Solid State Tesla Coil

last updated:14 Sept 2003

All informations in this page are published free and are intended for private/educational purposes and not for commercial applications .

New Solid State Tesla Coil using full wave bridge

Solid State High Power Tesla Coil (14 Sept 2003)

Here is my newest design for a solid state tesla coil. This uses a high frequency transformer in the input, and a full wave bridge architecture to deliver much more power, than the half bridge design I previously used. Above are some of the flame like discharges produced by this coil at around 390 kHz.

A spark gap Tesla coil will automatically detune as the streamer is formed on the high voltage terminal, but this solid state driver circuit only runs at a single frequency (with the function generatar I am presently using), thus limiting the maximum length of the spark. I found that detuning the driver to a frequency slightly above resonance give longer and thinner discharges.. but with less intensity. above are some examples...

Driving on resonance (or possible slightly below) produces very short and extremely intense flame like streamers.. The bottom picture shows my coil with the flame like 'electric fire' erupting from the pin point on the top of the coil. You may ask, why the interst in solid state tesla coils, when spark gap coils produce much higher output power??? The answer is that solid state tesla coils have the ability do things its spark gap relative can only dream of doing.. You can have absolute control of frequency and phase... This will be very importain when trying to replicate Hutchison's experiments and the Philadelphia Experiment (time machine). The flexibility of the solid state driver will allow me to phase multiple tesla coils together... in a reproducable way... (which will be absolutly essential for these types of experiments..)

Above are some picture of the new driver circuit. Since the power driver circuit (high frequency switching power supply) has a ferrite toriod HF transformer, to provide isolation between the two sides of the half wave bridges (matched n and p channel FET's), a predriver circuit is required to provide enough power to the input of this guy.. The next picture is a close up of the power driver circuit, using 8 fets (2 in parallel per leg). The third picture is a close up of the HF ferrite x-former. It actually has three sets of windings, one input and 2 output.. with about 45 turns on each set. Notice that I match the output of the HF transformer with 100 Ohm resistors..(on each side). This is essential for high power operation, as I will explain in a little bit. Since I am not using kilovolts to drive this guy, I can use a simple air gap / dielectric variable capacitor for matching input impedance to the primary tesla coil winding..

The impedance matching is very importain! I can not overemphasize this. My fets were burning up every time I tried running above a moderate power level. So I put the old O-scope on the output to see what was going on here. The top left trace is with driving the input with a square wave, and no termination resistors. Notice how the power rings on and off at a very high frequency? This means the fet is staying in the high resistance region of the I-V curve.. and disipating a huge amount of power in the poor little guys... But this situation can't last long.. Poof! time to replace the transistors. Now in the second trace (right), I use a triangle wave as the input and 100 Ohm termination resistors. Now the transistors operate relatively cool even at high power levels. Notice how the high frequency ringing is greatly subdued.. My next design will overcome the Band Width limitation of the HF transformer... and should allow me to build a prototype switching power supply to start some high power (time machine) experiments... More to come.. (P.S. See you later R.M.D.)

Copyright Information

Unless otherwise noted, all materials at this site (including without limitation all text, html markup, graphics, and graphic elements) are copyrighted ), 2002 by Reginald L. Jaynes. The material available through this site may be freely used for attributed noncommercial educational purposes only. We ask that due credit and notification be given the author.  

All materials appearing on this website may not be reproduced, stored in any retrieval system, or used in any way for commercial purposes without the express prior written permission of the copyright holder.  

Disclaimer: The author assumes no liability for any incidental, consequential or other liability from the use of this information. All risks and damages, incidental or otherwise, arising from the use or misuse of the information contained herein are entirely the responsibility of the user. Although careful precaution has been taken in the preparation of this material, we assume no responsibility for omissions or errors.  

HOME

Send e-mail to: dr_jaynes@hotmail.com