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SMPS used at 110v instead of 230v Question??

Discussion in 'Electronic Basics' started by Charger, Aug 6, 2005.

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  1. Charger

    Charger Guest

    I have 4 mobile phones and chargers, all different manufacturers.
    (Sony, Siemens, Nokia, Motorola)

    All apart from one (Sony Ericcsson) have labels stating 230v use only,
    one states 110v-240v.

    All seem to be made by Astec of China

    All 4 give an indication on the phone that enough voltage is being
    supplied to charge the phone when used at 110v, plugged into my bathroom
    110v shaver socket.

    Is it just a label thing, in fact are all these chargers capable of
    being used on 110v, in America, without the need to buy a specific 110v
    travel charger ?

    As I understand it, they may be switched mode power supplies, the
    technology I know very little about.

    Does it do any harm to operate these chargers on 110v, instead of the
    labelled 230v ?

    How do I tell if it's switched mode from the outside, or if I open it up
    ?
    Thanks
     
  2. Hi,

    (Charger) wrote in
    Quite strange! It seems as if they use a controller chip without
    UVL (undervoltage lockout) that stops operation when driven with
    too low a mains voltage.
    Not sure about this, but a "normal" SMPS should not be operated
    at excessive undervoltage because it works agains low input voltage
    by drawing more current from the primary. When you use with it
    half the nominal mains it draws twice the nominal input current
    (roughly ...). And more current means more heat which is dangerous
    for most power components.
    See above, it will probably not kill them immediately but they
    will in any case suffer from that! The mobile chargers are
    taken to the minimum cost point ... and cooling for the power
    components is one of the most expensive things in such small
    devices!
    Just compare the weight and size to a standard wallwart power
    supply! SMPS do not use "heavy" metalcore transformers but small
    and lightweight ferrite transformer.

    BTW: The one stating 110-240V is surely a SMPS!

    Regards
    Michael
     
  3. Charger

    Charger Guest

    The charger doesn't get hot at 110v at all, no discernible temp rise at
    all
     
  4. Rich Grise

    Rich Grise Guest

    If it's not specified, then the device isn't guaranteed - but if you've
    already tried it, it worked, and you didn't burn the house down, why
    are you asking? ;-P

    Cheers!
    Rich
     
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