day, so glad you made a tutorial. Great little project!
very cool
Bongmaster4 years ago
sweet :3