RE: Comments on my coil?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <teslalist-at-qwest-dot-net>" <gary.lau-at-hp-dot-com>

Hi Dave:

 >So heres A few ideas I had.....
 >  - make a nice smooooth toroid so only one arc is emitted instead of the
 >     3-5 I get now.
 >  - put some PF correction caps in front of the NSTs on the 120VAC line.
 >  - modify the EMI filter to use a lower series resistance value.
 >  - rebuild by SRSG to use smaller electrodes for a shorter "apeture"
 >    time.

I agree that your best bet to improving things lies with improving your 
toroid.  PFC's won't affect performance, unless your mains power is sagging 
due to losses in the house wiring.

Your "EMI" filter should be called a NST protection filter; it is not 
intended to reduce EMI sent to the mains.  But I agree that lowering the 
resistor value will reduce un-necessary losses there and improve 
performance.  You may also want to consider eliminating the series 
inductors, as these have been shown to cause more trouble than they 
solve.  If you want to diminish EMI going back to your mains wiring, you'll 
need an EMI filter on the primary side of your NST.

Regards, Gary Lau
MA, USA

  -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com]
Sent:	Thursday, July 03, 2003 7:21 AM
To:	tesla-at-pupman-dot-com
Subject:	Comments on my coil?

Original poster: "Dave Lewis by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
<hvdave-at-earthlink-dot-net>


Since I don't post here often and just mostly lurk around in the
background reading the first I want to say is THANKS to all the very
generous and bright people that contribute to this list for nothing
except the sheer love of coiling.  Reading the posts here is always
facinating.

Now my story.

Last year I put my 2nd coil together and got it all working.  This coil
I actually spent some time thinking about it first before building
stuff, as opposed to my first attempt.  It was so much fun to build and
troubleshoot.  However, after it was all working, I kind of lost
interest and dismantled it so I could park the car in the garage
again.   At least my wife was glad.

Well now I got the bug again and I'm thinking about doing some
modifications to improve the coils performance.   So I'm looking for
suggestions about things to try.

The facts of my coil can be viewed at this link:
http://home.sprintmail-dot-com/~patrat/tesla/tesla.html

Basically, its a medium sized coil running from a pair of 15kV 60mA
NSTs.  Its got a SRSG with an LC phase adjuster so I can tune it while
its running.  The secodary is 5"x27" coil form, 950T of #22, with a 31"
toroid poorly made from 7" aluminum ducting.   Primary is 8T of 1/4
copper tubing with a Maxwell 0.03uF 35kV capacitor.

When its up to full power I'll get 3 to "maybe" 4 foot arcs.  Thats not
too bad but I think it should do better with those two NSTs I have.  I
was expecting closer to 4-1/2 feet.

When I run it with a break-out on the torroid, there is mostly one
larger arc instead of the 3 to 5 somewhat smaller ones I get without the
break out.  The break-out arc seems more like what I was expecting and
will occasionally hit the ground.   Oddly, the arcs into free air are
longer that what I can draw to a grounded probe tip at the end of a long
stick.  I had thought it would be the other way around.

So heres A few ideas I had.....
   - make a nice smooooth toroid so only one arc is emitted instead of the
3-5 I get now.
   - put some PF correction caps in front of the NSTs on the 120VAC line.
   - modify the EMI filter to use a lower series resistance value.
   - rebuild by SRSG to use smaller electrodes for a shorter "apeture"
time.

Thanks everyone!
Dave Lewis