0-120vdc power supply

Discussion in 'Homework Help' started by Tamilselvan, Jun 29, 2012.

  1. Tamilselvan

    Thread Starter New Member

    Apr 26, 2011
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    Hello all

    This is selvan I have been designing a power supply can be able to operate between 0 to 120 Vdc (Variable)..

    Intially, I did 0 to 30Vdc power supply by obtained knowledge. Now I am looking for the power supply mentioned above.

    Since basic power supply like (0-30v) could be designed using the voltage regulators available in market.
    Once I get into higher power supply design i cant able to find it.
    I think there is no voltage regulators for (0-120vdc).
    Pls tell me how to design it
    Thanks in advance.
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    How about little things like current. Max allowed ripple?
     
  3. absf

    Senior Member

    Dec 29, 2010
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    You didnt mention how much current you need from your 0-120V DC power supply. The problem with such high voltage DC regulator is that when the output voltage is low say 12V, your regulator has to absorb 120-12=108V on the transistor C/E. If the current is 1A, there would be 108W of heat generated on the regulator.

    You can actually design this type of PSU with op-amps operating at lower voltage to control the driver and pass transistors which works on the higher voltages. Or you can use PWM techniques to control the duty cycles that goes to the gates/bases of the pass transistors.

    Of course if you're talking about SMPS, that would be different story.:D

    Allen
     
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Would probably use a variac followed by rectifier and caps.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Probably not, given that a variac doesn't isolate. That by itself woud put it outside the rules. I tend to think in terms of a SMPS, which will side step analog power dissipation.
     
  6. Tamilselvan

    Thread Starter New Member

    Apr 26, 2011
    8
    0
    Hello I found few high voltage regulators online, (ex : TL783).
    I sure about that i could able to control the output voltage between 0-120v
    My expected current would lies between 1 to 2 Amps, but is it possible to control the output current in terms of regulation.
    if so pls help me out to modify my circuit
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Do you understand wattage, how to caluculate it? Do some simple math on how much wattage a regulator will disapate, then get back with us.

    A power supply that does not take this into consideration is a stove, not a power supply.
     
    absf likes this.
  8. #12

    Expert

    Nov 30, 2010
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    Look at my blog #4 to see how to do this in an analog way. If you can't understand it, don't do it!
     
  9. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    A 120V/2A linear reg design is not a project for a newbie. A linear design for 240W load power is really not feasible. An offline switcher is pretty complicated. I know exactly how to build one, but I would rather buy one.
     
  10. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Actually, it's a FUSE.........:eek:
     
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