Re: Can't just change one thing! (fwd)

To: tesla-at-pupman-dot-com
Subject: Re: Can't just change one thing! (fwd)
From: Tesla List <mod1-at-pupman-dot-com>
Date: Wed, 5 Aug 1998 20:51:58 -0600 (MDT)
Approved: mod1-at-pupman-dot-com


---------- Forwarded message ----------
Date: Wed, 5 Aug 1998 12:04:37 EDT
From: FutureT-at-aol-dot-com
To: tesla-at-pupman-dot-com
Subject: Re: Can't just change one thing! (fwd)

In a message dated 98-08-05 00:58:51 EDT, you write:

<< ---------- Forwarded message ----------
> Date: Tue, 4 Aug 1998 15:04:27 +1200
> From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Can't just change one thing! (fwd)
 
>In light of John's post and the replies below, here are some queries 
> I would like answers to as this concerns some research I wish to do:
    
 snip> 
> Here are several cases to be confirmed/denied:
 
> (1) A change in ROC at the top. Can be done with differently shaped 
> terminals without the need to retune (if both add same capacitance 
> to the secondary)?

Hi Malcolm,

I did a test comparing a normal 4" by 17" toroid, with a special double
cone toroid of the same dia. and thickness, that had a relatively sharp
tapered edge. I got twice as many streamers with the double cone, and
they were much shorter.  The tuning stayed very similar (within one turn of
19 turns).  I didn't actually measure the capacitance of these toploads.
I was surprised that the double cone seemed to work best at 20 turns,
with the toroid best at 19 turns.
 
> (2) Primary reactance comparison: I wish to explore behaviour of a 10 
> Ohm vs 100 Ohm primary with the same resonator. I can change the L/C 
> ratio in the primary, change the primary voltage to keep bang size 
> the same (which keeps Vo the same) and change k so that k in both 
> cases are the same?  (OK - it does assume primary loss to be the same 
> in both cases).  

I guess you'd have to use thicker wire in the primary to keep losses
the same.  The quality of quenching may change.  Still, it should tell
whether one design is superior to the other in an overall sense.  I
think it's a valid test.

> (3) Resonator comparison: I wish to see the effect of resonator 
> impedance on output spark. I have two coils, same H/D (same 
> capacitance) but with different inductances. I can tailor Lp to 
>maintain tune and adjust k to allow for this. Reasonable?

Primary losses, quenching may change, and frequency will change,
but info from test (2) will give input into the primary and quench
issues, although the quench could be affected by frequency, and the
overall different frequency may have some effect.  But I don't think
frequency makes much difference unless it's changed radically.
Perhaps anywhere from 100kHz to 400kHz makes no real difference,
I don't know.  I like your idea of using the findings of one test (test 2) as
controls for other tests that involve the same sort of change.  Sort of
a substitution method.  Yes, I think it will work very well.
 
> (4) As for (3), but this time I will change Cp and Vp to maintain 
> same Ep and adjust k to be the same for both combinations. Can do?

Again, results of test (2) will act as a control.  If you see some variation
in test (2), this can be taken into account when judging tests, (3) and (4).
 
>      Do list members consider it possible or otherwise to make such 
> changes to explore the effects of just one or two parameter changes?

I've never tried this approach, but I like it.  I think the results will be
meaningful.
 
John Freau
 
>Malcolm
  >>