LED lights

Discussion in 'General Electronics Chat' started by robertkillen, May 2, 2011.

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  1. robertkillen

    Thread Starter New Member

    May 2, 2011
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    Can LED's be used to make a bridge rectifier? Is it possible to make an LED light bulb by connecting a bunch of LED's to a 120VAC source without a separate rectifier?
     
  2. marshallf3

    Well-Known Member

    Jul 26, 2010
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    LEDs wouldn't make good bridge. Although it would work you'd be limited to the 20 or so mA rating of the LEDs, you'd also lose 2 x the LED's voltage.

    Yes, a string of LEDs can be made to run directly off the mains so long as there's enough to add up to 120V or more, that's the way most LED Christmas light strings are made - with somewhere between 50 - 70 LEDs in series directly across the line voltage. Think about it = 60 LEDs, each with a forward voltage of 2V, would take 120V to light.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    Connecting anything other that a transformer (especially LEDs) is a reciepe for injury or death. It is done commercially, but it will get your thread closed if you want to go this route. It is a direct violation of the terms of service, specifically mentioned as such in the new TOS.

    You need two things, a transformer for isolation, and lower voltage. There really isn't any reason to try to run LEDs off high voltage, they are fundimentally low voltage components.
     
    Last edited: May 3, 2011
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
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    It's one heck of a lot cheaper just to buy LED Christmas light strings which are available in white, multi color or almost any solid color you can imagine - they even came out with pink and purple a few years ago.

    Most larger towns have year-round Christmas stores or some stores keep their left overs out from display for shelf usage reasons. Sometimes they'll have them but have moved them to the back - you just have to ask..

    This interesting surplus store I've been investigating sells some of them http://www.sciplus.com and I'm sure you can find any you might want if you just search for them. Eliminates a lot of hassle, costs a ton less than trying to do it yourself and you get UL approved items.

    http://www.google.com/search?hl=en&...&q=LED+Christmas+lights&aq=f&aqi=g10&aql=&oq=

    Even some auto parts stores have 3' strings of very thin tape with surface mount LEDs on them but thy're obviously 12V.
     
  5. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    According to the newly published ToS, the mains powerd leds are not allowed:
    Terms of Service
    Bertus
     
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