~ Bellend Lab's High Voltage Page.
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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...
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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. |
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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 |
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More dangerous shit alert!
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| '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
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| 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.
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Reworking an X-Ray Transformer.
(Or how to give yourself back problems)
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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. |
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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.
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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. |
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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. |
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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. |
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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. |
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| The finished unit ready for some power. It still weighs as
much as a car engine though! |
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