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Re: [TCML] Toroid Problems

Hi Nicholas,
Your tank cap appears to be the proper size (LTR) for your NST. If your main spark gap setting is too wide, your spark gap may not be firing consistently, possibly preventing streamer growth from bang to bang. The result is relatively short sparks that continually change their location from bang to bang instead of coalescing to form longer streamers. When this occurs, the gap will sound "ragged", not smooth running. Reducing the overall main spark gap distance to should fix this problem.
If your gap is firing smoothly, are you providing adequate cooling with a fan or blower? If your gap isn't quenching properly, most of your wall plug power will be used to burn up your gap instead of going into making long streamers. The usual symptom for this is long(er) sparks when you initially power up the coil, then shorter sparks as the gap overheats and stops quenching properly.
If your gap is firing smoothly, you're providing good gap cooling, and you've already tuned the system to get the longest spark, you can try increasing the coupling by either raising the primary (vs secondary) or lowering the secondary (vs the primary). Only do this in small increments (~ 1/4" at a time) and retest. Back off to lower coupling if you begin to see racing sparks along your secondary winding. 

Good luck,

Bert
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Nicholas J. Goble wrote:

Thanks for the responses.  I did however try a breakout point, but it
 was only with a 2" nail.  Maybe I'll try a bigger one.  I don't have
 the luxury of a variac (they seem too expensive), so I guess I'll
just run it at full strength despite the risks. However, will my performance suffer if my capacitor is too big? Also, could this 
issue have anything to do with the height of the toroid?

Nicholas Goble


DC Cox wrote:



while tuning, be sure to extend your sharp rod breakout point well


beyond

the toroid's field control area --- usually 2-3 inches for this
type of toroid. use a variac until you are the right tap point with
streamers hitting a grounded pole or wire. sometimes, if the toroid
is too large, there will not be a breakout as

the

toroid itself surpresses breakout.

Dr. Resonance





On Mon, Aug 4, 2008 at 2:30 PM, Nicholas J. Goble <ngoble@xxxxxxx>


wrote:
I did not wire together various components and hope they'd work together. I did my research and used the calculators listed on deepfriedneon.com. Here are the specs for my coil: 

Transformer: 9/30 transformer

Spark gap: air quenched, multi-electrode spark gap.  There are
five copper pipes, 3.5 inches in length that make up the
electrodes.  All the gaps fire beautifully.  I got the plans off
this website: http://www.kronjaeger.com/hv-old/misc/scotsgap/index.html 

Capacitor:  I used the "Capacitor to Transformer Match"
calculator on DeepFriedNeon and found that I needed a capacitance
of .0088uF.  The Tesla Map construction guide told me that I
needed to multiply that by 1.414 to get my LTR capacitance of
.01244uF.  I bought 12 942C20P15K-F caps that are rated at 2000V
and .15uF.  I wired them in series to get a capacitance of
.0124uF.  Correct me if I'm wrong with these measurements.

Primary: 1/4" OD copper tubing spaced 1/4".  Inner diameter is
6.5".  I did 13 turns just in case, but my calculations show that
I only need 11 turns to have the correct inductance.  With 11
turns, the inductance of the primary is 40.147uH.

Resonant Frequency of Primary: The capacitance is .0124uF.  And
the inductance (with some tuning) is .0345mH.  That makes the
resonant frequency 243.332kHz

Secondary:  For my secondary, I wound a 4.5" diameter PVC pipe
that was sprayed NUMEROUS times with acrylic spray sealer.  I
sealed the ends with some PVC caps that I bought at Lowes and
used caulk as a glue.  I wound the secondary with 24 AWG wire.
It was 21" tall.  All in all, there were about 950 turns of wire.
I sealed the form after winding too.  Inductance is 19930uH and
self cap is 8.316pF.

Toroid:  Explained in my main post, capacitance is approx
19.137pF.

Resonant Frequency of Secondary:  The capacitance of the toroid
is 19.137pF, and that of the secondary is 8.316pF.  Combined, the
 secondary circuit's capacitance is .000021453uF.  It's
inductance is 19.930mH.  The resonant frequency is 243.344kHz.
There are the specs. I thought that all those calculations were correct. What could be wrong? There are no wires on the inside 
of my secondary.  If the secondary wire sparks with no toroid,
could it just be a problem with my top load?  Is it to big?  Is
my connection not good?  I really want to get this thing working
well.  With a toroid. Any solutions or diagnoses?

Thanks

Nicholas Goble


Lau, Gary wrote:


I see no mention of what you're using for a capacitor, or
primary

coil.

You have verified that the primary and secondary resonant
frequencies match, right?  It does sound like they don't match
with the toroid in place, but YOU need to gather all the numbers
and verify this.  One can't just throw together an NST,
capacitor, primary and secondary coils, and hope it will all play
together.  If any one of them is the wrong value, it will be out
of tune and won't work.

Regards, Gary Lau MA, USA


-----Original Message----- From: tesla-bounces@xxxxxxxxxx
[mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Nicholas J.
Goble Sent: Monday, August 04, 2008 1:38 PM To:
tesla@xxxxxxxxxx Subject: [TCML] Toroid Problems

Last night, I fired up my coil for the first time.  I set

everything up

and made sure that all the connections were solid.  When I
plugged

the

NST in, the spark gap fired, but there were no sparks coming
from

the

toroid.  I tapped the entire primary, but got no streamers.
At a

few

points, the safety gap was firing, so I guessed that the caps
were working.  I thought that the only thing that could be
wrong was the toroid.  When I disconnected the toroid and ran
the coil, I got streamers and some corona coming from the tip
of the secondary

wire.  I

was able to tune the coil without the toroid.  I got 5-6 inch
 streamers/sparks from the wire.

Here are the specifications for my toroid: 4" height 17"
outer diameter 9" inner diameter I took two flimsy 9" pie
pans and glued them together.  Then I

wrapped

4" aluminum dryer duct tubing around it and secured the ends


together

with duct tape.  I secured the tube's connection to the base
with

caulk

on the rim of the pie pans.  I took some aluminum foil and
wrapped

it

around the duct taped section, and connected that to the base
(pie pans) with more duct tape.  I drilled a hole in the
middle of the

pans

and attached a nut and bolt.  I sanded off most of the enamel
of the end of the secondary wire and secured it to the middle
of the toroid with the bolt.

My secondary is 4" dia and 21" tall.  I'm using a 9/30 NST.
Can

anyone

diagnose my problem?  I dobut that my toroid is too big.  If


anything,

I thought it would be too small.  I used a nail to create a
breakout point on the toroid while it was running and it
still failed to

produce

streamers.  What's the problem?

Thanks

Nicholas Goble

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