Re: first coil help

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Ryan,

A 15kV 30mA coil system should put out 35 inch sparks if everything were
just perfectly right.  So something is wrong and it is just a matter of
locating it and fixing it.

I would wonder a bit about the air pressure on your gap being incorrect and
not allowing for the best firing.  You may want to play with the pressure
with a valve to be sure the pressure is best.

RF chokes have proven to be fairly ineffective but that is not the problem...

It is neat that you are using a dimmer for the transformer control!  Don't
use PFC caps and have another "off" switch handy incase the triac in the
dimmer blows up and shorts the thing full "on".  In other words, have an
"extra" "off" switch.  I think dimmers for NST control are pretty promising
if one is careful not to violate them too badly.  There is a chance that
the dimmer is doing something "strange" and causing the problem.

I assume your NST draws good arcs to ground off both terminals and is "good".

I think your problem is either the salt water cap or the thing is way out
of tune (thinking out loud...).  The cap for a 15/30 static system should
be 5.3nF (resonant) or 7nF (LTR static gap).  So you should be around
5-7nF.  7 beer bottles should be close enough but I am not sure you cover
the outside with foil and other tricks to get the resistance really low.
"i" would try 10 bottles my self...  Others on this list know far more
about making a good salt water cap than I.  

But, This sound like a big tuning problem...  The primary and the secondary
have to be tuned to the same frequency or it will not work well at all.  3
inch arcs to ground sounds like tuning...

Your secondary frequency:

4.5 in PVC pipe wound with #22 about 21.5 in.long roughly 800 turns---  A
tennis ball covered in foil--- 

That is about 450kHz for the secondary frequency.  You would need to tap
you secondary very roughly around turn 7.5 for best tuning.

So, you "should" be able to tune the thing...  I think that salt water cap
may be the problem.  Maybe some others could take a look at that area...  I
could string together 8 Panasonic caps and you could try that if all else
fails.  But, it looks like a primary cap problem to me...

Cheers,

	Terry




At 03:48 PM 7/16/2001 -0500, you wrote:
>
>ok, well my coil is getting more powerful, but im still not getting 
>breakout, here are my coil specs
>
>Tank circuit
>power    1- 15kv 30ma nst
>gap         1 gap 2 1.5in brass electrodes quenched with 30psi set at 3/8 in 
>wide
>cap         7 saltwater beer bottle caps filled with about 10 oz. ea
>s gap      3 1/4in carrage bolts
>chokes   2  2in pvc pipes wound with #28 wire about 7 in long ea.
>primary   16 turn helical primary 1/4 in dia. spaced 1/4 in ea. inner turn
8 in
>                at 45deg angle tapped at 12th turn
>secondary-4.5 in pvc pipe wound with #22 about 21.5 in.long roughly 800 turns
>discharge terminal- tennis ball covered in Al duct tape
>ground 2-4foot copper clad rods
>im also using a 600 watt dimmer to run the transformer
>
>so far im able to draw off about 2-3 in sparks, but im not getting any 
>breakout. im starting to think that
>maybe i need more nst's because my system might be too big for the one i 
>have also, i hope this isn't the
>problem, but maybe my primary it at too great of an angle. hope this helps
>
>thanks for everyones contributions, you have all been very helpful so far 
>and i look forward to getting
>this thing working one of these days.
>Ryan
>
>> > im using a helical primary, the inner turn is 8in. i set up a ground next
>> to the coil, and im getting
>> > drawing 2-3 in. sparks. i added another bottle to my tank cap, i will
>> test that tonight. i aslso bought
>> > an 8 foot ground that i am installing also. my gap is the air blast gap
>> from richard quick. im using 2-
>> > 1.5 in electrodes, and i have about 30psi guenching it. thanks for your
>> help, ill try your suggestions
>> > tonight thanks
>>
>> >
>> >
>> > there are 16 1/4in diameter primary turns, spaced at 1/4 in. im using a
>> > fluorescent bulb, and my caps are 6
>> > beer bottles filled with about 10oz ea.of saltwater. not sure how to test
>> > the capacitance, will look into
>> > that. im using 1-15kv30ma nst
>> >
>> > thanks for your help jonathan, and the rest of coilers on this list
>> >
>> > Tesla list wrote:
>> >
>> > > Original poster: "James Mathisrud by way of Terry Fritz
>> > <twftesla-at-qwest-dot-net>" <jrmathis-at-pressenter-dot-com>
>> > >
>> > > im a new coiler, and i have been trying to tune my first coil, and 
>have had
>> > > a few
>> > > problems. i am getting it to resonate, i know this because the 
>lightbulb is
>> > > glowing, but i just can't seem to get any sparks to breakout, i have a
>> > > small sphere
>> > > discharge terminal, the secondary is 4.5in, 800 winds #22, the primary
>> is  tapped at 11
>> > > turns,
>> > > because that seems to be the best spot from the testing ive been 
>doing, im
>> > > using
>> > > salt water caps, i have an air blast gap.thats set at about 1/2 in, im
>> > not sure
>> > > what the average spacing is supposed to be, but i keep opening it
>> farther and
>> > > farther, and the power of the coil seems to be increasing please advise
>> > > before i
>> > > break something!
>> > >
>> > > also, imy ground is a 1in copper water pipe, and is wetted down before 
>each
>> > > use its
>> > > been driven about 1.5 feet into the ground i don't know if this may be
>> > > affecting it
>> > > or not. thanks for your help
>> > > Ryan
>