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Switch mode question

Discussion in 'Hobby Electronics' started by atec77, May 2, 2011.

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  1. atec77

    atec77 Guest

    Is it permissable to run a couple of dc switch mode supplies in
    parallel to gain extra current capacity ?
    What are the potential problems
    Tnx
     
  2. atec77

    atec77 Guest

    I suspected as much but finding one large enough is if possible very
    expensive , might have to reconsider making another linear
     
  3. Mik DaDik

    Mik DaDik Guest


    What Voltage current are you looking for?

    Mik
     
  4. atec77

    atec77 Guest

    48Vdc 1500 watts
     
  5. atec77

    atec77 Guest

    I have a large junk box , I have caps , sinks and transformer free , now
    those switches look like decent supplies but are way over my hobby
    budget , if I can source suitable pass transistors for a 48cdv rail
    building a regulator control board will be easy
    Thanks anyway , ebay offers 400 watts for under $100.00 delivered just
    nothing large enough atm out of China
     
  6. atec77

    atec77 Guest

    I have two of the old telstra transformers here from when I started with
    them about 30 + years ago and the tranny from a 150 amp dc tig , just
    sold my 3.5kw 48 vdc supply , I have a copy of switchmode power supplies
    spice and p so when time permits might build one
    There is a Honkers bloke who does 350 and 400 watt supplies very cheaply
    , perhaps one of the blade server 48Vdc remote supplies will show up at
    a fair price
     
  7. Mr Mac

    Mr Mac Guest


    You could link 4 ATX power supplies in series. You would have to open up 3
    of them and cut the link between the negative terminal and earth.
    It will be safe if you hard wire all 4 outputs together in series in a way
    that they can not be disconnected. I think the only reason they earth the
    negative output is so that it doesn't float at a high voltage WRT mains. So
    if all your connections are good, the highest any output will float is 48V.

    Modern ATX supplies typically have two 12V 20A rails. But many dont realise
    that they are not actually separate rails. The rails are separately filtered
    with caps, but come from a single SM transformer. (typically)

    So each ATX supplies 12V at 40A. Cost is about $40 each from ebay, so $160
    is your total.
     
  8. atec77

    atec77 Guest

    I thought about it but I need 48vdc @1500 watts , atx wont cut it but
    I can get cheap Asian industrial supplies @450watt each , will have to
    check the schematic to see if it might work
    Ta
     
  9. Mr Mac

    Mr Mac Guest

    48V x 40A = 1920W
     
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