[Prev][Next][Index][Thread]
Re: Danger, and I don't understand why.
Tesla List wrote:
>
> Original Poster: "The Flavored Coffee Guy" <elgersmad-at-msn-dot-com>
>
> Have you ever heard of a magnetic circuit? I have a electromagnet that
> I picked up from Edmunds Scientifics that uses a flashlight battery to lift
> up to 200 lbs. I have a magnetic keeper and if I turn on the magnet, and
> leave the keeper on, then turn off the magnet. There is a residual magnetic
> field that is left behind. As long as I leave the keeper on the magnet,
> that residual magnetic field will remain. I can hook up an oscilliscope to
> that coil, and when I remove the keeper after magnetizing, and removing the
> battery. Just removing the keeper induces a relatively high voltage. If
> you have ever seen a horseshoe magnet, with a bar across the two poles, that
> is a keeper. Usually, very strong permanent magnets come with a keeper to
> help keep it magnetized. Now, if the wire in the secondary is resistance
> wire as most neon transformers are wound with a current limiting secondary,
> and do have several kilo ohms of resistance as a result. And if that
> resistance wire is ferro-magnetic, when you break the contact of the shorted
> wires, the magnetic circuit is broken within the resistance wire. Because,
> those windings can act like a keeper for a bar magnet.
Interesting speculations! However, NST's are actually wound with many
turns of fine copper magnet wire, an this alone accounts for the
comparatively large resistance of an NST secondary. The current limiting
behavior in an NST actually comes primarily from the addition of
magnetic "shunts". These bypass a portion of magnetic flux that would
otherwise link the primary and secondary windings. This results in a
substantial increase in the transformer's leakage inductance - and its
external behavior is similar to connecting an ideal transformer in
series with a very large inductor.
<SNIP>
-- Bert --