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TCBOR TC Video Primer

6/5/96

This past Sunday night I fired my first Tesla Coil.  The sparks were 18 
inches point to point.  Pretty exciting for my first attempt.  

Specs:

Secondary - 23 ga magnet wire wound on a 4 in dia PVC form x 26 in 
length.  Sealed with four coats of polyurethane.

Primary - 10 ga stranded Cu wire wound on a 6 in dia PVC x 17 turns.

TX - 15 kV 30 mA Neon

Gaps - 7 nonresistive spark plugs radially arranged around a 3 1/2 in 
PVC coupling.  The coupling was drilled and tapped for the spark plugs 
which were wired serially.  A muffin fan is mounted on one end of the 
coupling and blows across the gaps.  The spark plugs are barely warm 
after several minutes of firing.  Fouling has not occured.  Has anyone 
else used this configuration before?

Neon Protection - Two large split ferrite bead cylinders that snap 
around the HV leads.  The inductance is 2-3 uH per bead.  I placed a 
teflon sleeve over the lead and attach the ferrite bead around it.  
Multiple beads may be attached for higher inductance.  They're rather 
inexpensive and rugged. I plan to measure pre and post ferrite bead 
kickback with a megaohm voltage divider and scope.  I will post my 
findings.  I also plan to add a protective spark gap and perhaps 
capacitors in the future.

Caps - 3 x 40 kV Sprague doorknobs in parallel for 4.5 nF.  
Experimenting, I added another 1 nF glass oil filled cap in parallel.  
It heated fairly rapidly and blew up.  Luckily no PCBs.  A word of 
warning for those contemplating buying those caps with PCBs, caps will 
blow and the oil literaly explodes all over everything.

Toroid - Four 3 in dia metal flu pipe elbows fitted in a circle and 
covered with aluminum tape.  The outer diameter is 11 inches.  There 
are eight straight sides on the outer circumference surface.  

Variac - Old 120 V 28 Amp "Variac".


The secondary resonace is 402 kHz without the toroid and 381 kHz with 
the toroid.  I did not have the material on hand to build a flat spiral 
primary, so I chose the helical primary.  As I tuned it, I went all the 
way to the end of the seventeenth turn.  I will need to add more turns 
for peak tuning.  Also, I will build a flat spiral primary.

I wish to publically thank TCBOR, and in particular Richard Hull, for 
their TC Video Primer.  There is a wealth of information and technical 
know-how crammed into this excellent video.  It is extremely accurate, 
informative and a real hands-on reference for any first time builder 
(or anytime builder).  

Thanks,

RWW