The author has shown how he made a decent Solid StateTesla Coil that makes about 4 inch arcs.
Hook everything up like it says, to test and see if the tl494 is oscillating put a speaker where the fly back is and change the voltage to 12V, you should hear a loud screech, if nothing play with the pots or look over your circuit.
Tank capacitor & Spark Gap
For the tank cap he made a MMC (Multi-Mini Capacitors) I used 8 3000V .047uf CDE HV Meallized Polypropylene Film Capacitors. The reason we need to use eight is because we need to raise the voltage rating of the caps because the fly back will give off a massive amount of voltage! So we need to put the caps in series! So lets do some math 3000v x 8 = 24000v this should be good! Once you put them in series the capacitance will go down so .047uf / 8 = .0058uf or 5.8nF. Once you have them in series we need to put the 10Mohm resistors across each of the capacitors to drain the voltage out of the capacitors. The Primary coil
The Primary coil is the that goes around the outside of the secondary coil. I am using 10 FT 1/4 OD copper tubing made in a cone shape. I find the arcs are bigger at the third or fourth turn of the primary coil. Its best to use alligator clips on the wires to adjust the turns. The primary coil will be hooked up at one side on the tank capacitor and to the other side of the spark gap. The secondary coil
The secondary coil is the long vertical coil rising from the primary coil. This is where you spend a good chunk of time winding the coil. The secondary coil should be 5 times bigger than the diameter pipe you are using so I am using 1.5 in diameter then the length of the coil should be 7.5 in. I got my magnetic wire from radio shack remember it comes with 22, 27, and 30 gage wire. You are only going to use the 27 awg wire, it should be green. You are going to use all three of the rolls of wire! This will make the coil to turn out at 8 in which will be fine! I drilled 4 small holes at the bottom of the pvc pipe. Run the wire in then out, in the out and back in. There should be a little bit of wire sticking out the bottom of the pvc pipe. This will be connected to earth ground! After you have done that then start to roll! When your rolling the coil and run out of the first roll, put a piece of tape holding the wire to the pvc pipe, get the second roll that you have and solder the two leads together (make sure you scrape off some of the enamel). Get as little solder on them as possible, and just keep on rolling! You can check and see if you have a connection with a meter. If you find wire somewhere else and have enough then you can just skip this. After you are done rolling I drilled three holes where the coil ends and ran the wire in then out and back in and up the tube. This will hold the wire so it don t come unwound! Cut off the remaining pvc pipe but leave about 1 to 2 inches above the coil! Toroid
So your going to take the 1 Ft 2.5 inch drain pipe and curl it in on itself so it should be in a circle. Stretching it out a little bit will help it some. Measure the inside diameter of the circle and cut a piece of wood or cardboard and place it in the center of the tube. It will look like a space ship when your done! Take the Aluminum plated tape and start taping from the bottom of the cardboard, around the tube, to the top of the cardboard (it is extremely sticky!). Get the tape as smooth as possible! Its easier said than done but get is as best as you can! Once you got it covered with aluminum tape, Drill a hole in the center, put your nylon bolt threw the hole, place the washer and nut on the other side. Be sure to scrape the enamel off the wire to make a good connection with the toroid! Hook it up
After that then your done! Hook it all up and play with it! You can see the arcs better in the dark than in the light I wish my cam could pick up the little arcs. Im sure if I had a better power supply to the flyback they will be more impressive! If theres any I left out or could make this better please give your input
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