transformers

Discussion in 'The Projects Forum' started by chrisw1990, Oct 26, 2011.

  1. chrisw1990

    Thread Starter Active Member

    Oct 22, 2011
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    im trying to locate small transformers for mains supplies, e.g. 3.3V SMPS power supplies, does anyone know of a good source?
    tried my usual channels but can only find massive transformers
    ideally looking for small surface mount versions (if there are such things)
     
  2. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
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    I think you have to ordered special purpose transformer take 6v and use 3.3V regulators IC.
     
  3. chrisw1990

    Thread Starter Active Member

    Oct 22, 2011
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    i need a Mains: around 25V Transformer
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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  5. SgtWookie

    Expert

    Jul 17, 2007
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    I didn't see your "mains around 25v transformer" statement.

    I thought you wanted to go directly from mains to 3.3V DC. That's what the supplies I linked to will do.
     
  6. chrisw1990

    Thread Starter Active Member

    Oct 22, 2011
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    i already have a design for a switched mode power supply, i thought that just putting a transformer, with.. mains on primary : around 25V out (mains around 25v transformer statement) and rectifying it would be a supreme low cost solution compared to trying to get a transformer to work with 3.3V 4A make sense?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    A mains-frequency transformer capable of 4A @ 25VAC, 50Hz will be quite large, heavy, and not all that cheap.

    That's one of the reasons why SMPS's have become popular; the higher you go in frequency, the smaller the transformer can be - within certain limits, of course.
     
  8. chrisw1990

    Thread Starter Active Member

    Oct 22, 2011
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    i know :D
    i used the national semi/Texas instruments WebBench tool, says at about 24V input, it will take 450mA current, while this might not be hugely accurate, its a lot better than 4A!

    so maybe this is the place to put it, but the LED lighting strips, where they fit into the 5ft flourescent tube slots? how do they convert the AC to DC?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    LED lighting strips use LV supplies.
    Long fluorescent tubes have a ballast to generate high voltage necessary to ionize the gas in the tube.
    CCFL's have small HV flyback supplies that will generate 500v to ~1,300v or so to ionize the gas, then they maintain the ionization at a lower voltage with a controlled current.
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Line powered LEDs are a different animal, and the construction of the power supplies for them are forbidden by the rules of the forum.

    Some larger LED installations use a single output switching power supply, think 5V phone charger with USB jack output that only weighs an ounce, but built into the chassis of the light.

    The other method is very dangerous and not suited at all to people not well versed with electronics. The danger is the reason the topic is banned here. We can however, help you work with your 24V supply for an LED strip.
     
  11. chrisw1990

    Thread Starter Active Member

    Oct 22, 2011
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