Instructables
Picture of Simple music light show (lpt led)
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Really simple & cheap light-bar, powered and controlled from pc ( over lpt port ).

It will cost you something about $10-20 to build this
( I had the plexi and lpt cable for free, so I only paid $3 for led torch and $3 for nuts and bolts )

= killer raito fun for money

video in action


video from testing


In real world is even better looking because eyes are slower than digital camera, so it is glowing nicely.
 
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Step 1: What we need

Picture of What we need
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8 colorful pieces of plexi-glass ( or you can use same color, they just need to be discrete, I used 10 x 7 x 0.5 cm )
2 large pieces of transparent plexi-glass ( I used 56 x 12 x 0.3 cm )
8 leds ( I ripped them off from one $3 led torch, basically use wide angle! (with 15 or 45 degree LEDs it is looking bad, use as wide as possible ), high power, white LEDs )
bolts and nuts
black spray
wires
parallel port connector ( I used one from old printer )
hack-saw
sandpapers ( 200 & 400 )

I got the small pieces actually as testing samples from a company making plexi (plexiglass.de), they gave them to me for free. Big thanks for them :-)

Step 2: Scheme & testing

Picture of Scheme & testing
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Electrical scheme is really trivial, just connect leds to the LPT (parallel port) of your computer. Lpt outputs about 5V so if you are using white or blue high power leds you don't need resistors for them, just add 10-100 ohm for safety. ( if you are using red, green or other colors, use proper resistors acording to desired voltage, usually 200-300 ohm ). Longer feet of the led is anode (+).

I had to test if the plexi is translucent enough and if it is even working, right?

check video from testing on my desk..

In real world is even better looking because eyes are slower than digital camera, so it is glowing nicely.
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Can you make it Bluetooth so you can connect it to a phone 
karkox2 years ago
If I use this usb converter. He will work?
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guddagudda22 years ago
why not making it into a usb instead of the other cable because many computers don't have that connection anymore?
shawndur2 years ago
can you use an ethernet cable instead of the parallel port
N1CK4ND05 years ago
It would be really cool if you made it so the LED's went on when you touched the individual plates!
joudas (author)  N1CK4ND03 years ago
yeah, or make it something like this :) http://www.youtube.com/watch?v=6rCfhF-fNb4
brigs1643 years ago
is there a way to use 10 leds?
jgfresh3 years ago
i made one aswell:

http://www.youtube.com/watch?v=c3PsrWNzZPI
rens233 years ago
do want!
eptgrant5 years ago
Hey quick question, I believe I've set mine up correctly, but 2 of the 8 LED's are permantly lit up. Any suggestions?
e-vad eptgrant4 years ago
go to the settings for those two lights, and make sure the first slider isnt at 0. i had the same problem, and all i did was put them at 1.
joudas (author)  eptgrant5 years ago
you mean even if you start program or winamp plugin? 6 is working right and 2 are lit up all the time? actually never had that problem, there are random blinking during pc boot and after that it usually stays all lit up until I started program or plugin...
eptgrant joudas5 years ago
2 lights are lit up constantly. it would be approx. the middle 2. so weird. just wondering now if it might be windows 7...
wes1155 years ago
has anyone made one with all one color? im interested to see if it would look good or just blenf into a big.. blob. idk, i dont want alot of colors so i was thinking red blue red blue red blue ya know. but thnx man this looks great still not sure how to use the programs tho im not to goos at this stuff
not red blue but this also looks good. made it yesterday. very awesome instructable. = )
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Kruegem4 years ago
Is there anyway to hook this up to a mac computer?
wt will happen when we use extra LED's instead of resistors ???
like making a series of 3 LED's and connecting it to the pin ???
comsa424 years ago
I like this instructable sooo much i made my own version! And Made an instructable about it! :D http://www.instructables.com/id/LPT-BOX/
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Kruegem4 years ago
closed grit or open grit sand paper?
Think I will try that. http://www.instructables.com/id/No-solder-parallel-port-break-out/
acepilot324 years ago
could you use clear acrylic sheets with different colored LED's to get the same affect?
joudas (author)  acepilot324 years ago
probably yes, but diferent colors of leds means diferent resistor for each led to make sure they shine equaly and dont get burned from overvoltage.. and that acrylic still has to be "frosted/translucent" not just clear/transparent (if you know what I mean )
I know how to frost acrylic. Does it really matter if i use different resistors?
joudas (author)  acepilot324 years ago
try it and let us konw :)
I actually don't have a port on my computer for the computer connection so I'm going to do a static version with rgb leds
r_barnes5 years ago
where could you buy the colored plexi glass
robot+more5 years ago
could i use an USB cord
maroja5 years ago
how to connect this to the winamp..? to show the light show music..
joudas (author)  maroja5 years ago
download winamp plugin... just read the text man
Zem5 years ago
Is the parallel port connector male or female? Thanks.
osgeld Zem5 years ago
its female on the board, so you will need a male connector
yznaction5 years ago
Would it be possible to use a usb Parallel port adapter with this setup?
a usb port would require an extra piece, like a micro-controller...a Parallel port would be possible though with a similar set up (i am no expert in electricity nor I/0 ports so don't take my word as religion )
alright, i just ask because i only have usb ports on my laptop and I know there are a few companies that sell usb to 25 pin dsub parallels adapters
ahh, i would try the convertor...see what you can do
It would be more fun to create your own software . . Try using Visual Basic or Delphi.
If you're into python there's an extension called pyparallel that might help. There's a great example code here: http://pyserial.wiki.sourceforge.net/pyParallel
Couldn't agree more. I'd like to see it in plain old C though...
artiem855 years ago
This is my first project so maybe this goes without saying but I was wondering what size wire is used for the connection between the lpt cable and LEDs and how do you terminate at both the port and LED splice points?
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