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Tesla coil Instructables are not uncommon--I've written one myself--but in the following Instructable I'd like to not only describe building a simple upright coil, but also suggest some easy ways to assemble Tesla system components. Sometimes the parts of a Tesla coil system are harder to get than the coil itself. Then, at the end, I will demonstrate (in a small way) how Tesla coils can transmit electrical power through the air without wires.
The essence of this Instructable is simplicity rather than brute power or maximum efficiency. Because my coils are small, indoor models, I prefer to follow a modular method of building them. Most Tesla coils are unitized--everything packaged together in a single unit, just plug and play. I like to build in modular fashion so I can switch components around, try different coils, capacitors, or power supplies. Consequently my designs are clipped together with alligator clips and length of high voltage wire. If you
prefer the unitized approach, you can certainly adapt this design that way.
This Tesla coil system consists of these parts:
A high voltage (7,500 volts, 30 milliamps) AC transformer
A pressurized spark gap
A capacitor array
The coil itself, consisting of a primary and secondary coil on some kind of supporting
frame.
A "top load," or terminal
Wire to connect everything
Optional components you will want include a variable transformer (variac), and a small
hose-type vacuum cleaner.
Fluorescent light tubes, with stands
Each of these topics will covered on a separate page.
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Signing UpStep 1Power supplies
This may be the most expensive part of your Tesla coil system. You will need an AC transformer of at least 3,000 volts at 30 milliamps to get the spark gap to fire, and more is better--within reason. Once you exceed 15,000 volts at 60 mA, you're leaving the indoor, tabletop arena and graduating to garage maniac status. This system is designed around a 7,500 volt, 30 mA neon sign transformer.
Until a few years ago, most neon signs were powered by heavy transformers potted in insulating tar. Nowadays concerns for safety (and liability) have made the old heavyweight NST obsolete. Modern neon power supplies are light, solid state units with Ground Fault Interrupt (GFI) protection. This is all very well if you're trying to light up a Michelob sign, but GFI power supplies won't work in a Tesla coil system. GFI is designed to stop just the sort of continual sparking a Tesla coil requires, so avoid modern neon power supplies. If you can't tell by the label if a transformer has GFI, try this rule of thumb: if the unit is small and light, it has GFI and won't work on your Tesla coil. If it's heavy as lead and almost as big as a cinder block, it will.
Other power supplies can be used. Oil burner ignition transformers (OBITS) can often be had cheaply. They almost always come rated at 10,000 volts at 23 mA. As with neon sign transformers, the newest OBITs now come with solid state circuitry and GFI. Pay close attention to make sure you don't get stuck with a useless GFI model.
Some coilers use microwave oven transformers. My advice is, DON'T. MOTs, as they are called, are rude, crude, and develop lethal amounts of current. If you don't know what you're doing, you can easily harm yourself or others. Until you've learned a lot more about electrical engineering, leave MOTs alone.
Car ignition coils are sometimes used to power Tesla coils. Ignition coils have to be driven by some kind of circuitry, either a 555 timer and associated parts, or even by something as simple as a household dimmer switch. This can be a fun project on its own.
Tesla coils can be powered by DC, but that's a different topic not covered here.
For best and simplest results, get your hands on a neon sign transformer (NST). All the ones I own I got off eBay pretty cheaply. They're heavy and can be expensive to ship, so if your budget is really tight, try a local sign shop. Many businesses are still switching over to electronic GFI power supplies and discarding their old NSTs. You might get a bargain if you offer to take an old-style NST off their hands.
Many NSTs come without power cords. When I salvage parts from old microwave ovens, one thing I always keep is the sturdy, three-wire oven power cord. These are easily adapted to NSTs.
One thing to remember about using NSTs: never move or lift an NST by the ceramic terminals! They're brittle, and they can crack or snap right off, then you've got nothing but a doorstop. Always lift NSTs by the case. One thing you can do to improve the portability of an NST is mount it on a base. I put my 7,500 volt Allanson NST on a shellacked pine plaque, fitted with four rubber appliance 'feet.' This insulates the NST from the tabletop, and gives me a handy place to grab and lift it.
It happens my Allanson unit has a pull-chain on-off switch. This is unusual. Most NSTs I've seen do not have on-off switches. Once you have grafted on a power cord, the best way to handle the NST is through a variac (a variable transformer), or an isolation transformer (see "Variacs and Vacuum Cleaners"). Failing those, you may have to use a wall socket controlled by a wall switch, or else put together a switch using a household wall switch mounted in a utility box.
Until a few years ago, most neon signs were powered by heavy transformers potted in insulating tar. Nowadays concerns for safety (and liability) have made the old heavyweight NST obsolete. Modern neon power supplies are light, solid state units with Ground Fault Interrupt (GFI) protection. This is all very well if you're trying to light up a Michelob sign, but GFI power supplies won't work in a Tesla coil system. GFI is designed to stop just the sort of continual sparking a Tesla coil requires, so avoid modern neon power supplies. If you can't tell by the label if a transformer has GFI, try this rule of thumb: if the unit is small and light, it has GFI and won't work on your Tesla coil. If it's heavy as lead and almost as big as a cinder block, it will.
Other power supplies can be used. Oil burner ignition transformers (OBITS) can often be had cheaply. They almost always come rated at 10,000 volts at 23 mA. As with neon sign transformers, the newest OBITs now come with solid state circuitry and GFI. Pay close attention to make sure you don't get stuck with a useless GFI model.
Some coilers use microwave oven transformers. My advice is, DON'T. MOTs, as they are called, are rude, crude, and develop lethal amounts of current. If you don't know what you're doing, you can easily harm yourself or others. Until you've learned a lot more about electrical engineering, leave MOTs alone.
Car ignition coils are sometimes used to power Tesla coils. Ignition coils have to be driven by some kind of circuitry, either a 555 timer and associated parts, or even by something as simple as a household dimmer switch. This can be a fun project on its own.
Tesla coils can be powered by DC, but that's a different topic not covered here.
For best and simplest results, get your hands on a neon sign transformer (NST). All the ones I own I got off eBay pretty cheaply. They're heavy and can be expensive to ship, so if your budget is really tight, try a local sign shop. Many businesses are still switching over to electronic GFI power supplies and discarding their old NSTs. You might get a bargain if you offer to take an old-style NST off their hands.
Many NSTs come without power cords. When I salvage parts from old microwave ovens, one thing I always keep is the sturdy, three-wire oven power cord. These are easily adapted to NSTs.
One thing to remember about using NSTs: never move or lift an NST by the ceramic terminals! They're brittle, and they can crack or snap right off, then you've got nothing but a doorstop. Always lift NSTs by the case. One thing you can do to improve the portability of an NST is mount it on a base. I put my 7,500 volt Allanson NST on a shellacked pine plaque, fitted with four rubber appliance 'feet.' This insulates the NST from the tabletop, and gives me a handy place to grab and lift it.
It happens my Allanson unit has a pull-chain on-off switch. This is unusual. Most NSTs I've seen do not have on-off switches. Once you have grafted on a power cord, the best way to handle the NST is through a variac (a variable transformer), or an isolation transformer (see "Variacs and Vacuum Cleaners"). Failing those, you may have to use a wall socket controlled by a wall switch, or else put together a switch using a household wall switch mounted in a utility box.
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PBT
Paul
I can't remember where but I remember you offering a high voltage soviet era capacitor for sale- do you have a way of contacting me about this?
thanks, OzL
Paul
PBT
TeslaMap: http://www.teslamap.com/download.html
JavaTC: http://www.classictesla.com/java/javatc.html
Paul
Total for Tesla coil system, $51.50. This does not include the fluorescent tubes, etc.
Another benefit of building the coil modular fashion is that the components are easily reusable in other projects.
Paul
thanks for your advice!!!!
Paul
copper tube with 10 turns secondary made with 2inch PVC pipe.Winding
height 10.2inch(0.315mm enameled copper wire used) also made Capacitor
bank with 2kv 0.15uF polyester film capacitor.But the problem is my
Capacitor burnt several times but the coil works with LEYDEN JAR
capacitor.Why the capacitor burning??????
Please Help Me!!!!!!!!!!!!!!!
Or, stick to your Leyden jars! Though they are not as efficient as factory made capacitors, they are easily made, can withstand very high voltages, and can even be adjusted for the proper capacitance.
Try these changes and let me know how it goes.
Paul
Paul
Try multiplying the secondary current and voltage. i.e. 7500v x 30mA = 225W. Run it for an hour and you would use 225Wh of energy.
Paul
Paul