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Discussion in 'General Electronics Discussion' started by azkarter76, Jul 8, 2011.

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  1. azkarter76

    azkarter76

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    Jul 8, 2011
    Hey there everyone new here but i need some help. I have a problem. I have a water softner that has a 12vac output at 150 mA. I'm getting a power supply with a 24vac battery backup. I know i can use a step down transformer but how do I get the 150 mA I need?

    Thanks for any help

    Lee
     
  2. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    You need a step-down transformer with an output capacity of at least 150mA. It does not matter if it has a 1500mA capacity as long as the voltage is 12V (AC).
    Make sure you know the difference between AC and DC however. I get wary when I see AC and batteries mentioned in the same sentence.
     
  3. azkarter76

    azkarter76

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    Jul 8, 2011
    I know they make them. Where do I buy one and am i looking for a CT on the transformer? I thought that the 24VAC to 12VAC was a common transformer, but i guess not.

    Thanks for your help

    Lee
     
  4. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Even though I know next to nothing about your setup I'd say that any centertapped 24V transformer of 2VA or more will do. Just isolate & ignore the 110/230V primary.
     
  5. azkarter76

    azkarter76

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    Jul 8, 2011
    I'm sorry for bugging you but I do work with electronics but nothing AC related mainly DC stuff. But durring a power outage the water softner was stuck in the backwash mode all night long flushing 115 gallons or more down the drain while we were asleep. I found and ordered a altronics CCTV camera battery backup with a 24VAC the water softner has a 12VAC.

    I'm kanda lost how to isolate 110\220V promary? hook it up like a regular door bell circuit?

    Thanks for your help

    Lee
     
  6. Resqueline

    Resqueline

    2,848
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    Jul 31, 2009
    I'm also still kind of lost to how these products work and what you're tring to achieve with the setup. Can you find some links to both product descriptions?

    If I understand you correctly then the water softener runs on 12V AC (150mA) and stays in whatever mode it was in when power goes out.
    You want to "UPS" this to ensure it continues the program correctly.
    You've found a CCTV camera UPS unit that puts out 24V AC and want to use this to supply the water softener with power.

    One concern I have about camera UPS supplies is that I know CCTV cameras can run on both 24VAC and 12VDC, so how do you know the UPS doesn't just switch to DC?
    And, are you sure the water softener has to have AC, maybe it can operate on DC?

    About the transformer: Isolating the primary means insulating the connections so they can't be touched by anyone or anything, since mains voltage will appear there.
     

    Attached Files:

  7. azkarter76

    azkarter76

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    Jul 8, 2011
    Thank you for the picture. It is AC voltage only here is the link http://www.altronix.com/index.php?pid=2&model_num=ReServ2.
    The only DC voltage is when the unit switches over to batt backup. and from what I read it the altronix will convert over to ac. You are correct on what I want to do. I wish the darm thing was DC this would have been easier for me.

    Thanks

    Lee
     
  8. davenn

    davenn Moderator

    13,710
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    Sep 5, 2009
    no they wont be common, in fact probably dont exist at all

    what you want is a 110/120V (230-240V depending on your country) to 12V stepdown transformer they should be readily available as a plain transformer or as a plugpack from the likes of radioshack or whatever electronics outlets you have in your country where-ever that is :)

    That camera PSU is a huge and expensive overkill for what you are trying to achieve

    Dave
     
    Last edited: Jul 10, 2011
  9. Resqueline

    Resqueline

    2,848
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    Jul 31, 2009
    Ok, that unit does indeed seem to put out a pure sine at all times so it should work, but it does look hugely expensive though it's only 96VA.
    Does it cost more than an ordinary mains UPS?
    Sometimes, even if a unit comes with an AC supply, it may turn out to just be rectified and regulated inside. Can you get some info about it or some pic's of its guts?
    It would need AC only if it runs the solenoids on AC, or if it generates multiple internal voltages from the AC, or if it runs its clock from the mains frequency.
     
  10. azkarter76

    azkarter76

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    Jul 8, 2011
    Thank you for everyones reply. yes you can call it over kill but i can monitor the batteries on the security system.

    Thanks again for all the help

    Lee
     
  11. donkey

    donkey

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    Feb 26, 2011
    hey i looked at the basics of the link you sent, and as i am a newbie i am just stating this. but the enclosure houses 2 12volt 7ah batteries, i assume in series to create a 24volt power supply. couldn't the batteries be "seperated" to give the 24 volt supply it is intended as well as 2 supplies of 12volts while still be part of the scurity system?
    maybe even with a switchmode so they drain evenly.
    this may be way of the mark for ideas, but i also would like to know if its possible
    the part i am referring to on that page is

    Enclosure
    • Accommodates up to two (2) 12VDC/7AH batteries.
     
    Last edited: Jul 11, 2011
  12. MagicMatt

    MagicMatt

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    Jun 15, 2011
    A battery is a bank of cells, so what you have is essentially a load of 2V cells in series to give you 24V. The fact they're in two boxes of 6, giving you 12V per box, is almost irrelevant. ;-)

    What you need to avoid is cells becoming discharged unevenly, because if they discharge unevenly they'll also recharge unevenly, and this just damages the useful life of the battery and can even destroy cells completely.

    If you want two 12V supplies, you need to treat the two 12V batteries seperately, and charge independently.

    So yes, what you're doing is possible, but ill advised as it would put the battery at risk of much quicker failure. Also, given the massive cost of the unit you're proposing, I think I'd be more inclined to make your own 2:1 transformer.

    Or of course take a totally different route, and shut off the water supply to the softener if the power goes. I know devices like that exist as we have one installed in our heating system!
     
    Last edited: Jul 12, 2011
  13. azkarter76

    azkarter76

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    Jul 8, 2011
    how hard is it to make my own transformer? what do i need? im used to working on DC stuff its a lot easier.

    Lee
     
  14. davenn

    davenn Moderator

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    Sep 5, 2009
    they can be hand made but VERY difficult with out good workshop setup.
    thats why they are easy to buy

    Dave
     
  15. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
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    Jan 21, 2010
    You find a company that makes custom transformers and you give them the specs and some money.
     
  16. donkey

    donkey

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    Feb 26, 2011
    thanks magicmatt, i assumed there would be a problem charging, but couldn't figure out why.
    i also noticed from the page supplied the item purchased was the only one that had a single voltage the other 2 actually offered a 12v output.
     
  17. donkey

    donkey

    1,289
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    Feb 26, 2011
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