On this
page I will attempt to fill you in on concepts I have no personal
experience with, but have some understanding of. If you happen to
find some misinformation here, please notify me immediately by e-mail,
everything is correct to the best of my knowledge.
DC:
A Tesla coil can be built to run off of DC input as well as AC input. The thing is, a design modification is needed, you must insert what is called a charging reactor or a charging resister to prevent the high amperage pulse from your tank capacitor form wrecking your bridge rectifier or doubler. this is simply a HV side ballast, and you can employ may of the same things for this purpose, assuming you carefully calculate the value. Sometimes a MOT is used, wired to power against the flow, and controlled by a variac to limit inrush currents. Also, a DC coil generally (but not always) has the tank capacitor and spark gap in swapped positions.
Solid State:
Here is where my knowledge is very limited, basically you are replacing or modifying the tank circuit with little silicon chips. some solid state drivers pump pure RF into the secondary, others use pulsed RF. of the more modern popular types of SSTC (solid sate Tesla coil) are the following; SISG (sidac IGBT spark gap (IGBT stands for Insulated gate bi-polar transistor, it is a transistor that can be used at high voltages by increasing the base voltage, and can conduct in two directions)) DRSSTC (double (or dual) resonant solid state Tesla coil). I am not going into great detail of how these devices work, I will only say SISG is a "drop in replacement" for a spark gap on a conventional TC, and a DRSSTC uses a H-bridge of these IGBTs to drive a tank circuit.
Twin Coils:
A twin coil is two Tesla coils driven 180 degrees out of phase. They are generally as identical to one another as possible, and the RF ground is replaced by a strap connecting the two secondaries. They will arc from one top load to the other, and that is all I can say about them. People have also made triplet and quadruplet coils, by operating them 120 or 90 degrees out of phase.
3-Phase:
A three phase coil is something I don't know about, supposedly, someone is building one somewhere and it is supposed to be cool. you can use a three phase supply to power a DC coil with god results, as you need a much smaller filter cap.
VTTC:
A Vacuum Tube Tesla Coil is a coil that is driven by a valve oscillator or vacuum tube. Here is a schematic I drew of a Basic VTTC.
I plan on building one of these soon, so
look out world.
Audio Modulated:
Probably the coolest thing one can do with a solid state TC is audio modulate it. You know the plasma globes that blink to music or noise, this is not that. This is plugging your DRSSTC with some modifications into a keyboard, guitar, or MIDI source and hearing the sounds come from the arcs! It works by breaking up the 120 kHz or so resonate frequency into audible chunks, so the "Rf envelope" is an audible sound wave. Search the internet for these and you will get a good laugh, I promise.
Magnifier coil:
You can tell by the name that this must be seriously cool! The magnifier is the Tesla coil, as Tesla himself built it, and perfected it, for the purpose of his wireless power transmission research. Before I tell you what it is, I will tell you how it works. On a normal TC the primary is usually flat to keep the coupling low, the coupling must be low, or the secondary will die from the immense amount of energy, not to mention you can get multiple voltage nodes at places other than the top load! As a result of this low coupling, a lot of the energy is lost forever to space as radio waves. A magnifier gets around all of this, by using an oober tight coupling, and it prevents secondary breakdown by having a very low inductance secondary. But if you know your formulas, you will know that a low inductance kills your voltage out, this is very true. Once again a magnifier has a way around, 3 coils! The primary and secondary (or driver) function like a standard step up transformer, and are not tuned to resonance (so no breakdown) the tertiary (or resonator) is driven by the driver, at it's resonant frequency! Now the misconception some people have is assuming that the secondary has no effect on the resonance of the system, it does, but because it has such a low inductance, the effect is minimal, tuning is done by adjusting the primary, just like a conventional TC. The reduced coupling losses of the magnifier, mean it is more efficient, the extra coil, means it is more temperamental! Here is a picture of a magnifier made by Ed Wingate, I have seen this coil run in person, and can attest that it is truly awesome to behold, and a true feat of engineering! The distance to the door is about 10 feet, but his coil has struck things 16 feet away, running at about 1.5kW, the same power level I run on my 6-in coil (which gets about 4-5ft arcs).
DC:
A Tesla coil can be built to run off of DC input as well as AC input. The thing is, a design modification is needed, you must insert what is called a charging reactor or a charging resister to prevent the high amperage pulse from your tank capacitor form wrecking your bridge rectifier or doubler. this is simply a HV side ballast, and you can employ may of the same things for this purpose, assuming you carefully calculate the value. Sometimes a MOT is used, wired to power against the flow, and controlled by a variac to limit inrush currents. Also, a DC coil generally (but not always) has the tank capacitor and spark gap in swapped positions.
Solid State:
Here is where my knowledge is very limited, basically you are replacing or modifying the tank circuit with little silicon chips. some solid state drivers pump pure RF into the secondary, others use pulsed RF. of the more modern popular types of SSTC (solid sate Tesla coil) are the following; SISG (sidac IGBT spark gap (IGBT stands for Insulated gate bi-polar transistor, it is a transistor that can be used at high voltages by increasing the base voltage, and can conduct in two directions)) DRSSTC (double (or dual) resonant solid state Tesla coil). I am not going into great detail of how these devices work, I will only say SISG is a "drop in replacement" for a spark gap on a conventional TC, and a DRSSTC uses a H-bridge of these IGBTs to drive a tank circuit.
Twin Coils:
A twin coil is two Tesla coils driven 180 degrees out of phase. They are generally as identical to one another as possible, and the RF ground is replaced by a strap connecting the two secondaries. They will arc from one top load to the other, and that is all I can say about them. People have also made triplet and quadruplet coils, by operating them 120 or 90 degrees out of phase.
3-Phase:
A three phase coil is something I don't know about, supposedly, someone is building one somewhere and it is supposed to be cool. you can use a three phase supply to power a DC coil with god results, as you need a much smaller filter cap.
VTTC:
A Vacuum Tube Tesla Coil is a coil that is driven by a valve oscillator or vacuum tube. Here is a schematic I drew of a Basic VTTC.
Audio Modulated:
Probably the coolest thing one can do with a solid state TC is audio modulate it. You know the plasma globes that blink to music or noise, this is not that. This is plugging your DRSSTC with some modifications into a keyboard, guitar, or MIDI source and hearing the sounds come from the arcs! It works by breaking up the 120 kHz or so resonate frequency into audible chunks, so the "Rf envelope" is an audible sound wave. Search the internet for these and you will get a good laugh, I promise.
Magnifier coil:
You can tell by the name that this must be seriously cool! The magnifier is the Tesla coil, as Tesla himself built it, and perfected it, for the purpose of his wireless power transmission research. Before I tell you what it is, I will tell you how it works. On a normal TC the primary is usually flat to keep the coupling low, the coupling must be low, or the secondary will die from the immense amount of energy, not to mention you can get multiple voltage nodes at places other than the top load! As a result of this low coupling, a lot of the energy is lost forever to space as radio waves. A magnifier gets around all of this, by using an oober tight coupling, and it prevents secondary breakdown by having a very low inductance secondary. But if you know your formulas, you will know that a low inductance kills your voltage out, this is very true. Once again a magnifier has a way around, 3 coils! The primary and secondary (or driver) function like a standard step up transformer, and are not tuned to resonance (so no breakdown) the tertiary (or resonator) is driven by the driver, at it's resonant frequency! Now the misconception some people have is assuming that the secondary has no effect on the resonance of the system, it does, but because it has such a low inductance, the effect is minimal, tuning is done by adjusting the primary, just like a conventional TC. The reduced coupling losses of the magnifier, mean it is more efficient, the extra coil, means it is more temperamental! Here is a picture of a magnifier made by Ed Wingate, I have seen this coil run in person, and can attest that it is truly awesome to behold, and a true feat of engineering! The distance to the door is about 10 feet, but his coil has struck things 16 feet away, running at about 1.5kW, the same power level I run on my 6-in coil (which gets about 4-5ft arcs).
Knowing what a magnifier is capable
of, it is only a matter of time before I build one. Just got to
save up a little, do some more research, and find some time!