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Re: Home Made Variac



I would think the core would be the hard part of making a variac. The ones
I have
are round, toriodal cores. I guess you could probably use a different shape
to get
a more available form. I have no idea how it would effect the flux and
such. Our
primary coils have some autotransformer effects, so I would think that the core
style wouldn't make a huge difference. But I've been wrong before... ;)

Have you tried Ebay and various surplus places for commerical ones? How big a
variac do you need? I got a 5A unit for $30 from an online surplus place.
For NST
coils that would get you started. I run a 15/60 and a 15/30 on it in
parallel with
no heating or other ill effects. You can overload them, just make sure to
give them
a little down time too. I got a stack of 3 from an Ebay auction too for a great
price. A little searching will find you some for less than I could build one
anyway. If you do manage a cheap working variac be sure to share the plans. ;)

Travis



Tesla List wrote:

> Original Poster: "Michael Novak" <Acmnovak-at-execpc-dot-com>
>
>
>      I can't afford to buy a variac but I need some way to vary the line
> voltage... So, I decided to build one. I'm pretty sure I can get my hands on
> some 10 guage magnet wire, however, I still need to find a suitable core.
Isn't
> a variac basically a bifliar-wound 1:1 turns ratio transformer? If so, does
> anyone have some sort of formulas on the subject?  What would be the
> disadvantages of having a core which is not laminated such as the kind
found in
> transformers?
> Any thoughts?
>                                                             -Michael