Adjustable AC Supply

Discussion in 'The Projects Forum' started by Metalmann, Mar 14, 2013.

  1. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
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    A new project in the works....
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,452
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    Get a Variac.
     
  3. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
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    That's the thing, I just bought one...tried to upload pics with a couple questions, and somehow I screwed up the pics.


    I'll be back!;)
     
  4. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
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    Here she is:


    This is a lot bigger than I thought. 23 pounds of hunkin metal.

    I'll have to design a case/box for it after the shop warms up a bit.

    I'll probably install 2 outlets, what do you guys think?

    The wiring shouldn't be that hard, right?:confused:

    It's over 8" square and 3.8" thick/deep. Not a scratch on the humongous dial, and knob. The terminals look in good shape.


    The last few months, I've been watching a bunch of these, but the one I bought looks so much better made.:

    http://www.ebay.com/itm/SUPERIOR-PO...019?pt=LH_DefaultDomain_0&hash=item5d3a8aee43
     
    Last edited: Mar 17, 2013
  5. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
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    It took some time, but I think i have the pic thing figured out.:D
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
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    Variacs are not isolated, you might want a 1:1 mains transformer before it for isolation purposes.
     
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  7. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
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    Thanks for the advice, maybe I don't know how to wire this thing.:confused: Did not realize that...
     
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The biggest (only) maintenance issue with these is carbon / ash build-up on coil edge where the carbon brush sweeps. Dirty coils cause the power to cut-out and contacts to bounce as you turn the dial.

    If there is build up, don't use any solvents. That might destroy/ dissolve the laquer on the coil wire. Ther is no laquer where the carbon brush makes contact but the rest of the wire likely has laquer to insulate.

    After that, these things are tanks and last forever.

    As for the wiring / mounting, you can punch a hole in the bottom of a metal can or plasic bucket and slide the shaft. Bolt a 1 gang switch box to the left for an on/off switch and a 1 gang box to the right side for a duplex outlet. Add a neon indicator lamp to show power is on. This should be on the mains side so it will stay on / bright even if the transformer fails.

    EDIT: don't forget to add a fuse. Use an amp rating related to the circuit you are powering, not the max current of this beast variac.
     
    Last edited: Mar 18, 2013
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  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Transformer is important when you are working with any open wires so you don't get killed. If you are just using it to slowly power up some old electronics with closed cases, I don't personally think the transformer is necessary but it won't hurt.

    If you do add a transformer, you should ideally have a transformer that can pass the current that you need for your project - if you get one that will match the current handling capabilities of the variac you have, it will need to be huge - about 25 pounds as well.

    By the way, I hope you didn't have to pay for shipping on that beast.
     
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