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Re: MOT charging mysteries (was: Re: The RAT coil)



Original poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi> 

Hello.

This doesn't fully answer to Bob's question but it is at least "something".
Check the PDF at:

http://www.gensemi-dot-com/appnotespdf/volt_mul.pdf

It is an application note from General Semiconductors about designing voltage
multipliers. Although it deals much with
diode selection, I think it can be still of interest for someone.

Regards






"Tesla list" <tesla-at-pupman-dot-com> on 04.12.2000 23:30:56

To:   tesla-at-pupman-dot-com
cc:    (bcc: Marco Denicolai/MARTIS)
Subject:  Re: MOT charging mysteries (was: Re: The RAT coil)



Original poster: "bob golding" <yubba-at-clara-dot-net>

Bert all,
     What does one need to need to know about the trandsformer in order to
calculate the size of cap to use.? I am using a 8200v 250mA radar
transformer. My inductive ballast works fine, but it would be nice not
to have drag 75 lbs of iron and copper about. I assume one could use
more or less any type of cap as long as the voltage stand off is high
enough as it is in the 50/60 hz part of the circuit and the high current
part of the circuit is the "other side" of the gap. Have I got this
right.?

cheers
 bob golding


cc:    (bcc: Marco Denicolai/MARTIS)
> Subject:  Re: MOT charging mysteries (was: Re: The RAT coil)
>
> >The particular MOT and voltage doubler circuit in your system does not
> >need external ballasting since it uses 1 uF caps in series with the high
> >voltage MOT output legs (see http://www.saunalahti.fi/dncmrc/tank.html).
> >When the main gap fires, there's never a true short circuit placed
> >directly across your MOT's. In effect, your 1 uF caps are acting much
> >like a "capacitive" current ballast for your MOT supply, limiting the
> >short circuit current! While inductive ballasting is used in most
> >systems, capacitive ballasting is another option. In fact, a pig, if
> >used with this circuit, would not require external inductive ballasting!
>
> Hi Bert.
> You are right. The 1 uF caps must work as a ballast. I didn't see that...
>
> But so let's put it the other way: I haven't simulated it yet, but why not to
> use the doubler
> scheme instead of 4 MOTs? You get ballasting for free and the same voltage.
>
> Surely the charging speed (i.e. voltage) will not be the same, but (at least
> from Finn's
> scope pictures) looks like the MOT current protection plays nasty tricks
and he
> is loosing
> "bangs" anyway.
>
> Regards