Simple computer controlled lights

As many of you have mentioned, there are a lot of projects that are built with their own microprocessors, and are simply overkill. Here’s a reminder that we can do some pretty fun stuff light synchronized light shows without going overboard. This light show is controlled directly via the printer port on a computer. Sure you can’t un plug it and run it free standing, but you can build it for roughly $20.


  1. andrew says:

    waiiit a minute, why is a small microcontroller considered overkill but an entire PC is not? it should be the other way around!

  2. filc says:

    Nice, but today, who has LPT port an his PC ?

  3. calcprogrammer1 says:

    I tried this once by using an RG bi-color LED and an old P1 machine that I got for free. I was playing around with quick BASIC and got a pseudo-PWM driver to make it light up. I have a bunch of old PC’s and using the LPT port is cheaper than buying an arduino or other things that I can’t afford (arduino is $30 or so, old PC can be free at a yard sale).

  4. fartface says:

    Most everyone has a LPT port on a old outdated POS in the basement. Only someone who is like 8 years old would not have any PC without a LPT port.

  5. andrew says:

    What’s a printer port? Is that some kind of new usb specification?

  6. dirk says:

    This is interesting, but as a lighting designer, this project just feels very unfinished to me.

  7. michael says:

    This is a hack?

  8. vikki says:

    i agree with dirk, it’s a good start, it has potential, but needs refinement.

    andrew, that’s funny

  9. punmaster says:


    What if you’re 8 years old, but you still have a PC with a parallel port? And no, the answer is NOT “Don’t touch it you’ll hurt yourself.” :P

  10. hansinator says:

    well, if you think a microcontroller is overkill, then I’d like to remind you, that this project REQUIRES a computer to replicate it. Correct me if I’m wrong, but as far as I know a computer weighs in at $400+ versus an atmel microcontroller for roughly $2.

  11. davijordan says:

    just one 1 ohm resistor. Just does not seem right for safety. I would have expected more. I agree about the price of the microcontrollers. You can pick up an old motherboard for free or peanuts. Some of the original robots were built that way. McGuyver would not have ignored the motherboard.
    Good way to stay green and help save a landfill.

  12. hogiewan says:

    People are complaining that needing a computer makes it overkill, but everyone already has a computer, not everyone has the $2 microcontroller, not to mention the ease of building this over building a microcontroller project.

  13. Mythgarr says:

    The current draw from this project might well exceed the capability of USB LPT adapters. Additionally, it only saves $10 over a more functional unit with SSRs or for extra credit, some transistors and a connection to the ATX/AT power supply to supply more power than you might possibly need for a small-scale LED light show.
    Indeed, I’m using this method to build an 8-channel cubicle display for this Halloween.

  14. Haku says:

    The criticism from the “why not use a microcontroller?” crowd (me included) is that once the microcontroller is programmed for this sort of thing it becomes stand alone and doesn’t need a PC to power it.
    And it it’s a bit more portable than any PC or laptop which has a parallel port.

  15. skot123 says:

    ummm… where is the “wizards of winter” music in the backgroud?

  16. punmaster says:

    I only complain when projects like this are built on big, fancy, expensive microcontroller dev boards, or, even worse, big, fancy, expensive microcontroller dev boards that require a computer to be connected constantly while it is running. Direct-parallel (like this project) control, and standalone $2 microcontroler control are both totally fine by me. In fact, I’ve always thought directly using the parallel port as a set of GPIO pins was quite an elegant solution; certainly more elegant than an Audrino connected via USB.

  17. Alex says:

    Would it be possible to make this show HDD activity??

  18. tombola says:

    Hack a day at his worst

  19. This was featured on instructables. I already go there, need new content that I’ve never seen…

  20. Peter says:

    Old, most ppl have done this in their younger days and it’s nothing special. Why not add some circuitry to do some stuff other than toggle LED’s to make it interesting? I take it it’s a slow news day.

  21. georgegraves says:

    There is actually a surprisingly decent amount of things you can still do with a lpt port. A lot of the home made CNC machines are using a LPT port for communications to the stepper controller.

  22. RandomGuy says:

    hrm… a parallel port, eh? you could build a parallel pic programmer and use a 16f84… just sayin’…

  23. Brandon says:

    Hi, I’ve been trying to map out a lighting system similar to this. I want to apply a color changing (w/intensity control)lighting arrangement for my car. I was originally thinking RGB LED’s and a standard controller, but a computer in the car seems like a better idea. Ideas?

  24. cyberpunk64bit says:

    ===i been looking for something like this for years!!===

    …….but would it be possible to get a usb to printer(port) cable and make it via usb? if so, what would add twice as many lights! i wanna do this! (expecially if it can go usb!)

  25. Louis II says:

    Not a bad use of such parts.

    How about making a visualizer that plays LED’s mounted in/on a case/case window, or plays light panels in/on a case/case window?

    Since it is on a computer that may have network ability, put in an old wireless card, run a remote control program to access… then it’s stand alone.

    Also, complaining about recycled hardware being “overkill” by comparison to a micro-controller doesn’t seem to fit with a “hacking” mentality.
    //What are you doing on this site?//
    This is a site about //hacking// and //reusing// “old” hardware for “new” (different) things, as well as taking new hardware and doing the same to it.

  26. strider_mt2k says:


    hackaday commenting at it’s worst.

  27. Daley says:

    Granted this may not be earth-shattering or ground-breaking, but at the bare minimum it at least inspires ideas. Sure, we’ve been hooking different things to the parallel port for decades now and LED’s is nothing new. But the fact is that someone got a wild hair in a dark location and decided to do something with some old hardware they had laying around – and documented the process. Is it a hack? Define “hack”. To a beginner, this most certainly *is* a hack. To a seasoned -hacker- (those of us that have been doing this for decades), this should remind you of the joy you had when you were that aforementioned 8 year-old and discovered that you can hook a whole lot more to a parallel port than just a printer!

    I just consider this the “easy” level stuff. Then again, an EE would consider the stuff I do to be trivial. It’s all perspective. I credit the author – let’s face it, I can’t say that I have any instructables so at least they’ve got that on me. Then there’s the time spent in programming and timing the whole thing. Again, it’s not like we just sat down and wrote something like jd edwards, but nonetheless it’s an accomplishment.

  28. Daley says:

    Besides, the first word in the title is “simple”. Nobody’s claiming it’s the cure for world-hunger.

  29. dirk says:

    I personally would be interested in higher output. As it is it doesn’t really accomplish anything.

    And why not address color mixing? Set it up with banks of RGBAW cells, so that you could point it at a white wall and tone the whole thing.

    If the output can be increased (think simple transistor drivers, really up your current capability), this could rapidly become an interesting project.

    And worth noting is he’s using acrylic samples he got for free, a good alternative is theatrical gel from companies like rosco or apollo, it’ll run about eight bucks for a 24″x27″ or so sheet, and can give you a much wider variety of colors (some of which are designed for mixing and use in wash instruments such as this)

  30. Oren Beck says:

    Of course you could use multiple lpt isa cards with each one having some printer switches and the “pwm” is which ones are toggles at any one instant. and lest we forget- a led can be an optical trigger for other devices. Anyone want to try toggling one fast enough to kill a tv?

  31. JB says:

    How is a 70 cent micro overkill when a DSUB connector cost about twice as much.

  32. Chris says:

    I have been trying to find an easy way to hook up some LED’s to an old PC running Linux. I was hoping to avoid messing with a Micro-controller since this light bar will never be removed from the PC. It is testing network connectivity and displaying lights for the users, now when they call they just have to tell me which light on their desk is lit up. This article helped me find a starting point on the hardware end. Thank you.

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