Small -Mid SizeTesla Coils

Large Tesla Coils - "WartHog"

Vacuum Tube Tesla Coils

Pulse Discharge

Other High Voltage / Vacuum Projects

  NEW - TCBFW Teslathon 2001 Pictures! 


The Tesla Coil Builders of Ft. Worth was founded in 1994 by Bert Pool and Bill Emery.  The club had grown to include 5 core members that routinely meet to discuss projects of interesting to the High Voltage Amatuer Scientist.  I've been fortunate enough to hang out with the TCBFW team, learn many new things, and play with their amazing gear.  I've attempted to document my visits in the following page.  It's my hope, as well as the hope of the TCBFW, that this page will play a small role in inspiring others to learn more about the hobby that has taught us so much given us much joy.  

Note - All Images are clickable for a larger (800x600) size image.  
I can provide the originals (2048x1536, ~600kb) of almost any image upon request.  

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This is the main TCBFW Laboratory.  You can see thousands of lbs of assorted HV gear under the carport.  The workshop is equipped with all manner of high voltage devices - a true high voltage hobbyists' dream!  The workshop in the rear houses the Warthog and is equipped with shielding to help contain the havoc that the Warthog so happily creates. Although this lab sports many tons of HV goodies, it is only one of 4 facilities spread across the greater Ft Worth area.

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The TCBFW team (& me).  
From left to right you can see - 
Max Hempel, Bill Emery, Ross Overstreet, Bert Pool (standing), and Phil Rembold (sitting).  Norm Wootan is not pictured.

 Small to Mid-Sized Tesla Coils

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This is an antique bipolar Tesla Coil that is owned by Phil Rembold

Max Hempel's Coil

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It is powered by a small PT that is ballasted by 2 Microwave Oven Transformers (MOTs).  My camera didn't do the arcs justice.  It made really hot arcs for such a small package!

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Ross Overstreet's Small NST powered Coil

This is a picture of my single NST coil with Phil's 8" x 30" spun AL toroid placed on top.  I broke a new arc length record during my visit with the TCBFW team!  My little coil managed several 70" arcs from the breakout point on my toroid to the large toroid of the Warthog!  
My specs - single depotted and partially deshunted NST producing about 14KV (open circuit) and 200+ ma (short circuit).  I have a TCBOR/RQ gap set at .180" and 40nF of metallized polypropylene capacitors.  The secondary is about 6" dia by 24" long close wound with 22 ga magnet wire.

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Another shot of Ross' Coil along with the power controller for the Warthog

This shot displays the power controller for the warthog along with a lighted picture of my NST coil.  The power controller consists of the triple stack of variacs on the floor, the multi-tap inductor on the bench, and the resistive element mounted on the wall.  The philosophy of the TCBFW team is to maximize the electrical display and maximize the time spent on playing with HV gear while minimizing time (and money) spent on the non-electrical aspects of coiling.  There is much beauty in this philosophy!


Bert Pool made a page from the pictures taken during my February Visit.  It has some good pics of my coil along with an excellent pic showing what happens when a neon indicator light catastrophically fails an inch from my hand!  See

Wild Bill's Beginner Coil!

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Text directly copied from an email from Bill

"Here is the Rattler coil running at 6 and 7 kw making 7 to 8.5 footers. The one hitting the left side of the shop door is 8.5 feet. I have a whole role of pics and when it ran at 7 kw, it hit over there every time. The tube is 10 inches in dia. and has 30 inches of tight winds of 22 ga wire on it. It was running on .033 uf of cap that was home built. A flat poly plate cap in miner oil. I still have it. It had a three foot home built top on it with a 30 inch smooth spun toroid on top of that. I paid $300 for it back then. It had 13 turns of RG214 silver braid coax for the primary.  In a five min. run it would get hot but when I built a flat plate one for it that did not get hot, it did not run any better! It always blew out light bulbs when it ran too, never figured that out.... But I give Richard Hull the credit for getting me in the ball park with the ideas for coiling efficiently! I use to make 6 to 6.5 foot sparks in my old house with it! I kicked out the walls between the bedrooms to run it. Since it was a support wall, I put a 4 inch dia. pvc pipe there to hold up the roof. When it ran you had to stand behind the ground poles and the screen wire to be safe. No one including Bert Pool liked to come watch it run cause there was a water bed that kept you from getting far from it. You were always inches from getting hit. I just thought at the time that was coiling! I started a fire in the attic with it once and had to put it out to keep from burning down my house! I was Stupid. Good thing I am not stupid any more :)"

 Large Tesla Coils - "WartHog"

Ladies and Gentlemen - I present to you... THE WARTHOG
Feb 11, 2001 Vistit

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These images were taken with an Olympus C-3000z in automatic mode.  The camera chose an exposure time of 1s and an aperture setting of 3.6.  Unfortunately, I forgot my tripod at home and had to hold the camera by hand - this accounts for the slight motion blur.  Most of the arcs in the photo range from 8 to 12 feet in length.  This set of images were taken during the day as the bottom of the door demonstrates.

Feb 11, 2001 Vistit

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Here is another set of images taken at night.  Again, the images were taken with a hand held Olympus C-3000z in automatic mode.  The camera chose an exposure time of 1s and aperture setting of 2.8.  The intensity of the arcs is not due to some trick of the camera - those things were HOT


June 2, 2001 Visit

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 This trip turned out really well!  The Warthog ran better and I managed to operate my camera a bit better.  All pictures were taken with my Olympus C-3000z in 2048x1536 mode.  I set the camera for F2.8, manual focus, and time exposures from 2 seconds to 4 seconds.  It's important to note that the workshop was pitch black and the only light was provided by the arcs.  The arcs from the Hog are flashbulb bright! 

June 2, 2001 Visit - The Kevorkian Experiment!

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Wild Bill, Bert and I discussed the consequences of using a grounded rod to attract arcs from the Warthog.  
Once we concluded that it was a good idea and totally safe, we bravely handed Phil the stick and stood back!
The left pic shows some hot arcs attached to the stick.  The center shot shows Phil fending off a ferocious arc.  
The right pic shows arcs attached to the stick as well as to the garage door that is located some 12 FEET from the edge of the toroid.  
It's important to note that Phil is only about 8 or 9 feet away from the toroid! 

Click Here to see the Technical Details & Schematic of the Warthog

 Vacuum Tube Tesla Coils

Phil Rembold's VTTC

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The pictures above demonstrate the capabilities of a small tube coil (driven insanely beyond it's ratings, of course!).
The tube is the equivalent of a 3-250 and has a graphite plate.  It is being fed from an X-ray power supply.  Phil decided he needed a tube coil one evening but he only had about 2 hours of time to work on it.  As an exercise in innovation, he decided to build it entirely out of part that he had laying around from old (non VTTC) projects.  As the pictures show, nothing is hard mounted and everything is connected using jumpers and point-to-point wiring.  This VTTC easily produces 18" flaming hot arcs.  The photo on the right shows Phil taking arcs to a screwdriver that he is holding firmly in his hand.  The corner on the tip of the screwdriver were glowing red hot from the RF currents!   
<RANT> KIDS - Don't try this at home.  We know more than you. You will die if you screw this up! </RANT>

Wild Bill Emery's VTTC

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Bill has been working on VTTC since my last visit.  Here are a few pics and some quoted text from an email

"Here are the pics of the thing running with 2 footers coming out of it for a long time, for a tube coil. I think I need to re-design it to make it more efficient.  It is running at .8 amps at 6 kv ! Had to really put the power to it to make it come out like I wanted, and it still sucks! At 2.1 kw I get 17 inches, but to get two feet it must run at 4.8 kw !"

Bill is using a silver plated copper ribbon helix for his primary.  You can see the three triodes in their respective "sockets" in one of the pics.  This allows Bill to quickly switch between triodes for experiments.

 Pulse Discharge

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This is a 100KV, 0.4uF capacitor that is being charged by a 15KV/30ma NST through a 5 stage Cockcroft Walton Multiplier (CWM).  The CWM takes the 7.5KV from each bushing on the NST and turns it into about 50-60KV before feeding the capacitor.  The diodes on the CWM are 12KV, 333ma microwave oven diodes.  All capacitors in the CWM are 40KV with the center stack being 2200uF and the other stacks being 700uF each.

Do you spot the fatal design flaw here?  We don't have any resistance between the large pulse cap and the charging circuit.  The fast current reversal during the triggering of the airgap destroyed most all of the diodes in the CWM.

 Jim Lux's Website has good design information on Cockcroft-Walton Multipliers

Phil Rembold's Pulse Discharge Rigs

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The "ton-o-fun"
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The portable rig
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A shot of the Maxwell 
Triggered Spark Gap

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A close-up of the Maxwell
Triggered Spark Gap

Ton-O-Fun Specs:
You can see (8) 3.3KJ capacitors all connected in parallel.

Portable Rig Specs:
14.3 Mfd 40Kv  11,440 Joules Max.  You can see the electrostatic voltmeter sitting on top.  The upper bays of the rack is occupied by the charging circuit.  This HV PSU kicks ass because it can put out XXX V @ 20ma and has programmable limits for overvoltage protection as well as lots of other bells-and-whistles.  The nitrogen bottle is there to supply gas flow for the gap.  Note that the containment is located on the small shelf on the side of the rack.  Phil routed copper cable for both the hot and the ground on the portable rig where he only routed bus bar for the hot on his big system.  He reports that the copper return path on the portable rig enhanced the performance (smaller quarter for less energy).

Maxwell Gap Specs:
Phil uses a field-distortion gap made by Maxwell that was salvaged from a Linear Accelerator.  The gap can switch up to 100KV depending on the air flow supplied to it.  Typical shots at 25KV require 15psi.  Phil has used it down to 6Kv @ 8psi and the unit will self trigger @ 12 Kv with no air.  100KV requires 90psi!  Click on the above photo for more details.

Misc Details on the stuff that we shattered with the Portable Rig:
Phils's explanation - "We exploded a 52" Monstrous Laser XENON FLASHLAMP from a ND-Glass YAG LASER.  The system it came out of of had 16 of these flashlamps around the  lazing elements crystal (if memory serves correct this was the most powerful laser in the world back in 1999).  The tube was made to self trigger at 15KV.  We were able to pulse it OK with charges from 1500 to 3500 Joules but the tube didn't like it when it was shot with 30Kv @ 6500 Joules"  When Phil says that it "didn't like it", he is referring to the fact that there wasn't a flat spot in the lab that wasn't covered with deadly glass fragments!  

We also laid waste to standard 4' flourscent light bulb.  They do behave much like a flash lamp when pulsed by a large capacitor.  At low energy levels there was a bright flash followed by a dead tube (couldn't pulse it twice).  Higher energy levels vaporized the elements in each end and shattered them off of the main glass tube.

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Wild Bill's Pulse Discharge Rig


This shows Bill's bank of (12) 3.3KJ pulse capacitors.  It is being dumped through a home made field distortion gap that is a combination of ideas gained from the Maxwell gap and his own design.  The gap works reliably between 40 and 50 KV at its current setting.  This is possibly the most dangerous machine that I have ever seen!

My pulse quickened as I watched the needle on the electrostatic voltmeter swing between 60 KV (power supply voltage) and 45KV (bank target voltage).  Everything seemed alive with corona.  The resulting explosion when Bill hit the fire button was nothing like I had ever seen before.

When a TCBFW member tells you something... Listen to them. Case in point - Bill explained to me that he needed to stack a minimum of 250 lbs on top of the lid of his pulse-discharge containment.  I said "yeah, right" and smirked as he placed (2) 70lb sandbags and (3) 15/60 NSTs on top of the steel lid.  Upon hitting the FIRE switch, the lid of the containment lifted enough for a handful of wire frags to spew forth into the lab!

Bill's "Maxwell Clone" Triggered Spark Gap

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Hi Alan, here are pics of the big switch thrown together in an 8 inch drain pipe, don't let the simple picture fool you. This weighs 18 lbs. and has a center disc 1/4 inch thick in it with 2.5 inch electrodes.  Try finding the plate in copper to make it out of and then cut it to size.....the plate takes the brunt of the arc on the way by. Put a pulse on the center disc, and it arcs to one side and triggers the gap. The higher the voltage, the more the tolerance on the gap, and the less prefires. For magical reasons, there are always prefires, although I have not had one at 50 kv in over 30 shots!! Also I put pics of the 40 kj pulse circuit and the smaller high voltage switch. That size switch will explode at 15 kj with 12500 volts! At 50 to 60 kv, it will take 25 kj all day long......And if you will notice, I had to doll up the switch with balls etc. to hold in the 60 kvdc. Also you will notice I had to put the 100 meg bias resisters in plastic, and I put the pulse cap to trigger it in plastic also. And I had to go to a battery operated trigger circuit cause I blew up every plug into the wall thing I had, (the battery charger, my 10 amp supply, two of them, etc . etc. ) And in the teflon tube is a one meg resister that is 2 inches dia. by 16 inches long. And the bucket under the table has bypass in it to protect the diodes in the 10 kw z-ray tranny. And there is the hot tub sized 60kv electrostatic meter, which happens to be a voltage standard.


The vote about who has the most dangerous Pulse Discharge Rig became too hard to maintain and was adversely effecting Wild Bill's blood pressure!  There was violent disagreement between family, friends, complete strangers, an iguana, 2 cats, and 2 pet snakes about who was in the most danger of vaporizing themselves.  

A Serious Note:
The moral of the story is that ANY pulse discharge device is incredibly powerful.  That amount of power demands a level of respect and knowledge that is rarely required in our other day-to-day endeavors.  We are working with energy levels that are hard to comprehend.  Comparing the power of  large pulse discharge devices to high explosives is not unreasonable.  There are no second chances with these machines and they can strike in ways that the uninitiated would NEVER expect.  Please don't get into this area of experimentation unless you are totally aware of the dangers and are prepared to accept a high level of risk

you insist on doing pulse discharge experimentation - Please contact us and arrange a consultation.  
We are happy to discuss the operation, dangers, and required safety protocols to increase (not ensure) your odds of survivability.


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Bill did a quarter for me at 18.5 KJ @ 50 KV.  The quarter is actually considerably longer than it is wide now.  It has cracks on each face where some of the copper vaporized and blew through the ends!

 Other High Voltage / Vacuum Projects

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This is an interesting device that, frankly, scares the living hell out me (i.e., it's really cool!).  I can't reveal its entire purpose but I can tell you a little about what it does.  The devices on the on each side of the glass tube are magnetrons from Microwave Ovens.  The glass tube is connected to a vacuum pump.  A manifold is attached to the bottom of the platform that allows various test gasses to be passed into the chamber and circulated.  Upon achieving the proper mixture of gas in the chamber at the proper pressure the magnetrons are switched on and a super hot ball of plasma appears in the center of the chamber.  Bill has designed a faraday cage to go over the top but it apparently leaks pretty bad.  Bill's words of wisdom - "Distance is your Friend!".  

More info may be made available about this device by TCBFW after further research.

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Bill built this a custom vacuum manifold for his small Neon Sign business.  New systems cost between 3,000 to 5,000 dollars and Bill was told that it was not practical to attempt one of these at home.  Bill's system now out performs the professional system at a local Neon shop.  You gotta love it when the amateur scientist proves the "experts" wrong <grin>.  The system can attain an ultimate pressure of around 10^-4 torr on just the rotary vane pump and can get down around 10^-7 torr once the diffusion pump kicks in.  Bill has equipped the system with capacitive vacuum gauges to accurately measure the pressure.

I  express my deepest gratitude to Phil and his lovely wife Venice for their friendship and hospitality. 
The TCBFW are all great guys, build incredible gear, and really know how to have a good time.

Ross-O's Main Page  |  TCBFW Main Page  |  Contact Ross  |  Contact Phil of the TCBFW  |  Bert Pool's Website  ]

� 2001,  Ross Overstreet