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Re: Need help Tuning a new coil

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Again Jim,

You coil really needs about 13.7uH for the primary which would be about 7 turns...

Jim's Coil
5/1/2005
---------- Power Supply ----------
NST V Out       12 kV
NST I Out       30 mA
NST Input V     120 V
NST Input F     60 Hz
NST VA          360.0
NST Watts       371.4 W
NST Impedance   400 Kohms
Max Arc Length  32.8 in
NST PFC Cap     66.3 uF

---------- Primary Capacitor ----------
Your Cap        10 nF
Resonate Cap    6.6 nF
LTR Static Cap  9.3 nF
LTR Sync Cap    12.6 nF
Your Cap Joules 1.44
Resonate Joules 0.95
Static Joules   1.34
Sync Joules     1.81

---------- Secondary Coil ----------
Single build magnet wire
22 AWG
Wire Length     825.5 ft
Wire Weight     1.60 lbs
Wire Resistance 13.4 ohms
Coil Height     21 in
Coil Diameter   4 in
Coil H/W Ratio  5.3 : 1
Coil Turns      788.7
Inductance      10.91 mH
Capacitance     8.11 pF

---------- Top Load ----------
Overall Diameter (1)    9 in
Ring Diameter (1)               4 in
Overall Diameter (2)    unknown
Ring Diameter (2)               unknown
Sphere Diameter                 unknown
Top Load Adjustment     0100 %
Top Load Capacitance    11.94 pF

---------- Top Load + Secondary ----------
Resonate F      340.28 kHz

---------- Primary ----------
Wire Diameter   .25 in
Wire Spacing    .5 in
Hole Diameter   6 in
Coil Angle      unknown
Coil Adjust     100 %

Needed primary inductance with:
Your Cap        13.75 uH
Resonate Cap    20.73 uH
LTR Static Cap  14.81 uH
LTR Sync Cap    10.91 uH

Turn 1   0.3 uH
Turn 2   1.2 uH
Turn 3   2.7 uH
Turn 4   4.7 uH
Turn 5   7.4 uH
Turn 6   10.8 uH
Turn 7   15.0 uH
Turn 8   20.0 uH
Turn 9   26.0 uH
Turn 10  33.1 uH
Turn 11  41.2 uH
Turn 12  50.4 uH
Turn 13  61.0 uH
Turn 14  72.8 uH
Turn 15  86.0 uH
Turn 16  100.7 uH
Turn 17  116.9 uH
Turn 18  134.8 uH
Turn 19  154.3 uH
Turn 20  175.6 uH
Turn 21  198.7 uH
Turn 22  223.7 uH
Turn 23  250.8 uH
Turn 24  279.8 uH
Turn 25  311.1 uH

---------- Design Notes ----------
No Notes

-- End Summary --

Cheers,

        Terry



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