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Displays Hardware Hacking Build

DIY LED Array Marquee For Your PC 128

An anonymous reader writes "Ever wish you had one of those big LED displays to keep you up to date on e-mails, stock quotes, server uptimes, or weather? Here's a new video tutorial showing how to build your own computer-controlled LED array. You can code your own data feed, and just send it over a TCP socket. This looks like a fun weekend project for someone looking to get started with electronics by building something useful."
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DIY LED Array Marquee For Your PC

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  • Now... (Score:5, Interesting)

    by Spazztastic ( 814296 ) <spazztastic@gmai ... minus herbivore> on Friday January 23, 2009 @02:24PM (#26577993)
    The question is if I can do this and have it run from my car. I put in predefined phrases, and depending on which switch I hit or button, it says them?
    • I only need a bumper sticker that says:
      Pass or Move Right

      I have thought about others but living in the "Bible Belt", I would have likely gotten my car keyed.

    • There are actually already license plate frames with little LED displays built in that allow you to do this.
    • The question is if I can do this and have it run from my car. I put in predefined phrases, and depending on which switch I hit or button, it says them?

      Sure. Let's say you put mount this thing on your car someway, and put a server in the trunk, running off a power inverter hacked into the vehicles 12-volt power. You then run a serial line from there to the microcontroller and wiring to the LED sign, which also must be hooked into the vehicles 12-Volt in someway. The server is hooked to wifi, either adhoc or through a WAP in the trunk along with it.

      Then, you have a laptop in the front seat. You get yourself one of those keyboard macro thingies, and hook

      • running off a power inverter hacked into the vehicles 12-volt power

        No need to hack. They already have DC Power Supplies just for this purpose: [] []

        • Re: (Score:3, Informative)

          by petermgreen ( 876956 )

          If you do use a DC psu make sure you buy one that is explicitly designed for use with automotive power. Automotive power while "nominally" 12V has a wide voltage range depending on current conditions (whether the engine is running, if so how fast, if not the condition of the battery etc)

          • I am glad you pointed this out!

            Automotive electrical systems are designed around the concept of variable voltages, with a wider range than most computers.*

            It's not uncommon (actually designed this way) for your '12 VDC' auto electrical system to vary between 13.6VDC-11.8VDC. (11.8 may be stretching the low end, but have have started my vehicle with low of 11.2VDC a few years back---I will gladly pass the baton here)

            Most computers desire a more stable electrical environment than the usual auto can provide as

            • It's not uncommon (actually designed this way) for your '12 VDC' auto electrical system to vary between 13.6VDC-11.8VDC. (11.8 may be stretching the low end, but have have started my vehicle with low of 11.2VDC a few years back---I will gladly pass the baton here)
              I was under the impression that many cars had a much wider band of variation that that.

              And then there is the ignition system which can put pretty big spikes and dips in the supply.

              As you say it's not an insurmountable problem but you certainly do n

    • Re: (Score:2, Informative)

      by Anarkhia ( 2342 )

      Here you go: []

      I've been thinking about one of these, but am a little worried that I'll end up getting shot or something when I piss off some idiot with a gun in the glovebox.

      • by SkyDude ( 919251 )

        I've been thinking about one of these, but am a little worried that I'll end up getting shot or something when I piss off some idiot with a gun in the glovebox.

        Don't worry, I won't shoot you. My permit is for hunting only.

    • Re:Now... (Score:5, Informative)

      by Lumpy ( 12016 ) on Friday January 23, 2009 @02:49PM (#26578465) Homepage

      Yes but be ready for a ticket and a "fix it ticket" to require removal of said device. Most states make it illegal for a illuminated sign to be in view of drivers on a moving vehicle. TAXI's and delivery cars have a waiver and the signs are not in the line of sight.

      • Well then, let's get a howto for making a mechanical sign. You know, like the signs made out of spinning, clacking scrabble pieces they used in train stations before LCD/LED tech (and still use in Europe)?

        That would be awesome for both in-car use and the general steampunk feel.

      • So a HUD would be illegal?

    • Re: (Score:3, Funny)

      by Anonymous Coward
      I totally want to do this. So I can verbalize my frustrations with other drivers. Because right now all I have are Brights, Flash Brights, Honk, and Finger. Everything else seems to not get recognized. It would be great to ask people to pleas move out of the left lane. Request blinker changes. And comment on driving skill levels.
      • Yes, the immediate temptation is to mount this thing on our cars, so we can "communicate" with other drivers, who often are badly in need of a little more information. But we all know that are at least as many drivers out there who will act like butt-heads despite being made aware of their condition. Indeed, some will go out of their way to ratchet up their anti-social behavior.

        No. What we need is a DIY tool that can forcefully terminate the offending behavior. Then engineering specifics are left to the g

        • Re:Now... (Score:4, Funny)

          by onkelonkel ( 560274 ) on Friday January 23, 2009 @05:04PM (#26580745)
          Caltrops. A big bag of them. Scatter behind your car to discourage tailgaters and those guys with jacked up trucks sporting 2 squillion candlepower fog lights. A bit indiscriminate, and somewhat low tech but definitely effective

          Emp Gun. RF generating parts well shielded, waveguide pointing forward from under the hood. Somebody doing 50 in the passing lane? Push the big red button. Oh look, they're pulling over. Funny thing, no turn signals.
      • Car 1: Excuse me, I'd like to express my displeeeee...
        Car 2 speeds off into the distance

        Car 1 (Catching up): ...eeeeeeaaaaasure at having been subjected to your most egreee...
        Car 2 again speeds off.

        Car 1 (Catching up again):...eeegious overtaking maneouvre.
        Car 2 speeds off.

        Sometimes the finger is more appropriate. As a more eloquent, or at least, more quotable man than I once said:

        "Profanity is the crutch of the inarticulate, but every now and ag

      • by Mal-2 ( 675116 )

        All I need are two messages, one for the front (reversed so they can read it in the mirror) and one for the back. The one in front would say "YOUR BRAKE LIGHTS ARE BROKEN" (because this is the single most common and most dangerous condition I see that drivers would not be aware of), and the one in back would merely say "WTF". Tailgating? High beams on? I would hit a switch and the "WTF" sign becomes a fourth brake light.

        While I will probably never get around to the lit brake light sign (I might well make a

    • I picked up a kit at wal-mart that is designed for car use. It's a nice case with swivel feet (to allow hanging or standing mount) and comes with a remote control. Best of all, it was less than $20

      The handy part of this device is that it has 8 memory locations for user-defined messages. Here are my saved messages.

      1. Are you my proctologist? GET OUT OF MY ASS!
      2. Got Low Beams? You're blinding me!
      3. Your left turn signal is STILL on!
      4. Your right turn signal is STILL on!

      The other 4 slots remain empty unt

      • by deroby ( 568773 )

        * Where did the fog go ? (for those eejits that have their (rear) fog-lights on even when it was sunny all week)
        * I can't see you ! (for those that forget to turn any light on (*))
        * Your braking-lights are broken (can be very surprising when they suddenly come to a stop in front of you)
        * Your indicator is broken (for those that switch lane etc without using the indicator... not sure they'd get it though =)

        Et-voilÃ, 4 useful messages which all of them I've been willing to pass to my fellow road users at

      • 5. Don't tailgate - the end is near!
      • I just bagged a Call Center matrix display unit off ebay for £20!

        Mind you, it's 1.5M long!

      • 5. Such a nice shiny car. Too bad the turn signal is broken.
        6. They must let just anyone have a license

        I'm tapped.
        • For the people who have ridiculously loud subwoofers, installed in such a way as to cause outlandish vibrations, rattlings, and resonances, all of which annoy bystanders *and* decrease the sound quality to passengers of the vehicle (what's the point in volume when the bass drum comes out sounding like someone is kicking a steel trash can?), or who have modified their engine/catalytic-converter/muffler/exhaust-piping to make their cars make obnoxiously loud buzzing noises (I guess to sound like a motorcycle?

    • Sure, you can, but be careful. Department of Transportation has pretty strict rules about what kinds of lighting you can legally have on your vehicle.

      Having a *ahem* friend who experienced problems with law enforcement over a very similar deployment to the one you're envisioning, I'd simply recommend caution.

      Then again, the policies and practices of highway patrol / law enforcement in your state may vary. IANAL. This is not legal advice. Etc.

    • You can get scrolling marquee licence plate holders. [] This is just the first link I found, I have seen them cheaper at places like Canadian Tire (which will probably confuse 98 per cent of readers here). But they do exist.

      Still, making my own would be fun, I could put it up on the wall of my cubicle and do Facebook-style status updates with it. "Jabbrwokk is picking his nose and flicking it at the back of Jeff's head."

    • by S-100 ( 1295224 )
      Yeah, on eBay for less than $40. Half the cost of the controller alone in the "geek" version from TFA.
    • toy from Ideal. I bought one for my daughter in 1981(!) it was a hand-held wand that you would wave to-and-fro, and a row of LED's would leave a message of up to 40 characters scrolling by in mid air. The penultimate night-time road rage instigater
    • by Ihmhi ( 1206036 )

      I want one that says GHOSTBUSTERS on it.

      Next weekend, rigging up a dozen sets of sirens and an annoying horn to your station wagon!

  • Yes but... (Score:4, Funny)

    by senatosa ( 1453155 ) on Friday January 23, 2009 @02:24PM (#26577999)
    can we get it to synch to Trans-siberian Orchestra's Wizards in Winter?
  • What will really help this technology take off is if it's able to convert your porn into an LED display. Stick figure porn FTW!
    • Re: (Score:2, Insightful)

      by senatosa ( 1453155 )
      yeah but then you'd have self esteem issues because every stick of the stick figure would be the same size...
  • by thomasdz ( 178114 ) on Friday January 23, 2009 @02:33PM (#26578153)

    I know LEDs are all the big rage now for displays. You see the seven-segment LED displays on calculators. But, while watching TV a year ago, I had an idea... what if I were to somehow connect up a TV to my computer? It took me a couple months, but I finally got it working... yes, a TV screen (well, actually it's not a TV anymore since I had to take out the receiver guts) connected to a computer. Since I use it to MONITOR the status of the various programs running on the computer, I'm going to call this contraption a "Monitor"
    I'll make millions!
    Also...I was out in my garage the other day cleaning and I found a dead mouse in the corner...and again, my mind is always working... I though...what would happen if I plugged this little guy's tail into the back of my computer, and replaced his legs with little motion-sensing wheels? I'll let you alll know the results when I finish my new invention. I'm calling it the Mobile Organic Universal Sensor Emulator, or MOUSE for short.

  • But without seeing the article it's fairly safe to assume this involves a microcontroller. I'm guessing an AVR -that's what I'd use, and people have been able to put together TCP interfaces on 'em.

    Considering that, I doubt I'd consider this as a good project to 'get started' with electronics. Or microcontrollers even.. AVR's STK500 'starter kit' is a rather nice, if a bit pricey. (I've heard the Basic Stamp system is beginner-oriented. I have no experience with them though)

    It's still sounds like a fun kit t

  • It's so cute... (Score:5, Informative)

    by Majik Sheff ( 930627 ) on Friday January 23, 2009 @03:00PM (#26578629) Journal

    I remember when I first realized that you could double your row-column population. Then I extrapolated it to its logical conclusion... that you could connect n(n-1) leds where n is the number of control lines. I was so proud! Then in an unrelated search I learned that not only was this an established technique, but it even had a cute name: Charlieplexing.

    There's a neat little story here: []

  • Low intensity??? (Score:3, Insightful)

    by spectrokid ( 660550 ) on Friday January 23, 2009 @03:02PM (#26578653) Homepage
    They have a lot more LEDs than controller outputs and use tricks to multiplex. But this means each LED only is turned on for a few milliseconds at a time. Can you get out a reasonable intensity this way?
    • by Smidge204 ( 605297 ) on Friday January 23, 2009 @03:22PM (#26579025) Journal

      Sure, just up the current. The LEDs will be brighter for a shorter duration and it will look the same.

      Not sure I like the idea of draining so much current through the uC though...

    • by jhfry ( 829244 )

      Not if you scale it beyond a certain level... as stated in the article, the author feels that this particular arrangement allows for good intensity.

      You could, theoretically, use capacitors to increase the intensity.

      Additionally, if you wanted to use multiple or a more powerful controller you could do that too.

      Like with any electronic design, there are sacrifices to be made to keep things simple.

      • I was thinking about this. (Also, not being an electrical engineer by any means.) Could you place a relatively small capacitor on each LED to increase the burn time?

        • by jhfry ( 829244 )

          Surely you could... might have to make some design adjustments but I can't see why you couldn't use a cap to smooth out some of the (imperceptible) flicker that makes the LEDs dimmer.

          However, you would need on cap for every LED... and the result may not be worth the effort. There are surely cheaper ways. Like buying a controller with more outputs, increasing the number of LED's that can be illuminated at the same time, thus increasing the amount of time that can be spent illuminating each LED.

          • by hvdh ( 1447205 )
            A cap per LED is a bad idea. It had to be in parallel to the LED (bridging the LED diode), so you'd need another diode per LED. It might reduce flicker somewhat, but the peak current will be even higher as it has to light the LED and load the cap. This multiplexing scheme already is limited by pin current at the microcontroller, so you don't gain brightness.

            There are surely cheaper ways. Like buying a controller with more outputs, increasing the number of LED's that can be illuminated at the same time, thus increasing the amount of time that can be spent illuminating each LED.

            You also could add some cheap latch ICs (74LS373, 20 cents in single quantities here) to make a lot of digital outputs (though not tristate ones). Th

  • Small version (Score:3, Interesting)

    by Hogwash McFly ( 678207 ) on Friday January 23, 2009 @03:02PM (#26578655)

    My boss gave me a USB-powered LED screen as a Christmas present, aimed as one of those endless throwaway novelty USB gadgets (other one was a whack-a-mole game. It's far smaller than the one in TFA though, about the size of a pack of smokes. Still, it scrolls text and displays bitmaps pretty niftily. The font and configuration files are stored in plain text (the scroll speed was a fun one to tweak) so the option for even-triggered (e.g. server in trouble) scripting is there.

    Granted, there's no geek cred from building it yourself, but at least the soft aspect is similar. Now if only there support calls would stop coming in so fast that I had time to play with the thing...

  • Pinball games uses the same row-column setup to drive lights and read switches.

  • by compumike ( 454538 ) on Friday January 23, 2009 @03:03PM (#26578677) Homepage

    Hi all,

    We had tuned the [] site to survive slashdottings with its old PHP backend, but we recently started experimenting with some Django []. Django is great as a programming framework, but I suppose we have discovered that our tuning of the server settings isn't quite up to handling a Slashdotting! We've temporarily disabled that stuff so the site is back and running. My apologies for the downtime.

    - The NerdKits Team

  • Put this at the beginning after s is assigned, to reduce the time you have to wait between restarts for old connections to go away.

      s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

  • by jtara ( 133429 ) on Friday January 23, 2009 @03:08PM (#26578775)

    I wrote the firmware for one of these thingies about 20 years ago. (I did it for a company that was in the electronic sign business - they made those flip-dot signs you see on buses, subways, etc.) I was lucky to have been given pretty-much complete flexibility in the firmware design, including functionality.

    We used a Z-80 as the controller. The display panel was built on two identical circuit boards - they could be chained endlessly, though I don't think they ever made a wider model. It was a BIG DEAL getting the component-stuffing machine to place all those LEDs! (This wasn't surface mount, but through-holes.)

    Each display panel had a shift-register - one bit per column, and just passed the bits down to the next panel. The CPU banged out bits to the shift register until the row was filled, and then enabled the row driver. Yes, we were careful to avoid refresh rates that could be a problem for epileptics.

    They insisted on an asymmetrical case design - the case had a "base" that it could sit on on a desk or other surface, or it could be mounted from a ceiling. Only problem was, if it was mounted from a ceiling, it was then "upside down" and the characters had to be flipped. They were going to put a switch on the back, but I figured they would get support calls from people who wouldn't read the manual, so at my suggestion they put in a mercury switch, mounted at a 45 degree angle. The processor read the mercury switch and flipped the characters if needed.

    We used an RCA flat-panel keyboard with a custom overlay. I designed icons for the various effects, and the icons were printed over letters and accessed during programming with the "ALT" key. The icons appeared on screen when in programming mode. There was a simple text-editor, and some icons accepted parameters (for example, transition effects all took an optional transition time parameter) I implemented a simple macro system [macro_name] so that text snippets could be stored and referenced from within messages. You could store multiple messages and select the one or ones to be displayed, or a timer could trigger them.

    There was also a serial port through which it could be programmed. I think the idea was that it could be programmed remotely in, say, a store location. I don't know if this was ever implemented, but I vaguely recall that the idea was to send a subcarrier signal on a muzak station (that stores would already have access to) that would be decoded and passed to the serial port.

    I never did install one of these in the back window of my car. I certainly entertained the thought, though. :)

    I had one of the pre-production samples kicking around for years, and finally discarded it. Yea, I wish I still had that Schelbi Mark 8 too... (Mine was build on a wirewrap board - somebody was selling a kit with a wirewrap board and all the parts).

    (Would be interesting to compare the designs. However, the site referenced by the article has been slashdotted...)

    • Re: (Score:3, Informative)

      by jtara ( 133429 )

      To clarify, each display board had a number of serial-in parallel-out TTL shift registers across the top of the board. The parallel outputs went to latches (or maybe the shift registers had latched outputs?) which went to the column drivers. I think there were about 800 LEDs total on the two boards, so quite a bit larger display than this kit! The addressing technique used by the kit would be impractical for this size of display.

      It would bang out the bits, latch the outputs, turn on the row driver, and star

    • Re: (Score:3, Funny)

      Excellent...that way, if the bus ever flipped over, one would still be able to read where it was going to know whether they needed to call a taxi or just keep waiting.
      Well done!
  • by British ( 51765 )

    I can have a wall of these LEDs randomly blinking, then my computer room looks like some "secret headquarters" with big monoliths of useless lights, just like in science fiction films of yesteryear. Now only if I could get that sound loop of the "computer beeping" stock audio it would be complete. Maybe a tractor feed printer on a stand, aww yeah.

  • Shame the TCP/IP stack isn't on the microcontroller. Putting uIP on there, or grabbing bits from my stack ( would be awesome.

  • by linhux ( 104645 ) on Friday January 23, 2009 @03:55PM (#26579509) Homepage

    "Ever wish you had one of those big LED displays to keep you up to date on e-mails, stock quotes, server uptimes, or weather?

    Yeah, I used to wish exactly that, but I took the easy (well, I did have to reverse-engineer the serial protocol, but that was fairly easy) way out and went to the hardware store and bought one. It's been serving my team very well since then []. :-)

  • I suppose it has a nostalgic "cool factor" as far as building it from scratch and all, but in terms of money spent and the practicality of the end result, why not just use existing technology? Such as those fancy multi-row mini-LCD displays and hook it up to lcdproc []? I did, and I love it. Crystalfontz 20x4 blue-backlit display with network, temps, weather, slashdot... whatever I want.
  • from 10 16x16x(red, green) modules. Problematic was the (theoretical) current required to drive the whole assemblage: 512 * 10 * 20mA = 102 Ampere, at 5 Volt is 512 Watts Although I'm not really sure whether the modules were even able to fully light all LEDs at once, they had a built in shift register. At first I wired them directly to my parallel port and later wanted to wire an Atmega32 to it, but caused a short while playing around, bricking the development board. The modules rest in my basement, since
    • by heeen ( 1245200 )
      Just checked the Datasheets to the modules (Samsung SLM1606), current supply is 3.2 Ampere per module, which sums up to 160 Watts for a 32x80 pixel display, which puts a PC power supply under some stress.
  • I'm starting to see more & more DIY hardware articles on this site, articles that are perfectly at home on and more suited to Revision3's Systm,, & - which incedentally is where I first saw this DIY LED array (hackedgadgets).

    So is slashdot becomming yet another "Look At What You Can Build If You Have Teh Mad Hacking Skillz!!!11!!" site or what?
    • by Tokerat ( 150341 )
      Considering many new users on Slashdot have problems with the concept of how a capacitor works, I think they're trying to encourage people to once again learn how to build electronics. Being a geek used to be about soldering and assembly language, but most people these days stop at, say JavaScript. We're going to need people who understand the bits before we can keep inventing new uses for the objects.
  • If you like playing with LEDs, follow the Hack A Day [] blog. At least once a week, there's a post involving home-brew LED projects, some of them quite massive and/or impressive. For instance,

  • The first thing I do with newly set up browsers (user interfaces in general) is to disable marquee.. blinking and then ads. I hate those things. They are distracting me and are hell of annoying. So why exactly should I want to put a huge marquee on my desk?
  • by NixieBunny ( 859050 ) on Friday January 23, 2009 @07:19PM (#26582811) Homepage

    I found a couple hundred big 8x8 matrix LED displays on ebay for way too little money last year, and I'm working on a low-resolution but huge flat TV for video fun at Burning Man this summer.

    But I'm going with a standard video signal such as your DVD player makes, so it will display shades of gray for realistic reproduction of video images.

    It's a bit tricky to make a TV display out of LEDs, but I found that using a couple dozen FPGAs makes the job a lot easier. Pulse width modulation provides the brightness control per pixel.

    It should be a lot of fun when completed. I';ll post photos.

  • Making something that's been around a long, long, long time, and acting as if it's 'new' or 'improved'.

    Wake me when someone does something impressive, and get off my lawn.

  • So the question is, if you're buying a MCU kit from a company, how is this a DIY project?
  • I developed a Windows program which works with Betabrite signs. The USB connected LED-signs and software are available at: []

    I use it to show news, weather, and friend-updates.

    It has some side features such as generating marquee HTML, wml, etc., so you don't immediately need an LED-sign to use the software.

    There's also some free software available for that brand of LED-sign at: []

  • Wouldn't it be easier just to find a surplus beat up LED sign with a serial port and write a script to handle the updates? A lot of them have serial ports and they can be found on the cheap.

    This is an awesome homebrew DIY project though, I'm just kinda lazy.

  • Ever wish you had one of those big LED displays to keep you up to date on e-mails, stock quotes, server uptimes, or weather?

    No, of course I haven't. People actually buy those things? What the hell is wrong with people?

  • It must be hard to get excited about learning electronics these days. When I was building stuff in high school (late 80's) part of the fun was that I could make things that I couldn't readily go out and buy... or that didn't exist. A little later with an early micro-controller I could put a computer in a tiny box and build brains into anything I wanted... something new.

    Now everything's been pushed down a level and this project almost seems more like an exercise than a real project... It makes me kind of

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