0-30 v Variable DC Power supply!!!!

Discussion in 'The Projects Forum' started by farhan89, Mar 28, 2010.

  1. farhan89

    Thread Starter Member

    Feb 13, 2010
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    0
    Hello All,
    I want to make a 0-30v DC Power supply. I want separate pot for 0 to +30v and s separate pot for 0 to -30 V .

    I also want high current in output approx 15-20 Amps

    Is it possible ????

    If yes then kindly send me the schematic for this power supply i would be very thankful to you guys

    Thanks!

    Waiting for reply!

    Bye and Take care!
     
  2. dsp_redux

    Active Member

    Apr 11, 2009
    182
    5
    Regulated or Unregulated? Linear or Switching? Do you have anymore details? Do you know how much a transformer meeting your first requirement costs? What is your budget?
     
  3. farhan89

    Thread Starter Member

    Feb 13, 2010
    34
    0
    Regulated,
    Linear or Switching ???
    Can u define what is linear and what is switching ??

    don't worry about the budget, but the transformer and the whole circuit should be installed in the 14*14 CM box
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    \frac{{2x30voltsx20amps}}{{efficiency}}\quad  = \quad 2KW

    is one big SOB.

    Perhaps Bill Marsden will lend you his welder.
     
  5. farhan89

    Thread Starter Member

    Feb 13, 2010
    34
    0
    @^
    Didn't got u?????
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    You probably won't be able to build a linear power supply in a 5.5" x 5.5" box, unless you can have the box be a couple of feet tall.

    You will have a very hard time even making a switching power supply of that size.
     
  7. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
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    It is a do able project, size aside. But from the thread so far I think the op, farhan89, is way over his head.
     
  8. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Actually there was a nice 15amp variac for sale on our E__y this week.
    That would be the way to go, feeding a standard bridge/rectifier smoothing condenser farm.

    A pair of these fed from a 1:1 two Kilowatt isolation transformer would suffice.

    They would just about all fit into the 5 foot by 5 foot box as well.

    Otherwise a pair of lorry batteries and a compound emitter follower with darlington-triple output stages would also do this job.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    15-20 amps is a lot of current, you actually want twice that, each at 30V. That is going to be largish.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    Our OP wants it in a 14cm by 14cm box, or about 5.5" by 5.5".

    That is about the size of my 250 Watt ATX form factor power supply.

    Our OP wants 8x that much power output, and for it to be adjustable.

    That's a mighty tall order.
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    I've been trying to figure out how to do something similar, dual 24V at 6A using switching regulators. Near as I can figure I'm going to have to make a box, with at least 8" X 8" X 8", and that will still be too small, what with controls, displays, AC power in and whatnot.

    The regulator isn't the issue, though you need to figure a heat sink design, the problem is the base DC converters. I was planning on using two switchers that output 24V at 6.5A. These are about as small as you can get.

    My power supply modules measure 1.4" X 3.7" X 6.7". I believe this is as small as I can get them. In your case, with the extra amps, it will be bigger. If you go the traditional transformer / capacitor route it will be much bigger, since both components are basically huge.

    So instead of setting a size limit (which is unrealistic), start from a design and try to figure out how big a case will be to hold everything. If you go with transformers and caps it will be well over 1' square, by a large margin. If you can find some switchers for the basic DC power that will likely set the limits on your case size.

    If you were to try to do something with care batteries as the source (a bad idea) it would take 6 big batteries.
     
  12. farhan89

    Thread Starter Member

    Feb 13, 2010
    34
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    Ok
    Just provide me the schematic of the circuit , i will make a box by my self according the size of the Circuit.

    Thanks Guys!
     
  13. Audioguru

    New Member

    Dec 20, 2007
    9,411
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    But we are not a free design service for such a complicated high power project. Its transistors must be able to dissipate up to 2000W of heat unless the circuit has a complicated high power switching converter.

    If you find and build a circuit or design it yourself then have a problem with how it works then we might help you fix it.
     
  14. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    LMAOF :D
    Good One.
     
  15. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    OK... Do you need my paypal address.
    It's going to cost you USD 500.00.

    I have one working schematic
     
  16. SgtWookie

    Expert

    Jul 17, 2007
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    One problem that you may have is a source of mains power for such a hefty supply.

    Since we do not know where you are located, we have no idea what mains supply you have.

    In the States, a typical wall outlet has 120VAC 60Hz power that is limited to 15A current. That is 1.8KW, and is not enough power for a project like you are considering - even if the supply were 100% efficient, which is impossible.
     
  17. farhan89

    Thread Starter Member

    Feb 13, 2010
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    @^^: I live in pakistan and we have 220VAC 50 HZ voltage

    OK guys So provide me the schematic of -30-0-+30 vairaible power supply with 10Amp constant current?

    So now it's easy or it would cost more?????
     
  18. Wendy

    Moderator

    Mar 24, 2008
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    First, show us your access to 2 10A 28VAC transformers. I suspect they will be fairly hard to get.

    That or qty 2 10A 35V switching power supplies.
     
  19. farhan89

    Thread Starter Member

    Feb 13, 2010
    34
    0
    What you all say on this

    [​IMG]


    It's for +30 v , what additions should be made for -ve 30 volts????
     
  20. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Then U can use the same circuit in opposite polarity
     
    Last edited: Mar 30, 2010
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