LED - Transformer

Discussion in 'Anything DIY Related' started by Charl_Stanhope, 1 Dec 2012.

  1. Charl_Stanhope

    Charl_Stanhope

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    I have received three of these [​IMG]
    from a guy that took a big led setup out of a shop. Ihave hooked up
    8 x 3w LED chips to it. The problem I have is that the leds are on, not
    as bright as they should be and they seem to be flickering really fast.
    Any ideas of what the problem is. I have tested my soldering and all the leds seems
    to be soldered corrctly. These are conected in series. positve to negative.

    The details of the transformer :

    50VA . 230 -12v L/VOLT XMER
    input is 0-230V
    output is 0-12V and the transformer is fused.

    any ideas for the electrical gurus ? :)
     
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  3. butcherman

    butcherman Moderator MASA Contributor

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    What is the forward voltage and amp rating of the leds? Are they wired up in series?
     
  4. butcherman

    butcherman Moderator MASA Contributor

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    What amps is the transformer putting out?
     
  5. Pri$m

    Pri$m

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    How were the LEDs connected previously and to what power supply such that they are not as bright?

    Looks like you have a 12V low voltage lighting transformer there. Connecting it to the LEDs will invariably cause flicker because the LEDs will receive 12v 50hz AC and 50hz is what is causing the flicker you see
     
  6. Charl_Stanhope

    Charl_Stanhope Thread Starter

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    Thanx for the replies @butcherman and @Pri$m . Sorry I am only repying now.


    I havent tested yet to be honest. I will do a test when I get home tomorrow.


    • Forward voltage: 3.7V @700mA
    • Lumens: 180-200
    • Max. current: 700mA
    These leds are wired up in series

    What is the correct transformer to connect to these leds?
     
    Last edited by a moderator: 26 Nov 2015
  7. Gerhard DP

    Gerhard DP

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    LEDS run on constant current so it will all depend on the current output of the transformer.
     
  8. Pri$m

    Pri$m

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    Those LEDs you have should not be run off of a transformer as such (I'm guessing they are individual LED's?). They require a driver instead. The driver will supply the necessary voltage and current to the LEDs and dependent on the driver, how many LEDs in series.

    The down-lighter replacement LED globes that are available have the necessary drive electronics within them to run off a transformer as you have.

    If you try for example 3 or 4 LED's in series off that transformer they will run a great deal brighter but then you run the risk of burning them up as that transformer is capable of outputting about 4 amps at 12V. Your LED's are only designed for 700mA or 0.7A. They are a Current driven device and not a Voltage driven device and hence the critical variable is the current
     
  9. butcherman

    butcherman Moderator MASA Contributor

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    Im with prism, that driver more than likly is for down lighters,

    For 8 led's in series you will need about 24v dc @ 700ma.

    If you run the led's on this transformer in all liklyhood you will burn out the LED's
     
  10. Charl_Stanhope

    Charl_Stanhope Thread Starter

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    Thanks for the input guys. Found an old driver I had lying around,connected the leds. Perfect. As bright as can be. so it was a driver I needed to run the leds and not the transformer. For some reason I thought they do the same job:blush:
     
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