Re: Need help Tuning a new coil

["Tesla list" <tesla@xxxxxxxxxx>]

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