# Re: DIY HV transformer

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• Subject: Re: DIY HV transformer
• From: "Tesla list" <tesla@xxxxxxxxxx>
• Date: Sat, 16 Jul 2005 13:28:24 -0600
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`Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>`

`Hi guys,`

```> Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>
>
> Hello Rob, nice to hear from you again.
>
>  > Now suppose I want a k value of k = 0.95 (which is a 'typical' value
>  > of k in a NST). The question is now: what value of the above ratio will
>  > produce this k? Is it (0.05/0.015)*10% = 33 %, or goes it with a SQRT
>  > (i.e. 18 %)?
> I'd guess the latter one, bt this can be easily verified by experiments.
> Sorry, I know this is probably the worst advice ever, just wanted to add
> my two cents.
> What are you trying? bosst the power of your doubler PSU?
>```

```I was curious at to what a k values mean in an NST.
It would be the ratio of the open circuit (o/c) voltage with the shunts to
the o/c voltage without the shunts.
i.e. the ration secondary flux to primary flux when the secondary is o/c.```

```Ok so what.
Ignoring the primary/secondary resistance and magnetic saturation.
The primary flux is determined primary voltage and frequency other things
kept constant.
With the output o/c, the input current is the magnetizing current to produce
the primary flux that is the sum of the shunt and secondary flux.
Assuming no change input V and f when the secondary is shorted the primary
flux does not change so it now must flow thru the shunt.
The shunt path reluctance must be k/(1-k) times the secondary reluctance.
Making the assumption (about right) that the primary reluctance is equal to
the secondary reluctance (depends one where the shunt is)
The primary current increases to (1+k)/(1-k) times the o/c condition (quick
calculation) to maintain the original flux.
Still don't know what the so what is.```

```Robert (R. A.) Jones
A1 Accounting, Inc., Fl
407 649 6400```