240v AU to 110v USA

Discussion in 'Electronics & Electrics' started by Intensify, Jan 15, 2020.

  1. Intensify

    Intensify Member

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    So the wife is looking at sewing machines and i found out they are about 50% cheaper or more from the USA.

    So the model i am looking at is a Singer Quantum Stylist 9960. So it says 120 Volts, 55 watts, and 60Hz usage. So i figured i could get a step down converter/ transformer and run it from that and i still would be saving over $300 than what i can buy it for here in the AUS.

    So something like this, i know 1000w is a lot more than the 55w required but it isn't a whole lot more and i am happy to pay a little extra for the inbuilt fuse.

    https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com.au/ulk/itm/372523513967

    Does this make sense or would/ wouldn't work?
     
  2. Hater

    Hater Member

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    don't do it

    just spend the money and get an Australian machine with 240V motors in it.

    as it's an AC motor, the motor is tied in to the Hz of the power (50 here, 60 in the USA) and cheap transformers never provide this properly. your wifes stitches will be all over the place with the motor unable to keep a stable speed unless you spend decent money on a transformer, but theres that $300 saving gone.

    i have this problem with a kitchenaid mixer. ended up just spending the $280 getting the motor converted to 240V rather than mess around with the pain of a transformer.

    i assume transformers also use or waste electricity themselves in the conversion, making running costs dearer too
     
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  3. power

    power Member

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    i don't see an issue, i have a Dreamcast and CD32 that both need stepdowns it's nbd.

    I did end up converting the DC and might do the same with the CD32 just for convenience/tidyness factor. Replacing the PSU is also a good option.

    I'd be more worried about warranty tbh on a new item though.
     
  4. Hater

    Hater Member

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    both those don't use big AC motors in them.
     
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  5. power

    power Member

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    they do not.
     
  6. hippyhippy

    hippyhippy Member

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    After the cost of the transformer and then the shopping costs , conversion... Why bother? The local model will give warranty also.
     
    Last edited: Jan 15, 2020
  7. OP
    OP
    Intensify

    Intensify Member

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    ~$530 delivered + transformer like the one listed if thats whats required.
    Same machine in AU is $899

    Just saying.
     
  8. hippyhippy

    hippyhippy Member

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    10% off ebay the tis friday
     
  9. OP
    OP
    Intensify

    Intensify Member

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    Whats considered a big AC motor?
    55watts?
    Google tells me
    amps = watts ÷ volts
    So 55÷110 = 0.5A?

    This 50hz to 60hz is concerning it seems. The transformer linked is claiming dual hz compadiable.
     
    Last edited: Jan 15, 2020
  10. aXis

    aXis Member

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    Transformers are highly efficient, in the order of 97 or 98%.

    55W is not a *big* AC motor either.

    The most common motor for sub-horsepower appliances is actually a universal motor, which doesn't care about frequency. That said, 55W is so small I expect it to be something else like a brushless DC. Considering the smart speed control features it claims I'd expect that to be even more likely. Ideally they could have had an automatic switching power supply that had a wide range of voltage / frequency support, but it looks like they havent been that generous.

    At 55W a power transformer *should* be OK. Overrating it will help with voltage fluctuations, 100W here for $75: https://www.altronics.com.au/p/m8182-powertran-100va-240v-to-120v-stepdown-transformer/
     
    Last edited: Jan 15, 2020
  11. cvidler

    cvidler Member

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    The problem is the Hz difference, running a motor designed for 60Hz, on 50Hz, will do two things.

    Make it run slower - this may or may not be a problem for what it does.
    Make it run hotter - this may or may not start a fire.

    Buy the Australian one. Also prevents the missus accidentally plugging it into 240 by accident because she wants to sew in the other room one day and blowing it up.

    Also all the stuff re warranty etc.

    Make zero sense to use a US model.
     
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  12. cvidler

    cvidler Member

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    "compadiable" and "converting" are two very different things.

    cheap transformers (indeed ALL transformers) won't change the frequency, you need something more complicated (and expensive) than just a transformer to convert the frequency.
     
  13. Hater

    Hater Member

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    55W seems mighty tiny, my old motorised singer 201 has a 300W 1.5amp motor and it's from like 19 dickety two
     
  14. OP
    OP
    Intensify

    Intensify Member

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    At a guess i would agree. I think it would be converting AC into dc for the motor then possible 5v for the electronics. I could have a little look into it more see what i can find.

    As said above warranty is a issue using a transformer to power a appliance. I don't like the sound of that to much. In the comments there are successful uses with this.
     
  15. cvidler

    cvidler Member

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    Did you use it to sew an onion to your belt?
     
  16. Hater

    Hater Member

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    obviously, it was the style at the time
     
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  17. JSmithDTV

    JSmithDTV Member

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    Yes I think that was the style at the time...



    :D


    JSmith
     
  18. aXis

    aXis Member

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    This is usually only a problem for induction / synchronous / shaded pole motors - residentially you'll usually only see these in fridges, aircons and exhaust fans. Going from 60Hz to 50Hz is worse, you'll generate less power and more likely to increase torque or stall the motor, which produces heat that burns them out.

    It's a very different scenarios for appliances (like blenders) as these are usually universal motors and they don't care about frequency.

    But yeah accidentally plugging things into 240V is an issue and you;d want to try to permanently attach them. Warranty is a valid concern too.
     
    Last edited: Jan 15, 2020
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  19. mjunek

    mjunek Member

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    Most sewing machines are all computer controlled for speed, which needs to be relatively accurate.
    You'd probably find that this is a DC motor or separately driven (such as VFD), and are not directly tied to the mains frequency.
     
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  20. mAJORD

    mAJORD Member

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