Re: [TCML] How linear does a ballast need to be

[David Dean <deano@xxxxxxxxxxxxxxxx>]

Hi

On Wednesday 08 July 2009 11:40:18 pm jhowson4@xxxxxxxxxxx wrote:
> alright my not so great understanding of ballast coils just went out the
> window.
>
> I had the understanding that as you added an air gap to the core the
> current being drawn goes down
>
http://www.richieburnett.co.uk/ballast.html can explain better than I.
> and in the case of the ballast type that the core is physically pulled from
> the coils that as the core is removed the current goes down.
>
No, the inductance of the coil without the "slug" is simply its "air core 
inductance". Iron has a much higher permeability than air, so inserting the 
slug increases the inductance.
> I am asking because according to his graph my understanding is exactly
> opposite of reality. could some one please explain how these work to me.
>
> thanks ,
> Jay Howson
>
> ----- Original Message -----
> From: "David Dean" <deano@xxxxxxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Wednesday, July 8, 2009 10:03:59 PM GMT -05:00 US/Canada Eastern
> Subject: [TCML] How linear does a ballast need to be
>
> Hi
>
> I just improvised a ballast from two MOT primaries in series on a single
> MOT core with adjustable gap A La Richie Burnett.
>
> Core cross sectional area 3.5 sqin
>
> Number turns, wire gauge, unknown-- whatever a MOT primary has
>
> I am looking for 100mA short circuit 14400V open circuit for my
> application, that is about 6A at 240V input. That hits on the dark blue
> line (0.035" gap) of my improvised ballast from the test I just did-- see:
>
> http://deanostoybox.com/temp/vi.png
>
> My Question, is this linear enough to use as is, or do I need to go back to
> the drawing board?
>
> later
> deano

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