Nikola Tesla, Inventor of the Tesla Coil

Nikola Tesla

And His Celebrated Tesla Coil

Nikola Tesla, Inventor of the Tesla Coil

Nikola Tesla, Serbian-American inventor, remains shrouded in controversy and mystery sixty years after his death. Establishment historians try to sweep Tesla under the rug. Cult followers believe Tesla was centuries ahead of today's technology, inventing antimatter, antigravity, free energy, and that Tesla and his followers left Earth to live on another planet. Coilers just love to design and build versions of the famous Tesla Coil. By any measure Tesla was eccentric and brilliant, and his patents founded empires of industry and technology.

Yet other men rode to fame and fortune on Teslas inventions. Teslas AC generators and motors power the wheels of industry, while the name of Tesla was all but forgotten. Tesla died in poverty in a New York hotel in January 1943, his papers were quickly siezed by the FBI. For years after the death of Tesla, lawsuits raged over Tesla patents. Out of only eleven patent suits ever heard by the US Supreme Court in its history before 1960, two were suits over tesla inventions, and the Court found that Tesla was indeed the inventor of Polyphase AC, and of practical Radio Frequency Transmission.

Tesla's Avengers

Nikola Tesla, Inventor of the Tesla Coil

John Wagner, school teacher, mobilized his third grade classes to raise thousands of dollars to create this commemorative bronze bust of Tesla. Wagner accuses the Smithsonian's National Museum of American History of presenting "a deliberate assault on factual history" and is crusading to set the record straight. Read how Tesla was Erased at the Smithsonian and get a kewul Tesla Tshirt while helping the class raise funds for more busts like this one at Yale University.

"In a single burst of invention he created the polyphase alternating current system of motors and generators that powers our world. He gave us every essential of radio, and laid the foundation for much of todays technology."
-- Epitath on bronze bust of Tesla, refused by the Smithsonian, now displayed at Yale University.

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UPDATE

New diagrams of Mk III Tesla Coil and Mk IV Tesla Coil

Jump to diagrams of Mk III Tesla Coil and Mk IV Tesla Coil

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Tesla Coiling

While Teslas polyphase AC system spans the world today, a different invention, the Tesla Coil, never saw commercial use. The Tesla Coil however is the most awe inspiring electrical device, transforming ordinary power into high frequencies at tremendous voltages. During his brief peropd of poularity Tesla with his coil created spectacular displays of live electricity, such as the 1893 Worlds Fair in Chicago. Tesla coils are still individually hand made by intrepid Coilers following in Teslas footsteps.

I discovered the Tesla Coil in 1978 while reading a 19th century article by Tesla in a cracked, leather and wood bound volume from an obscure corner at Georgia Tech. Back in my dormitory, I began building a Tesla Coil. Several nights later, I powered up the coil. My terrified roomate fled in panic. The Tesla Coil was delightfully awe inspiring, with its shattering roar and streamers of purple fire writhing in the air. I was in love.

sparx 5
Call Me Sparky !
sparx 3 sparx 4
Mk II Coil in operation

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Altairs Tesla Coils, Coil Plans, and How to Make a Tesla Coil

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! ! WARNING ! !

This device involves extreme voltages, possibility of fire, explosion, violent ruptures of glass components and other risks.

 


Construction of such devices may be illegal in your area.
You could be hurt. You could die.
Take cover. Turn it on.
Fear what you have created.

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High Voltage

Click Hazard Icon For More Info

 

This device involves very high voltages.

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PCBs

Click Hazard Icon For More Info

 

Don't Die Like a Poisoned Roach ! Test For PCBs in old High Voltage components !

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UPDATE

New diagrams of Mk III Tesla Coil and Mk IV Tesla Coil

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Altair's First Tesla Coil, Mk I

Mk I Tesla Coil Schematic Diagram

Made in 1978 in Heffner dormitory at Gerogia Tech. Was wound on a 2-1/2 inch grey PVC pipe and was excited from a 15kV neon transformer, a spark gap made of coat hanger and a plastic cup liberated from the lunch room. My favorite capacitor bank was six 1 qt beer bottles, with brine and copper wire inside, wrapped in foil on a metal plate on a stack of computer paper. It was also fun to empty the bottles.

Mk I Tesla Coil Construction Pictorial

Status September 1978, purple corona at top, 12 in streamers. Eventually died by external arcing on the secondary.
Lessons Learned: use more top load (toroid or sphere electrode capacitance); dont use black or gray PVC pipe; secondary coil should not be very long and thin, aspect ratio should be 3 - 5 ; secondary should have heavier wire, lower resistance, higher resonance.

Altair's Mk II Tesla Coil

Mk II Tesla Coil Schematic Diagram

My second Tesla coil will drive 40 inch streamers, photos above. Its vital statistics are:
Sedcondary Coil : Cylindrical , 4.5 in dia, 30 in tall, PVC form, 880 turns of #20 copper wire.
Top Load : Toroid, stovepipe, 8 x 24 inches.
Primary Coil A: Cylindrical , 40 in dia, 18 in tall, on PVC posts, ten turns of 1/4 inch copper tubing.
Primary Coil B: Cylindrical , 9 in dia, 18 in tall, on 8in PVC, 30 turns of #6 copper wire.
Primary Coil C: Conical Helix, 10 in to 48 in dia, 120 deg included, 23 turns of #6 copper wire.
Power: Potential Transformer, 14400 V AC, 1500 VA, External Ballast 1 to 4 hot water heater elements, 1500 W each.
Hawg Capacitor A: One plastic soda bottle, 0.008 uF
Hawg Capacitor B: One glass gallon cider jugg, 0.003 uF
Hawg Capacitor C: Seven glass gallon cider juggs, 0.017 uF
Surplus Capacitor: Old surplus GE capacitor, 50 kV, 0.022 uF

Mk II Tesla Coil Construction Pictorial

Progress to Date : see Altair's Tesla Lab Notes
Status Feb 1999:
Streamers 44 in, controlled strikes 10 in.
Switched to GE Capacitor, 22 nF. Primary Coil tunes at 6 1/2 turns.
Expanded 240 V ballast bank to 12 kW, for 1.5 kVA potential transformer.
Next: Construction of asynchronous tungsten rotary gap. Increase primary conductor size to 1/2 in dia or more.

Altair's Mk III Tesla Coil

Mk III Tesla Coil Schematic Diagram

My Mk III Tesla coil will drive 50 inch streamers. Dont get too close. Its vital statistics are:
Sedcondary Coil : Cylindrical , 9 in dia, 31 in tall, 880 turns of #20 copper wire on a PVC form.
Top Load : Toroid, stovepipe, 8 x 24 inches.
Primary Coil D: Conical Helix, 10 in to 48 in dia, 120 deg included, 23 turns of 3/4 in copper tubing.
Power: Potential Transformer, 14400 V AC, 1500 VA, External Ballast 1 to 8 hot water heater elements, 1500 W each.
Hawg Capacitor C: Seven glass gallon cider juggs, 0.017 uF
Surplus Capacitor: Old surplus GE capacitor, 50 kV, 0.022 uF

Mk III Tesla Coil Construction Pictorial

Progress to Date : see Altair's Tesla Lab Notes
Status Feb 2000:
Streamers 54 in, controlled strikes 14 in.
Switched to GE Capacitor, 22 nF. Primary Coil tunes at 6 1/2 turns.
Rewound Primary Coil with 3/4 in Cu tubing.
Expanded 240 V ballast bank to 12 kW, for 1.5 kVA potential transformer.
Next: Fiber Optic Instrumentation System, Increase Toroid size. Construction of asynchronous tungsten rotary gap.

Altair's Mk IV Tesla Coil

Mk III Tesla Coil Schematic Diagram

My Mk IV Tesla coil will drive 50 inch streamers, looking for more. Its vital statistics are:
Sedcondary Coil : Cylindrical , 12.5 in dia, 46 in tall, 1040 turns of #17 copper wire on a fiberglass form.
Top Load : Toroid, stovepipe, 8 x 24 inches.
Primary Coil D: Conical Helix, 16 in to 48 in dia, 120 deg included, 16 turns of 3/4 in copper tubing.
Power: Potential Transformer, 14400 V AC, 1500 VA, External Ballast 1 to 8 hot water heater elements, 1500 W each.
Hawg Capacitor C: Seven glass gallon cider juggs, 0.017 uF
Surplus Capacitor: Old surplus GE capacitor, 50 kV, 0.022 uF

Mk IV Tesla Coil Construction Pictorial

Progress to Date : see Altair's Tesla Lab Notes
Status Sep 2002:
First Light , Streamers 36 in.
Switched to GE Capacitor, 22 nF. Primary Coil tunes at 6 1/2 turns.
Unwound 2 inner turns of Mk III Primary Coil, 3/4 in Cu tubing, and enlarged center hole.
240 V / 12 kW ballast bank for 1.5 kVA potential transformer.
Next: Fiber Optic Instrumentation System, Increase Toroid size. Construction of asynchronous tungsten rotary gap.

Hawg Capacitor

Hawg Capacitor made of plastic soda bottle

The HAWG CAPACITOR is a cheap way to home-grow a useable high voltage capacitor from a plastic soda pop bottle. These wont stand a lot of abuse, but a plastic soda bottle is cheap to replace.
Theory of Hawg Capacitor design.
Hawg Capacitor experiments to date.
Archive of HV capacitor email excerpts

Hawg Capacitor made of glass cider Jugg

The BOSS HAWG CAPACITOR is much more rugged and almost as cheap. This version uses glass gallon apple cider juggs, for construction details and a great recipe, see High Voltage Apple Cider.

Party Cup Capacitor

The PARTY CUP CAPACITOR, designed by Marc Metlicka, is the cheapest useable high voltage capacitor, made from plastic party cups. The prototype withstands 33kV AC in spark gap duty.

Party Cup Capacitor

i pulled out about 5" by 18" strip, i rolled it around the cup at about 1" from the top holding the overlap of about 1" tightly, then tearing off the excess. holding the seam i started rubbing the foil tightly around the cup with the other hand, then folding it under the cup and pressing flat. then i put the cup inside another cup and putting my hand inside i pressed, squeezed, pushed, twisted, and rubbed the two cups together. when i pulled the cups apart i was surprised at how flat and form fitting the foil had become.

Party Cup Capacitor

i then rubbed the foil even smoother with a sharpie marker, burnishing the bottom folds tightly against the cup. i took the foil cup and pushed it inside the other cup and did the rub, twist, push routine again then pulled them apart one more time, i took the torn off piece and folded it over twice to make the contact strip, i slid it under the foil about 1" then put the cups back together. this made one cell.

Party Cup Capacitor

Party Cup Capacitor

Marc Metlicka died in 2004. He is remembered by coilers for his generosity and willingness to help others.

FlexiGap

Altair Flexigap diagram

The FLEXIGAP is a fully adjustible modification to the Richard Quick multiple spark gap. It is still Quick and Hawg cheap, but it includes a simple method of continuously and simultaneously varying the gap spacing in an (almost) uniform manner.

Multiple spark gaps are used to improve 'quenching' which is the gaps' ability to stop conducting after it has delivered the proper amount of charge. In high power Tesla coils, the RF energy in the primary may cause the gap to continue conducting RF after the capacitor is discharged, which depletes the energy from the primary-secondary system.

Multiple gaps are optimized by three main parameters: number of gaps, gap spacing, and airflow. Airflow is optimized by a blower, number of gaps is optimized by a selectable tap in a chain of gaps. In this version, the spacings are also adjustible by bowing a flexible substrate.

SuckerGap

Altair SuckerGap diagram

The SuckerGap is an idea from. It is a static gap using two hollow tubular electrodes with air being sucked into the electrodes. The air promotes good quenching and cools the gap.

This gap is sucked by a ShopVac. The blower of the ShopVac is mounted onto a plastic bucket which has a two-horned PVC manifold. The electrodes are copper pipe fittings at the ends of the manifold facing each other.

Cone Primary Coil

Primary Coil C, inverted cone spiral

Primary coils spirally wound in the shape of an inverted cone allow the coupling to be adjusted by raising or lowering the secondary. This inverted conical spiral primary uses coil supports cut from pegboard to form notches for the wire to be laid into. I use pegboard with 1/4 in holes which fits #6 copper ground wire. Later, I used 3/4 inch copper tubing on the same coil form.

Extending MOT Stacks

Many experimenters stack MOTs (Microwave Oven Transformers) with their primaries in parallel and secondaries in series to get several kV. Usually with more than 4 MOTs in series, the secondary to core insulation begins to fail. Those who have PLENTY of MOTs might try this hookup to extend their MOT stack farther before insulation failure.

Extending MOT stacks diagram

This connection allows four MOTs to be stacked with only a 2x overstress of the insulation, even in one end of the stack is grounded.
Two such stacks oppositely phased will give eight MOTs in series with a grounded center tap with only 2x overstress.

Extending MOT stacks diagram

This connection allows four MOTs to be stacked with NO overstress of the insulation.

Tesla Coil Design Data

Coiling Terms

A brief lexicon of TC terms and acronyms, you wanna bookmark this if you lurk on a Tesla Coil list server. Collections by Reinhard, Fritz, et al.

Tesla
Coil
Basics

A brief theory of operation of Tesla Coils, in FAQ form according to Bert Hickman. Excellent into for the coiler newbie, covers all the bases, including formulas for rolling your own.

Tesla
Coil
Design
Data

A collection of data for TC designers and builders, including dielectric property tables, conductances of electrolytes, household leyden jars, etc. Data formulas for rolling your own capacitors, coils, etc.


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Vic and Kip's Excellent Tesla Coil

Another Altair member, Kip Turner, W4KIP, built a fine coil. In his own words:

(Our 1,000 KV Tesla coil) was a pulsed device with a pulse input power of about 6.5 MW. ( 13 Kv @ 500 A. ) Just the kind of toy you'd expect a teenager to build. (The average was about 1 KW). (We also built a "Jacob's ladder that was 10 feet high with a 2 foot gap...but that was one of our low voltage gadgets...160 KV). No pix of it.

How big a spark are these guys after ?

( Mine did about six feet ! ...Limited by distance to grounded objects. )

Heres more from Kip :

The tesla coil that I and Vic made used a rug core for the coil form. I still have some of the wire we used...I think it's #26. My memory is a little flaky, but I believe it was about 6 feet long and 6 in (more or less) diameter. The primary was about 2 feet in diameter. We operated with one end grounded and the freq was about 135 KHz. It used a tungsten rotary spark gap (homemade) and had a 13.5 KVDC , 500 watt power source. The arc was limited by the 6 foot distance to ground. I have a picture...somewhere. If I can find it, I'll send you a copy. I think Vic lost it during a move a few years ago. The cap was a very high voltage indeed WWII surplus unit.
Kip

Vic and Kip's Excellent Tesla Coil

Kip supplied the info to draw a schematic of Vic and Kip's unusual Tesla Coil. Note the high voltage supply is DC and the coil runs at a low rate of about 10 BPS. The 3B24 rectifiers and transformer required no RFI protection.

Kip died in 2003. We still have not found his old TC photo for this page.

Bert Behlow made an unusual secondary coil which was immersed in mineral oil. This secondary had LOTS of turns of very fine wire. A valiant effort, but fell short of our grand expectations. Bert, if you're out there somewhere, it would be really good to hear from you.

I have collected materials for a secondary coil about 60" tall and 9" in diameter. Would like to resonate it at 184.32 KHz so it could double as an output stage for Lowfer beacon YWK. Might be a fun group project for folks in the Atlanta area?

Meet other Happy Coilers on the

a collection of personal and profesional pages housing a wealth of knowledge and experience. There are diagrams, tekno-glamour shots, design software, plenty of advice for the beginner and discussion for the experienced.

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