Help with customizing LED string

Discussion in 'The Projects Forum' started by Tomdas, Apr 16, 2015.

  1. Tomdas

    Thread Starter New Member

    Apr 16, 2015
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    Hey guys,
    I am working on a little project and i was wondering if i could get any advise.
    I bought a series of 100 LEDs on a string with the Driver/transformer built into the plug. It had a switch offering 8 different patterns.
    What i wanted to do was remove the original plug (pictured) and hard wire them into a lamp i am building. I bought a replacement LED Driver as advised by my local electrical supplier (pictured)
    I was hoping that i could have it turn on now with all the LEDS turning on at the same time.
    When i wired it up i found that only half the string lit up. As there was no reference to + or - on the wires, i switched them to find that still only half lit up, but this time it as teh opposite ones that lit this time.
    I then tried putting both wires in the same input but then had no lights.
    Im not an electrical master by any means and LEDS seem even more confusing.
    Any ideas?

    Cheers for any help in advance
    Tom
    Original LED Driver and plug.jpg LED Driver replacement.jpg Original LED Driver and plug.jpg LED Driver replacement.jpg
     
  2. Tomdas

    Thread Starter New Member

    Apr 16, 2015
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    Oh, i forget to mention that i asked the original supplier the wattage of the whole string of 100 LEDS and he said bewteen 8 and 10w.
    Hope that helps
    Thanks again
    Tom
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    sounds like you need an AC supply, the leds will have reverse diodes across them to make it work on ac.
     
  4. #12

    Expert

    Nov 30, 2010
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    Yes. The half and half response is the clue. What to do about providing the proper voltage and current escapes me.
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    yet your original black psu says 31V DC, can you measure the output on your old psu?
     
  6. #12

    Expert

    Nov 30, 2010
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    I'm afraid the DC label is correct and the polarity control is in the controller box. Your job, should you decide to accept it, is to get both polarities to the LEDs, in an alternating fashion. The obvious way is to use an AC adapter, but the devil is in the details. Can you merely apply some voltage and expect the LEDs to have current limiting already installed in the light string? I think so. You must measure the original output. Problem: You can't measure a fast, chopped, output with a $10 meter. Try to use an AC voltage setting and see if the reading makes sense or just goes random.
     
  7. Tomdas

    Thread Starter New Member

    Apr 16, 2015
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    Cheers for your responses, am now realising it wasn't as simple as i thought..
    Ive taken the original plug to pieces and wired in the transformer to the unit I've made but the default setting is flashing between alternate lights. I wonder if there is a way of getting the default to have both sets in.
    Ive attached a pic showing both sides of the circuit if it helps.
    So i guess i need to find an 240vac to 32vac transformer?

    Cheers
    Tom
    led driver circuit board front.jpg led driver circuit board back.jpg
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    you could use a 555 timer oscillator with four mosfets, in an H bridge switching your leds , or just put a transformer on the leds directly.
     
    #12 likes this.
  9. Tomdas

    Thread Starter New Member

    Apr 16, 2015
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    Excuse my naivety, but what do you mean by put a transformer on the leds directly? is that not what i did?
     
  10. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    no ,you put a DC power supply on the leds, you need to put a transformer pure AC, so that both sets of leds will light up,the original black psu will reverse the dc output, so it makes them all light.
     
  11. Tomdas

    Thread Starter New Member

    Apr 16, 2015
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    Cheers, I'm having trouble trying to find a 32volt AC transformer. Any ideas where i can get one? I tried with an ac adaptor but it only went up to 12v which was not enough power.
    Seems like 12vac transformers are everywhere but 32vac transformers seem illusive.
    thanks for all your help and advise
    Tom
     
  12. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  13. Tomdas

    Thread Starter New Member

    Apr 16, 2015
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