Re: Variac rebuild

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

If you halve the turns, you would then have a 60 vac variac. If you try to 
run  it on 120 vac the core will saturate and burn it up rather quickly. 
What I would do if i was determined to keep the core is wind a smaller wire 
(awg 24?) that has half the cir mil area and run it at half the original 
current rating, tho not a very efficient use of space. Doesn't seem like 
it'd be a problem if there's a single layer on the outer dia. and 2 layers 
on the inner, but I've never actually tried to rewind one.

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, February 05, 2005 1:21 PM
Subject: Re: Variac rebuild


> Original poster: Blake Hartley <teslaspud@xxxxxxxxx>
>
> Hello all,
>
> I got around to trying to wind the variac, and there is a problem: no
> matter how hard I try, I cant get the wire on the inside to form two
> layers. I would give up, but I have a small spool of 20 AWG wire and a
> chunk of iron that isnt going anywhere fast, so I am going to make one
> layer on the inside of the form, which will half the number of turns,
> making it 148. Would this work well ( i am running on 120 AC)? Also, i
> am going to put the tap points on the 23rd turn from both sides. Any
> comments on this design would be much appreciated.
>
> Cheers,
> Blake
>
>
> On Thu, 03 Feb 2005 07:30:27 -0700, Tesla list <tesla@xxxxxxxxxx> wrote:
> > Original poster: Finn Hammer <f-h@xxxx>
> >
> > Blake,
> >
> > Looking at thoseindustrial variacs, I tend to think I am loking at a
> > genuine example of industrial art.
> > Getting the wire trough that small hole in the center is the hard 
> part, > as
> > I see it. That`s why I had the core made so big for my project. Not 
> so > neat
> > and refined as the professionally evolved types, but manageable on a > hand
> > work level.
> > Another thing, the contact area: on pro stuff, the wires are rolled > flat,
> > you will have to file it flat, which decreases the cross section. 
> more > heat
> > in a critical spot.
> > I see these hand winding endeveours as zen activity, more than anything,
> > and rewarding as such.
> > I wish you luck!
> > Cheers, Finn Hammer
> >
> >
> > Tesla list wrote:
> >
> > >Original poster: Blake Hartley <teslaspud@xxxxxxxxx>
> > >
> > >All,
> > >
> > >Maybe you remember, but a while ago my four amp variac brokedown due
> > >to several burned and broken turns. Seeing Finn Hammers homemade
> > >variac inspired me to dig up the remains to see if it would be
> > >possible to rebuild. I took all of the stuff off except for the core
> > >and windings, and the physical specs of the core are as follows:
> > >height=2.9", ID=2", OD=4.1". It is wound 45 turns until the first tap
> > >point, 206 turns in between the two tap points, and 45 more turns
> > >until the last turn. The inside is two layered, but the outside is
> > >single layered (because the inside radius is ~ half the outside
> > >radius.) I plan to figure out the type of wire and re-wind it in the
> > >same manner as it was wound. would this work, or is there any other
> > >way i should go? Any help would be much appreciated. Thanks
> > >
> > >Cheers,
> > >
> > >Blake
> > >
> > >
> > >
> >
> >