How to make a simple Tesla coil

Hello! Today I’m going to show you how I build a Tesla coil! Probably you may know this device from computer games, movies or some “music tesla show” whatever they call it. If we ignore the mystique around the Tesla coils, it’s just a high-voltage resonance transformer working without a core. So as not to get bored from theory let’s jump to practice.


There is a

circuit of coil, as you can see it’s very simple and we need only few components.

power supply, 9-21V, also it’s gonna work from batteries with same voltage

little heatsink

Transistor 13009 or 13007, or almost any NPN transistors with similar parameters

variable 50kohm resistor

180Ohm resistor

cooper winding wire 0.1-0.3mm, I used 0.19mm which is 36 American wire gauge, about 200 meters.

Also we need a frame for secondary coil, it’s could be any dielectric cylinder diameter of approximately 5cm and length of 20cm. In my case it’s piece of 1-1/2 inch pvc pipe from home depot.


Let’s begin from the most complicated part – secondary coil. It has 500-1500 turns turn to turn, my is about 1000 turns. Fix the beginning of wire and wind, actually you don’t need to count every turns, simply multiply diameter of wire to number of turns you planning to make – it’s going to be your winding length. When you done fix wire with some tape or better by couple layers of varnish.

Primary coil is much easier I put paper tape sticky side out, in case to save the ability to move it, and wind on it 10 turns of regular wire in pvc insolation.


Next is soldering, all under the circuit, PCB is not necessary. Be careful when soldering variable resistor! 9/10 coils didn’t work because of wrong soldered resistor. Connect primary and secondary coils, latter has a special insulation which must be scraped off before soldering.

Turn On

So we done. Before you turn on the power at first time, place the variable resistor in middle position and put light bulb near to the coil, because usually you’ll not see high voltage sparks immediately and only thing notice that it’s working is light bulb. Turn on power, and slowly turn the variable resistor. It’s quite weak coil, and you can not get electrical shock because of skin-effect, but any way be careful and don’t place any electronic devices such as cellphones, computers etc. near to the working coil and notice that high voltage sparks is made of plasma and it’s actually very hot, be careful when touch it. If Tesla coil doesn’t work, try to flip wires from primary coil, usually it helps, also you can try add or subtract a couple of turns from it.


Now lets talk about improving results, first you can do is rise voltage, but I don’t recommend go over 25V at this circuit. Second is playing with primary coil, logic is simple, fewer turns – more current equal more power and more hitting, I stopped at 5 turns, also try to move it around secondary.

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