just what exactly is a tesla coil ? are we talking about one of them thing you see in "red alert" where a shot of electricity is "dispensed" to an unsuspecting thing ?
There are probably variations of the definition of tesla coils but in a nutshell it is this:
High voltage source such as ignition transformer is caused to arc. In series with the high voltage lead is a small number of turns of wire, 25 or so. This forms a primary winding of a transformer. This so-called transformer has no core other than air. The secondary is many many turns of very fine wire placed in close proximity, either around or inside the primary. The number of turns may vary from one design to the next. The number of turns is somewhat important to the operation of the coil. Not only does the number of turns determine the output of the coil, but its length needs to somewhat match the frequency of the arc which is typically several megahertz. The length of the secondary winding is adjusted until it resonates with the frequency of the arc. So technically it is more than just a step up transformer. Millions of high frequency high voltage arcs jump of of the secondary lead to surroundings. Since it is high in frequency it doesn't shock you. High frequencies only travel over the surface of conductors. It travels barely skin deep. The current is VERY low also. If you are getting shocked off of your tesla coil it is probably not adjusted or built correctly. I understand also that capacitors can be used in the primary winding to help form a resonate circuit that is more frequency stable than without the capacitor. Adjustment of the arc can also be critical I understand. My details may be a little off, but you get the general idea. If you want to know more I would order a book.