Using Global Power Converter

Preamble - My wife is going to England to visit her bother who is then fling back with her for three week visit. I have given her my old laptop to use while there. Primarily to watch DVD's on plane and while is is there and to play some card games.

Info: The power pak is for 120VAC (Not the 120 -> 240). Output rated at 19VDC @ 3.2 Amps = 61 Watts.

Radio shack recommended a 50 W converter which stated that it was for small Electronic devices such as DVD players, radios, and Laptops.

Best Buy salesman recommended a 1000W unit. When I asked about the "use for small appliances ie curling irons and hair driers ..... Not recommended for electronic Devices." he said that he often goes to Germany and that is what he used to Power his Portables.

OK Bought one that converts 240 to 120 with a switch for 50W and 1600W. Again for 1600W setting it says " ... May damage electronic devices.

Measurements on Power Pac @ 120VAC input.
Booting with battery installed: Approx peak 0.7 Amps (84Watts)
Light load and charging battery: Approx 0.6 Amps (72 Watts)
No Battery installed, whating DVD: Approx 0.5 Amps (60W)
No Battery installed, Playing card game: Approx 0.35 Amps (42 Watts)

(1) Safe to use on 1600 W setting?? (Prabably not)
(2) OK to use on 50 Watts setting
( 3) Use on Battery, and only use the converter to Recarge the Battery.

5 answers Last reply
More about using global power converter
  1. Never seen a step down power pack with "May damage electronic devices" written on it... most just have a dumb 240 - 120V transformer inside, no fancy circuitry or the like.

    1) I'm not sure, having never come across this type of transformer
    2)Probably not. Your laptop PSU can output 61W of power. Even assuming that you laptop PSU has an extraordinary efficiency of 85%, thats still 72W that it can draw from the mains side.
    3)Can't advise you on that, really depends on how the laptop charging circuitry operates. (IE, the laptop may still draw full power, as it just diverts what normally would be used to power the laptop, into the battery instead, and thus making the charge quicker)

    It may be too later, but if you can, why not just refund this power pack, and buy a universal laptop power supply? They come with multiple plugs to suit different laptops, selectable output voltages, and run from 90 - 250VAC, 49-65hz.
  2. Thanks for the reponse Tech-sponge.
    Didn't have time to order a replacement power-pac from newegg and locally they run around $80 vs $20 for the converters.

    If it was a plain 2 to 1 xformer it would have been a no brainer. Output Power is strickly a function of wire gauge (and Freq).

    I had forgotten, but I think I may have given one of her borthers a 2 to 1 Xformer. We used some (For Computers) when we were working in Moscow. Have to ask her to check.

    The power pac (I believe) are a AC->DC->AC converters and output a pseudo sine-wave. The low power ones for electronics have an output close to a sinewave while the high wattage (>1000 Watts) output a very poor waveform, but then heating type divices don.t care whereas the waveform would be very hard on an electronic device especially if applied to a input xformer.
  3. Wait, may have posted for nothing, so in that description you mean it doesn't have the range on the brick, it's 120V only, if so ignore .

    When I travelled through Europe (Including Ireland and Scotland, but not England other than a night at Gatwick) and Australia, I just use a universal plug adapter (doesn't convert anything but the pins) and simply let the brick handle the power.

    the only thing I ever had a problem with is the rare 50hz 110-120V power in the Carribean - Barbados and Jamaica (Bermuda and Bahamas use 110/60).

    Anywhoo 110-120V 60hz and 220-240 50Hz never had an issue with personally, and that's with, battery chargers (and running camcorder/camera), PSP, and G4 Macbook (sister's - which she also used in Korea same way for a whole year).

    Check the power brick it should tell you right on it if it support the 230/50 of the UK.
  4. Hmm okay.

    If these power pac's do output a "dirty/impure sine wave" (I'm assuming something resembling a square wave), then to accommodate for that, you would need to de-rate the power pac's total capacity, when using electronic devices.


    As a point of interest, I'm looking in a copy of the Jaycar 2007 Engineering Catalogue, and there's a blurb in here about pure sine wave, and modified sine wave inverters. Although inverters mainly do DC > AC, it would still apply for your situation.

    (from the catalogue )

    Modified sine wave is a crude approximation of the mains waveform, with square wave components in this. Most appliances are OK with this. Typically these are:
    -Most TV's, VCR's, CD/DVD Players
    -Small power tools
    -Fax machines
    -SOME audio equipment
    -Computers (MOST)
    -All incandescent lighting
    -MOST switchmode power supplies

    Sine Wave is closer to mains and these inverters are much more efficient.
    Best for:
    -Electric Clocks
    -Sensitive equipment
    -Electronic Weighing Machines
    -Mains powered PA equipment
    -All other TV's
    -Plug pack powered equipment
    -Anything where you want to get the most out of a battery charge.


    I really don't know whether a laptop PSU could run off that, perhaps a trip to a dedicated electronics store may help.

    (Not sure what the US equivalent to Jaycar/Altronics is, but i mean actual electronic stores that sell components, wires, hardware etc, not just appliance retailers like best buy)

    Hope you get your problem sorted out.
  5. The GreatGrapeApe – Thanks for the input
    The “Brick” does state only 110 supported. The Laptop is a 7 year old Compaq.
    Bottom line, she there so will see if the converter works. Need to have here check with her brother to see if he still has the one I used in Moscow, I know it worked as I used it with this Laptop (Was a Higher end unit.)
    Somewhat familiar with 50/60 Hz effect. (1) Came back from England, forgot to change the gear in the clock/radio (1972). Set the alarm for 5 AM. It went off around 3:30 AM.. Electronics with a motor that is sync to AC will run slower and heating elements and xformers are efferent as freq decrease. An American toaster took almost double the time to toast bread in England. Used a 2 to 1 transformer. Boy does an electric solder gun heat up fast when plugged into 120VAC @ 400 Hz kind of shortens the life (aircraft power). Side comment – Wiped out my Cassette player by accidentally plugging it into 240 VAC while station in Vietnam ( The Ass____ used the same receptacles for 120 as 240.

    Technology-sponge: I really was looking more toward practical experience ie someone who had used one to power their laptop. Please do not take this the wrong way as I value all inputs, nor as a belittlement for electronic techs working in retail; But.
    (1) My knowledge and experience is on the upper end of the scale Not ego, just fact.. Taught both basic and advanced Electronics in the military for 10 years, Ran the ET department for a community college for three years and spent the last 18 years working on satellite and research B737 Data collection system for NASA ( They normally don’t pay $60K for average knowledge. (2) Specifically; I have looked at inputs/outputs of various PSs such as series/parallel regulated, switching PSs, and UPSs with regulated outputs. If I had the schematics and access to 220/240 (Have my own digital O’scope) and the time (She was leaving the next day) I could have answered my question. (Ref to VCR – If the drive motor is an AC synchronous motor, it would not work as apposed to a DC motor
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