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DC Wall Adapter...

Discussion in 'General Electronics Discussion' started by BlueJello, Jan 4, 2017.

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  1. BlueJello

    BlueJello

    23
    2
    Dec 15, 2016
    I'm attempting to use a DC wall adapter to drive a circuit. I'm integrating into my circuit, so I pulled apart the casing. I would like to have 800 watts running through it, but the resistance of the primary coil is approximately 135, far to high to draw the necessary 6.66 amps needed to achieve 800 watts at 120 volts. Is there some sort of resistor inside the coil that I could remove? If I removed it, would there be issues with running the transformer? My input would be 120 Volts at 6.66 Amps, and my output would be 18 Volts at 44.44 amps. I don't know if the secondary coil can handle 44 amps. It would only be run for a short period of time, and would remain as a part of this project, instead of a potential fire hazard.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,779
    Jan 21, 2010
    It's not going to happen. An 800W power supply using a transformer to step the mains down will not only pull the plug out of the socket, it will also probably crush your foot.

    On the other hand, if you can get a -135 resistor, anything might happen.
     
    Last edited: Jan 4, 2017
  3. AnalogKid

    AnalogKid

    2,391
    665
    Jun 10, 2015
    If you are talking about a linear power supply (as opposed to a switching supply), an 800 W transformer weighs over 10 pounds and is larger than a softball. There is no way to modify a smaller transformer, because the total power you can move through a transformer is set by the physical size of the metal core. Small core = low power. Period.

    And, what you are trying to do is lethally dangerous. Opening up a sealed power supply instantly violates all of its safety certifications. When you die, your family can't sue. It's a Darwin thing.

    ak
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    2,249
    Nov 17, 2011
    Your questions indicate a lack of knowledge which is all the more dangerous as you are dealing with potentially lethal voltages and currents!

    My recommendation: hands off.

    Get a suitable safe (certified) power supply and work on the low voltage side only. Even at low voltages the high currents involved can be rather dangerous - not only in terms of fire hazard.
     
  5. BlueJello

    BlueJello

    23
    2
    Dec 15, 2016
    Okay, I didn't know if I could do something like that. I'll be sure to look into certified power supplies. Thanks for the help, and I won't mess around with this transformer.
     
    HellasTechn and Harald Kapp like this.
  6. HellasTechn

    HellasTechn

    1,537
    213
    Apr 14, 2013
    That is certainly the best thing to do since you are playing with massive currents.
    You say you need 44 Amps while my house mains fuse is 35 Amps. can you imagine ?
    It is not that we dont want to help you but it is our duty to keep you at the safe side.
     
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