Re: 120 bps vs. 240 bps comparison tests

• To: tesla-at-pupman-dot-com
• Subject: Re: 120 bps vs. 240 bps comparison tests
• From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Fri, 28 May 1999 06:46:59 -0600
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi John,
            Thanks for doing all these wonderful tests!

> Original Poster: FutureT-at-aol-dot-com 
> 
> All,
> 
> In previous work, I found that 120bps sync operation produced longer
> sparks than higher non-sync break rates using the same power
> input.  I wasn't sure at the time if this was due more to greater
> transformer losses, or rather to non-linear spark growth with 
> increased bps.  What was needed was to measure the voltages
> on the caps, and I did this in these new tests.

<snip>
> Conclusions:   I am getting good power throughput at 240 bps, but
> this is not translating into long sparks.  Whether one looks at Joules,
> cap watts, wallplug watts, VA, etc., the higher break rate is using
> up almost 50% more power to produce the same spark length.  The
> sparks at 240 bps appear brighter, fuller and more fan-like, and less
> bolt-like than the 120 bps sparks.  This is the same effect I saw at
> higher break rates with non-sync gaps.  I did not try different toroid
> sizes, but I did try different toroid sizes in the past when using the
> higher break rate non-sync gaps, and it didn't help the situation. 
> I'll work some more on trying to even out the bang sizes, and verify
> the absolute firing voltages.  It would appear from these results, that
> a large bang size contributes much more greatly to spark length 
> than higher break rates, for a given power input.  It would seem to 
> me that both small and large TC's might benefit greatly by using
> large caps and 120 bps sync gaps, unless the spark growth behaves
> differently at high powers.  I doubt it would behave differently, but I'm 
> not in a position to test this (I have no room to build a large coil).  

I too am a fan of big primary bangs at modest breakrates (read long 
sparks). What I'd really like to see now is whether matching an 
increase in Ep with an increase in toroid capacitance (to maintain 
same Vout) produces longer sparks. I don't think it matters too much 
whether Ep is increased by increasing Cp or Vp.

?
Malcolm

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