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Soft start for power supply

Discussion in 'Home Brew' started by Samson34, Feb 20, 2010.

  1. Samson34

    Samson34 Member

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    I'm looking for some information on a "soft start kit" or at least some schematics or something for building a soft start for a 400 amp unregulated power supply on 220 volts. Thanks.


     

  2. n8fgb

    n8fgb Well-Known Member

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  3. Samson34

    Samson34 Member

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    Thanks, N8fgb...that's great..
     
  4. Crusher

    Crusher Well-Known Member

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    A soft start is pretty simple. I use a 40 amp DPDT open frame relay. The relay is a 120V version. A resistor across each leg about 25-50 ohms. At least 25 watt I go overkill and use a 50 watt. You can use a time delay relay generally 3-5 seconds will be all you need. You could use a simple RC circuit instead, but some modifications will be needed to be done, but a lot cheaper. But if its you first time, the time delay relay is the way to go. Much simpler and the time delay relay will work off of just one leg (120V) and you use this to engage DPDT relay. I used this in my 300 amp unregulated 28 volt supply.
     

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