3.5kW Demonstration Tesla Coil

The 3.5kW Demonstration Tesla Coil

Introduction

One of the biggest problems I am facing right now is the fact that I don't really have a portable tesla coil to use for

demonstrations. The coils themselves are by no means large coils, but given the fact I don't have a SUV or pick-up truck

really limits the size of coil I can successfully transport. To solve this problem, I built a new primary coil which measures

a mere 2 ft. x 2 ft in size and easily fits in the trunks of both of my cars. Coupled with a basic four inch secondary, the system

is very portable and lightweight.

Primary Coil

The primary coil was built to be a portable as possible. Measuring only 2ft. x 2ft square it is lightweight and

easily fits in the trunks of my two cars.

The primary coil itself is comprised of 13 turns of 0.25" diameter copper tubing spaced 0.25" apart. There is also a

strike rail which sits about 2 inches above the primary coil. This strike rail helps prevent discharged from the secondary

from striking the primary coil ultimately protecting the primary circuit from dangerous transients. The base of the

primary is made from 23/32" thick plywood and the primary supports are made from Ultra High Molecular Weight (UHMW)

Polyethylene.

Primary Tank Capacitor

The primary tank capacitor I am using is the MMC capacitor shown above.

To create this new MMC, I used twelve (12) 0.33uF, 2kV capacitors in series to create a 0.0275uF, 24kV MMC.

The capacitors used are GE 42L3332, 0.33uF, 2kV Poly Capacitors. These can be obtained at Newark Electronics

(www.newark.com) for about $4.50 each.

Spark Gap

Asynchronous Rotary Spark Gap (ARSG)

Rotor Assembly and Tungsten Electrodes custom machined by Ed Wingate.

Click here for more information regarding this rotary spark gap.

High Voltage Transformer

GE Potential Transformer

Primary 14.4kV

Secondary 120V

Rated for 1.5kVA, but will run up to 3.5kVA for short durations.

Output current: 240mA (with ballast)

Weight: 100 LBS (and a brutal 100 LBS at that!)

High Voltage Transformer Ballast

Because the Potential Transformer is not internally current limited, the transformer must have an external ballast.

For this, I simply use a 500ft, 12 AWG spool of wire which can be purchased at the local Home Depot for under

$20.00. This "Poor Man's Ballast" limits input current to about 26A and total output power of the Potential Transformer

to about 3.5kW. This ballast was first used by Terry Blake and demonstrated at the Rochester 2002 Teslathon.

The 500ft, 12 AWG spool of wire is simply wired in series with the input 120VAC to the Potential Transformer.

Ballast Measured Rs = 0.9 ohms, Ls = 10.50mH

(Photo by Terry Blake)

Terry's Coil can be found here.

Secondary Coil

1000 Turns, 23.5" Winding Length, 4.5" diameter PVC

Secondary self-resonant frequency: 340 kHz

Secondary resonant frequency with 5x20" toroid topload: 195 kHz

Secondary Top Load (Toroid)

D&M Voltage 5" x 20" Toroid

3.5kW Demonstration Tesla Coil Action Photos

Click here to see photos of this coil in action

This demonstration coil had its initial run at Lou Bazan's house in October 2003.

It was a very cold evening, but the coil ran spectacularly!

Last modified August 16, 2005 08:05:23 PM