Re: Need help Tuning a new coil (reply)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: JBarrett@xxxxxxxxxxxxxxxx 


Ok Terry now you've got me really scared! No seriously I reinput my data 
into a spreadsheet and win-Tesla and I'm getting conflicting results.
Spreadsheet Input
4.5"= outside diameter of my pvc pipe
22 gauge wire
21" length
Output
Wire dia=0.025
Turns/in=39.4
number turns @ 97%=803
14.2 mH
Win-Tesla results varies somewhat.
This is the data I built my coil to. I guess I'm still missing some 
rudimentary concept.

I'm trying to find the papers on the caps I'm using for the safety gap. 
Printed on the cap is N4700 30k. I'm wondering if this is the biggest part 
of my problem.

The main cap I'm using is rather large. Can a large resistor be wired 
across the terminals in a similar manner as the MMC configuration or is it 
safer to discharge the caps another way?
Thanks
Jim



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05/01/2005 02:34 PM
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Re: Need help Tuning a new coil




Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Jim,

At 06:50 PM 4/30/2005, you wrote:
>Hello,
>I recently rebuilt my first coil but it still doesn't fire.
>Specs:
>21" of 22 guage wire on a 4" PVC pipe

That would be about 777 turns.  10.6 mH.

>12,000 volt 30 ma Neon Sign Transformer
>9 pieces of 1" thick wall copper pipes 6" long for spark gap

10nF cap would be just right.

>small fan to cool gap 9 pipes 8 gaps spaced very close but not touching
>Small Aluminum Toroid probably 8" across and 3 to 4 inches minor diameter

About 375kHz...

>Safety gap with 30k 4700 doorknob type capacitors (5) paralleled after
>safety gap

I trust that is like 470pF and not 4700pF.  4700pF would be way to big!

>1 1000 ohm/50W ceramic wire wound resistors in series of each high voltage
>leg of the Neon transformer
>The safety gap is like the one shown at
><http://hot-streamer.com/greg/filter.htm>http://hot-streamer.com/greg/filter.htm
>I tried two separate caps 1 is a Universal Voltronics 28 kvdc 0.01 uf oil
>filled
>the other is a GE 0.01 25 kvdc 700 disch/sec
>I'm also using a variac to control the Neon Sign Transformer
>Two 8 foot ground rods
>
>What's happening is the spark gap begins to fire at about 50% power and
>gets louder to about 80% power then begins to subside at 100%. It just
>doesn't seem like this thing has got any power. I downloaded some tuning
>instructions from Mike Hammer's web site but no adjustment has made a
>difference. I held a Fluorescent bulb next to the coil but it didn't
>flicker. Safety gap hasn't fired either. Transformer and caps test OK.

You don't say much about the primary???  It needs to be around 40uH.

Odd that the fluorescent bulb did not light...  I would double check the
wiring.

Cheers,

     Terry


>
>HELP!
>JIM
>
>