Re: Coil Efficiency

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Coil Efficiency
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 22 Jun 1997 08:44:44 -0500
Approved: tesla-at-stic-dot-net

From: 	Julian Green[SMTP:julian-at-glosilk.demon.co.uk]
Sent: 	Sunday, June 01, 1997 5:03 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Coil Efficiency

----------
> 
> From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent: 	Wednesday, June 18, 1997 3:55 PM
> To: 	tesla-at-pupman-dot-com
> Subject: 	Coil Efficiency
> 
> Hi all,
>          I think we could be on the verge of making some real 
> progress in nailing down the merits of actual coil parameters. There 
> is much to be done in the wall socket -> coil efficiency stakes. But 
> if we look at the raw E x BPS vs spark length figures, we can start 
> to see where the coils themselves might be improved. I think there is 
> now a most fruitful area of research open to us. We might at last 
> have a platform from which to examine L/C ratios and the like. It 
> seems obvious now that when using current efficiency measurements we 
> are floundering around in the dark (with an arc to light the way :)
> 
> Malcolm
> 
> 
> 

Not having much luck with my coil and effeciency is terrible!

My coil is now powered by a pole pig and draws 20A at 240v thats 4800VA!
And all I get is a miserable 3' spark.  The tune is OK as adjustments of
the primary plus/minus one turn result in shorter spark length.  

I have had longer sparks than this from the coil before the rotary spark
gap broke, but still not as long as I would like.   Its the darn spark 
gap that gives me trouble.

One point of interest though, I am running my pole pig without balast and
I am achieving 'smooth' running.   I put this down to my spark gap which
is built around a 10,000 rpm motor.   The rotor on the gap has only two 
electrodes mounted on a 6" disk.   Only when I run the motor at maximum 
speed do I get this smooth running, with lower speeds loud bangs and blown
fuses result.   Have others tried fast motors and few electrodes on their 
spark gaps?

Questions:

Is the apparant high VA a result of 'out of phase' amps and volts?  If I
added some PFC capacitors would this help.

Is the spark gap quenching well enough?  If not then how do I tell?  I
have a scope and I remember a thread on monitoring quenching using a scope.
Can anyone recall how this can be done?

Julian Green