TESLA COIL

A WEBSITE WITH SOME THINGS ON IT.

~ Bellend Lab's High Voltage Page. ~ We Bodge. We drink tea. We get painful shocks..

Dangerous shit alert!

MOST OF THE STUFF ON THIS PAGE WILL TRY TO KILL YOU.

DR BELLEND DOES NOT ACCEPT RESPONSIBILITY FOR DEAD PEOPLE.

A Tesla Coil built in a few hours with junk and tea.

Introduction.

At the turn of the century Nikola Tesla invented a high frequency air-cored transformer with the aim of transmitting electricity without wires. He carried out many successful experiments, but it never came to fruition. Since then geeks have built small coils based on neon sign transformers. However the web changed all that, and fellow geeks could share the results of their experiments and pretty soon sites were showing big coils ablaze in a mass of sparks.

All over the web, anoraks are devoting their lives to building high voltage stuff. It's no big deal. We built this in hours, out of junk and it works fine. If you're looking for polished brass parts and expertly machined components though, you're looking at the wrong site.

Remember also that the size of your Tesla coil is inversely proportional to the extent of your social life, the people with time to build and run ten-foot coils are people who don't let a social life get in the way. Either they're single, with facial hair, and wear Apple tee-shirts and sandals or they have partners who don't care if they aren't around. If I spent weeks in my workshop building 10 foot Tesla coils I'd be divorced and probably end up living on Pot-Noodles, wearing the aforementioned Apple tee-shirt, growing facial hair and looking at a lot of internet pornography. This page shows you how you can build a coil out of junk in a few hours.

The coil below was built without the use of a calculator, oscilloscope, resonance formulas or any other unnecessary rubbish.

Ingredients: 4 microwave oven transformers, (from old microwaves please), capacitors (Maplin or RS), car brake pipe (Dirty Barry's car parts), various plumbing bits (B&Q), transformer wire (Maplin or RS), Variac or old convector heater for ballast. An fast motor from a Hoover/Strimmer and access to lots of assorted electrical junk.

Building a Tesla Coil...

Power supply. 4 X microwave oven transformers wired in series-parallel to give about 8Kv at approx 0.5 Amp full power. These must be current limited so they are supplied from a variac. The 2 outer transformers are stressed to 8X their normal voltage between core and primary so the whole thing is dumped in transformer oil. Don't use engine oil, we tested some and it was rubbish (water would probably have been better).
Capacitor. 10 X 0.033uF 2Kv in series to give 33nF at 20Kv. I bunged these in a piece of waste pipe.
Spark gap. My first attempt exploded on 10,000 rpm test and stuck in the garage ceiling. Oops. Built a stronger one out of some Plexiglass I scrounged. Motor is from a Strimmer. Balancing is a mile out so it sits on a few layers of carpet underlay for vibration control.



Supply. dedicated switch fuse that doesn't come through our RCD. Coil runs with a 20A breaker ok without tripping it.
The variac. Fitted with a beacon to remind me not to fry myself on the 8Kv power supply.

First test of the coil running on a Neon Transformer.
Same coil at about 60% power trying to set my garage on fire.
Tesla's magnifying coil from 1899. He wasn't daft enough to sit there, it's a double exposure.

Circuit diagram click here: images\tesla diag.pdf

Video of coil in action on U Tube: http://www.youtube.com/watch?v=EaX_hyyG35o

Climbing Arc, (as seen in Frankenstein's Lab).

Ingredients: 1 High voltage transformer from a neon sign, boiler ignition or other equipment.

2 Wire coathangers.

Some people call them 'Jacob's Ladders' but I think Jacob should be left to the God-botherers, it's a climbing arc as far as I'm concerned. I've had to call it a Jacob's Ladder on U-Tube however because everyone else does. The proper name, if you're an engineer is a 'Horn Gap Electrode'. They were originally used for breaking arcs in surge arrestors on early overhead lines. My first attempts were using my 4 MOT supply despite warnings from people all over the web not to use them because they're lethal. (We play with these things precisely for that reason). They didn't work well. Lots of current but not really enough voltage.
The transformer. 120 Volts in 35,000 Volts out, air insulated. Its very difficult in the UK to source anything bigger than a 10Kv NST. Something like this is a rare find. Running your climbing arc at 50 Hz also means you get that classic 'Frankenstein' sound unlike flyback and ignition coil driven gaps. Climbing Arc. Done. See the Climbing arc in action: http://www.youtube.com/watch?v=TcowS9c2Uz4

More dangerous shit alert!
'Electric Human' I watched a Sky documentary called 'Electric Human' recently and nearly popped when I saw it. What a load of crap. They devoted nearly a whole hour to a bloke who could make a 1/2 inch spark jump to his finger. I've had bigger sparks getting out of the car. Here's a picture of me taking about 150,000V straight to my hand. I'm holding a screwdriver but that's just to prevent a burn when it goes in, I'm still carrying the full current through my arm and body. Video link below: http://uk.youtube.com/watch?v=6nZ45xgzl80
So far as connecting yourself to the mains goes, here's another 'miracle' he did. Here I am holding the live conductor of the UK mains at 240 Volts. It's not magic, I'm not an 'Electric Human', it's just knowing the rules. The Doctor is a complete bellend, DON'T attempt ANYTHING you see on this page.
Reworking an X-Ray Transformer. (Or how to give yourself back problems)
I do a lot of work in hospitals and just happened to be around when they were stripping this out. Despite weighing 150 pounds, this was too good an opportunity to miss. It took a bit of getting in the car bearing in mind it weighs as much as an average person* at nearly 10 stones. After doing some checking on the web I found that this is in fact a 'small' one! *Not an average American.
A bit of work later and here it is out of its oil tank. I took some time here to trace all the circuits and record them. There are two high voltage transformers feeding voltage doublers working in opposition. There are also 2 filament transformers for heating the x-ray tube cathode, resistors for monitoring output voltage and current, and on this particular model 4 solenoid switches for selecting outputs as it's a dual output unit.
The 2 voltage doublers. As a separate project, these are going in an oil bath and going to become a voltage quadrupler in the classic Cockroft-Walton circuit. It would be a shame to waste good high voltage gear.
The 2 filament transformers. Their job is to supply a few volts to the X-ray tube filament, but it's a difficult job when the end of the tube is at 70Kv hence the extreme insulation on their secondary windings. These aren't much use but the ferrite cores could be useful.
All unnecessary gear stripped out. The transformers are now wired straight to the output sockets and earthed in the centre. I did some low voltage tests at this stage to determine transformation ratio and the phasing of the windings. This unit should be good for 70Kv between output terminals or 35Kv to earth. The only other device I left in was one of the voltage-monitoring high-resistances which I brought out to a spare terminal. I may be able to calibrate a meter to read output voltage using this terminal.
The removal of those big capacitors and filament transformers means the oil level would be dropping considerably, so I fitted these boxes of solid expanding foam to displace some oil. This minimised the amount of oil required to top up the unit. The 2 spare unconnected outputs were blanked off with Perspex disks.
The finished unit ready for some power. It still weighs as much as a car engine though!