Do you want to build a simple Tesla coil and experiment with wireless energy transmission? This Tesla coil is solid state and only requires about 25 dollars to make if you visit radio shack. Safety warning: One thing to keep in mind is that it is not recommended to run your Tesla coil without a top load, although it will function (with a bit less output). The spark generated by the L2 may be fun to observe and tinker with, however it is dangerous by nature (in seen and unseen ways) and produces ozone.
L1 ( the primary inductor coil) may consist of a pancake, 5-8 turns of any magnet wire approx. 22AWG. The inner diameter of the first most inner winding should not touch the L2 (1/8 inch gap all the way around is acceptable), and there should be a small gap between the subsequent windings of the L1. A small piece of cardboard can serve as the base of the pancake; use small slivers of electrical tape to maintain separation of the windings as you progress around the doughnut, from the center, outward.
L2 may consist of 500-2000+ turns of any magnet wire tightly wrapped on PVC , between half an inch and 3 inches in diameter. The longer the final the length of the wire, the more internal resistance it will have. TeslaTronix Tesla Coils use Inch and a quarter PVC. Within reason, the wider the ratio of windings between the primary and secondary, the grater the final output voltage of the tower. There is no connection from L2 to ground; only to the resistor, base, diode node. It is recommended to immediately spray with lacquer your L2 or wrap it in electrical tape double helix as changes in temperature will change the length of your coil, and cause imperfections.
In any Tesla coil the toroid (or top capacitance load) is a key component. Using a Sphere is the best because of it’s shape. also bear in mind that sharp points leak the energy so no sharp points on the top. that is a different story if you want to receive the energy then you can use sharp points on the receiver.
There are several ways to approach toroids from a hobbyist perspective. Depending on available materials in your area, and budget, there are several avenues you can choose when seeking a toroid. There are generally two types of top loads- spherical, and actual toroidal shaped loads. Spherical loads are generally best for wireless power distribution, while the actual toroidal shaped loads are best for visible breakout arching.
If you want to buy the kit for building this there here http://www.teslatronix.com/single-kits/
This is a list of parts in the kit with spare parts also just in case you need them.
mini breadboard (solderless) and 2x project board (solderable)
male/female universal power adapters w/terminals
inline fuse holder
625-650 feet 32 AWG magnet wire
Approximately 10.5 inches of PVC for L2 (coil is not pre wound)
3-4 feet 22 AWG magnet wire + wooden mini spool
1 male, + 2X female universal TO 220 transistor socket kit
3X tinned transistor socket kit leads
Transistor heat sink with M3 hardware
2X 100KΩ Potentiometer
4x 1N4007 Diode
2X 9V battery leads
3X bi-polar solderable terminals
Envelope with warnings, instructions, and drawings