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I am new to led lights. I want to make some lamps that run off ac power. My qt is what do I need to run a dc led on ac. Simple I know but I still need help. Thanks

Tags:LEDAC

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NachoMahma (author)2008-01-29

. If you are talking about mains AC (110-220VAC), then all you need is a transformer to step the voltage down and run two LEDs in parallel, with the polarity swapped on one on them. More practically, you'll probably want to use a rectifier bridge and some form of current limiting.

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tech-king (author)NachoMahma2008-01-29

i could swear i already said that. you forgot a fuse and a capacitor though.

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NachoMahma (author)tech-king2008-01-29

. Yeah, but I said it different. heehee

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NachoMahma (author)tech-king2008-01-29

. It might be! If my slightly different explanation is the one that causes the lightbulb to turn on, it's "better," isn't it? Maybe my way of phrasing things will fit better with the way s/he thinks. Maybe not. Only The Shadow knows.

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tech-king (author)NachoMahma2008-01-29

you forgot the capacitor and fuse!! how can it be better? and oscar also knows.

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NachoMahma (author)tech-king2008-01-30

. Well, if I can trigger an epiphany, then s/he can turn to you for the details. ;)
. Who's Oscar? Oscar T. Grouch?
. Fuses?!?!? We don' need no stinkin' fuses!LOL

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tech-king (author)NachoMahma2008-02-06

oscar is my lab coat. i got the idea from a sci-fi novel.

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guyfrom7up (author)2008-01-29

straight off of ac: a 1n1004 diode, and a (forgot the value) 1 W resistor. I think you might need a capacitor too so you don't see the flicker. or just take a cell charger, google led calculator, enter all the values and find a resistor

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tech-king (author)guyfrom7up2008-01-29

a wall wart transformer with and extra capacitor and zener diode would work fine i dont think 1 watt is enough to reduce 110 to 4 or so

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guyfrom7up (author)tech-king2008-01-29

I just went and to see if there's a similar circuit in my electronic book and here's what I got. take a 200volt, 0.47 uf capacitor, hook one end up to the ac. attach the other end to the led. Attach the other side of the led to a 1k ohm, 1 watt resistor. Atach the other end of the resistor to the ac. put a 1n4001 diode across the led (so it conducts when the led doesn't, they face the opposite ways.) I'd think a 1n4001 diode would break down at 120 volts, but apparently not...

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tech-king (author)guyfrom7up2008-01-30

the capacitor must be ceramic though. electrolitic one have NO tolerance of inverse voltage

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Goodhart (author)tech-king2008-01-30

Bipolar electrolytics contain two capacitors connected in series, but they do exist...

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tech-king (author)Goodhart2008-01-30

true. i was talking about standard electrolytics. like the ones at radio-sh*t

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rdy2sail (author)2008-01-30

I really love the help yall have been. Thank you very much now I know where to go to when I need help. Thanks again

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Bran (author)2008-01-28

A transformer and a very strong resistor.

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tech-king (author)Bran2008-01-29

and a diode bridge. and a fuse. and preferably some form of voltage regulator.

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rdy2sail (author)2008-01-29

Thanks Bran. I am also thinking of using an old cell phone charger.

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