Index

Introduction About this page, general introduction
How Tesla Coils Work Description of how tesla coils work.
Spark Gap Tesla Coils Basic Introduction
     Tesla Coil 1 My first Tesla Coil, 180W
     Tesla Coil 2 The large medium sized 3kW coil
     Tesla Coil 3 A rather small Tesla Coil
Solid State Tesla Coils

About this page

This page serves as in index page to the several tesla coil I've made, as well as some basic design and theory about tesla coils.

Introduction to the Tesla Coil

A dark ominous cloud engulfs the land, the atmosphere thickens and raindrops begin to fall. Suddenly, a forked tongue of immense brightness and fury leaps from the heavens to the ground followed by a thundering rumbling noise as if the earth had been ripped apart. This is lightning.

For as long as mankind has walked the face of this earth, we have always marveled at nature’s lightshow. It’s is one of the most beautiful and magnificent displays of mother earth, and yet it is also one of the deadliest natural phenomenon. Lightning is usually associated with storms or bad weather, but can you imagine lightning being generated at home?

Imagine an empty dark room. In the middle sits a strange contraption which looks liked a metal doughnut sitting on top of a tube with wires sticking out at the bottom. The mad scientist turns on the power and small sparks sprays out from the doughnut like a magic fountain. The scientist cranks up the power and the wispy sparks turn into longer and brighter looking bolts resembling lightning. Then the scientist cranks up the power all the way and it seemed as if the whole room would explode anytime. The doughnut shaped object at the top of the contraption lashed out continuously morphing dagger like sparks which threatened anything within its reach, setting everything it touched on fire. It was as if there was a thunderstorm in the room. This is a tesla coil.

The tesla coil, invented by Serbian-American Physicist Nicola Tesla in the late 1800s, is a high-voltage, air-cored resonant transformer capable of extremely high voltages at high frequencies and colossal discharges. The tesla coil achieves such great voltage gains by means of a resonant circuit and is therefore not limited by the ratio of the number of turns of wire in the windings like normal transformer is. Their high operating frequency combined with the high voltage can also create interesting gaseous ionization, skin effects and current displacement effects. Furthermore, tesla coils can transmit high frequency energy at high efficiencies and can be used for radio communication.

Although these lightning-producing devices have been emulated in many ways since it was invented, the classic tesla coil can still be found! They are built by High-voltage hobbyists, often called "Coilers", who share a passion for high-voltage. Over the years, the classic spark-gap excited tesla coil has evolved into many different types of tesla coils, like the solid state tesla coils. Some have even made music from the tesla coil by means of audio modulation. Imagine a thunderstorm becoming a loudspeaker! The frequency of the spark output can be adjusted, and if done properly, the changing frequency of the spark creates music.

Even though tesla coils were invented more than a century ago, they still prove to be endearing objects which still continue fascinate and amaze people with their stunning display of electrical, light and sound display.

Introduction

Introduction

The 180W 40mm Tesla Coil 1 The Tesla Coil 1 Webpage (For Comprehensive Construction details and others)

My first Tesla Coil, previously powered by a 7.5kV 30mA Neon Sign Transformer but now powered by a 6kV 30mA Neon Sign Transformer. A normal classic Tesla Coil, portable and good for demonstrations. However, due to the limited power supply, this tesla coil has not reached its full potential.

Construction began on15th October 2003 when I was in Secondary 2 (13 years old) and was completed in slightly more than a month on 20th November 2003. However, from 8th to 12th August 2004, I made a nice wooden stand for it to mount all the components and did some slight changes including the toroid, the spark gap, and the primary coil, resulting in improved arc lengths.

On the right is a schematic of the completed Tesla Coil.

1 Mains is 240VAC at 50hz
2 I am using a normal 3 Amp rated EMI filter for 240VAC. Good enough.
3 I got the 6kV 30mA Neon Sign Transformer from my friend. Used to be a 7.5kV one though until it died.
4 (s.g) is the Safety Gap to protect my capacitors and the neon sign transformer. Made from two aluminium pieces.
5 (m.g.) is the Main spark Gap made out 3 pieces copper pipe and a brass bolt for tuning.
6 C1 is my main MMC design capacitor bank rated at 12kV 0.017625uF (17.625nF).
7 (p.c.) is my Primary Coil with 8+ tappable turns. I used a small diameter fuse holder as an adjustable tuner.
8 s.c. is the secondary coil.

Specifications

Primary Transformer: 6000VAC 30mA Neon Sign Transformer, 50hZ

Capacitor for Pri. Transformer Z Match: 15.9nF

Actual Capacitor Bank: 12kV 17.625nF for a slightly larger than resonant cap bank. Multi-Mini Capacitor design made with 3 strings of 8 capacitors. Each cap is a 0.047uF 1.5kV Polypropylene Film Foil Axial capacitor. 10MOhm bleeder resistors across each capacitor for charge equalization and for safety.

Primary Coil: 3.2" Inside dia, made with 1/8" Copper tubing, with 0.275" turn spacing. There are a total of  8 tappable turns, tapped at turn 5. Shape is a 15^o inverse conical, built on 4 HDPE supports from chopping boards.

Secondary Coil: Wound on a 40mm dia. white PVC tube, with 0.2mm enameled copper wire. Wound for 23.6cm, with a total estimated 1100 turns. Coated with 4 layers of polyurethane varnish.

Secondary Coil Calculations: Inductance of 7.76mH; 3.60pF self capacitance, Secondary coil frequency 952.75kHz.

Toroid: Made with 5.5cm dia PVC ducting, toroid dia. tube centre-to-centre, 23.5cm. Capacitance 12.0867pF

Secondary Frequency with toroid:  456.23kHz.

Calculated Voltage: 201,161V ... 201kV

Spark Gap: Static Multiple electrode spark gap, made from 3 2" long 1" dia copper pipes bolted onto a HDPE plastic sheet, with a M6 brass bolt as the last electrode for spark gap spacing tuning. Quenched by a fan from a microwave oven.

Max Spark Length to date: 27cm with 225W input (original coil) ; 25cm with 180W input (improved coil)
 

Click here for comprehensive construction details and other things related to this coil.
 

 The 3000W 4" Tesla Coil 2

A dark ominous cloud engulfs

A Rather Small Tesla Coil

A dark ominous cloud engulfs

[Under Construction]