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need 240 vac to 12 vac transformer

Discussion in 'General Electronics Discussion' started by bratwurst626, Jun 15, 2011.

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  1. bratwurst626

    bratwurst626

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    Jun 15, 2011
    So would anybody have any idea where I would be able to find a wall transformer that meets these specifications: 240 VAC input and 12 VAC 1.6 Amps output. Also it needs to have a 5.5mm x 2.5mm coax connector.
    The problem is that I already have the ac adapter that inputs 120vac, but I need one that inputs 240 ac. I've been looking around different websites such as digikey and even just googling different things and I've been able to find more of the 120vac transformers but I haven't been able to find any 240vac capable transformers that meet those requirements.If anyone has any suggestions on where to go to find it please let me know, or if they have anything that can point me in the right direction, any help would be greatly appreciated.
     
  2. davenn

    davenn Moderator

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    if you are in the USA with the 120VAC, then chances are you are going to have to get one from overseas. 12VAC 1.5 - 2 A is available here in Australia.

    Coax connecter ? a RF coax connector ? or do you mean a standard DC connector like the ones on the right side of the pic ?...


    [​IMG]

    cheers
    Dave
     

    Attached Files:

  3. bratwurst626

    bratwurst626

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    Jun 15, 2011
    it has a 6' coaxial cord, but i do believe the plug is lke the dc connectors on the right of the pic
     
  4. bratwurst626

    bratwurst626

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    Jun 15, 2011
    ok, just talked to the person that I'm looking for. The only specifications that I need are that it needs to input 240vac and output 12vac and preferably have either a c13 or a c14 plug. I'm having trouble finding it, but that might be because I'm in america where the standard is 110 not 240, but its for something that is going oversees. If you guys know of any or possible have links to share that would be great.
     
  5. donkey

    donkey

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    Feb 26, 2011
    i googled the plugs you are talking about. they seem to be iec or standard australian house plugs.is this for a laptop or something else?
    anyway as from what i have seen is the australian standard try google.com.au or ebay.com.au to start. here in australia we have a few electronic suppliers, "dick smith", "jaycar", "altronics". those are the ones i can think of the top of my head. if you could inform me on what the chord is for i can probably google an item real quick for you.
     
  6. bratwurst626

    bratwurst626

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    Jun 15, 2011
    Its just that I have an controller that has a 120vac to 12vac power supply. Its just a standard wall transformer. Well now we need to take this controller internationally, we would resort in a simple 240v to 120v converter, but we need something we could possible use more commercially, so an actual power supply, i guess does that answer your question. Also I'm sorry to sound so need but I'm in the US its a pain in the butt to find even international parts.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I think you can scratch Dick Smith off that list. They don't sell electronic components any more.

    edit: This might do the job.

    But you may find that the device will run fine from DC. In that case you would be better off looking for a 12VDC 2A switchmode power supply that is rated for an input voltage between 90 and 250 volts (as is reasonably typical)
     
    Last edited: Jun 16, 2011
  8. bratwurst626

    bratwurst626

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    Jun 15, 2011
    Just wondering, can you run a dc signal into a rectifier? the reason i ask is because the controller has a rectifier inside of it, reason why I'm looking for an ac/ac transformer. I can find a lot of 120v-240v ac to 12v dc, so if its fine to run the dc signal through the rectifier then hopefully we should be home free
     
  9. donkey

    donkey

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    i understand that this is a standard wall transformer, but if its for a commercial product we could probably find the equivilent for you if you let us know what you're powering.
    the transformer supplied from steve will require wiring plus the lead and plugs also you can try items like http://www.ebay.com.au/itm/STEP-DOW...20796324113?pt=AU_Gadgets&hash=item33687c8911 and then you will be able to convert power to the us standard 110 volts from the aus 240v. beware when buying adapters that they convert the power or you will fry(technical term lol) the item you are trying to power. there are converters available if you look around that will adapt the the plug so you can bring the transformer you already have and plug it into a converter.
    http://www.jaycar.com.au/productView.asp?ID=MP3057&CATID=27&form=CAT&SUBCATID=521
    is 2 amps ac
    thats about the best i can find for you for now but if you need anything closer to 1.6amps at 12vac look at australian sites. and one last thing http://www.automation-drive.com/EX/05-15-01/c-14%20to%20c-13%20V.jpg thats the plug i get when i google c13 and c14. is this what is being plugged into your item?
     
    Last edited: Jun 16, 2011
  10. donkey

    donkey

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    a rectifier from what i understand only does ac-dc voltage it should work from the little i know.
     
    Last edited: Jun 16, 2011
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    You certainly can, and that forms the basis of my edited comment above yours.

    Look for a DC power supply that can run on voltages between at least 100 and 240 volts (wider range is better) and then all you'll have to do is get adapters (so the plug fits) to suit any country you take it to.

    edit: but test it first. You may need anything up to about 16VDC.
     
    Last edited: Jun 16, 2011
  12. bratwurst626

    bratwurst626

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    Jun 15, 2011
    yeah, that's the plug, The power supply is going to fit into a rack that uses those connectors, but that would be a completely ideal situation if i can't find those we can still make it work
    so it will pass the dc voltage without harming anything
     
  13. donkey

    donkey

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    could you use a standard power pack with the plugs shown by dave and then make your own adapter? iec or c13 and c14 plugs are easy to obtain and if its ac wiring should be easy as well. the only problem i see is the earth wire unless that terminal is not in use.
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    AC passes through a rectifier to become pulsing DC.

    This is filtered by a capacitor to produce DC with some ripples on it.

    This generally then goes to a regulator which reduces the voltage to a fixed value and removes almost all the ripple.

    If you replace with DC:

    the DC goes straight through the rectifier leaving DC

    The filter capacitor charges up, but has less to do because it sees DC (or DC with some minute amount of ripple) rather than pulsed DC.

    The regulator reduces the voltage, and what comes out has even less ripple because the input was a higher quality DC.

    So the short answer is YES.

    The longer answer is that 12VAC could produce up to 16VDC (or even higher off load) and the regulator *MAY* not work correctly with a lower (10.8V) input voltage (a bridge rectifier could drop as much as 1.2V). If the regulator is 8V or less (5 is common) it is most likely that there will be no problems. If it is higher than this, you may need a higher voltage DC input.
     
  15. davenn

    davenn Moderator

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    yes you can, no probs, just take into account the loss in the diodes ~ 1.7V
    the nice thing about using a bridge rectifier is that provides polarity reversal protection.

    ie. it doesnt matter which way around the input DC is connected the polarity out will always be correct :)


    cheers
    Dave
     
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