## Step 2: The Driver Circuit

This design is very simple and only uses four components! It is also very versatile and the input voltage can be as low as 5 volts or higher than 18 volts if the transistor is attached to a heat sink.

------THEORY OF OPERATION------

-   5 to 18 volts is fed into the circuit, a resistor (R1) is placed before the Base pin of the transistor in order to limit the amount of current the pin receives. If too much current is allowed into the Base pin the transistor can produce excessive heat and fail.

-   One end of the secondary (L2) is connected to the Base pin of the transistor in order to feed it with oscillations. The two diodes (D1 and D2) prevent the oscillations from going directly to ground. (Learn more about oscillations and why they're important, below).

-   The transistor is made up of three pins: the Collector, the Emitter, and the Base. If you were to think of the transistor as a garden hose spigot (See picture 2), the Collector would be the reservoir of water. The Emitter would be the hose and the Base would be the valve that would allow water from the reservoir (Collector) to the hose (Emitter). The valve (Base) is in the closed position (no water flowing) until it is given a little nudge. When it receives a nudge, the valve opens and a lot of water is allowed to flow from the reservoir through the hose as long as the valve is still getting a nudge. However, as soon as the nudge goes away the valve will close, cutting off the water from the reservoir to the hose until the valve gets another nudge.

-   When the Base receives a little bit of current, it closes the circuit and electricity is allowed to flow through the primary coil (L1). However, electricity likes to take the path of least resistance so when the electricity is allowed to flow from the collector to the emitter (~0 ohm resistance) it will stop flowing to the base because there is 47,000 ohms of resistance there. When the electricity stops flowing to the base, the base will open up the circuit again until the resistor offers less resistance than the Collector-Emitter path. This cycle repeats itself many times a second.

-   The primary coil collapses when the electricity stops flowing through it, when this happens, the secondary coil picks up the magnetic field and converts it back into voltage which gets stepped up to around a thousand volts in the process. The top load acts as a capacitor and increases the output from the secondary causing electrons in the air to become excited.

-   Finally, the oscillations from the secondary coil are fed back into the transistor in order to 'tune' or achieve maximum output from the Slayer Exciter.
<p>I am using a 2N2222 transistor and a 22 kilo-ohm resistor with a 9V battery. My secondary is 30 awg (380 turns). I'm not sure what to use as a primary; I cut 20 cm out of a charger cable--will this work? Will the rest of what I have work?</p>
<p>did you get it to work?</p>
<p>I had a one foot pre beveled PVC pipe 130 turns from an antenna build. I wound it in 10 minutes while watching TV. 3D printed out the ball (free at Library). I will try to program a 3D print for the blank tube with guide gullys to assist in winding.</p><div><p></p><div><p>These are my measurements taken during construction for comparison: windings only 48.03 uHy; with cap 52.75 to 60.00 uHy, touching cap 65.00 uHy.</p></div></div><p>I will post more about my build as I continue. Having trouble finding UF diodes so will have to order on line. I am also designing a 3D base to hold the batteries, componants and some additions like a switch, trim on inductance and a 12v power supply plug. Basic operation first.</p><p>Don VE3REO</p>
<p>I made it and it worked with a 12 v battery .But the coil broke the battery because it used up more than 20 amps at a time .Any ideas about what i did wrong , or what i can do to power it with any other way ?</p>
Can I use an led light instead of diodes??
And is it connected to the wire connected to the no. 3 terminal of transistor??
any constrains on the dimensions of the coils ?
<p>I've built the coil, but it's range is too short. I'm only able to light a small light bulb when kept really close to it while running at 50 volts. What can I do to increase it's range?</p>
<p>Hi Sir,I had build a Tesla coil using a circuit as the image show but when connected the 9v battery the transistor become very hot and is not working. The picture I took it without the battery.Please help, I need to fix the by thursday. Thanks</p>
<p>Um.. hi so, I am not in a place to say anything as I haven't made it myself as of now but from what I can see, the your primary coil has around two coils try increasing those as this instructable also recommends at least eight coils for 18V of power supply so by doing the math the least no. of coils in yours (if the power supply really is only 9V) should be four. But you can try increasing (or decreasing )the no. of coils even further until it's working alright.</p><p>*Oh and yeah I kinda don't know why I wrote decreasing the no. of coils but you can try that too right :) </p>
Thanks for your answer.<br>On the video from Youtube were I got this, they only say that 2 coils are necesary and a 9 vots battery (please see the attached pic). I will try with more today. Also the secondary coil have 140 turns.
<p>hi uh.. again i guess. I get your point but i still need to see the video to make sure that the instructions were correct or not. Well but anyways did you still try increasing the no. of coils in the primary coil (just to see what happens, you know :p)</p>
<p>This is the link for the video on Youtube were I got the instruction. <iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/uAFvjVTSXes" width="500"></iframe></p><p>I made some changes in order to make it work but I couldn't. I change the PVC tube (larger one) in order to have more secondary turns (I reach 400) and I made a 8 turns primary but didn't work. I will try with more primary turns in order to see if it works. I appreciate your advice.</p>
<p>Try reversing the connections of the primary coil. Switch the top end of the primary to the connections where the bottom end of the coil on your circuit and do the same for the bottom.</p>
<p>uf4007 diodes arent available where i live, where can i get some / can i use 1n4007?</p>
<p>Hi, I am doing a tesla coil for a school project... I have see that in your coil you use 2 diode led, please can you tell how should I realize the drive circuit? In particular how I should connect the 2 diode, in series....? </p>
<p>I used a BD135 transister and 47k ohm 1 watt resistor and one LED and 9 volt battery and a 34 AWG wire with about 300 turns around a 2 inch diameter cardbord.........</p><p>When I switch it on the LED lights up and transistor gets heated up.....</p><p>And the LED doesnt go off when I touch the secondary coil......</p><p>Pls help.............</p><p>Pls give a solution....... </p>
it is ok if I use this kind of pipe
<p>Can a 1&quot; wooden dowel be used instead of a PVC pipe? Can I use thicker gauge wire and a bigger top load to compensate?</p>
<p>It is a nice design. I used a 2.5 cm tube with 9 turns of 0.8 mm primary and 400 turns of 0.3 mm wire for the secondary. The coils have inductances of about 2.7 uH and 725-750 uH. Thanks for posting!</p>
<p>what is the value of the resistor that you used because i used 47k ohm resistor and i get only little spark and it was so tiny!</p>
I use a 47k as well. I do not get a spark. The idea is to light the TL tube. I have build a full Tesla Coil but that is quite a step up from something like this...
<p>unfortunately,mine stoped working i didn't know what's the probleme ,i tried fixing it by using other transistors like D304X,13003B, BUl128d but non of them worked i think the C5027s transistor works great ! :(</p>
<p>no it's working now better then befour i replace the transistor with pnp A1129 and remove the led and flip the connection of the battery and now i am getting juicy sparks that burns my finger instantly!</p>
I actually run this on 63vdc 1amps awesome arcs but I use 3watt 47kohm and a big npn transistor
<p>Nice build, and thank you for providing us with details of your build.</p><p>By chance, have you measured the power draw?</p>
<p>Hey, this is an amazing creation and i've tried to build the same.</p><p>I've used same components, the only difference is that my pipe is 1.18&quot; diameter. </p><p>I've 340 turns on my secondary and i've tried between 2 and 8 turns for my primary, but this isn't working :(</p><p>I've already tried to invert the primary after reading the comments, and i've tried with and without a breadboard ...</p><p>My transistor heat a bit but it's not very hot.</p><p>I need some help, thanks in advance !</p>
<p>I had similar problem. my transistor was getting heated up but output was not as expected. i was using a 9V battery and the problem got solved when i used 12V battery instead of 9V. </p>
<p>hey, helo, plz help me brother, i want to know how to increase the range and output power of this type of tesla coils. i've already searched the whole google. there is very less information on the google about the concept, principle and working of the tesla coils. i want to know that how this coil light up's the bulb'b without any connection to the bulbs. plz tell me the mathematical equations showing relationship between all of the parameters of the tesla coil. thnk u........</p>
<p>Thank You So Much Chip Fixes and all those who commented. I was able to make a S Layer Exciter with all the information you guys gave. Thank a Lot :)</p>
<p>I used d667ac transistor and it works.</p>
<p>Hello, I am trying to understand the calculation behind the circuit, are the primary and secondary work like a transformer or better like Ruhmkorff induction coil ? Can i so apply the following equations... (N1/V1=N2/V2) and (V1*I1=V2*I2) ? </p><p>Also how can I calculate the frequency? Thanks for your time.</p>
Help. I build one with 4 turns of 1mm copper wire nd used 2n 3055 transistor nd also used 10k ohm resistor. The secondary is 7 cm around 1/2 inch pvc. Nd is of 29awg gauge wire. My tesla coil does'nt work. I did swap the primary connection still with no success.can u help me make it work??
<p>The instructions say 5 to 15 turns on the primary. His PVC is 1 inch diameter and 6 inches long (2.5cm by 15cm), significantly larger than yours. This will put the self-resonant frequency much higher, perhaps too high for a 2N3055 to oscillate.</p>
<p>Check diode direction? Are you using ultrafast recovery diodes? Doublecheck the transistor pinout.</p>
<p>Check diode direction? Are you using ultrafast recovery diodes? Doublecheck the transistor pinout.</p>
Hi,I use TIP31C circuit<br> primary coil 4turns,<br> secondary coil 900 turns,<br> 12V UPS battery.<br>But,it can support one or two lamps with very low brightness.<br>It produce loo small spark.<br>Please,help me.How can I fix it.
<p>The instructions say 5 to 15 turns on the primary.</p>
<p>Hi! Thank you for your instructable, it's amazing =) . I have a really big problem. With the Physics Lab Assistant, I made the secondary coil and the first coil. I made the circuit with a NPN BC337 Transistor, a 10K Ohm resistor and a Red Diode (I don't remember the part number). The power passes through the resistor and the Diode, the Voltage inside the transistor and the primary coil is good (similar to the transformer input), but the secondary coil's Voltage is locked to 0,7 V and the experiment doesn't work. I don't know what I must do to make it work. The copper wire used in the secondary coil is a 1mm with no case (but, on top of it there is a sort of insulating paint, I don't know why), the primary coil have the similar wire with case. Please, help me as soon as possible. =( Thank you in advance.</p>
<p>Do you mean that your secondary wire is enameled wire? That is what you should be using. By &quot;case&quot; do you mean insulation? The enamel on the secondary wire is insulation, used instead of a plastic insulation because the enamel is so much thinner.</p><p>Without that insulating coating, the secondary is not a coil but just a pipe and it won't work.</p><p>1mm is pretty thick wire for the secondary. It means fewer turns, which means higher frequency. Perhaps it is resonant at too high a frequency for the transistor. If you cannot get thinner enameled wire, you might try winding a much longer coil.</p><p>Enameled wire is also called magnet wire.</p><p>Do you have two ultrafast recovery diodes in series, in the proper direction? A 1N4007 won't work as it is too slow. A single red LED has been used by others instead of the fast diodes. An LED switches pretty fast, and a red LED drops about 1.5V, which is about what two silicon diodes drop.</p><p>It also will only light up if the circuit is oscillating.</p>
<p>chip I have used a 24 AWG wire else I followed all other instructions properly but I am not able to get the result.</p><p>My transistor(2n2222) gets heated up and I used a 22k resistor.</p>
<p>A 2N2222 is a pretty small transistor, it can't handle much power. Also, the pinouts vary by manufacturer. Perhaps you are not connecting to the correct pins.</p>
<p>Why transistor is used in tesla coil?</p>
<p>It acts as an amplifier. There is feedback that is inverted so it is 180 degrees out of phase, if the coils are connected in the correct direction. The transistor itself amplified and inverts, so the feedback is amplified and it oscillates. The frequency is determined by the resonant frequency of the secondary, which is determined by the inductance and the parasitic capacitance between windings, from the windings to ground, and the self-capacitance of the ball on top.</p>
<p>It acts as an amplifier. There is feedback that is inverted so it is 180 degrees out of phase, if the coils are connected in the correct direction. The transistor itself amplified and inverts, so the feedback is amplified and it oscillates. The frequency is determined by the resonant frequency of the secondary, which is determined by the inductance and the parasitic capacitance between windings, from the windings to ground, and the self-capacitance of the ball on top.</p>
<p>Hello I really want to build this and I have been trying to get this circuit to work for some time, i <br>used all the same parts as you did except for the diodes I used 2 LEDS. When <br> I tried it the circuit LEDS didn't light up and got no voltage in the <br> <br> secondary i already tried switching the primary leads, I am using a 15v <br> supply and have used many different resistor values without success and <br> the transistor does heat up please help.</p>
<p>Try using one red LED. A single red LED drops about 1.5V, which is about the same as two silicon diodes in series. The diodes (or LED) is there to prevent the Base-Emitter voltage from exceeding the reverse breakdown voltage, which is quite low depending on the transistor. It must be a fast switching ultrafast reverse recovery diode. The 1N4007 is NOT suitable. An LED will switch pretty quickly.<br><br>I know this is 8 months later, but please let us know if you got it working, or if my suggestions help.</p>
Bro help me plz<br>i made this with all new parts and under your supervisions but my CFF bulb lights in the the begining and my transistor gets hot but its not a major problem but after sometime my bulb doesn't glow i found that my transistor is not working properly so i changed it with new one and again starts working but same problem happend again i changed 5 transistors but problem is happening i also used heatsink with my all transistors.<br>help me plz beacuse i don wnt to change transistor again and again
<p>What voltage are you supplying it with? You may just need to give it less voltage. It sounds like the power level is burning out your transistor. Are you using the proper UF4007 ultrafast reverse recovery diodes? A 1N4007 is NOT the same thing. I see someone else here used one LED in place of the diodes. LEDs switch pretty quickly and a single red LED will drop about 1.5V, about the same as two silicon diodes.<br><br>If you don't use the diodes, it may be slowly destroying the transistor by exceeding the reverse breakdown voltage of the Base-Emitter junction, causing the transistor to have high leakage current, heating it up.</p>
Pretty cool. I substituted the diodes with an led. Does that affect the output power in anyway.!? I wouldnt think so but this is the first one of these ive made. Also mine didnt work at first and all i had to do was swap the wires on the primary, guess i had it backwards.! I now want to make a real tesla coil and get some arcs.!