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Old 12th April 2009, 07:55 PM   #1
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Default building a variac

Hi again..anyone have plans for building a variac ? How hard can it be ?
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Old 12th April 2009, 08:03 PM   #2
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Why would you bother? They're cheap enough second hand.
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Old 12th April 2009, 08:42 PM   #3
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I guess just for the sake of accomplishment...
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Old 14th April 2009, 06:42 PM   #4
zman3 is offline zman3  United States
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I'll have to agree with Brett; there are many other things you can do in this hobby that would fill you with a greater sense of accomplishment for far less money and/or aggravation (custom winding an output transformer or building a line-level preamp both spring to mind).

Just in case nobody has mentioned it, try to attend a local hamfest. I've picked up 10 A variacs fused and in housings for as little as $5 - and I can assure you they're FAR safer and more reliable than anything you can build.
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Old 15th April 2009, 12:43 AM   #5
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Location: Stittsville, Ontario, Canada
Here is a possible compromise answer :
Buy one of the cheap readily available variacs, you will have a good safe one, as Brett and Zman3 suggest,
copy it, and your desire for a sense of accomplishment will be satisfied.
Robert McLean
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Old 15th April 2009, 12:59 AM   #6
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I didn't mean to rain on anyone's parade, but for the same effort you could wind your own audio transformers which will teach you more and you'll get a lot more use out of. I use my variac a bit, and on a busy week it'd be lucky to get an hours use.
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Old 15th April 2009, 01:13 AM   #7
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Thanks for the input. Winding trannies is on my accomplishment list, but I don't think I'm quite ready for it steps first. I'm kind of a Rube Goldberg-type, so anything is gratifying to me. With the clunkers I have around, a variac will get quite a workout in my laboratory.
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Old 15th April 2009, 01:21 AM   #8
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Some reading for you then.
Turner Audio Educational pages

There's quite a bit on load matching, as well as OPT design info a bit further down.
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Old 15th April 2009, 01:22 AM   #9
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I have to reinforce the sentiment here...

A variac is an instrument of death (anything that connects directly to the mains is lethal) This isn't a good choice for a 1st build.

Buy a good safe one and it will help protect you during your other experiments
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Old 15th April 2009, 01:49 AM   #10
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Any recomendations? I just picked up one as a part of a test equipment buy. It looks to be from the 30's,and the cord appears to have caught fire! I'm guessing I shoud just junk it. I'd like something newish and cheap.
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