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Re: How to rise the secondary? (fwd)



---------- Forwarded message ----------
Date: Wed, 8 Jul 1998 12:12:19 -0600
From: terryf-at-verinet-dot-com
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: How to rise the secondary? (fwd)

Hi Bill,
        I use a simple hand held LCR meter to find Cp an LS.  Lp is rather
low, usually, to get good meter readings with an inexpensive meter.  I use a
resistor connected to a signal generator and find the resonance of the LC
combination.  I use the signal generator and resistor to find the resonance
of the secondary with and without the top terminal and back calculate to get
Cself and Cs ( Cs = Cself + Cterminal).  Note that adding the top terminal
places the terminal into the coil's Cself field so the combined Cs is less
than Cself plus Cterminal separately. I just measure Ls with the LCR meter.
Nothing special there.

These days, I usually just fire the coil and capture the waveforms on the
digital scope.  The scope measures the frequency of the primary ring up and
secondary system after the gap quenches.  Since I know Cp and Ls to very
good accuracy, Back caluculation gives me Lp and Cs very easily.  Using the
digital scope in this way, makes primary to secondary tuning child's play.

Most of the equations can predict all these values very well in advance.
Still takes some fine tuning, but you should never be very far away from
what all the equations say.


        Terry Fritz


> Date: Tue, 07 Jul 1998 08:52:28 PDT
> From: Bill the arcstarter <arcstarter-at-hotmail-dot-com>
> To: tesla-at-pupman-dot-com, couturejh-at-worldnet.att-dot-net
> Subject: Re: How to rise the secondary?
> 
> 
> I have questions regarding how these values are determined.
> 
> Lp, Cp, are easily measured using any number of techniques.  But what
> about Ls or Cs?
> 
> Does Ls represent the "lumped' inductance of the secondary, measured (as
> above) between the base and top toroid?  I would bet this is the case
> but an not 100% sure.
> 
> But the really tricky one is Cs.  The only way I can see to determine
> this is by measuring the actual self resonant frequency of the secondary
> and toroid using a sig gen, 'scope and all that.  Then - you compute Cs
> via the frequency and Ls..
> 
> Any hints?  How are you folks determining these values?
> 
> -Bill Pollack (arcstarter)
> 
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