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  1. #1
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    Constant Current or Constant Voltage, Which are Phone AC Adaptors?

    Friends,
    What type of circuitry is in phone AC adapters constant current or constant voltage? I want to make one out of a beefy 12vdc AC adapter and nine feet of 18ga. two conductor wire that is soldered on one end and the USB micro on the other.
    Sincerely
    Jon

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  2. #2
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    Re: Constant Current or Constant Voltage, Which are Phone AC Adaptors?

    Neither; usually they're fairly lousy regulation (if any).
    Nobody cares since they only have to charge the
    battery without burning it up (and the phone has
    some smarts about that, inside).

    But I have used many of them, with some added
    filter caps and a 3-terminal regulator, to make low
    cost (wall wart is free when the thing it powered,
    died) power supplies for various uses (like testing
    stuff at remote sites, when I don't want 50 pounds
    of HP power supplies in the luggage and a 1-pound
    wall wart lashup will do the job).



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    Re: Constant Current or Constant Voltage, Which are Phone AC Adaptors?

    Hi,

    I want to make one out of a beefy 12vdc AC adapter and .... on one end and the USB micro on the other.
    12Vdc AC makes no sense. Either DC or AC.

    Don't use AC with USB connectors.
    Don't use 12V with USB connectors.
    For USB version 1 and 2 only 5V DC is allowed.
    USB 3 voltage standards are more complicated. Therefor I don't recommend it at all for hobby projects.

    Klaus



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  4. #4
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    Re: Constant Current or Constant Voltage, Which are Phone AC Adaptors?

    Quote Originally Posted by KlausST View Post
    Hi,

    12Vdc AC makes no sense. Either DC or AC.

    Don't use AC with USB connectors.
    Don't use 12V with USB connectors.
    For USB version 1 and 2 only 5V DC is allowed.
    USB 3 voltage standards are more complicated. Therefor I don't recommend it at all for hobby projects.

    Klaus
    Klaus, here the chargers that come with our phones are both AC and DC which is why we call them "Adapters", they convert AC to DC. It makes sense when you look closely, as you'll notice the VDC was with the 12 without a space (12vdc), that was indicative of the output of the (AC wall adapter) speaking of the AC input that will be (adapted).

    About the 12 volts, if you'll noticed I was talking about making a (constant) current or voltage regulator, to do so it is best to have a higher voltage that the target voltage. I could use a 9vdc and I might just have one, it doesn't matter just as long as it is significantly more than the target voltage of 5vdc that will go through the USB connector. Keep in mind that I am considering making a higher quality AC Wall adapter to replace the one that came with my tablet.



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