Re: current limiting choke

Hello Jim,

On Sat, 8 Jun 1996, Tesla List wrote:

> Start out smaller. It will get warm over several minutes, just let it
> cool. Mine weighs about 2kg +-.

A smaller one has the risk of core saturation not to mention that it will
not limit current too much because of low inductance.. 

I did come to that huge choke design because it seems that a smaller one
would require huge amount of wire (turns)  to reach any adequate
inductance and be able to pass a maximum of 50amps through it.. (3*1.5
wire minimum)..

> My first (and only one so far) is 1000 turns of #16/1.3mm, well that
> is what I started out to do! I ran out of the 1.3mm at about 400
> turns, wound another 100 turns using #18/1.02mm and then finished off
> with #22/.64mm wire. I used a 12"/30cm by 3"/7.62cm PVC form (plastic
> water pipe, large;) I filled the form with all the I sections from
> some old transformers that I haven't built yet. About 3.8cm by 3.8cm
> by 18cm. The air core inductance is about 1mH, the iron core is about
> 9mH. I also use 10 ohms of resistive ballast in parallel.

9mH -> 2*pi*60*9/1000 Ohms = 3 Ohms and with 10 ohms in parallel
only 30/13 = 2.3 ohms and that "limits" the current to 230/2.3=100amps..

Are you certain of those figures or did you really run 100 amps
through the thing? (it would have melt very quickly though if
not in LN2 immersion or something:)

If one has to include the tank capasitor as "seen" through the
pig it would limit the current more than that choke..

> Fun things to do: place 10ohms of resistance in series, remove iron
> core, place small ferrite core inside. Stand out of the way, apply
> power. Watch the ferrite core "shoot" out. Or, place your iron core

Yes, coil guns are nice things - I guess that discharging a
1670uF 2kV capasitor with low ESR might have an effect too >:)
More on coil-guns at hv-list as they are not Tesla-things..

  Kristian Ukkonen.