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Does amp rating of PSU effect output ?

  1. Feb 3, 2010 #1
    i have used different PSU on a simple electromagnetic motor (tattoo machine) and have notice a machine will run a certain way at 2 volts on one power supply but require 9 volts from another power supply to run the same.

    Question being is it the amp rating of the power supply that does this ?

    the resistance of 1.5 ohm is constant so different power supplies set at say 3volts with different amp ratings will behave differently . why?
     
  2. jcsd
  3. Feb 3, 2010 #2

    berkeman

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    Staff: Mentor

    If you exceed the output current rating of the power supply, it will go into current limit. Often it will use foldback current limit for linear power supplies, which means that the current and output voltage both fall, until the output short or excessive load is removed.
     
  4. Feb 3, 2010 #3
    ??? HUH that way more than im asking about , i just want to know if 2 different power supplies with different amp ratings will put out a stronger effect. more current at the same voltage = more power , yes or no ?. only using 3 v on 15v psu's,

    unite #1 set at 3v runs strong
    unite #2 set at 3v barley runs and runs the same as the other when set at 9v

    is it because unite one is 2A and #2 is 1.5 ? does it matter or is it something else
     
  5. Feb 3, 2010 #4

    berkeman

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    Staff: Mentor

    Yes, the output current rating is the max that the supply can put out. You should actually measure the output voltage with a voltmeter to see if the output voltage matches the setting. If you try to draw too much current, the supply goes into current limit as I explained, and the output voltage will drop below your setting.
     
  6. Feb 3, 2010 #5
    ok well no matter what i set it at 1 v or 10 it read 41v no wounder it is so strong , this unite is a very basic old set up made of a 20v stepdown trans former a filter cap rheostat , dont even know if it has a rectifier can i fix it?

    and thanks
     
  7. Feb 3, 2010 #6
    actually the power unite consist of only

    a 25ohm 1amp rheo, 25.2v 1A transformer that goes to a small board that holds #1 a small black rectangle (with = - 2kbp06 printed on it) and#2 , 2 big *** caps 1000uf 200wv , and that goes to a filter reactor (.32HY-600MADC 10OHMS) and a 3 amp fuse


    so what is making it put out a 41v reading ?
     
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