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Thread: how can I power these led in the house?

  1. #1

    Default how can I power these led in the house?

    I have a little project to power 3-5 flickering LED to mimic flames. I'm trying to keep it as small as possible without the need to use a wall adapter. Thinking of a power circuit board or something. The spec of the LED is below. Can someone help me what I'll need? I know I'll need a resistor and a power supply circuit board of some kind. Just not sure what watt/amp I'll need.

    Color: Yellow
    Peak Wavelength: 619 nm
    Package: Round 5 mm (T-1 3/4)
    Lens type: Milky-white
    Viewing angle: 60 degrees
    Intensity: 320 mCd typ. at 20 mA
    DC forward current: 30 mA
    Forward voltage (typical): 2.10 V
    Lead-free (RoHS compliant)

  2. #2

    Default Re: how can I power these led in the house?

    Quote Originally Posted by dannieboiz View Post
    I have a little project to power 3-5 flickering LED to mimic flames. I'm trying to keep it as small as possible without the need to use a wall adapter. Thinking of a power circuit board or something. The spec of the LED is below. Can someone help me what I'll need? I know I'll need a resistor and a power supply circuit board of some kind. Just not sure what watt/amp I'll need.

    Color: Yellow
    Peak Wavelength: 619 nm
    Package: Round 5 mm (T-1 3/4)
    Lens type: Milky-white
    Viewing angle: 60 degrees
    Intensity: 320 mCd typ. at 20 mA
    DC forward current: 30 mA
    Forward voltage (typical): 2.10 V
    Lead-free (RoHS compliant)
    Often a single 5mm LED can be powered directly off a 3V button cell battery like a CR2016. The battery has enough internal resistance to keep the current down. But it won't last too long.

    My wife has a few simple LED decorations around powered by button cells but they don't last. So I end up wiring in a 3 AAA battery holder and a current limiting resistor if needed. Lasts a long time. The 3 AAA holder gets hidden behind some other knick-knack.

  3. #3

    Default Re: how can I power these led in the house?

    Quote Originally Posted by Revolvr View Post
    Often a single 5mm LED can be powered directly off a 3V button cell battery like a CR2016. The battery has enough internal resistance to keep the current down. But it won't last too long.

    My wife has a few simple LED decorations around powered by button cells but they don't last. So I end up wiring in a 3 AAA battery holder and a current limiting resistor if needed. Lasts a long time. The 3 AAA holder gets hidden behind some other knick-knack.
    Sorry I should have been more clear. It's going to be mounted in a lighted picture frame. There's a couple spots with fire in the photo that I want to highlight with a flickering LED to make it look like real flame. I want to feed 110v into a small transformer or something so it can all fit nicely behind the frame. The frame is probably 20x30 so I got some room to play with.

  4. #4
    Flashaholic* DIWdiver's Avatar
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    Default Re: how can I power these led in the house?


  5. #5

    Default Re: how can I power these led in the house?

    That's exactly what I'm looking for, I like how the second is cause it has a pigtail already so I don't need to deal with soldering.

    So do I just run an LED to them with no resistor? 2nd one say it's only good for 1 LED. Is there one I can use for multiple?

  6. #6
    Flashaholic* DIWdiver's Avatar
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    Default Re: how can I power these led in the house?

    Actually, its good for one HIGH POWER emitter. Since yours are very low power, you could power 10-15 of them from this. I would use a 140 ohm resistor in series with each LED. That should give you about 20 mA in each one, and theoretically you should be able to run 15 of them.

    If you want them brighter, use a 90.9 ohm resistor. That should get you 30 mA each, and you should be able to run 10 of them. Anything between 140 and 90.9 ohms would be suitable, and current (and brightness) is inversely proportional to resistance.

    You can get a handful of both of these resistors for less than the cost of shipping from Digikey, Mouser, Newark, or your favorite online electronics distributor. Your local Radio Shack or other dealer will be more expensive (but maybe not when you consider shipping), and won't stock as many different values (probably only 100 and 120 ohms in the range you are interested in), but they may be local.

  7. #7

    Default Re: how can I power these led in the house?

    I got all excited and was about to order it then read the review about the loud buzz this unit makes. I can't have any noise coming out of this since it's going to be installed on the wall right behind our couch. This would be totally annoying when watching a movie.

    Any other suggestion?

  8. #8
    Flashaholic* DIWdiver's Avatar
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    Default Re: how can I power these led in the house?

    Why don't you want to use a wall adapter? That's by far the simplest solution. Unless you are going to replace or recharge batteries periodically, you have to plug it in somehow.

  9. #9

    Default Re: how can I power these led in the house?

    Quote Originally Posted by DIWdiver View Post
    Why don't you want to use a wall adapter? That's by far the simplest solution. Unless you are going to replace or recharge batteries periodically, you have to plug it in somehow.
    Because behind the lighted photobox I already have t5 tubes from under cabinet fixture and there's a plug to tap into for 110v out to daisy chain more fixture. I'm using that output as the power source. I suppose what I can do is open up a wall adapter and take the guts inside.

  10. #10
    Flashaholic* DIWdiver's Avatar
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    Default Re: how can I power these led in the house?

    I guess there's still something I'm missing. If there's a plug to tap into, why not plug the wall adapter into it?

    If you really want something wired in rather than plugged, then how about a small wall adapter and a cheap extension cord. Cut the socket end off the cord, plug the adapter into it, then wire the cut end into your system.

  11. #11

    Default Re: how can I power these led in the house?

    Quote Originally Posted by dannieboiz View Post
    the loud buzz this unit makes.
    Buy a couple, try potting them? You could try epoxy, cement, liquid rubber, woodworking glue w/sawdust, just have a little box with wires coming out.

  12. #12
    Unenlightened
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    Default Re: how can I power these led in the house?

    You could use an old cell phone charger if you put a few in series.

    Quote Originally Posted by dannieboiz View Post
    I have a little project to power 3-5 flickering LED to mimic flames. I'm trying to keep it as small as possible without the need to use a wall adapter. Thinking of a power circuit board or something. The spec of the LED is below. Can someone help me what I'll need? I know I'll need a resistor and a power supply circuit board of some kind. Just not sure what watt/amp I'll need.

    Color: Yellow
    Peak Wavelength: 619 nm
    Package: Round 5 mm (T-1 3/4)
    Lens type: Milky-white
    Viewing angle: 60 degrees
    Intensity: 320 mCd typ. at 20 mA
    DC forward current: 30 mA
    Forward voltage (typical): 2.10 V
    Lead-free (RoHS compliant)

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