Simple Music Light Show (lpt Led)




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.

Step 1: What We Need

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
parallel port connector ( I used one from old printer )
sandpapers ( 200 & 400 )

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

Step 2: Scheme & Testing

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.

Step 3: Drilling & Sanding

Let's put it together, I used chewing-gum like material to fix it in place.
And drilled about 40 holes. It is better with some vertical-fixed drill for better quality. And take it slow
with plexi-glass, or train few holes on dummy piece.

Even if you did carefully drilled all holes like me, there may be not-matching edges (foto3) after putting together. It will look better if you shape them to one line. First use 180 grid sand paper if you end with big gaps like me. Then use 250 grid. Finally you can play hour or so with number 400. Until it's looking perfect.

Step 4: Paint & Wires

Clean up all the mess from sanding.
Remove protection foil from inside side of the big pieces.
Mask it properly and paint thin line to cover cables and leds.
Wire it.

Step 5: Final Foto & Software

Put it together and we are almost done.

Connect it to pc, sometimes it flashes randomly when booting.
If you are using speedfan, uninstall it.

For programmable effects I recommend you ( first half of my final video)
LPT LED EFFECT 0.9.4.beta

there are a lot of them, this is just example, you can select another one. Just search "lpt led". It can show your cpu / memory utilization, lots of effects, etc..

For music light show, you need a winamp plugin

a simple one

Diskolitez is more customizable
and here is my settings fot diskolitez if you want to try
you can even manage up to 32 leds (or big-lights) acording to plan on

If nothing happened try if you have right parallel port adress (378) set in bios.

And if you run any OS based on the NT kernel (ie- Windows NT, 2000, or XP), you may need an additional program called Userport UserPort allows you to control hardware resources (such as a parallel port), which is normally prevented in NT except by system functions. You will need to install then run UserPort and type "0x378-0x378" in the left hand box and then click "add". Then click "start" and "update". If you get a "Driver already started!" message, just click update. Now the plugins should work.

- solution found at

Step 6: Action!

In real world is even better looking because eyes are slower than digital camera, so it is glowing nicely.

have fun, hope you like my first instructable :-]

Runner Up in the
Get the LED Out! Contest

Finalist in the
Art of Sound Contest



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    87 Discussions


    7 years ago on Introduction

    why not making it into a usb instead of the other cable because many computers don't have that connection anymore?


    7 years ago on Introduction

    can you use an ethernet cable instead of the parallel port


    9 years ago on Introduction

    It would be really cool if you made it so the LED's went on when you touched the individual plates!

    1 reply

    Reply 7 years ago on Introduction

    yeah, or make it something like this :)


    7 years ago on Introduction

    i made one aswell:


    9 years ago on Introduction

    Hey quick question, I believe I've set mine up correctly, but 2 of the 8 LED's are permantly lit up. Any suggestions?

    3 replies

    Reply 8 years ago on Introduction

    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.


    Reply 9 years ago on Introduction

    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...


    Reply 9 years ago on Introduction

    2 lights are lit up constantly. it would be approx. the middle 2. so weird. just wondering now if it might be windows 7...


    9 years ago on Step 5

    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

    1 reply

    Reply 8 years ago on Step 5

    not red blue but this also looks good. made it yesterday. very awesome instructable. = )


    8 years ago on Introduction

    Is there anyway to hook this up to a mac computer?


    8 years ago on Step 2

    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 ???


    8 years ago on Introduction

    I like this instructable sooo much i made my own version! And Made an instructable about it! :D


    Think I will try that.