Epic 1,000,000 Volt Tesla Coil

A tesla coil is a device that can generate millions of volts of electricity and make artificial lightning.

A tesla coil is a type of "resonant transformer". A Resonant Transformer works by passing electricity through a circuit consisting of an inductor and a capacitor. This causes the electricity to oscillate back and forth at a certain frequency, which depends on the value of the capacitor and an inductor. When this circuit oscillates the inductor produces a changing magnetic field. If a coil of wire is placed inside the magnetic field it will induce pulses of electricity in the coil. If the receiving coil(known as the secondary) has more turns of wire than the transmitting coil(Primary coil) the voltage in the secondary will increase. If the oscillations in the primary circuit are tuned to the natural frequency that the secondary wants to oscillate at the voltage in the secondary will be exponentially magnified. Using this principle the tesla coil can generate millions of volts.

WARNING: Tesla Coils are EXTREMELY DANGEROUS.

Stay far away, don't touch any part of it while it's on and do research on high voltage safety before turning it on.

Alright, now that we've got safety out of the way let's get building this thing!

A few thousand feet of magnet wire

A 20'' piece of 4'' PVC pipe

Metal bolts

3'' flexible aluminum dryer ducting

2 Microwave Transformers(or 1 Neon Sign Transformer)

8 gauge copper grounding wire

16 gauge insulated wire

18 Cornell - Dublier 942c20p15k-f Capacitors

18 10mOhm resistors

Plywood

Cheap end table

To power a tesla coil you need a high voltage transformer capable of supplying 4,000-15,000 volts at 60-1000 mA. I used a Microwave oven transformer. These high voltage transformers can be easily salvaged from old microwaves and supply 2,000 volts at 500 mA. THESE ARE EXTREMELY DANGEROUS. THEY HAVE NO CURRENT LIMITATION SO THEY CAN KILL YOU. I suggest using a much safer Neon Sign Transformer. I didn't have one when I built this so I used MOTs. For my tesla coil I used 2 microwave transformers wired with the primary coils in parallel and the secondaries in series. This doubles the voltage to 4,600 volts, which is important so the voltage can jump the spark gap. The primaries are wired to a power cord to supply them with 110 volts at 15 amps.

The tesla coil capacitor has to be rated to run at high frequencies, high voltages, and high peak currents of hundreds of amps.if it doesn't: BOOM. There is pretty much only one type of capacitor that can handle this: the polypropylene capacitor. These capacitors only come with voltage ratings of 1,000 - 2,000 volts. Not enough. The best option is to wire a bunch of them together to make a Multi Mini Capacitor bank or MMC bank. I used 9 cornell dublier 942c20p15k-f caps in series to get a bank rated for 18,000 volts. Why an 18,000 volt bank for 4,000 volts? Because voltage spikes are common in a circuit like this so you need a capacitor bank rated for 2-4 times the power supply voltage. Another problem is that when you wire capacitors in series the capacitance decreases and for currents this high you need at least 30-50nF. To fix this I used 18 capacitors and put 2 strings of 9 capacitors in parallel to get 18,000 volt rating at 33.4 nanofarads. For safety I put a 10mOhm resistor across each capacitor to prevent a dangerous charge from being stored in the capacitors when the coil is turned off. All the parts are mounted on a wooden board.

I used a complicated rotary spark gap for my coil. But for beginners I suggest just screwing 2 bolts into a piece of PVC pipe as seen in the photo. Put a computer fan on one end of the pipe to blow air through the arc and stop the gap from overheating.

I drilled 8 holes in each of 4 plywood strips. These are mounted in an x shape. I then wound a pancake shaped coil of wire with 8 turns. I used 8 gauge grounding wire because it needs to be thick due to the high current of the capacitor pulses. I connected another wire to turn 6. The point on the coil where this wire connects can be changed. This makes it easy to tune the primary oscillations to match the resonant frequency of the secondary and get the biggest arcs.

The secondary coil is wound on a 20" long piece of 4'' PVC Wind 1,200 turns of 30AWG enamel coated Magnet wire perfectly tight and smooth. Any overlaps will cause arcs to shoot out of the surface of the coil and burn the coil. once the coil is finished the ends are taped off to prevent it from unwinding. The coil is mounted upright in the center of the primary coil. Make sure there are a few inches of space between the primary and secondary coils. otherwise there will be unwanted arcing between these coils.

Take some 3'' flexible aluminum dryer ducting and bend it into a circle.Tape the ends together. attach some kind of disk to the bottom and mount it on top of the secondary. connect the wire from the top of the secondary to the topload. attach a metal nail to the side of the topload to allow lightning bolts to jump out of it easier!

Wire all the components according to the schematic shown earlier and you are ready to make some lightning!

Use a 140V 10A Variac to slowly increase the voltage going into the transformers, starting from zero until the spark gap fires. If the sparks coming off the topload are tiny, change the position of the tap wire on the primary coil to different spots until the sparks become a few feet long. when they do,

If you have any other problems getting it working, leave a comment