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220V AC-DC adapter on a 120V outlet

Discussion in 'General Electronics' started by Willard van Orman Quine, Aug 6, 2004.

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  1. I've already tried this, so I know it "works," but I just want to see
    what you guys here who know way more about this stuff than I do think
    about it. Is it actually working perfectly or is something possibly
    not exactly right and maybe even causing hidden damage?

    I have an AC-DC wall adapter rated 220-240V 50Hz input 6V 300mA output
    that I want to use directly on a 120V U.S. outlet. In case it's
    important, what this is supposed to do is recharge the Ni-MH batteries
    in a portable radio using the radio's own recharging ability. It
    seems to do the job fine, but I want to know if there's any slow and
    accumulating damage being done.

    Now, I know it's not recommended, so no one has to tell me that, but
    if someone who understands the theory of electricity can explain what
    a transformer that outputs 6V and wants 220V does when it gets 120V,
    that would be great. My only thought is that perhaps it's outputting
    a lower amperage? How bad would that really be for the radio or the

    I also have a bonus related question: how do step-up converters work?
    Do they just draw a massive amount of wattage or something?

    Thanks in advance for any answers.

    ....word is bondage...
  2. Ryan Wheeler

    Ryan Wheeler Guest

    is that a european adapter, englisch, french or german type plug?
    how did you get to fit it in a US outlet?
    you may have an adapter that has a wide input range, 110V to 220/230VAC
    and has a reasonable output at the lower 110VAC input. 50 or 60 HZ
    does not matter. Good luck.
  3. The answer can be fairly complex, and the performance is dependend on
    many factors of the power supply design. Basicly, if you are putting
    in a lower than rated voltage for the power supply, its performance
    will be degraded. If it is a simple non-regulated supply, it will
    work, but with very poor performance if the input voltage is under
    spec for it. If the supply is a regulated supply, most likely it would
    not put out anything.

    The simple non-regulated supplies using a simple current source
    limiting resistor will put some voltage, but at a much lower level
    than rated.

    As for charging the batteries if the supply is working, it will charge
    them as long as the break-over current the voltage to charge the
    batteries is high enough.

    This is a practice that I would not recomend. Charging batteries at
    much too low a current is something that is not good for most types of
    batteries. I cannot get in to details of the chemestry of these
    batteries over an email, or the deep theories of what is going on.

    Batteries work on an electrochemica reaction. They are designed to be
    recharged and discharged within a particular range and demand. It
    would be ideal for the lifespan of the batteries to properly charge
    and discharge them within their lifecycle and design range.

    Jerry G.
  4. SolarWind

    SolarWind Guest

    I've already tried this, so I know it "works," but I just want to see

    OK, If to use directly on a 120V U.S. outlet instead of AC 200-240V
    input and the output keeps at 6V 300mA DC that means this adapter had
    been designed with 200% over spec., I suggest you to watch it's 6V
    output with a oscilloscope under loading condition, watch the scope to
    verify there are not AC ripple or hum found. Usually, the maker to
    increase the internal transformer AC output voltage will reduce the DC
    ripple that is part of considerations in design processing.

    However, if 110V AC will do the job for you and not any other side
    effect found such as Radio hum etc. ( I don't know your
    application!)just do it, that will increase your adapter life over 10
  5. BobGardner

    BobGardner Guest

    The box is a 'universal input switching regulator'. The ac goes thru a diode
    onto a capacitor... if its 110, theres about 170 volts on the cap. If its 220,
    its twice that. Then its chopped at 20KHz or something and sent thru a
    transformer as about 6v ac at 20KHz and then full wave rectified and either
    linear regulated or PWM regulated to the 6V DC output. Step up is the same
    basic guts with a step up transformer instead of a step down transformer.
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