Re: [TCML] Coil V4 fail

[Futuret <futuret@xxxxxxx>]

Joe,

Another thing to consider is that your coil may have been
over-coupled for the input power.  Also, your toroid size
is limiting your spark length.  If' you're putting in about
4800 watts, then the coil should be able to produce
almost 10 foot sparks.  But to do that you'd need an
8" x 30" toroid.  This toroid should be placed above
your existing toroids, to raise it up as high as
possible to prevent ground strikes, and strikes 
to your primary.   The corregated aluminum dryer hose
type toroid will work OK.  However I'm not sure if your
secondary coil will withstand the stresses with
such long sparks.  It may be better if the secondary
was at least 30" tall.  But I think some folks have
obtained spark lengths almost 5X the secondary length.  
A high break rate may help for getting a long spark
from a short secondary, due to the smaller bang size.

I assume you used a variable speed motor for you
ARSG?  If not, then the break rate may be too
close to a multiple of the 60Hz rate, and the coil
may be pulsing.  Putting in the resistors may have
reduced your current draw and slightly altered the
speed of the ARSG.... and thereby stopped or
minimized the pulsing effect.  Ideally you want
a variable speed motor for an ARSG.  I don't 
remember if you used such, I wasn't following
the thread.    

Cheers,
John

 

 


 

 

-----Original Message-----
From: Joe Mastroianni <joe@xxxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sun, Oct 17, 2010 2:44 pm
Subject: [TCML] Coil V4 fail


snippage.....

The coil specs:   6.5" X 24" secondary 26ga.   Ribbon primary made of spring 

bronze & 1/4" foam weather stripping,  a la Terry Blake's "huge coil".  Stacked 

toroids.  4.5x18 over 3x12.  5kVA pig.  Arc Welder ballast.  Dual 1296D 

powerstats.  See pics.  Running 0.09uf tank.


But my spark production still sucked, and in fact would start out looking like 

it was going to be good, then fade and increase in a sputtering fashion with a 

period of about 0.5 seconds imposed upon a 3-4 second larger "wave".   

Then I remember reading here on TCML about inserting some resistance in series 

with the ballast inductor would smooth that out.  a bag load of power resistors I got for $20, and among them was a 

0.15ohm 300W version that I wired up.   Smoothness ensued.


Now the coil was behaving quite well, and the arcs were 5-6', but honestly, the 

delta in improvement between this pig powered coil and my NST versions did not 

warrant the 2 months of work and countless $$$ I put into it.  


Then I eyed my bench and spotted a crummy Maxwell cap I'd won on eBay. 


I adjusted the primary tuning to account for the additional cap, went back to 

the operating point & fired it up.


The sparkage was incredibly gorgeous.  For about 3 seconds.


Joe__________

 
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