Tesla Coil

 

So here you will find pictures, videos and eventually music of/from my Tesla Coil. It has taken me nearly 3 years to get it to the stage it is at now and it is nowhere near finished yet! It works to some degree but but I need to spend some time tuning it up before I can upgrade it to a musical version.

I guess I should tell you a bit about what a Tesla Coil is and how it works for those of you who don't know. A Tesla Coil's full name is an Air Cored Resonant Transformer, in laypersons terms this means a transformer that has an air core as opposed to an iron core like standard transformers that you get in things like laptop chargers. The resonant part of the name means that the circuits within the Tesla Coil resonate with each other to step up the voltage more than you would normally get from a transformers primary and secondary windings.

If this still makes no sense to you feel free to leave a comment in the box below or send me an email from the contact page.

So let me tell you the story of my Tesla coil and how it has been developed. I started in August of 2007 after finding a video of a cymatics display which uses a resonating plate to create patterns in sand and iron filings. I looked around to find ways of building this and stumbled upon a website that was showing people how to create various different electronic experiments including Tesla Coils! From that day on I was hooked as they say, if you are interested in the website I found you can find it here they are very helpfull and have various parts for sale too.

My Mk1 Tesla Coil was a battery powered version running of two car ignition coils, however this seemed a bit small to me and I decided to scrap it before it was finished! Here are some pics of the circuitry though, as you can see it was very very amateur and probably would not have worked anyway.

 

Mk2 Tesla Coil

On to Mk2, this is where it get serious!! I managed to get hold of a Neon Sign Transformer from my local neon shop, this gives me an input voltage of around 8,500 Volts! Now thats more like it. Of course when you are dealing with these sorts of voltages you have some inherent safety issues, not least the fact that if you touch the wrong part at the wrong time YOU WILL DIE!!!

I had to rethink the whole design of the system to enable safe operation and avoid destroying everything that is plugged into the same circuit as the coil. The main component used for this is called a Terry Filter named after its inventor Terry Fritz

(German I believe but i could be wrong leave a comment if you know better). This circuit basically filters out and high frequency kickback from the output of the coil from destroying anything further back from the filter. I'm not 100% sure exactly how it works but I know it works so I'm happy! However this does not mean I can go in and touch every part of the Tesla Coil willy nilly, I still have to be extremely carefull and make sure everything is completely discharged before making any adjustments.

The next part I had to redesign was the main structure and housing for the coil. After browsing the web and different mailing lists I decided to go with a design that has been used by many others using round discs of wood separated by lengths of PVC tubing. This enabled me to have different layers for different parts of the circuitry, and it also meant I was able to have some separation between the high and low voltage sections of the coil.

On the bottom floor is the Neon Sign Transformer or NST and the PC power supply which generated 12V DC to power the fans for quenching the spark gap (I'll go into this in more detail lower down. The high voltage output from the NST goes up to the next level and into the Terry Filter, from here it passes through the spark gap and then up to the the high voltage capacitor bank.

The capacitor bank is then rapidly charged and discharged by the high speed switching of the spark gap into the primary coil that is made from 8mm copper tubing. The amount of turns on the primary coil and the size of the charge capacitor determine the primary resonant frequency. This has to be matched to the designed resonant frequency of the secondary coil and topload.