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Transformer for Power Supply

Discussion in 'Home Brew' started by Nitmare67, Mar 24, 2009.

  1. Nitmare67

    Nitmare67 Member

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    I am having hard time finding a power transformer to my homebrew power supply. I want my power supply to idle about around 18-20 volts but no higher than 20. I tried a regular 12v transformer but it idles at around 15.8 and drops to 11.5-12 volts while keyed. The transformer was 1 kva with 100,000mfd filter, 75amps bridge rectifiers and only drawing 55amps max from it.


    So any ideas where to purchase at a decent price?

    Thanks


     

  2. linearone

    linearone King of NY

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  3. Nitmare67

    Nitmare67 Member

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    I had actually found Ica but they are almost always out of the 70 amp versions. I see most transformers are 430-7101 or 7102's. Are these the correct transformers here?

    [​IMG]
     
  4. linearone

    linearone King of NY

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    those be fine.

    whered you find it
     
  5. Nitmare67

    Nitmare67 Member

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    A friend of mine actually has 2 of them but is not aware of their output. I noticed that the part numbers match what he says he has but is unable to check them. I will have to pay for him to ship them down south to me. I believe they will be 14 volts ac out with 120 in correct?

    What is the current rating on these? The amp I am building this supply to hold is a 1x4 (1446) that is rated at 55amps max draw at 14.5volts. Will 1 of these hold this box at 14 volts or should I use both transformers with 4 bridge rectifiers and parrallel the dc side of the rectifiers before the 100,000mfc cap?
     
  6. unit_399

    unit_399 EL CAPO

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    Nitmare -

    I made the transformers for my supply from ones I got out of burned out microwave ovens. Cut the HV winding off and rewound using #8 ga teflon-coated wire. Rough rule of thumb is one turn per volt. I used 6 auto headlights as a load for testing. My transformers needed 14 1/2 turns. Got the #8 wire at Home Depot. It works good, and the price was right.

    - 399
     
  7. W9WD

    W9WD Guest

    I have a collection of transformers I have gathered over the years. A lot of them out of old machine tools. Some large enough that they are hard to pickup.
    I also have a collection of variable transformers (variacs). By using one or more transformers you can get close to the voltage range you want. Then just take the output of the variac and feed it to the transformers and you can hit the (any) voltage you want.
    Add a bridge rectifier and some smoothing caps voi-la.
     

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