Making a 1Ampere Square Wave Current Generator From 18V/18A Power Suppky

Discussion in 'The Projects Forum' started by richeek.arya, Oct 21, 2009.

  1. richeek.arya

    Thread Starter New Member

    Oct 21, 2009
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    Hi
    I have a 18V/18A DC power supply. I want to use this power supply to generate a 1Ampere CURRENT SQUARE WAVE. The load that I am driving is of 200Ohms approximately.

    I used a transistor with its base given a square pulse from the function generator. The load is connected on the collector. Emitter is grounded. Transistor is repeatedly going in CUT-OFF and SATURATION. But in this way the maximum current that I am getting is (18V/200ohms) which is quite less.

    Now I am not getting how to increase this current using the SAME DC power supply. Problem which I am facing is that potential across load will be (200x1=200V) so how to handle this with 18V DC power supply.
    Should I use transformer?

    Any help would be appreciated.

    Sincerely
    Richeek
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    What frequency?
     
  3. richeek.arya

    Thread Starter New Member

    Oct 21, 2009
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    Ideally it should go as high as possible. But for now 100KHz is good enough.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Is your load purely resistive, or are there reactive components? ie: inductive; capacitive.
     
  5. richeek.arya

    Thread Starter New Member

    Oct 21, 2009
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    For now I just want the concept. So any frequency would do. I guess I need to have something like a transformer but I have never used the transformer for this type of operation(I just use them to step down mains power supply). So not sure about that.
     
  6. richeek.arya

    Thread Starter New Member

    Oct 21, 2009
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    It is a purely resistive load. I should have mentioned all these things in the first post itself. My mistake.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    If the load is purely resistive, you might be able to do it using a toroidal transformer. You'll probably need around 12a or so current in the primary winding, and you'll need an H-bridge that will handle that much current.
     
  8. richeek.arya

    Thread Starter New Member

    Oct 21, 2009
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    How will I generate 12A current? Could you please elaborate more on this? I was also thinking of transformer but do not know up to what frequency it can go and how much current can I get from it?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    You will need an H-bridge that is rated for around 30A @ 20v, and you will need to wind your own toroidal transformer. The H-bridge will need to be able to switch pretty quickly. The high current will be on the primary side of the toroidal transformer. The secondary side will have around 200v RMS current at 1A. You'll need somewhere around a 1:12 ratio for the turns.

    The higher the frequency, the smaller the toroidal transformer can be - up to a point. Then you wind up with power dissipation problems.
     
  10. richeek.arya

    Thread Starter New Member

    Oct 21, 2009
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    Thank you very much for the information. Instead of making one can I buy this type of transformer? That would be lot easier for me. Also are there any other solutions to this problem?
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    You'd be better off to start with a 200v DC power supply that is capable of at least 1A output.
     
  12. Wendy

    Moderator

    Mar 24, 2008
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    Ohm's law:

    I = V/R, 200V/200Ω = 1A

    Resistance and voltage dictate current.
     
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