LED Sign

Discussion in 'The Projects Forum' started by MrWhippyO, Dec 23, 2011.

  1. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    Hi there,
    I'm planning to make a sign to advertise my new business (Ayrshire Music Solutions). To make it more eye catching I plan to have LEDs making the shapes of the letters. This will require roughly 480 LEDs, and another separate circuit with roughly 190 LEDs. How will I wire these two circuits, preferably with a pot connected to control the brightness of the LEDs? Would series or parallel be better? And what sort of power supply would be required? Any help much appreciated! Thanks, James
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    How you wire them will kind of depend upon their wattage/current/Vf (forward voltage). If they are 5mm 20mA blue LEDs with an average Vf of 3.8v, that will be a total of 50.92 Watts. You might see the sign if it's dark outside.

    You won't be able to use a simple potentiometer to dim the LEDs; you'll need to use PWM or other method of current limiting.

    You might like to have a "movie marquee" effect, which would make the LEDs look like they are moving. That would also reduce your average power consumption by 1/3. The wiring would get a bit more complex though.

    But first, you'll need to decide on your LEDs, and how you're going to try to keep them cool. If they are some of those high-power 1W to 5W LEDs, you'll have a lot of heat to dissipate.

    You'll also have to be concerned with the illumination pattern of the LEDs. If the sign is going to be placed on a pole above people, then you want the light pattern to be mostly down, and fairly wide. Most LEDs that you find nowadays are focused very narrowly, which means that if you bought a pile of LEDs already, you probably won't be happy with how they look when it's done. You may need to experiment with re-shaping the lens using a buffing wheel.

    Your site says absolutely nothing about where you are. You could be in the UK, in Canada, the States, Africa, Australia or anywhere else that English is the predominant language. Having a reservation from far away won't help you at all.
     
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  3. Wendy

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  4. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    Would wide-angle LED's work better then? The sign itself would usually be in front of the table where the equipment would be set up. I want the sign to be clearly read from a decent distance. I don't mind doing complex wiring as long as I know what I'm doing, would that moving effect require any IC's though?
    Thanks for the quick replies.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Hitting every LED on a belt sander would do the trick as well, take off the round lens part, but then the apparent brightness goes down a bit.

    I'd suggest adding EL Wire or thin neon if the sign isn't bright enough, let the LEDs add a bit of movement to attract attention, but the neon give the information without eye strain.

    Also: Pay to get a professional site built after buying a domain name. Most people find stuff on the net these days, and yours needs... improvement.
     
  6. SgtWookie

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    Jul 17, 2007
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    Moderately wide angle. You don't want the 15° to 25° focus, because when you are slightly off-center from the LED at a distance, you can barely see them - and once you're in line, they are far too bright.

    The moving effect would require ICs and a few MOSFETs. Not much added, perhaps a dozen extra parts. Compared to 670 LEDs, that's a drop in the bucket. But, it really depends on what kind of look you want.

    If you were really industrious, you could make a spectrum analyzer out of it. That would take a bit longer, of course.
     
  7. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    I thought LEDs would be best because they are most efficient, so would another form of lighting display the name more clearly?
    Thanks.
     
  8. MrWhippyO

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    Dec 23, 2011
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    I have been looking around to see if I can get a decent deal on having the site professionally done, hopefully it will be done in the not so distant future!
     
  9. SgtWookie

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    LEDs ARE very efficient compared to incandescent. Fluorescent lighting is pretty efficient, too - but you probably don't want to be dragging a FL around in a vehicle.

    Thatoneguy came up with some interesting ideas with the EL wire and the thin neon. You might have a look at those.
     
  10. MrWhippyO

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    Dec 23, 2011
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    My only concern with EL wire is getting to fit the shapes of the letters clearly and make sure lines are straight curves are smooth etc, so it doesn't have that "homemade" look about it, I do like the idea of creating flashing or moving patterns in the LED's, it would look more professional.
     
  11. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Lay it out first, then go slowly, with cyanoacrylate glue and accelerator, tacking spots, then filling in curves once the shape is correct. Straight lines - Glue down one side, pull it straight, tack down that end - viola! Straight line! Then go back and glue the rest. You can do the same thing with slow drying glue, or 30 minute epoxy, and that might be a good thing to add once the shape is set.

    practice with a piece of string on cardboard a few times before you do the actual layout. A Neon company would do the layout perfectly, that's their job.

    Look at this, mute the music, and just have the LEDs go in a "music pattern" that pretty much everybody recognizes.
    http://www.youtube.com/watch?v=9M5OOPE06x4

    Drilling several hundred holes in the right places sounds more daunting to me. :p
     
    Last edited: Dec 23, 2011
  12. John P

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    Oct 14, 2008
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    EL wire produces very little light; next to LEDs you'll hardly see it.
     
  13. thatoneguy

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    Then ask about for a thin neon solution. The outside/exterior/weather side would need to be encased in plexiglass anyway, no hard corners, heat and make smooth curves for sheet to come back into contact with surface, usually 4 people with straight edges and heat guns to make it professional.
     
  14. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    Would flat top LEDs be more easily read? Do they have the same ratings as ordinary LEDs? And what sort of supply would nearly 700 LEDs need to be bright?
     
  15. thatoneguy

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    If you purchase flat topped LEDs, they might have a fresnel lens, which makes their viewing angle very bad.

    What you should look for is called "Diffused" water clear for the case, but they aren't extremely common.
     
  16. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    I am planning to have "AMS" in red LEDs and "Ayrshire Music Solutions" in blue LEDs
    Is this the sort of thing that would work for the Blues? Here

    And this sort of thing for the red LEDs. Here

    When I post this it will be the 25th here in Scotland so Merry Christmas!
     
  17. thatoneguy

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    Those should work, but be aware that large lots from eBay typically do not always match in brightness, and a couple in every batch are often bad.

    This isn't normally an issue, unless they are spaced closely together.

    If you are on a budget, those are probably your only choice, however.
     
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  18. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    So what in the way of circuitry would I need to make all the LEDs appear to be moving and does anyone have a schematic of any circuits that would work?
     
  19. SgtWookie

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    I've attached a schematic I put together for someone a couple of years ago.

    Basically, it's just a 555 timer, a 4017 Johnson counter, and some P-ch power MOSFETs to switch the LEDs on and off.

    I just show a few LEDs. You would have quite a few connected. The MOSFETs shown probably wound not be adequate for the number of LEDs you want to operate.

    Two of the MOSFETs (Q1, Q2, Q3) are on at any one time; the other is off. The MOSFETs are constantly being turned on and off in sequence to create the illusion of motion.
     
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  20. MrWhippyO

    Thread Starter New Member

    Dec 23, 2011
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    What sort of power supply would be used for this? Would a 12V DC transformer from an old Netgear router be good enough for the LEDs to be bright?
     
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