The violet wand is basically a modified Tesla coil. What a Tesla coil is and how it functions is the subject of this section. Note that this is a very general description of Tesla coil function. Although working Tesla coils function as described, they feature safeguards and efficiency enhancing features that we do not delve into here.

A Tesla coil is a device that uses resonance to boost an electrical signal to many times its original amplitude. The circuitry times the pulses of current so that they reinforce and build on each other, boosting the output. Imagine a swing. If you push on the swing randomly the swing will swing chaotically, never going much higher than a certain level. However, if you time your pushesjust right, the swing will climb ever higher. You have determined the “resonance” of the swing. That’s the basic principle behind a Tesla coil: keep sending out electrical pulses, at the resonant frequency, in one section of the circuit, to induce the other section of the circuit to ever higher potentials.

BASIC TESLA COIL FUNCTION (REFER TO FIGURE ONE FOR THIS SECTION)
The first thing we start out with is a transformer. They convert from one voltage to another. We have used them in toy train sets for instance to convert the voltage from the wall to a lower, safer level to run the train without electrocuting ourselves. Transformers can also be used to increase the voltage. From say 110 volts at the wall outlet to 1,000 volts at the transformers output (note – due to conservation of energy however, there is no net power gain, the voltage at the output is increased, but the amperage is decreased. The power (volts x amps) at the output is the same as the power at the input (minus some small amount lost to heat). Neon signs use transformers of this type.

Connected to the high voltage side of the transformer is a capacitor. A capacitor in simple terms is a device for storing an electrical charge. Capacitors are what store the charge from the batteries in a camera flash unit. The charge is built up from the battery until there is enough power to fire the flash bulb. The delay experienced in firing the flash is because the capacitors are still building up a charge. Capacitors are constructed of two metal plates separated by a thin dielectric, an insulator. When connectedto the output of the transformer a negative charge builds on one of the plates in the capacitor, positive on the other. This charge builds upon itself over time until it is so intense that is will overcome the air gap in the diagram and send a spark across it. Once the spark is sent, the capacitor has discharged itself (just as when you fire your camera flash). It will now start charging again (in our example, you hear the camera flash start that high pitched whine all over again). The spark jumping across the air gap is a very high power electrical pulse. It goes down the wire to our primary coil, which is made of heavy gauge wire to accept this high power pulse. This pulse is basically our “push” on the swing mentioned above. Eventually the capacitor will fully charge until it can again overcome the air gap and send another pulse. This will happen several times per second. The rate is determined by the size of the capacitor, the air gap and the primary coil size.

MAGNETIC FLUX:
So far we have established a high energy pulse traveling towards our primary coil. The primary coil is composed of a few turns of wire, usually in cylindrical form. The wire is fairly heavy gauge (sometimes copper tubing orbar stock is even used) to handle the energy. As the pulse travels through the coil it establishes a magnetic field at the center of the coil (the field is actually donut shaped, running through the center of the coil, out the top, around the outside of the coil, and back in the bottom. For this discussion we are concerned with what happens at the center of the coil). This is basically simple electro magnetism. For example: if you wrap a wire around a nail and then connect the ends of the wire to a battery, the nail will be magnetized as long as the electricity is applied. Many of us may have performed this experiment as children. What many might not realize is that this phenomenon will also work in reverse. If you run a magnetic field through the center of a coil, it will generate electricity in the coil. This is exactly what we will do here. We establish a magnetic field by running electricity through the primary. We situate the secondary coil at the center of the primary coil (they both are cylinders, one nested inside the other). There are no wires connecting the two coils. The magnetic field from the primary coil is also running through the secondary coil however. This inducesan electric current in the secondary coil.

THE KEY TO THE WHOLE THING:
What is the point of using the magnetic field to induce the voltage in the secondary coil? Why not connect them directly? Well, using induction enables two things. The first is a voltage increase. Note from our diagram that the primary has a few turns, the secondary has many turns. The voltage induced in the secondary will be in direct proportion to the turn ratio. Twice as many turns on the secondary as the primary means a simple doubling of the voltage, all things being equal (note that while voltage will increase, the amperage will decrease, again due to conservation of energy.)

All things are not equal however. In addition to the secondary having more turns than the primary, those turns are set up in a precise proportion to the turns in the primary. This is the second reason to use this method: to set up a resonance between the two coils so that each pulse will build upon the previous one. This is the same effect as being in a room and finding that one note where the room seems to reinforce the sound and make that note sound much louder than other tones. So it is with the two coils, we set up a ratio between the them so that eachpulse from the capacitor will induce a rush of electricity at the precise time that the previously induced rush in the secondary coil needs it to build and build (pushing the swing higher and higher). This not only results in higher voltage (more than the simple ratio between the turns) but higherfrequency output. High frequency signals, among other things, are more able to jump air gaps than low frequency ones.