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Thread: LED resistor?

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    LED resistor?

    I'm not sure what part of the forum to post this on, but

    I have some small circuit boards that have 4, 3014 LEDs wired in parallel (these are SMDs) When choosing a resistor for these, can I treat the whole board as a single LED with 4 X the forward current of a single 3014 LED and the same voltage as a single 3014?

    Thanks

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    Lifetime Member Enzo's Avatar
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    Yes.

    If I have four LEDs, I usually run them in series, letting the same 10ma (or whateever)of current light them all.

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    Supporting Member The Dude's Avatar
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    The way I read it, they are on little circuit boards and already paralleled, but maybe I'm wrong. As to the original question, I'd say yes.

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    Lifetime Member Enzo's Avatar
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    I think you are right, I just added the series thing for someone starting from scratch.

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    Thanks guys. I thought that was correct, but wasn't sure.

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    Old Timer J M Fahey's Avatar
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    In theory each Led should have its own current controlling resistor because otherwise the one with lower voltage threshold mau hog current from others in parallel.

    In practice, if all Leds are from same batch, they are even enough to light close enough even if in parallel and sharing a single resistor.

    At least within the same batch; modern electronic components are incredibly consistent.

    Now if different colour, they DO need individual resistors or else.

    In fact there is a common designer trick which I also use: I turn a Green Led ON (to indicate clean channel) and when activating the Distortion channel I just activate a Red Led in parallel with it.

    Not only Red lights full power but hogs most current so Green (even more Yellow or Blue or White)) turn off at the same time, without any dedicated circuit to do so, just relying on difference in turn on voltage, go figure.

    In fact, Green does not turn FULLY OFF, it still shines very weakly, but on normal Stage conditions it is invisible, overcome by the strong Red one.

    That said, the typical bedroom warrior is usually annally obsessive and complains about it, so in that case I add a 1N4002 in series with Green to ensure it does not light at all.
    Delights of modern customers.

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    Juan Manuel Fahey

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    These are all blue, salvaged from a Toyota add
    Click image for larger version. 

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    I'm building an ABY pedal in a small canned ham can, with a plexiglass bottom. The LEDs will light different areas of the base depending on what mode it is in. Just for fun

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    Old Timer Leo_Gnardo's Avatar
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    Quote Originally Posted by dmartn149 View Post
    These are all blue, salvaged from a Toyota add

    I'm building an ABY pedal in a small canned ham can, with a plexiglass bottom. The LEDs will light different areas of the base depending on what mode it is in. Just for fun
    LED's look sorta purple in the photo, very kool if that's the real color, besides that's some fancy ad, for a Camry. I think it's terrific you're recycling the LEDs and the ham can. Make sure you post photos of the build, this oughta be a lot of fun all right. Have you thought up an amusing name for your pedal-to-be yet?

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    Supporting Member The Dude's Avatar
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    Quote Originally Posted by Leo_Gnardo View Post
    ......Have you thought up an amusing name for your pedal-to-be yet?
    How about the "Canry"?

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    Quote Originally Posted by Leo_Gnardo View Post
    LED's look sorta purple in the photo, very kool if that's the real color, besides that's some fancy ad, for a Camry. I think it's terrific you're recycling the LEDs and the ham can. Make sure you post photos of the build, this oughta be a lot of fun all right. Have you thought up an amusing name for your pedal-to-be yet?
    No, they are really bright blue (electric blue?) I had saved the add because of the LEDs, though I didn't know what I was going to do with them. Then I cooked this small ham that had been in the pantry for a long time, and realized that the can was pretty sturdy, and a good size for a pedal. Started thinking how to close the bottom, and thought of the plexy that was in the garage, then remembered the LEDs. I don't think I'll name it. It's only an ABY switch.

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    Old Timer Leo_Gnardo's Avatar
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    Quote Originally Posted by dmartn149 View Post
    I don't think I'll name it. It's only an ABY switch.
    Good story. You'll always remember that ham dinner, yum.

    One last pitch then, a "character" from Young Frankenstein, though it was just a brain. In a jar. ABY Normal.

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