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I have strips of 12 volt DC LED's that can be cut into groups of three that I am using to light buildings on a model railroad and am happy with the results. I can vary the voltage from about 6 to 12 depending on lighting needs for a specific building. I was surprised to learn that all these strips also work using the same voltage but in AC. Using AC to power these LED's would save me a lot of extra wiring.

Will running these LED's on AC harm them?

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    You can just convert to DC at the end of your run of wire, that would save rewiring. Depending on the frequency of the AC, a few diodes and maybe a capacitor could be a quick fix. – Jason Aug 5 '13 at 17:36
  • It may be fine, but I would find the 50/60 Hz flashing annoying. – Brad Gilbert Aug 6 '13 at 5:31
  • Look at the LED strips in the very edge of your peripheral vision. That's where the flicker is the most apparent, but still some people can see it more than others. – JPhi1618 Feb 22 at 15:56
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Depending on the type of LED element and the driver circuit, you could either be fine or significantly shortening the lifespan of your lights. If the instructions or markings don't indicate that AC is acceptable then it's probably not.

However, a failure is not likely to be dangerous or cause a fire.

So you have to decide if the hassle of replacing burned out LED lighting later outweighs the hassle of giving it the proper power now.

  • +1 LEDs are diodes that pass current only in one direction. On AC they are lighting half the time, but you cannot see this because of persistence of vision (the effect that makes movies move). The LEDs themselves would probably not be hurt assuming the voltage was in range. The other circuits tied to the LEDs are a different matter. – bib Aug 5 '13 at 17:20
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    @bib it depends on the breakdown voltage of the LED. Cheap ones usually have a breakdown vvoltage that is about the same as their typical operating voltage, sometimes less. If you bump up against that limit a lot, that can put a lot of stress on the LED. – longneck Aug 5 '13 at 17:25
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If you didn't need the color changing box I'd say no problem. I have landscape lights that run 12VAC and changed the bulbs over to LEDs way before anyone had thought of it. They have been in there for probably 7 years with not one failure. The little box that runs the remote is a different story. It may or may not work right, but I don't think the LEDs themselves care if it's AC or DC. I've run 12" single color LEDs on 12VAC with no problem.

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Led's do care. The breakdown voltage is usually much lower in the forward bias old school prior to Lgas led's would have approx .6v breakdown forward bias and 1.7v reverse bias. In either direction if the heat dissipation capability of the diode was exceeded the led was destroyed so putting a 30ma diode in a circuit backward usually instantly blew the diode. You would need to know the breakdown voltage before trying or your leds may flash and be damaged. ( If you let the magic smoke out they won't work until you can put it back in, find a way to put it back in and you will be rich$)

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I replace an alarm clock buzzer that was getting 11vAC with a short LED strip 2 years ago, all still good. (I have a dark room that faces North, the light helps feeling awake, often only need that and have it set to go off 10 minutes before other alarm).

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I took my broken Milwaukee radio apart and have a 15v AC transformer powering 10 ft of LED DC tape light.

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