Re: [TCML] Effect of doubling the input current

["Phil Tuck" <follies@xxxxxxxxxxxx>]

Hello Scot

 

My gap is a static sucker consisting of two 0.75 inch copper bars with the
centres drilled out 9mm  for the suction from a vacuum cleaner. It never
gets past warm. My BPS will be 100 (50hz)

 

I didn't think the caps were over volting as surely the safety would fire.
This has been set up quiet carefully to fire occasionally when just the
NST's are across it with everything else disconnected. 

 

Interested to know if you disagree with my logic, as I'm thinking of making
the duel NST setup permanent. I don't wish to blow anything until I get
around too increasing the cap capacity by buying some more- once the
exchange rate with the US improves!  (I'll also go ARSG when that time comes
so the outlay will be big) 

At present my caps are 21.43 nF which is about 67% of the resonant value for
a 10/100  [31.8nF]  or 45% of the recommended Static gap LTR value of 47.7
nF

 

The weather is too damp and cold to fire it up again but the best solution
would be to compare just a single 50 ma New nst, with the original 48ma nst,
to see if the original nst was poorly.

 

My original query was based on my version of Frau's formula that I quoted
earlier from the archives:- 1.7 x SQRT(Bang Energy x BPS)

See

http://www.google.com/custom?q=SQRT(Bang+Energy+x+BPS)
<http://www.google.com/custom?q=SQRT(Bang+Energy+x+BPS)&btnG=Search&hl=en&co
f=&domains=www.pupman.com&sitesearch=www.pupman.com&sa=2>
&btnG=Search&hl=en&cof=&domains=www.pupman.com&sitesearch=www.pupman.com&sa=
2

 

 

Revisiting the archives again, a lot of postings also give the formula as
1.7 x sqrt(input watts)

 

This would tie in with what I'm finding.

 

Phil

 

======================================================================

Scot D wrote:

Hey Phil...

 

seems as if the previous set up ( power supply) was not fully charging the
caps to start with. Now that you have the additional power to charge the
caps in the time available, you are getting more joules per bang thus
leading to longer streamers. Not knowing what type of spark gap you are
using also puts a bit of a damper on properly answering your question... :) 

 

Another thought, you maybe driving the caps into a slight over-voltage
situation if you are using an ARSG or if using a static gap set, the BPS
have increased due to quicker charge rates. 

 

Scot D

 

=====================================================================

Phil Tuck wrote:

 

Hello Group.

 

 

I have a query over charging currents following an exercise on my coil of

doubling the input current.

 

I was originally running my old 10k/48 into a 0.02143 uF cap. 

 

However I recently acquired two identical [new] 10K/50 's and tried these in

parallel for 100 ma.

 

My coil was already 'ball park' tuned for the 48m/a  NST, when I substituted

the two new 50 ma NST's. 

I left all other settings on the coil alone (apart from making sure the

safety gap was still appropriately gapped - voltage outputs can vary despite

what the labels say)

 

I did not expect any really significant difference as it was only the

current that had increased not the voltage, nor my cap size. 

The 'Freau' formula of Spark length is 1.7 x SQRT(Bang Energy x BPS). Now

the bang energy [or so I thought] depended on the value of the cap x the

voltage at the gap squared.

 

As I was still using my original sized CD' MMC caps of  0.02143 uF and not

the recommended size for 10/100 of 0.0477uF,  why did I get such a massive

increase in performance. I would estimate the spark lengths are double to

the 48 ma original NST.

 

If I had doubled the  current  and also doubled the cap size [necessary to

have charged to them the same level] I could understand why.

 

Is it that my tuning was less than perfect originally and with the 100ma

NST's it is nearer the mark ?

 

Phil

 

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