RE: ballast core

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi Malcolm

This is the way I want to build a ballast. I have been toying with the idea
for several months now, well at least since July. I have found several
formulas for the inductance of a multi layer solenoid, and using 1 as the
relative permeability, calculated a coil. Then I wound the coil that I made,
then I measured the coil, then recalculated. I can not get agreement between
the real coil and the calculated value. I am guessing that it is because I
am using THHN insulated wire for the test coil and the formulas must assume
magnet wire. Anyway I always get significantly less inductance as measured
than as calculated.

Help!

later

deano

> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Sunday, April 01, 2001 10:32 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: ballast core
>
>
> Original poster: "Malcolm Watts by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>
>
> On 1 Apr 01, at 14:54, Tesla list wrote:
>
> > Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> > <CTCDW-at-aol-dot-com>
> >
> > No, I would not have the E from this core. I just have a large (4.5 x
> > 4.5 x 14") straight core. My understanding is that open ended cores do
> > not saturate easily. I know of ballast inductors made of 300 turns of
> > wire around a form stuffed with 'I's from old NSTs I don't think I
> > would have to make this a multi-layer winding.. I'm pretty sure I have
> > enough length to do it in one shot, but I haven't actually checked it
> > yet. I'm still in the "can I do this without wasting money" stage :)
> >
> > Chris W
>
> Why 300 turns? My approach would be to build an air-cored inductor to
> meet the minimum inductance requirements of my system in such a way
> as to allow the core to be slid in to boost inductance when required.
>
> Malcolm
>
>
>
>