| RMCybernetics | Tuesday, 29th August 2006 12:27pm - No.207 |
| The capacitance of the MMC used for this Tesla Coil was 15.18 nF |
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| Your name here Joseph Lovell | Wednesday, 6th September 2006 11:06am - No.234 |
Type your message here
Thank you for reply and sorry here is an other question: what is a maxim. length of sparks ? |
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| RMCybernetics | Wednesday, 6th September 2006 4:00pm - No.236 |
| Running on 24V from a set of fully charged batteries, this setup could produce arcs of about 20cm to a grounded terminal. This could be increased to over 25cm when the flame was used |
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| john | Thursday, 12th October 2006 6:10am - No.411 |
| with a tesler coil how much coil would be needed and could you run it on ac from you houses power points all i have at the moment is microwave oven transformers |
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| RMCybernetics | Thursday, 12th October 2006 1:47pm - No.414 |
| It is strongly recommended that you DO NOT use mains to drive a Tesla coil! The plasma generated could arc unexpectedly to any surrounding objects (including yourself). Also, the power generated is lethal. Using a battery source limits the total amount of energy it is possible to create (the mains supply is limited by the power generating capacity of a power station!) |
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| john | Saturday, 14th October 2006 9:25am - No.418 |
| im worried about the amps because only 60 will kill you but 100 thats out of the question and would advise people not to try this with microwave oven transformers as this comes close it only takes 2 seconds and your dead |
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| RMCybernetics | Saturday, 14th October 2006 3:14pm - No.422 |
60 Amps is way more than enough to kill you. You can be killed with a thousand times less current than that.
Arc welders use a low voltage output so that you only get high current when it strikes low resistance materials like metal. Using ohms law you can see that there is not enough voltage to cause a large current to flow in a person.
A MOT is a super dangerous transformer. It puts out around 2kV and is able to deliver a lot of current. Don't use them. |
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| Kiro | Tuesday, 14th November 2006 8:47pm - No.468 |
| It looks really easy. Was it hard to make? We are working on a larger model in my class. I like the little light show, though, from yours. |
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| RMCybernetics | Wednesday, 15th November 2006 1:58am - No.472 |
Making the coils and putting it together was quite straight forward, but making an effective driving circuit was a little tricky as transistors are easily destroyed when used in HV circuits.
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| Stephen | Thursday, 16th November 2006 3:31pm - No.477 |
Can you please tell me hwo to wire the primary and secondary coil. Where do they go and where do i put them. Also can you tell me how and where to put in the 555timer which legs do i use of that. Also what kind of capacitors did you use such as the voltage rating and the rating and how many. Thank you fo all your help.
Thanks again,
Stephen |
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| RMCybernetics | Thursday, 16th November 2006 9:09pm - No.478 |
Most of the information you require is allready on this website.
On the Tesla Coil Page you can find a diagram of how the coils and capcitors are connected, and a description of how the system works.
The primary coil is usualy a flat or conical coil with widley spaced windings like the one shown on this page. The centre of this coil is where the secondary coil is placed.
The secondary coil is wound around a plastic tube. It uses thin enamel coated wire (aka magnet wire) wound tightly for hundreds of turns down the length of the tube.
The 555 timer is used in the circuit for making a high voltage DC supply to power the tesla coil from batteries. You can see schemaitcs for the 555 circuits on the PWM Signal Generator page. This 555 circuit is used to drive transformers for stepping up the battery voltage to one high enough for the spark gap to work. You can see circuits for that on the Pulse Controler page, the Power pulse genrator page, and the ignition coil driver page.
The tank capacitor in this coil was 15nF @ 20kV which was made by linking smaller capactors together. You can see the electonics section to learn about connecting capacitors together. |
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| john | Tuesday, 21st November 2006 11:56pm - No.486 |
| when making a tela coil should the pipe its wound onto be plastic and how much copper wire would be needed because you can get heaps from an ignition coil |
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| RMCybernetics | Wednesday, 22nd November 2006 1:28am - No.487 |
Yes it should be plastic or any other non conductive material.
The length of wire needed depends upon all the other components used to make the tesla coil. It is usually several hundred turns. |
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| john | Wednesday, 22nd November 2006 9:50am - No.492 |
thanx but would more turns mean more induction and there for more power? i need all the facts first
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| RMCybernetics | Wednesday, 22nd November 2006 2:35pm - No.500 |
More turns means more inductance, but this is totally unrelated to the power output you can achive.
The inductance of the coils simply determines the frequncy at which they will resonate.
e.g. A large inductance in parallel with a small capacitor (secondary coil and top sphere) will have the same resonant frequency as a small inductance in parallel with a large capacitor (primary coil and MMC or pulse capacitor) |
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| Santa | Friday, 1st December 2006 11:25pm - No.538 |
I `m Back :-)..
I had put this project on hold Several weeks ago due to a fairly heavy cold, an email asking for advice with another coil awoke my interest in a 12 volt system again.
I have mounted 7x2n3055`s onto a heatsink that was given to me ( overkill but, it was free ).. Now i need to connect to a signal generator.
I made the Power pulser from this website which works very well.
Is there a simple way to drive the 2N3055`s with that circuit.
Using my 3inch coil powered from the pulser I am able to draw a spark of about 25mm, in low light the corona is visible at the top of the coil. |
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| RMCybernetics | Sunday, 3rd December 2006 7:43pm - No.551 |
| You can drive a preamplifying transistor such as a BFY51 by connecting a 100 ohm resistor between the output of the 393 and the base pin of the BFY51. This can then be used to drive your array of 2n3055's like shown in the 1st digram on the Ignition coil driver page. |
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| Chris Henderson | Wednesday, 13th December 2006 2:24pm - No.597 |
I have two questions about this coil.
1. How can you calculate/measure the output characteristics of an ignition coil esp. it's current and voltage. I have estimated my single ignition coil puts out about 15kv using spark length as a rough guide. And, using the transformer equation calculated the current was a tiny 0.5mA. Do you know a better way to ascertain the current output?
Is the high voltage output of the coils rectified using a string of high voltage diodes, if so how should they be connected to the circuit, which way round the cathode/anode etc?
Is it necessary for the output to be rectified before applying to the tank capacitor (MMC)I dont really know. |
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| RMCybernetics | Wednesday, 13th December 2006 9:39pm - No.598 |
To measure the voltage output you could use a voltage divider made from a string of very high ohm resistors and a lower valued one. You could then measure a portion the voltage with a standard multimeter / voltmeter then calculate the total.
The current can be calculated in a similar way. If the HV output is shorted with a low ohm, high power resistor, the small voltage measured between its terminals can be used with ohms law to calculate the current flow.
The HV output from the ignition coils in this example was rectified with a full bridge rectifier arangement of HV diodes. You can see how they were connected on the Power Pulse Generator page.
When using ignition coils it is most effective to fully rectify the output. This is because the output is pulsed and more +ve than -ve. Mains powered Tesla Coils use proper AC which has enough current to charge the tank capacitor on each half cycle (e.g. UK Mais frequency = 50Hz, Cap gets charged 100 times per second but with alternating polarity.) |
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| Crispy | Wednesday, 27th December 2006 2:04am - No.635 |
| At what frequency are you running the ignition coils? And is this coil a standard single spark gap coil, or something else? Thanks. |
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| RMCybernetics | Wednesday, 27th December 2006 2:42am - No.636 |
The ignition coils are driven with a variable frequency source. Optimum power throughput seems to be around mid-high audio frequency.
This uses a spark gap made from a few sections of brass tube. |
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| Jason | Thursday, 28th December 2006 8:09pm - No.641 |
| I am making a similar coil. It is powered by a fixed-frequency 555 timer pulsing squarewave into a 2N3055. This turns 12 volts on/off into an ignition coil. The device is truly a work of art. My question though: I can generate about 2.5 inch sparks( at around 6 bps) to my finger, but only .5 inch sparks to the back of my hand(flat). Is this difference in spark production the result of sharper objects(finger), and higher field stresses? |
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| RMCybernetics | Thursday, 28th December 2006 10:40pm - No.642 |
You are correct. A sharper point will cause a higher concentration of the electric field lines.
The breakdown voltage of air is often stated as around 10kV/cm. This is a rough value because the density, humidity, etc vary and can effect the outcome. The value given refers to the elctric field in a reigion of space rather than the voltage between two terminals. |
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| ShockingEvent | Sunday, 18th February 2007 2:18am - No.787 |
| If you do this indoors, be sure the ceiling is at least six feet above the top of the coil. I built a Jacob's ladder (similar). One arc kept going up and set the cork panel ceiling on fire. Old commercial fluorescent sign transformers work great for either Tesla or Jacobs Ladders. They usually fail by the secondary shorting to the case. They are still useful but you now have to insulate the entire transformer. Putting them in wooden boxes works. Sign companies throw them out. A dozen wired in series will generate 200 kilovolts, or more, at a very low current. I put fifty in series and drew an arc that could be heard for a mile when it would snap off the top of the Jacob's Ladder rods. I'd stop whenever I'd see the police cruising looking for the source of a bang louder than a shotgun. Be sure to wear heavy gloves, rubber sole shoes and welder glasses plus stand behind a safety panel if possible. I only had to set myself on fire once to learn "safety first". |
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| brmwk | Tuesday, 20th February 2007 1:11pm - No.801 |
2 questions...
1) Is there any reason why you chose Butane for the gas? Are there any other gases that would also create effects?
2) How long would one of these as built on this site run on 1 battery? |
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| RMCybernetics | Tuesday, 20th February 2007 2:09pm - No.802 |
1) Butane was chosen to make the flame as it is commonly available lighter gas. Other flammable gasses would have similar effects. Other non flammable gasses were used and they created some fantastic plasma images.
2)Depends upon the battery size!:) It can draw aroun 5A @ 12V so if the SLA battery was like this one (7Ah) it would last about 40 mins non stop. |
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| justin | Saturday, 24th February 2007 7:44am - No.805 |
 i built this mini tesla coil but need some info
would the primary coil have to have the same electrical resistance as the secondary ? by this i mean secondary windings = more resistance . is this why there is lesser primary widings?
the copper i have is 'secondary windings'= 0.5mm 2000 windings and the primary = 1 mm 5 windings
and would the frequency of ossilations matter |
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| RMCybernetics | Saturday, 24th February 2007 3:22pm - No.806 |
Resistance effects are negligible, but the inductace is important as this will partly determine the frequency. The frequency is absoloutly crucial. If the resonant frequency of the primary and secondary circuits do not match, then you will not be able to transfer the energy properly.
You could try diferent numbers of turns, or different sized capacitors in the primary circuit. Try starting with a larger number of primary turns (maybe 20), then reduce by 1 turn at a time untill you see some results.
This still may not work if your frequencys are really far off. You could try using the Tesla Coil Tuner to match your circuits. |
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| justin | Wednesday, 28th February 2007 12:23pm - No.818 |
 hey iv worked out a simple technique for tuning the primary. im planning on just sliding a clip 1 cm around the long primary till i find resonance. i have a few questions though
1 would a tv fly back circuit be suitable for the power source or enven a ignition coil?
2for tuning frequency of ossilations would a series of capcitors be better or different size compacitors?
3 can the compacitor be dialetric or a laten jar design?
and last but the least is your circuit diagram at the top for protecting spikes in ossilations rather than the frequency circuit its self? |
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| RMCybernetics | Wednesday, 28th February 2007 1:38pm - No.819 |
A TV flyback may work if it is large enough. The same applies for ignition coils. For the design shown on this page it was neccesary to use two ignition coils in parallel.
The simplest way for adjusting the capacitance is to just buy/make several capacitors that are rated for the correct voltage, then connect them in parralel. You can then add or remove a capacitor to adjust the capacitance. You will probably still need to move the clip on the primary coil to get fine tuning. The caps can be any type as long as they can withstand the voltage they will be exposed to. Use thick wire between the capacitor, spark gap, and primary coil for better efficiency.
The circuit diagram on this page is just a simple ignition coil driver with no spike protection. The ignition coil driver is used to charge the primary tank capacitor.
This thread in our forum may be useful. Unfortunatley the forum is closed for new members now because of constant spam. It may get removed alltogether. |
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| justin | Thursday, 1st March 2007 6:59am - No.821 |
| thank i just need to know this stuff because when working with high voltage there arent amny second chances |
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| justin | Thursday, 1st March 2007 10:44am - No.822 |
would you suggest that i start with microwave capacitors or somthing smaller also it i didnt have the right size copper could i twist together smaller strands to make the primary thicker i would think it would work?
thanks for helping when i get it working ill post on my web page |
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| RMCybernetics | Thursday, 1st March 2007 11:05am - No.823 |
Yes, HV can be very dangerous. Double and triple check that there are no live connections or charged capacitors before touching your circuit. Its also a good idea to avoid touching a different part of the circuit with each hand. This helps reduce the chance of getting an electric current to flow between your arms and across the heart.
I'm not too sure about microwave oven caps. If they can handle the voltage then I assume they will be ok. It may be easier to use several smaller ones so you can make smaller adjustments.
Yes you can twist wires together to increase the current handling capacity. |
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| justin | Friday, 2nd March 2007 7:09am - No.828 |
 This is the circuit diagram im using
and i came up with a cleva idea for a spark gap i have two screws mounted over a cooling fan but the screws are tied on copper which was wraped around a pen to get a coil. |
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| RMCybernetics | Friday, 2nd March 2007 2:13pm - No.832 |
The capacitor was made from lots of smaller ones joined together in series and parallel combinations. Its total was 15.18 nF and 20kV.
I'm not quite sure how you have made your secondary, but I think thousands of turns may be too many. There was around 850 in this coil, and I have also been able to to drive coils about half that size without changing any other components.
All circuits will have some resistance, capacitance and inductance, deliberate or not. It is often labled as 'parasitic' if it is not deliberate. For a Tesla Coil most consideration is given to the inductance and capacitance values. In the primary circuit, thick wires are used so that the resistance of these does not reduce the current flow. In the secondary coil a long thin wire is used, so the resistance is much higher, but this resistance is not very significant in comparison to the reactance.
The resonant frequency of a TC is determined by the product or inductance, resistance, and capacitance (LRC). Both the inductance (L) and the capcitance (C) are 'storage vessels' for energy. The capacitance stores energy in an electric field, while the inductance stores energy in a magnetic field.
When the spark gap first fires, the energy in the primary capacitor is dumped into the primary coil which stores the energy in a magnetic field. When the capacitor is empty, the current will stop flowing, causing the magnetic field to collapse. As it collapses a current is induced back into the coil (in the other direction) which then charges the capacitor again.
The time taken for this cycle is calculated from the LRC values, but we can ignore R because it is very small. Bigger values for L and C mean it takes longer for the energy to move around, therfore resonating at a lower frequency.
The secondary coil also takes some of the energy from the magnetic field collapsing around the primary coil. This larger coil has a much higher inductance (L) and it also has a small amount of parasitic / self capacitance (C). Again the resonant frequency of this coil is a product of LRC. In the secondary, L is large and C is small, but in the primary, L is small and C is large.
If the frequencies of the two LRC circuits match, then energy can be effectivley transfered between the two. The initial store of energy is in the large primary capacitor, but we are transfering this energy into the tiny self capcitance of the secondary coil and its sphere. For the laws of conservation of energy to hold true, the voltge in this smaller capacitance has to be proportionaly higher.
This probably all sounds complex, but you can get a TC to work without calculating all these factors as long as you are able to tune part of it. The LRC and frequency of the secondary coil are pretty much fixed, so it is common to tune the primary circuit to match this. Increasing L, R or C will decrease the frequency of that circuit. |
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| J. Morton | Sunday, 4th March 2007 7:23am - No.839 |
Hi.
I haven't a very good understanding of capacitors so I'll ask. Is there any way that you could provide me with a diagram or schematic of how you built your MMC. If not, could you tell me what capacitors you used |
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| RMCybernetics | Sunday, 4th March 2007 11:57pm - No.843 |
 You need a bag of capacitors of the same type. Just look for the highest voltage ones you can find. They will probably rated for about 500V unless you find some special high voltage types.
If you want your MMC to be rated for 5kV for example, you would need to connect 10 of your 500V caps in series.
The two remaining teminals at the end of this string of capacitors make the new terminals for A 5Kv capacitor.
When the caps are places in series, it reduces the overall capacitance. To get around this you make lots of strings of capacitors then connect these in parralel.
The diagram shows strings of 10 caps in series, and 3 of these in parralel. |
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| abdia | Friday, 9th March 2007 7:50am - No.862 |
| I use 3A power supply for the main ,can u give me circuit to protect my household electronic from spike/high voltage? |
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| RMCybernetics | Friday, 9th March 2007 11:19am - No.866 |
| There's many circuis around the web if you search for "Tesla Coil EMI Filter" on google. You can also buy ready made EMI mains filters. |
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| Jolyon | Sunday, 18th March 2007 2:38am - No.907 |
Contrary to popular wisdom, death by fibrillation has been recorded from a 12 volt battery. The victim managed to puncture skin on both hands, which results in a sufficiently low resistance for fib current. One hand only!
In addition to possible damage to mains from high voltage discharge, Tesla coils radiate over much of the radio spectrum and may play hob with low power systems.
EMI filters are a good idea, but may be sacrificed to a direct hit. |
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| abdia | Thursday, 22nd March 2007 3:12am - No.943 |
I'm from Indonesia,i have experiment use only one 10nf/20kv ,i think it will explode instantly when i turn on the tesla but this cap even not warm.it's work but has limited
the space of spark gap become shorter and make the arc become smaller.if i can make a longer space of spark gap,does it give bigger output(arc)? also what is it possible to touch the arc with our finger?
cause i have seen this on the Guinnes world record it's so amazing can generate arc from the tongue. |
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| Daniel | Thursday, 22nd March 2007 6:08am - No.944 |
| Hi, i am a 13 year old and want to build a tesla coil for a science project. i have acess to ignition coils and would like to use them to make it. i was wondering what things i would need to make one with sparks at least 10cm. |
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| RMCybernetics | Thursday, 22nd March 2007 2:06pm - No.949 |
Abdia:
I can't really understand what you are describing, but I'll make a guess.
If the voltage rating of you capacitor is larger than the voltage you are charging it with, then it is not likley to explode. It would only overheat if you over powered it significantly.
The energy stored in a capacitor is proportional to the voltage squared (E = 1/2 C V2)
Increasing the size of your spark gap will means it will fire at a higher voltage and therfore dump much more energy into your coil on each pulse.
You will need to find a compromise between spark gap voltage and firing rate. This is because a faster firing rate allows the sparks (on the output of the tesla coil) to re-use the channel of ionized air left behind by the previous spark and therefore grow longer over a series of cycles.
Daniel:
Even battery powered Tesla coils are very dangerous and can kill instantly. All tesla coil construction and operation should be supervised by a responsible adult. There is more information about powering a TC from ignition coils on the power pulse generator page, or visit the page with the tesla coil theory. |
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| abdia | Friday, 23rd March 2007 7:48am - No.960 |
| ups.,sorry i mean the cap was single 10nf/2kv.spark lenght output from the ignition is 3cm.so it's likely i'm overvoltage the cap. another question:1.is it okay to charge cap directly from ignition without rectifier (ac)?(why you're using DC ) 2.is it possible to generate arc or touching arc/corona with human body? 3.thank a lot... |
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| RMCybernetics | Friday, 23rd March 2007 3:23pm - No.962 |
The cap probably wont charge directly from the ignition coil. The output form the coil is mostly unidirectional but the shape of the waveform causes the capacitor to discharge back into the coil before the next pulse arrives.
A single HV diode would be enough to alllow the cap to hold its charge. A full rectifier arrangement will only give a small boost in voltage compared to the single diode.
I couldn't possibly suggest that it is safe to touch any high voltage device (except maybe a small VDG). There is wide belief that the skin effect will prevent the dangerous currents entering the body, but this not exactly true. The conductivity of the body is quite varied and there are often low frequency components in the Tesla coil output.
I have had the occasional accidental zap from the top of this TC, but it does not feel healthy :). I certainly wouldn't do it deliberatley. About halfway down this page is a table showing the levels of current needed to cause fibrilation and other effects. |
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| Vandrail | Wednesday, 11th April 2007 11:06am - No.1125 |
| Hm. I'm currently working on a project. Nothing particularly useful, more for my own ammusment. While I could probably use the information provided here to fashion what I'm working on, simply doing that wouldnt provide much understanding of how it actually does work. While thats not a problem persay, I intend to use the basic principals to create a taser like device. With that intention, I want a full understanding of the electrical mechanics in question. So I dont have a specific question, but more of what sources you would recomend for learning about how such things work. |
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| RMCybernetics | Wednesday, 11th April 2007 1:12pm - No.1126 |
The setup of a stun gun is actually quite similar to the TC.
It basically involves charging up a capacitor then dumping the energy into a high ratio transformer to get a pulse of high voltage with low current. A page called explore a stun gun shows you the basics. |
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| RMCybernetics | Friday, 13th April 2007 5:33pm - No.1157 |
Just a few tips on TC building......
With my battery powered tesla coil, just a few turns out on the primary coil would make the difference between 1cm and 20cm sparks. Here are a few tips that may help you in the process.
Reducing Losses
Connecting wires in the primary circuit (between spark gap, capacitor, and primary coil) should be as short as possible and using thick wire. This helps reduce lost energy due to current heating in the wires.
All HV interconnecting wires should be well insulated and kept away from eachother. Avoid trailing wires accross surfaces such as a wooden base too. This helps reduce losses from capacitave coupling and eddy currents.
Using a transistor to switch the ignition coil, could also be adding resistance to the circuit. You could add more identical transistors in parralel so that more current can be pulsed through the coil.
Use a seperate ground connection for the base of your secondary coil. Using thick wire connect it to a good ground source such as a long copper pipe hammered into the ground
Tuning
It is important that all the parts in a tesla coil are resonating at the same frequency, otherwise power is not effectivley transfered.
The secondary coil is pretty much set in its resonant frequency, but small adjustments can be made by altering the size of the topload (torroid or sphere). Increasing the size of the topload will reduce the resonant frequency of the secondary coil (think about a bigger sphere means it takes more time to 'fill' with charge). It will also mean that sparks will not jump out on their own as easily, but they will be bigger when they do.
Tuning the primary curcuit is achived by altering the capacitance of the tank cap, or adjusting the number of turns in the primary circuit. The easiest way is usualy to adjust the number of turns, but this can also be tricky if your wire is insulated.
The simplest way (without any extra equipment) to make sure your primary and secondary circuits are resonating is to operate your TC using different primary coils, then look how long your output arcs are. Start off with one turn, then increase by one full turn each time you try it out. If you see a rise in the output, make a note of the turn number, but keep going as there are often multiple points of harmonic resonance.
When you are satisfied you have found the best turn number, you should fine tune it bu making smaller adjustments. A quater to an eighth of a turn is about a small as will be noticable on the output. This method involves repeatedly firing up the coil and then adjusting the the HV circuit. It is very imprtant that you isolate all power, and discharge the capacitor before making any adjustments.
A safer method is to tune the circuits with a low voltage. This can be done by using a simple device known as a Tesla Coil Tuner. This device will find the resonant frequencies of your components and allow you to adjust them so that they match, but without using any dangerous high voltage.
If using a variable frequncy HV supply, then this can also be adjusted when you adjust your spark gap size. This is to make the incoming HV pulses match up with the charging and discharging of your capacitor bank.
Also a full bridge rectifier like shown on the power pulse generator circuit diagram, will mean you get twice the number of DC pulses, therfore increasing the overall power throughput.
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| dodol | Saturday, 21st April 2007 8:28pm - No.1190 |
how to calculate the resonance frequency?
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| RMCybernetics | Tuesday, 24th April 2007 1:34pm - No.1195 |
 Trying to calculate (accuratley) the resonant frequency of a Tesla coil system can be difficult and time consuming. There are a few free programs and websites available that will help you. You can input things like your wire size and number of turns, the Tesla coil calculator will then give you an answer. You should take it as a pretty rough guide though. Tuning is almost always required after construction. As a formula you get the one shown on the left, but you may need further calculations/measurments to get the values to plug into this formula. |
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| artemon | Wednesday, 9th May 2007 8:06pm - No.1237 |
| also i'd like to know what is BFY51 alternative? because i cant find bfy51 in nearest shops,but signal from generator(running at separate battery 9v) is too poor,to drive 2n3055. is there popular models similar to bfy51? |
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| RMCybernetics | Wednesday, 9th May 2007 9:35pm - No.1241 |
| Almost any medium power bipolar npn transistor will do. |
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| artemon | Wednesday, 9th May 2007 9:45pm - No.1242 |
| thanks. Heh) now i started smoking lm393) heh) i've purchased voltage suppressor 1.5Ke15A and putted it between ground and signal output of lm393..and no use) lm393 burns when 1st arc creates. hm. any idea how to prevent this? because Santa (in homemade pulse controller post) had same problem,but i cant understand the solution((( |
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| RMCybernetics | Wednesday, 9th May 2007 9:55pm - No.1243 |
Making and breaking arcs causes big voltage spikes that need to be snubbed before they reach the sensitive components.
Placing a snubber (such as a capacitor and resistor in series) in parralel with the coils input terminals will help. You will need to experiment with the values of capacitance you need. The snubber will absorb some of the energy so that the circuit is protected but there will be a small reduction in the output voltage. |
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| Santa | Friday, 11th May 2007 11:35pm - No.1255 |
 Ignition Coil powered Tesla.First Light..
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| mad scientist | Sunday, 13th May 2007 2:50pm - No.1257 |
what is the measurements for the secondary tube?
how to increase the output voltage for this tesla coil? |
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| mad scientist | Sunday, 13th May 2007 3:01pm - No.1258 |
| can i use a flyback power supply obtained from a monitor of a computer? would it enough to create high voltages needed by the tesla coil? |
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| artemonster | Sunday, 13th May 2007 3:23pm - No.1259 |
| Very nice. What type of spark gap do u used? static or rotary? eem. input was 220vac or 12vdc? and what is your mmc cap size? about 0.025 uF? |
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| artemon | Sunday, 13th May 2007 9:03pm - No.1260 |
to Santa: nice work! i like it) what is your mmc cap size? what's the spark gap? static or rotary?
to RMCybernetics: also,question about MMC cap size) what is it? ) |
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| RMCybernetics | Sunday, 13th May 2007 9:54pm - No.1261 |
Nice1 Santa.
artemon: See post 832 and replies for some more MMC info
mad scientist: The flyback transformers in a CRT have a built in rectifier so that the output is already DC. This should be able to handle about the same sort of power as a single ignition coil. |
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| artemon | Monday, 14th May 2007 4:29pm - No.1262 |
| also some questions: why 20kv mmc? cause 2 ignition coil in parallel gives 20kv??O_o and i have only 0.15 mm copper wire,for secondary coil,and i've maked 1 small coil(it is about 13.5 cm tall and has about 830 turns) but if i will use this wire on larger tesla coil,and there will be about 2-3k of turns? it will only changes the resonant frequency,or turns surely need to be in 800-1000 range? thanks) |
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| RMCybernetics | Tuesday, 15th May 2007 9:09pm - No.1271 |
The total voltage rating for your MMC should be about 2x the voltage that you will charge it to. This is just a safety margin so that any voltage spikes wont destroy it. A typical metal can style ignition coil like shown on this page will give about 20-30kV peak when unloaded and driven with a good 12V driver circuit. The rectified DC voltage would probably be about 50% less.
800 or so turns is pretty typical for a TC secondary coil. 2-3k would be too many for a couple of reasons. The inductance and self capacitance will be very large and therefore give the coil a very low resonant frequency. Your MMC or primary coil would need to be very large to match the frequency. The other reason is that the long thin wire will have a large resistance therefore lowering the Q factor of the coil.
You will need to rectify the output of the ignition coils to charge the MMC. A single high voltage diode between the coil output and the MMC would do it. The anode of the diode (the end with a stripe) would be connected to the MMC. I would recommend placing a choke (an inductor) between the diode and MMC to help protect the diode from surges.
The base of the secondary coil should be connected to the ground for it to resonate properly. The ground connection used sould not be the same as the rest of the circuit. You need a dedicated RF ground such as a metal rod in the earth. |
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| Santa | Tuesday, 15th May 2007 9:34pm - No.1272 |
 Primary coil:- 14 turns on 6 inch plastic tube.
Secondary Coil:- 950 turns on 2 inch cardboard tube.About 5 coats of Varnish.
Spark Gap:- Static, 2*10mm bolts.
Capacitor:- 1 wine bottle filled with salt solution and covered with foil ( value unkown ).
Power:- 2 ignition coils ( not matched pair ).
oops nearly forgot :-4k7 Capacitor across the load.
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| artemon | Tuesday, 15th May 2007 10:06pm - No.1273 |
| a chain of 1n4007 wont pass? :) |
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| RMCybernetics | Tuesday, 15th May 2007 10:08pm - No.1274 |
| You may get away with it. I'd add about 10M resistor in parallel with each diode though. This helps equalize the voltage along the chain. |
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| artemon | Wednesday, 16th May 2007 3:15pm - No.1275 |
| How many i would need of them?) and could you explain what is soild state tesla coil? cause i cant find even basic information of it..only strange circuits)))) |
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| RMCybernetics | Wednesday, 16th May 2007 3:21pm - No.1276 |
A least 15.
A solid state tesla coil (SSTC) uses a solid state device such as a transistor instead of a spark gap. Unfortunatley it is not as simple as just replacing the spark gap as there are alls sorts of things needed to make it all work well. They are expensive and difficult to make. They are also easy to break if they are not made well enough. |
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| mad scientist | Wednesday, 16th May 2007 3:33pm - No.1277 |
| Now, I have two flyback transformer. Could you show me some circuits that can use with my flyback transformer? Also can I connect these transformers in series to get higher voltage? |
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| RMCybernetics | Wednesday, 16th May 2007 3:37pm - No.1278 |
A pulse generator will work to drive the flybacks.
You can't connect them in series. |
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| artemon | Wednesday, 16th May 2007 8:33pm - No.1279 |
But how chain of diodes will work? 1st problem:all diodes has inner opening resistance and chain of 15 diodes will give pretty enough.
2nd: 10M resistor across each diode will conduct pulse back,so diode will be useless...or i'm wrong? |
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| RMCybernetics | Wednesday, 16th May 2007 9:08pm - No.1280 |
Yes there will be a large voltage drop across the chain and yes some current will flow back through the resistors. It's not useless though because the total resistance of the chain is very large which allows only a small reverse current to flow.
The only alternative is to use proper high voltage diodes. There's usually plenty on eBay. |
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| mad scientist | Thursday, 17th May 2007 2:45pm - No.1283 |
| Can I use 0.8 inch diameter PVC pipe for my secondary coil? |
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| artemon | Thursday, 17th May 2007 4:47pm - No.1284 |
| eem. whats wrong? i've burned my second MMC ((( why it happening? it is 21kv 18.85 nF. It is charged by ignition coil powered by 20V 3A. it burns in 1 shot. it charges,then fire...and no fire more((( WHYY??? |
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| artemon | Thursday, 17th May 2007 4:55pm - No.1285 |
| Could you please draw a wire connections diagram,starting from HV output of ignition coil. maybe im doing something wrong.... thanks. |
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| RMCyberentics | Thursday, 17th May 2007 7:05pm - No.1286 |
 There are a few reasons that an MMC could fail.
1. Over voltage. It's quite possible that you are getting more than 21 kV from you coil. If your spark gap is smaller then the cap will discharge before it reaches a higher voltage. As I mentioned before, the cap should be rated for about 2x the voltage you intend to charge it to.
2. Over current. The capacitors you used may not be able to handle the large current pulse caused when rapidly discharged.
3. Internal mechanical failiure. When a cap is charged, the internal plates are strongly attacted to eachother. When they are suddenly discharged the force is released which causes a shockwave in the caps. This can cause some caps to fail but it is usually after many cycles. |
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| artemon | Thursday, 17th May 2007 7:09pm - No.1287 |
Heh.damn i'm a flooder) Ok. i've managed with my MMC . ok. my tesla partially work,giving a 5 mm sparks)))) it is less,than from ignition coil)))ok. problem no1: first time it occured in my jacobs ladder. So:between wire(im holding it in a hand) and fixed electrode occurs sparks,arcs..so ok. But if i'll attach this wire to another electrode of my Vee shape,it wont fire! Why? also in my tesla coil: if i attach all HV wires to their places(input of TC),spark gap will not shoot. But if i take (-) wire and slightly move it to my input of tesla coil,spark will occur between wire and input, and also spark gap will work normally. What is this?
Question: what's the difference between ~8nF mmc or ~18nF? (i know that changes resonant frequency,but what else changes? performace changes?longer time to recharge?) thanks. and sorry for that amount of questions( |
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| RMCyberentics | Thursday, 17th May 2007 7:37pm - No.1290 |
Not sure I understand what you are doing in the fist part of your message (can u draw a diagram?) but I have to say; Don't hold any wires when making sparks! Especially if there is a capacitor in the circuit. One jolt could stop your heart or make you jump and injure yourself.
The capacitance of a capacitor is a measure of how much energy it can store for a given voltage. 18nF is 2.25x the 8nF capcitor so it will hold 2.25x the energy when charge to the same voltage. Imagine it as a container with a size measured in farads. A bigger container will hold more but it will take longer to fill and longer to empty. |
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| mad scientist | Friday, 18th May 2007 4:27am - No.1297 |
| Instead of four 2N3055, can I use just only one brand new 2N3055(for a flyback transformer)? What is the length of enameled wire needed of the secondary coil?(AWG 37, Diameter of coil=2 inch) Can a flyback transformer operated at high frequencies about 68khz? |
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| RMCybernetics | Friday, 18th May 2007 10:37am - No.1298 |
New or old 2n3055 makes no difference.
The number you use just depends on how much current you want to switch. Each 2n3055 will handle a maximum of 15A.
The wire you need depends on eveything else you use (size of topload, primary inductance, primary capacitance). You must calculate this yourself.
Flyback transformers are usually designed to work at high frequencies. |
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| mad scientist | Saturday, 19th May 2007 6:26pm - No.1309 |
| Finally, my flyback transformer works, giving 1.2cm arc. Now, I am out of enameled copper wire, Ihave many AWG 40 wires as much as 50metres long but awg 33 is just only a little.Could you suggest some sources of enameled wire?(except transformer) |
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| artemon | Saturday, 19th May 2007 9:41pm - No.1311 |
| Hm. there is difference between Primary coil will be flat spiral,helical or inverted conical spiral coil? and what are the best-type for small,medium and big coils? thanks. and also,where to find all-in-one tesla coil calculator? Because in mine there's no one for inverted conical spiral coil( |
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| mad scientist | Sunday, 20th May 2007 5:01am - No.1313 |
| For safety reasons, i want to earth my power supply. where should i joint the earth wire?(the primary coil, or the flyback transformer?) |
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| mad scientist | Sunday, 20th May 2007 8:59am - No.1316 |
| S#*t! when i change 2N3055 to an MOSFET(for my flyback transformer), the arc produced over1 inch, and i shocked myself. The spark was amazing and how do i estimate the voltage produced? |
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| RMCybernetics | Sunday, 20th May 2007 1:11pm - No.1317 |
artemon:
Was it your diode string or did you find some other problem that you fixed to get it working?
The most common primary coil is a flat spiral for spark gap Tesla coils because it concentrates the magnetic flux at the base of the secondary coil and allows for loose coupling to prevent flashover. Some people use a conical one to increasec coupling slightly but it makes only a little difference in practice.
For very small tesla coils such as single or dual ignition coil driven types it is sometimes possible to use much tighter coupling. Wrapping the base of the secondary with several layers of insulation and then wrapping a primary coil onto that can provide a large amount of coupling for situations where the output power is not too great.
mad scientist:
Transformers, motors, or the ballasts from inside flourescent light fittings are typical sources of enamled wire.
Your transformer should be earthed, but Tesla coils are just not safe and should never be touched when active.
A very rough estimate for output voltage is for each mm of spark there is 1kV. This applies for a spark between two smooth round electrodes. The spark will jump further between wire tips because of the higher concentration of electic field. |
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| mad scientist | Tuesday, 22nd May 2007 2:32pm - No.1329 |
| I would like to ask whether neon sign transformer can work better than these electric supply (like power pulse generator)? How much(estimate) the cost of one small neon sign transformer?Iwant to set up my budget for buying these appliences. |
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| RMCybernetics | Tuesday, 22nd May 2007 8:29pm - No.1331 |
An NST running from mains will provide more power but it means that there is a greatly increased danger of fatal electric shock.
Small ones can often be found on ebay for about £30 + shipping. |
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| artemon | Wednesday, 23rd May 2007 7:14pm - No.1335 |
| Ok. My sgtc works well. Again many many thanks for the useful information. Also question: if i extend diameter of my secondary coil (with remaining turns and wire diameter) as well as changes inductance,capacitance,etc output power will also increase? |
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| RMCybernetics | Friday, 25th May 2007 1:27pm - No.1340 |
Cool. Post a picture if you can.
It's difficult to say if this would improve your power output. Making the coil shorter and wider may improve the coupling but it could increase the losses in the system due to corona discharge or capacitive coupling to ground.
If you have the time and materials it may be worth trying a few different versions of your secondary coil to help you learn how changing different parameters will effect the system. |
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| Winston | Tuesday, 19th June 2007 12:25pm - No.1411 |
Did you consider using N-channel power MOSFETs in the ignition coil driver circuit rather than BJTs?
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| RMCybernetics | Tuesday, 19th June 2007 12:38pm - No.1412 |
Not at the time as it was made with pretty much what was allready available.
There is a version of this driver circuit which uses a MOSFET. It is avalable as a power pulse modulator or the DIY pulse controller |
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| DyD | Monday, 9th July 2007 3:45pm - No.1425 |
 Peter et alia!
I am a high schooler who has had a long time fascination with electronics, esp. high voltage.In one of my attempts to amuse myself with metal etching, I constructed an arc welder USING A MW TRANSFORMER! Please, Please don't risk injuring yourself. My blog is caringbridge.com/visit/iandaniher
I wound up in Shriner's Burn Hospital for THREE MONTHS! Please email me at explodingmind@gmail.com with any questions. |
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| Jim | Friday, 13th July 2007 8:36pm - No.1439 |
After seeing Ian's site, I now understand why my grandpa has said "Never, ever, EVER, use a MW transformer..."
Although the can picture is pretty sweet... |
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| RMCybernetics | Friday, 13th July 2007 9:33pm - No.1440 |
mad scientist:
The current depends on the size of the transformer. It could be anything. A higher firing rate for a spark gap Tesla coil will give longer output arcs.
Jim:
Yep (thanks for sharing your story DyD). I say the same thing myself Jim. Unfortunately some peoples curiosity overrides common sense and they end up learning the hard way.
For those who don't know, an MW transformer is the transformer from a microwave oven. These things will deliver lethal electric current in an instant. Don't mess with them. |
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| Dragunov-21 | Monday, 16th July 2007 3:48am - No.1451 |
| I'm building a tesla and so far have managed to get a auto-coil. I've been running it off a 12VDC Lab Powerpack at 4VDC, using a relay as a rapid switching circuit, (haven't actually built primary or secondary coils yet, just been messing around with a spark gap). There's a repair shop that's willing to give me a half dozen MOTs, but after reading Ian's story I'm thinking I'd be better off wearing the cost of buying a bunch more autocoils. If I'm running a bunch of MOTs from a DC Powerpack, am I putting myself in danger? (Output at 4V is around 3A). |
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| Dan | Monday, 16th July 2007 8:13pm - No.1454 |
| What the average output current of an ignition coil? Is is based upon the current going into the coil? |
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| RMCybernetics | Tuesday, 17th July 2007 10:50pm - No.1458 |
Dragunov-21:
MOT's are dangerous because they have a low impedance which allows them to put out a large amount of power. The impedance is what limits the current drawn from the power supply (the mains in most cases)
If you run your MOT from your power pack, the current will already be limited to 3A because of the impedance (or overload protection) of the power pack its self. The low input voltage (4V) will also prevent any large currents from flowing. The MOT is designed for a mains input of 240V (UK) and gives an output of a few kV. This is only a small step up ratio of about 10x the input voltage. So if you use an input of 4V you are only likely to get about 40V out.
Personally I would just completely avoid using an MOT and stick to high ratio coils like ignition coils. They are safer, but you should still be very careful as no DIY high voltage device should ever be considered safe. Also if you are charging capacitors, the danger is hugely magnified because they can store a lethal energy jolt that can be delivered in an instant.
Dan:
The current you get depends on a lot of things like input power, frequency and pulse width. It also varies between the different coil types or models.
You can measure the current using a standard voltmeter and a low resistance (1 ohm or less) power resistor.
If you place the resistor between the output and ground it will be almost shorting your coil and therefore drawing lots of current. If you measure the voltage across the resistor you can then use ohms law to calculate the current flowing through it. (I = V / R) |
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| Aditya | Thursday, 19th July 2007 4:35pm - No.1471 |
Hi i just got net n found tesla coil.
I want to know that the simple coil prepared is hazardous for a person? what if someone got in contact to discharge from the coil? n can some one use a 12/ 24 adapter instead of a battery? |
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| RMCybernetics | Thursday, 19th July 2007 4:52pm - No.1474 |
The current at the output of this TC is below what would be considered lethal, but it would still give a painful prickling sensation if you were to be struck by an arc.
There is still a lethal level of current flowing in the primary circuit though. Touching this would likely result in serious injury or death.
A mains adapter is not likely to be able to provide enough power (unless it's a real expensive one) and it may be susceptible to damage from RF as well as allowing RF to get on your mains line and damage your household electrical items. |
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| black_hat | Friday, 20th July 2007 5:01am - No.1482 |
every thing rocks here but a complete diagram is completely missing
how have u created the capacitor bank provided logical diagram n reality has lot differences
how to connect the coil
seems like i m going to need a complete diagram
n the cheaper, smaller n safer version of the TC will have same beautiful arcs |
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| RMCybernetics | Sunday, 22nd July 2007 7:07pm - No.1491 |
 .... and here it is. The DIY Mini Tesla Coil / Plasma Gun! |
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| jack | Tuesday, 14th August 2007 9:55pm - No.1589 |
| wouldnt the current from a SLA battery fry the ne555 chip? or would the chip only withdraw the current that it requires from the battery? great website by the way. |
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| jay | Monday, 20th August 2007 1:16am - No.1623 |
i got my tesla kinda working but the spark gap on switches every 20 seconds or so . do i need a higher voltage input ? the voltage isnt all that high. im using a flyback at about 10,000 to 20,000 volts or about 1cm long. could you suggest a flyback driver circuit?
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| RMCybernetics | Monday, 20th August 2007 12:07pm - No.1624 |
20 secs is a long time between fring.
What gap do you have? About 5mm should do it. If your cpacitor is only small (< 10nF) then it should charge quickly, so if it's not, your HV supply may not be delivering enough current.
Our Power Pulse Modulator makes a great flyback driver. It is similar to this circuit, but with added features such as inductive spike protection, back EMF and power monitoring, and built in cooling. |
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| RMCybernetics | Monday, 20th August 2007 9:35pm - No.1628 |
That sort of driver circuit offers the advantage of automatically running at the resonant frequency of the transformer, but this also means you can't adjust the frequency to match your spark gap for example. Also those big resistors dissipate energy as heat, reducing the overall efficiency.
Generally the frequency of a TC output is too high and the current is too low for use as a power supply like this.
Some people consider the car ignition coil and flyback transformers as Tesla coils with solid ferromagnetic cores. Either of these will work like shown on this page.
Another version is the Tesla magnifier which is a standard (air cored) TC with an extra coil simply connected to the output. |
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| jay | Tuesday, 21st August 2007 4:45am - No.1630 |
| thanks i have replaced my cap with a high voltage ceramic cap 0.1 uf = 100nf witch should work better than the dialectric cap i have currently. i was also thinking of taling apart my auto coil as it is crappy and rapping the wires around a ferret core so i can put in the self resinator circuit would this be a good idea? |
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| RMCybernetics | Tuesday, 21st August 2007 10:13am - No.1631 |
| I have seen a circuit where someone just wrapped a few turns of wire around the metal can of the ignition coil for use as the feedback signal. It's probably worth trying that first. |
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| al | Friday, 24th August 2007 2:42pm - No.1652 |
| why do you use 2n3055 power transistors, is it just because they are easily available and would mosfets connected in parrallel work or is there some problem with using them. |
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| RMCybernetics | Friday, 24th August 2007 2:57pm - No.1653 |
2n3055 transistors are used because they have a high current switching capability, are available pretty much anywere that sells transistors, and are resonably priced. They are not the best choice, but they are popular for this sort of circuit.
A MOSFET would work as long as its rated for enough current. You will also need to use a higher gate (base for NPN) voltage and make sure there is a resistor from gate to ground. This is important for switching the transistor off as quickly as possible. |
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| kenny | Sunday, 26th August 2007 8:15pm - No.1657 |
| I wish i knew how to make a solid state tesla coil, my coil uses a 15,000v 30 millamp neon transformer i need Rf chokes to protect the transformer how can i make my own Rf chokes? Im going to use a 1 inch 25mm diameter pvc pipe wound with a few hundred turns of 20 or 22 awg insulated wire will this work? are my dimensions correct? |
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| RMCybernetics | Monday, 27th August 2007 11:04am - No.1662 |
| Sounds about right. |
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| john keth junior | Tuesday, 28th August 2007 7:48am - No.1668 |
| hey rmc i was pondering around your site and from what i gather people seem to have trouble finding a good transformer. would a magneto be good you know those thigs from the little petrol lawn mower engines? i thought they had high current as well as voltage if not please notify me right away |
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| will | Sunday, 2nd September 2007 2:00pm - No.1681 |
| hi, ive made a tesla coil and everything is working perfectly apart from the secondry coil, i am getting no sparks from the top and i dont have a clue whats wrong, can u help?? |
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| RMCybernetics | Sunday, 2nd September 2007 4:02pm - No.1683 |
john keth junior:
I've never used a magneto, so I couldn't say.
will:
Check the lower end of the coil is connected to a good ground (like a metal rod in the earth.
Check the coupling is not so close that plasma is forming between the primary and secondary coils at the closest point.
If they are ok then I would guess that it is not in tune. The primary circuit must be adjusted so that its resonant frequency exactly matches that of the secondary coil with topload. The most common way to do this is to adjust the number of primary turns by tapping off at different points. More turns = lower frequency
Bigger capacitor = lower frequency
Bigger Topload = lower frequency |
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| nino-de-voltaje | Friday, 7th September 2007 10:08pm - No.1692 |
Hey! I want to make a 6 ft tall tesla coil for a science project. i've drawn out all the plans and everything, but i still can't figure out what kind of xfmr to use for something that size. all ive got is an old 12 v Bosch ignition coil that i got for free, and i dont think that would work very well for a giant TC.
I've read that neon sign xfmrs are often used for tesla coils that size, but i just can't get my hands on ANY!!! any other suggestions?
Thanx a lot!!!
--nino-de-voltaje
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| RMCybernetics | Saturday, 8th September 2007 4:53pm - No.1694 |
| An ignition coil will only be enough for very small tesla coils. You can usually get a neon sign transformer (NST) from eBay. |
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| der Strom | Monday, 10th September 2007 4:15pm - No.1701 |
(changed from nino de alto voltaje)
I would love to be able to buy stuff on ebay, but i'm "underage". i'm not 18.
a couple of days ago i tried ebay, but they wouldn't allow me to register because i am under 18. |
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| RMCybernetics | Thursday, 13th September 2007 2:15am - No.1702 |
| You should be supervised by an adult familiar with the safety precautions for high voltage devices. This person would be able to purchase an NST and help install it safely. |
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| Chris Henderson | Thursday, 13th September 2007 10:27am - No.1703 |
| I have costructed a 4x 2n3055 driver hooked up to a pair of ignition coils, works ok but output only 1 and a 1/2" sparks from tesla. However as I try to increase power i.e. widening spark gap,or increasing supply voltage to driver, the 2nd 2n3055 in the chain of 4 gets extremely hot and often blows. The other 3 power transistors don't get particularly hot at all...So, do you have any ideas for solving this problem as I have'nt many transistors left to replace the blown ones with! |
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| der Strom | Thursday, 13th September 2007 1:33pm - No.1706 |
 Ok. Thanx a lot!!!
Another question: What ignition coil/tesla coil circuit should i use for a tesla coil only 4 inches high?
here is a picture of it. |
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| RMCybernetics | Thursday, 13th September 2007 1:50pm - No.1707 |
Chris Henderson,
If you are replacing a transistor in the same position in your array than there must be something wrong with either the wiring of the circuit or the other transistors.
If it's heating up and eventually blowing, this is due to it switching power beyond its ratings. This would lead me to believe that the other transistors are either faulty not switching on for some reason.
You can test a 2n3055 by replacing your ignition coil with a load that will give you an idea of current flow such as a motor or light bulb. The faster/brighter it is the more current is flowing.
Remove the signal source from the base pins of the transistors and make sure all transistors are separated from each other. Now connect the signal or a DC voltage to the base pin of the 2n3055 under test and take note of the power level shown my your load. Test each 2n3055 like this to see if there are any major differences. Compare results to a new transistor so you can tell if they are performing correctly.
der Strom,
The rectified output of a single ignition coil driven by a 12V pulse modulation circuit is likley to be enough power for charging the tank capacitor of such a small TC. You should refer to the DIY Plasma gun page for details of building a tiny Tesla coil. |
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| der Strom | Thursday, 13th September 2007 4:26pm - No.1708 |
gr8! thanks a lot. the only problem is that i only have 1 ignition coil. is there a way to make it work with only 1 of them?
by the way, i built a simple driver circuit for the ignition coil. it plugs into 120v AC from the wall, and it has a dimmer switch so the coil does'n get fried. is it possible, or safe, to use power that is directly plugged into the wall for my mini tesla coil? or will the "backflow" ruin the power supply?
Again, thanx a lot! |
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| RMCybernetics | Friday, 14th September 2007 1:30am - No.1710 |
A single HV diode in series with the output of the ignition coil will be enough to allow you to charge the tank capacitor.
120V @ 50Hz would cause too much current to flow in the ignition coil. This would cause it to burn out.
Mains powered Tesla coils often use a neon sign transformer as it can be powered from mains voltage. |
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| RMCybernetics | Friday, 14th September 2007 2:34pm - No.1713 |
The value of the cap will need to be adjusted so that the resonant frequency of the primary circuit can be made to match that of the secondary.
It's probably best to make some sort of MMC or have a selection of different sized caps to try. With an MMC you can add/remove a cap to increase/decrease the frequency as needed. The cap used in the plasma gun was just 2nF made from two 1nF ceramic disc caps in parallel. The optimum value was found by using an MMC of much smaller valued caps and adjusting it as described above. |
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| der Strom | Friday, 14th September 2007 3:25pm - No.1714 |
Ok. thanx. I have a question about my ignition coil: How come it only charges 200v-400v capacitors, but not my 1kv-2kv caps? is there any way i can adjust this?
Also, I have never seen a cap rated for nF. I have only seen them in uF and F. could u send a pic or something?
Thanks very much for all of your answers!!! |
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| RMCybernetics | Friday, 14th September 2007 11:39pm - No.1715 |
 If your ignition coil/driver is working properly it should destroy capacitors rated for anything less than about 15 - 20 kV. You can measure the output voltage by using a voltage divider made from a chain of high value resistors and a standard voltmeter/multimeter.
If the caps you have are of similar physical size, the HV ones are likely to have a much lower capacitance. Most capacitors rated in the kV range will be much smaller than F or uF unless they are physically quite large. This image show some typical HV ceramic capacitors and some HV diodes) The left most caps are rated for 1kV and 4.7nF. |
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| der strom | Monday, 17th September 2007 1:27pm - No.1726 |
| Ok. thanks a lot. Do you know where i can get a rectifier rated for a high voltage? do you think Radio Shack might carry them? |
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| RMCybernetics | Monday, 17th September 2007 2:41pm - No.1727 |
We have some HV diodes in the surplus items section. Our online payments are handled by PayPal, but you can pay using a card without a PayPal account if required. You can also pay by post, but make sure to email your order details before sending any payment.
I'm not sure about Radio Shack stores as we don't have those in the UK. If it is the same as RS, then you may be able to find some there. |
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| der strom | Monday, 17th September 2007 3:24pm - No.1731 |
| Ok. thanks. Earlier you said that i would need nF capacitors for my mini tesla coil. i looked them up on the internet, and the film capacitor i found was rated for 1 nF and had the number 102 on it. is this what i need? |
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| RMCybernetics | Monday, 17th September 2007 6:15pm - No.1732 |
| Yes if its also rated for 15kV or more. |
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| Claydough | Friday, 28th September 2007 5:06am - No.1773 |
| Hello all, first off i want to say, i love your site, and second, I'm a beginner coiler, and i've noticed that there isn't alot of information about the toroids. How are they attached to the secondary coils exactly? Is there just one wire from the coil connecting the two parts? THANKS SO MUCH! |
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| RMCybernetics | Saturday, 29th September 2007 1:24pm - No.1781 |
der strom,
Look up information about a 'Faraday Cage' works for info on shielding EM interference.
Claydough,
There is not much info because they are simply a single piece of metal (or several joined to make one).
Imagine the metal as a reservoir for 'electrical water'. You connect this to one end of a hose (your secondary coil) to allow it to be filled and emptied while the current flows back and forth in the coil. The opposite end of the coil is connected to the ground (literally) which supply's all the 'water'. The 'water' is pumped up and down the secondary coil with the magnetic fields produced by the primary circuit. |
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| RMCybernetics | Tuesday, 2nd October 2007 4:31pm - No.1802 |
I would guess that this is your problem. Without a proper HV diode, you will not be able to charge caps correctly.
I would now assume that the diode you do have is damaged and will probably allow current to flow in both directions.
You might be able to get away with connecting lots of lower voltage diodes in series, but this method can cause diode failiure. |
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| RMCybernetics | Tuesday, 2nd October 2007 4:54pm - No.1804 |
The higher voltage capacitors will probably have a much lower capacitance. If you charge them with only a small voltage the spark you get from shorting its terminals would be negligible.
You are charging your low voltage caps because the small gap you leave breaks the connection to your coil just in time for some of the charge to remain. |
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| RMCybernetics | Tuesday, 2nd October 2007 5:22pm - No.1807 |
| You can use our shop. You can pay with credit/debit card without having to sign up to paypal. After clicking "checkout" there is a small text link above the pictures of credit card logos which are near the bottom of the page. I don't know where else to suggest. They are getting discontinued from lots of shops these days. |
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| chrisH | Wednesday, 3rd October 2007 11:53am - No.1816 |
I have a flyback generator exactly like the one in your surplus shop but wondered if you could kindly supply any info on pin out identification....there are a dozen to choose from on the underside!
Also, any chance of you turning up at the Cambrige Teslathon with your mini tesla and latest tesla project...It's at the Cambridge Museum of industrial technology on w/e of 27-28th of October...I'm sure your gas plasma tesla coil would generate alot of interest! hope you and your team can make it. |
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| RMCybernetics | Wednesday, 3rd October 2007 2:35pm - No.1819 |
der strom,
The magnetic field is pretty well conntained within the case but you certainly should see some deflection of the compass if it close enough.
Making sparks broadcasts a wide spectrum of RF noise which will intefere with many appliences. Most modern exipment has some sort of filter to tr to reduce interference problems.
crisH,
You can get a rough idea of the pinout by measuring the resistance between the pins and drawing a diagram as you go. The one in our surplus store was tested with our PWM-OC10A by just trying combinations of pins and measuring the corresponding output voltage. Two of the pins (I can't remember which) had a low impedance and gave a steady 20kV output.
Yes a few of us should be visiting the Teslathon. I'll bring the plasma gun too. See you there. |
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| RICK | Friday, 5th October 2007 9:55am - No.1840 |
| In your shop I've seen the high voltage rectifier your selling will it work ok in my circuit or need a much highier current rating? Thanks again. Your doing great with your great website. More power to you. |
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| Rick | Saturday, 6th October 2007 10:34pm - No.1858 |
| Can you please explain why the conventional tesla coil are not using high voltage rectifier but are capable of producing strong sparks. |
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| RMCybernetics | Sunday, 7th October 2007 12:19am - No.1859 |
This circuit will drive an ignition coil alone but the MOSFET will heat up quickly so a good heat sink is needed. You should still use the snubber RC1 shown on the ignition coil driver page to help protect the circuit from HV spikes.
You can also connect the MOSFETs in parallel.
Common mains driven TCs use sine wave driven transformers with a low frequency (50 - 60 Hz). This allows the tank capacitor to charge in 1/4 of a cycle and therefore fire many times per second. The voltage change in these types of transformers is proportional to the difference in turns on the primary and secondary sides.
The voltage rise in an ignition coil is a proportional to dI/dt (the rate of change of current). The square wave driver gives a HV output made from high frequency pulses which are too quick to charge the tank capacitor fully on each cycle. The diode serves to keep the pulses unidirectional and to stop the capacitor discharging back into the ignition coil. |
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| RICK | Tuesday, 9th October 2007 12:05pm - No.1876 |
I tried to use the PWM alone to drive my ignition coil CR-800 12 volts but it did not work and I just cant figure-out why? Can you still help me on this? Thanks again.
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| RMCybernetics | Tuesday, 9th October 2007 2:48pm - No.1877 |
| Start simple. Use the 555/393 oscillator circuit to dim or flash an LED. If that doesn't work there is no point adding aything else to the circuit. |
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| machine of pure excellance | Tuesday, 9th October 2007 7:38pm - No.1881 |
MR rmc do you have any palns for a solid state tesla coil driver? if not will a standard square wave oscillator drive a tesla? ohh and one more thing does the tesla exert a lot of feedback current into the primary drive circuit, if so i need to make a gate or something.
sincerly machine of pure excellance. |
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| RMCybernetics | Tuesday, 9th October 2007 9:58pm - No.1882 |
No SSTC yet. A standard square wave oscillator will be ok for a drive signal but you will still need something like IGBT's for power switching.
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| der strom | Wednesday, 10th October 2007 3:26pm - No.1896 |
| Hey. I looked around your shop online yesterday. Do you sell electrical components seperately? I couldn't find any. Which category are they under? |
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| RMCybernetics | Wednesday, 10th October 2007 4:07pm - No.1897 |
Not normally. If we have some left after a project they will go in the surplus store. Low voltage bits would go in the electronics category and HV components in the High Voltage category.
Some more items have been added today. |
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| RMCybernetics | Wednesday, 10th October 2007 5:35pm - No.1906 |
| My advice is to start small and simple. Without some HV experience or even general electronics, the result of your project is likely to be the death/injury of you or a bystander. I can't emphasise enough how dangerous a hobby Tesla coiling is for a beginner. Power electronics (especially at this voltage and frequency) is as much of an art as it is science. Allthough the operation of a TC is theoreticaly quite simple, there are many variables to be considered for a real system, and some which are not known precisley. Any mistakes in a large high power system will be expensive and potentially deadly. Mistakes made when making a small battery operated system are much less expensive and less likley to kill anyone. |
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| der strom | Wednesday, 10th October 2007 5:44pm - No.1908 |
| I am planning to start simple-- with the mini tesla coil that i showed you earlier on, and then I also built a 14 inch tesla coil. The 6 foot tall tesla coil is a future plan that I will probably wait to build until I am more experienced in high voltage electronics. I am just trying to get all the info now, so when I'm ready I can know exactly what i'm doing. |
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Using
Butane gas and air, a blue flame can be used as an interesting discharge
terminal. The heated CO2 emissions provide a low pressure channel
to conduct the electricity more easily than air. This produces a large
plasma column above the flame. At certain spark gap discharge rates the
plasma column can be made to resemble a stable double helix formation.
Small quantities of other gasses such as neon or helium can be mixed with
the butane to produce slightly different colours and effects. The table
below should help you find some of the components needed for this project.
Capacitor
Bank - The capacitor used in this project was made by combining
a large number of lower valued capacitors. By connecting smaller capacitors
in series the overall voltage they will tolerate is increased. To obtain
a higher storage capacity (capacitance) the capacitors can be connected
in parallel. This type of capacitor bank is known as an MMC (Multi Mini
Capacitors). The next version of this project will use specially designed
large pulse discharge capacitors. These capacitors can be more efficient
than an MMC, but they can be expensive and hard to find.
Primary
Transformer - Ignition coils (Induction coils) obtained from
a scrap yard are used for this design. The old ignition coils provide
a very cheap way of generating a high voltage for charging the capacitor.
The voltage increase in an ignition coil is not determined by the turns
ratio like in normal transformers. The secondary voltage depends upon
the rate of change of the current in the primary coil. Older ignition
coils such as ones from a scrap yard may not work as well as new ones.
Over time the insulating oil inside the casing becomes less effective
and can lead to internal arcing. This can damage the transistors and the
control circuit, rendering them useless
Control
Circuit - The control
circuit is based on a simple oscillator provided by an NE555 timer
chip. The square wave pulses are sent to a set of four 2N3055 power transistors
mounted on a large heatsink. These transistors can switch a good amount
of power quite quickly, but they can be sensitive to voltage spikes caused
by feedback in the circuit, or faulty ignition coils. The Ignition
coil driver circuit shown below shows how the signal from the 555
chip is pre-amplified, so that the large transistor array can be driven
effectively.
Coils
- The primary coil is simply made from 2mm enameled copper wire, wound
around a plastic stand. There are six turns in total, but the connection
is made at about 4.5 turns when tuned. The secondary coil is wound from
0.4mm enameled copper wire around a plastic drainage pipe.
Special
Features - This project has several extra features compared to
a common Tesla Coil. The topload sphere has a small hole to allow gas
to be emitted. A 5mm plastic pipe runs down the inside of the secondary
coil, and out of the plastic base.
Future
Developments - This project is currently being upgraded. The
new design aims to achieve a higher power throughput. By using more ignition
coils in parallel it should be possible to increase the size of the spark
gap, or to fire it more rapidly. New ignition coils will used instead
of the second hand ones for improved stability. The new design also incorporates
voltage and power monitoring features. It also has a neat metal finish
and multiple outputs so that it can be used as a multi purpose portable
high voltage power supply
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