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A/C L E D Answered

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
NachoMahma

13 years ago

. 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
tech-king

Reply 13 years ago

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

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NachoMahma
NachoMahma

Reply 13 years ago

. Yeah, but I said it different. heehee

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tech-king
tech-king

Reply 13 years ago

but not better!!

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NachoMahma
NachoMahma

Reply 13 years ago

. 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
tech-king

Reply 13 years ago

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

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tech-king
tech-king

Reply 13 years ago

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

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guyfrom7up
guyfrom7up

13 years ago

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
tech-king

Reply 13 years ago

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
guyfrom7up

Reply 13 years ago

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
tech-king

Reply 13 years ago

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

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Goodhart
Goodhart

Reply 13 years ago

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

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tech-king
tech-king

Reply 13 years ago

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

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rdy2sail
rdy2sail

13 years ago

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
Bran

13 years ago

A transformer and a very strong resistor.

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tech-king
tech-king

Reply 13 years ago

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

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rdy2sail
rdy2sail

13 years ago

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