Introduction: Variable Voltage Ignition Coil Power Supply

Picture of Variable Voltage Ignition Coil Power Supply

This instructable deals with the creation of a very simple high voltage power supply using a car ignition coil. Please take care if you are going to build this as the voltages exceed 30,000. Also do not attempt this project unless you know the dangers of high voltage. This supply can be used for tesla coils and with the right component values produce an arc like a neon sign transformer.

Step 1: Parts

Picture of Parts

First of all your going to need:
- A gluegun
- A car ignition coil
- A light dimmer (400w+)
- A capacitor with a voltage rating of around 600v and a capitance between 0.1 and 30 microfarads
- some 2 core mains cable with a flug
- Sunflower oil
- Some bolts
- Some insulated wire (stripped mains cable will do)
- A drill
- Zipties
- A plastic box ( I used a 3Litre box from maplins)

Step 2: Putting It Together

Picture of Putting It Together

This step is fairly simple.

Live wire:
You will need to wire the live input from the mains to the dimmer and out again.
Then from the dimmer the live wire goes to the capacitor ( make sure its the + terminal if it is a polarised capacitor)
After the capacitor the live goes to the + terminal on the ignition coil

Neutral wire:
This wire goes straignt from the mains to the - terminal on the ignition coil
Also this wire will have to be extended past the ignition coil so it is attached to a bolt through your case. Basically this serves as the high voltage return for the high voltage secondary output.

Middle terminal on ignition coil:
This terminal is high voltage positive and will be arcing to the - of the primary. Run  a wire from the middle of this terminal to a bolt in the case.

This whole setup will need to be submerged in oil to prevent arc overs. Transformer oil is expensive so I used sunflower oil ( £3 for 3litres in Tescos) and it works just as well. Do NOT use motor oil as this is volatile and might explode.

Use zipties to secure your apparatus and cover the drill holes with hot glue to prevent the oil leaking out.

For my power supplyI used a 400w dimmer switch, a 0.1microfarad MOT capacitor.

Step 3: Results

Picture of Results

Here are some pics of the output. My camera is crap but this at max ( dimmer turned all the way up) produces around 40KV.



DudunG1 (author)2017-11-26

Is it possible to build a welding using a car coil run by accu 12 v?

Is there any DC voltage variable regulator?

How long it's can run?


Azeotrope117 (author)2016-12-29

Can i use a flyback transformer instead of an ignition coil?

TeslaBoy (author)2013-05-29

I have a motor run cap with a voltage rating of 370v
and a capacitance of 6microfareds.
Would this work in place of your micowave cap

armorer243 (author)TeslaBoy2015-08-07

Yep, your capacitor will work fine. It's close to what I use.

DevCoder (author)2010-08-24

I'm pretty sure these transformers aren't meant to take 120V AC...

armorer243 (author)DevCoder2015-08-07

They aren't. I don't expect my coil to live forever, which is why I only run it in short bursts long enough only to light the flammable mixture I need. Eventually it will carbon bridge internally and not work any more. When that happens years from now I can get another coil for next to nothing.

pyromadness (author)DevCoder2010-08-26

well i live in the uk. its 230v in. i have a UK ignition coil

DevCoder (author)pyromadness2010-08-26

or 230V for that matter - cars run on 12V DC

pyromadness (author)DevCoder2010-08-27

true.however this is an inductive kick transformer. What matters is the rate of change in the input voltage. Despite being designed for 12v input, these transformers are very robust arnd can handle 230v no problem.

_BiG_ (author)2011-05-14

pyromadness: Are you crazy or suicide??

This circuit is very-very dangerous and strictly speaking, lethal!!!

It uses live mains connectings and the high voltage pole of the ignition coil is directly connected to the mains (because the ignition coil is an autotransformer - do you know what this means?)! You can get lethal shock through that point!
Nobody use this device!
(A good question: have any professional ever checked these circuits up??)

You may avoid the graveyard using a good safety transformer between the circuit and the mains. Nobody use the mains directly when playing with high voltage! Protect your life - or you may get a Darwin awards...

armorer243 (author)_BiG_2015-08-07

Most fun or useful things can hurt you if you go about it in a stupid way. I am burning hydrocarbons to reach temperatures in a furnace that reaches 3000F and pouring molten metal within feet of my body. The electricity used to start it all in motion is only one small part of the dangerous equation. Use common sense and this is a workable project.

-max- (author)_BiG_2012-05-12

the transformer is not connected directly to mains, the capacitor and ballast linit the current significantly, and its boxed up.

I do agree it is still very dangerous, but so is everyday risks, like walking down stairs, i can always trip fall, and break my neck... and if one take extreme caution with the circuit it is fine.

armorer243 (author)2015-08-07

Thanks for the write up. This circuit works great, I have made two of them, one to light my waste oil fired foundry, the other lights the waste oil heater for my garage. I used an el-cheapo dimmer and a 370/480v 10uF motor start capacitor and it lights oil vapor every time.

lcs5000 (author)2015-03-21

can you use aa 2kv capacitor with 2200 pf

RBMAY (author)2013-12-13

I had something like this that was professionally made, and I believe that it had about 50,000 volts (1955?) when I was about 10 (we used to trade toys like this, bb guns, sling shots and fireworks). It was a plug in device, and it had two curved rods that were very thin where the lightning bolt would jump from one side to the other. Each rod had a wood extension so that you could adjust the distance. The box was about 12" x 12" and the spark would jump as much as 8 inches or so. It did not feel particularly good when you put your hand in the way. Don't ask how I am still here, today.

There is a great use for these things. I grew up in the age where all the adults smoked their filterless Camels and Pall Malls. If you know someone who smokes sneak out a couple of their weeds and put them in the path of the sparks being sure to do as much of the cigarette as you can in a bunch of directions. Then sneak them back into the pack.

You won't see any difference in the cigarette (at least with the machine I had), but watch as your friend starts to take a drag. It is like sucking on a 4 inch drain pipe filled with one inch holes. Your friend will start sucking so hard that you would think he was deflating a basket ball in two seconds. You won't see the smoke drawn into the weed.

eoeoe69 (author)2013-08-13

what is the frequency output?

Raul the Researcher (author)2013-07-22

Can this be used to charge Pulse Caps? 40KV 5uF?

-max- (author)2010-07-27

what does the dimmer do, help prevent from blowing fuses?

Jimmy Proton (author)-max-2010-08-26

voltage control i guess

pyromadness (author)Jimmy Proton2010-08-27

to an extent, yes. When the dimmer is fully turned up, rate of change in the input voltag is highest so the output voltage its at its maximum.

-max- (author)pyromadness2012-05-12

by the way, how does it change the waveform? (i just bumped into this instructable again)

pyromadness (author)-max-2010-08-27

nope. The dimmer changes the waveform of the input voltage, making it suitable for the ignition coil.

bswt (author)2012-01-15

could i use a 1000w dimmer switch?

-max- (author)bswt2012-05-12

i would guess so, he wrote 400W plus, so i ausume the more watts, the better.

gladiator327 (author)2011-12-06

I was playing with building a Plasma automotive ignition system. I built a circuit that is exactly the same as this one. It is very dangerous, and if you arent carefull you might not live. It's fun to play with, and common sense is a necessity.

Timberbeats (author)2011-07-04

Thanks for this, i have a very good working power supply, and the best is, it doesnt get warm! I have a 1000 watt variac that goes to the dimmer, so i can work on a lower voltage. If i open the box (without oil) the smell of ozon is terrible!
Get about 4 - 5 centimeter sparks :)

Jimmy Proton (author)2010-08-26

mine doesnt say + or -, how can i find out

zeroatu (author)2010-08-18

For the 2 core mains, those are just wires that have an outer and inner coating of insulation, right? I'm also having trouble finding a flug for one, so if you could point me in the right direction that'd be awesome.

pyromadness (author)zeroatu2010-08-18

Yes any 2 core mains cable will be fine. There are usually two types, rated at 3amps, and 6 amps. If you live in the UK I suggest electrical suppliers such as TLC or QVS. Two core mains cable is very cheap. I bought 100meters of it for £12 from QVS

zeroatu (author)pyromadness2010-08-18

Alright, and one other quick question. What is the thing at the top of the box in the picture that looks like a cylinder with 2 black circles on it? I can't seem to find it in the supplies list...

pyromadness (author)zeroatu2010-08-18

that would be the capacitor. that capacitor is taken from a microwave. You don't need this specific capacitor. Try a capacitor from maplins. A motor run cap would be suitable. Remember, the microfarad value greatly determines the output current. (higher UF, higher current and don't exceed 30UF) any more questions feel free to ask =)

pyromadness (author)2010-08-02

The capacitor is in the cicuit to limit the flow of current. The higher the capacitance value, the more current can flow - this changes the appearance of the arc from blue to yellow. However, I recommend you dont exceed a vaue of 30uF (micro farads) or the ignition will overheat VERY quickly. To understand what the dimmer is for you need to know how the ignition coil works. It is an inductive trnsformer, where the collapse of a magnetic field in the primary triggers a high voltage in the secondary. The faster the rate of collapse the higher the voltage. Essentialy, the dimmer squashes the main AC sine wave into a sort or rounded sawtooth- this is suitable for running the ignition coil. One last thing, if you don't have a high enough cap value you can put the caps in PARALLEL with the ignition coil. But this is a tad more dangerous =D zker666 put 3 MOT caps in parralel with his coil:

-max- (author)2010-07-27

and what about the capacitor?

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