Re: Current Limiting and Impedence

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Paul,
          Whatever rods you purchase for the core, they have to have
a very small x-sectional area. They should also not retain much if
any magnetism after being de-energized (check with a magnet) or they
will have large hysteresis losses resulting in lots of heating.
Silicon steel such as used in transformer cores is preferred if you
can get them.

Malcolm

On 9 May 2005, at 20:25, Tesla list wrote:

> Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>
>
> Gerry,
> When I was in Home Depot the other day looking for polyurethane, I
> noticed a bin full of all thread that also had many sizes of
> unthreaded steel rod as well. While going through some of the rods it
> came to me that I could fill a piece of PVC with a bunch of these rods
> to use as a core for an inductor, similar to a laminated core. I think
> I would probably need to insulate the rods from each other with
> varnish or polyurethane, right? Without having to worry about how much
> space is available, like with an E/I core, the selection of wire gauge
> should be simpler and you could just keep adding layers of wire until
> you get the inductance required. The thing I stupidly didn't do was
> write down the prices of the steel rod. I'm also quite sure that there
> is a less expensive place to obtain steel rod. In fact, it just came
> to me that back when I had a TIG welder, I bought 1/8" uncoated steel
> rod from the welding supply where I bought Argon. If I remember
> correctly, this steel rod is available in many different types of
> steel from brass to soft low carbon steel to several different types
> of stainless steel. Later. Paul Think Positive
>
>
> ----- Original Message -----
> From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
> To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
> Sent: Monday, May 09, 2005 12:52 PM
> Subject: Re: Current Limiting and Impedence
>
>  > Original poster: "Gerald  Reynolds"
> <<mailto:gerryreynolds@xxxxxxxxxxxxx>gerryreynolds@xxxxxxxxxxxxx>
>  >
>  > Hi Paul,
>  >
>  > It seems you can always turn a gapless toroid into a gapped toroid
>  with a > hacksaw.  I use a toroid as an example only because the math
>  is simplier > and it is easier to talk about concepts.  The ballast
>  I'm planning on will > use cyclindrical geometry and welding rods as
>  a core so it will be > "gapped". I'll probably strip off the flux and
>  varnish the rods (or I'll > just get steel rod, which ever is
>  cheaper) > > Gerry R > >>Original poster: "Paul B. Brodie"
> <<mailto:pbbrodie@xxxxxxxxxxxxx>pbbrodie@xxxxxxxxxxxxx>
>  >>
>  >>Gerry,
>  >>I'm really interested in what you guys have had to say on this
>  thread. >>Please let us know the results of your investigations into
>  gapless >>toroids. I do have one little question: are there gapped
>  toroids? I've >>never seen one and it seems that would defeat the
>  purpose of using the >>toroid shape in the first place. Regards.
>  >>Paul >>Think Positive > > > >
>
>
>