To make a spark you need much more than 12V on the primary of the coil. You need the back EMF to have enough voltage to make a good spark. You control the back EMF with a small capacitor in parallel with the primary, but it has to get up to about 200 V so the transistor has to be able to stand that.

The circuit shows the transistor as an emitter follower. If you arrange it that way, the output voltage will only change as much as the input voltage so you won't get 200 V.

2 sparks per second is too few. A Jacob's ladder rises because the air heated by the sparks rises, but 2 sparks per second won't keep the air hot.

 

do i have to use the 2n3055 transistor or can i just use any npn transistor?
Aswell do you have a schematic, or can you make one please?

 

Here is some schematics i found on the web, but im kind of lost whats going on here and how its creating pulsed current?

Aswell that condenser is a non-polarised capacitor in other words right?
Whats better for producing better sparks 6 volt lantern batteries in series(for more voltage) or parralel(for more current)

thanks

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The relay is normally closed, so current flows, into both the ignition coil and the relay coil. Both are inductive, so the current takes time to build up in both. A few milliseconds is all that is needed.

When the current builds up in the relay coil, the contacts open. The current drops very quickly. The high rate of change of current gives a high voltage, which is transformed by the ignition coil to give a spark.

The condenser is a high voltage capacitor. It stops the voltage getting too big, and allows the arc at the contacts to stop. Old contact-breaker ignition systems needed one.

The system is very similar to the spark ignition system on an old car. The only difference is what opens the contacts.

I have no idea whether series or parallel batteries would be better.

 

Since you need 12 Volts, Series them.

But Lattern Batterys Won't last very long.

And such a RELAY Circuit isn't very good.
The Contacts Arc, causing them to burn.

A Mosfet Driven circuit is Much Better.

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Hi Spitso,
You might want to check out the projects on the Elektor website. I can remember 2 circuits for this, However the one that used the car ignition coil was intended for use as an electric fence. The other one was a ladder created with several caps.
http://www.elektor-electronics.co.uk...cs.58103.lynkx

 

Hi Trevors,

the electric fence doesn't even cause sparks. With an on-time of max 31ms there isn't enough power to make them. (I wouldn't P on the wire though.)

The German title of the Elektor project is "Lichtboegen auf der Jakobsleiter", literally translated to English: light arcs on the jacobs ladder. That device could also be named St. Elmo's fire. It uses + and - 10.000V gained of two cascades of caps and HV-rectifier diodes, one for the positive voltage and the other one for the negative. It also uses a modified toroidal transformer rated 225VA. Additionally it uses a chicken circuit not to fry the parts or electrocute yourself.

This project was published in March 2006.

Hope that helps a bit.

Kind regards

Hans

 

Ive just quickly tested the attacheted schematic without succes.
Where is the earth on the ignition coil, theres only negative going in via common of the relay.

Aswell how is this making a pulse?

On my relay (which ive borrowed from another project) ive got attached a diode across the negative and positive so it cant short, should this be removed?

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The ignition coil has two primary connections, one is connected to each side of the relay coil.

The diode will stop it working. Read my description of the 31st March. To get a spark, the current in the ignition coil has to stop very quickly. The diode lets the current continue.

If you want a physical analogy, imagine how you would produce a large force with a hammer. You are not strong enough to produce a big force on your own, so you use your strength to accelerate the hammer. When it is going fast, you swing the hammer into something solid. The big force comes when you stop the hammer, because there is a large deceleration of the hammer. If you swing the hammer and do not hit anything, there is no big force, because the hammer does not decelerate quickly.

In the coil, the current builds up slowly with the 6V supply, like you hammer gets faster over about 1/2 second as you accelerate it.

When the contacts open, the current has nowhere to go so stops quickly. There is a big voltage created. That is like when the hammer hits something and stops very quickly. A big force is created.

If you add a diode the current slows down slowly. There is very little voltage created. That is like when the hammer misses and swings free. There is little force and it takes longer to stop.

I hope this helps.

 

Yes, it works alright, although what capacitor would your recomend and its in series right (im just a bit confused on how the schematics drawn)