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Making a sparkplug 'spark'

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L3wis

New Member
ok all i have been wondering about this for quite sometime now... How do i make a sparkplug spark!? Would this circuit work? I simulated the sparkplug with the 2 zero rails. What i would want is when u press the push to make switch is for the spark to be made... This is so then i can incorprate it into making a potato gun :D Another question related to this is how do i wire a sparkplug? do i need a sparkplug cap? Like on engines? Or can i directly wire them an easier way?
 

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Someone Electro

New Member
In a car a spark is made becose of the big curent of the car batery!

Try holding the + and -! :lol: Just a jocke (you can get a good feling how electricety get mad) :lol: :lol: :lol:

To get the big cutent from a batery conect a big capacitor parallel(with batery)

PS:
Big charged capacitor can give you some shoking! :!: :!: :!:
 

Klaus

New Member
Lewis, you cannot make a sparkplug "spark" with just a 12V battery :D
You need about 10000 - 30000 Volts to get a spark to jump the electrodes.
How do you get that many volts from a battery? With an ignition coil just like the one car petrol engines have.
So, in your diagram you need to wire the + primary terminal on the ignition coil to the switch and the negative coil terminal to the negative battery post.
The centre of the coil has the spark plug lead attached (its a special wire - do not use anything else, it MUST be spark plug lead :!: )
The other end of this wire goes to a spark plug cap which fits over the ceramic plug insulator, the metal thread of the spark plug base connects to the negative battery terminal.
You might draw a nice circuit again and I will tell you if you got it right.

Perhaps you best get the coil and lead parts from a car scap yard. Your pushbutton switch must be able to handle 3 Amps or so.

Now, when you got all wired up, STOP a minute and think what will happen to you if you touch 30000 Volts :( Yes, you will be thrown right across the room and hurt yourself. So DO NOT TOUCH the spark plug lead,the plug or the ignition coil.
Now, what happens when you push your switch is nothing :) but, as soon as you let your finger off there would be a spark at the plug. The spark occurs when the switch opens after it was closed for a short time. Do not close it for too long or your battery will go flat.

The other advise you got about a capacitor is a bit misleading, if you charge it from the 12V battery nothing will happen. But, if you charge it from 100's of volts you see fireworks if you touch it. DO NOT try to charge capacitors from the mains voltage - it will kill you.
Klaus
 

L3wis

New Member
hi all thxs for the advice so far... more complicated that it first seemed then. I've made an electric shock box before which had huge voltages (but very small current!) i touched that and was fine. Current that kills not voltage right? but anyway i try and get a drawning done later today.
 

Klaus

New Member
Lewis, what kills you with electric shocks is the current that passes through your heart. Now, the dry skin has quite a high resistance so it requires more volts to pass sufficient current (about 5 mA, 0.005A) to upset your heart beat.
Of course, there has to be sufficient current available from the source. A small shock coil might not have that much current available at a high enough voltage output to overcome your skin resistance.
Now, if your hands were wet or you are sweating a bit your skin resistance will be a lot lower, ditto if you have cuts in your skin. So, less voltages will give you a much bigger shock.
Always wear good insulating shoes and touch your projects with one hand only to avoid current flowing through your heart to the ground via your feet or via the other hand.
So, its voltage *and* current that's dangerous. DC will cramp your muscles so you cannot let go what you touched, AC might throw you off (if you are lucky and you are not dead already).
Take care with that stuff.
Klaus
 

David M

New Member
Why not use a barbeque butane lighter. You can buy them for 4 dollars at Canadian Tire. The principle is like a spark plug, but doesn't use any batteries at all. You just press the red button and a spark is emitted!! That s what I use to ignite my potato gun.
 

Klaus

New Member
"The principle is like a spark plug, but doesn't use any batteries at all."

Sorry, these BBQ lighters do not at all work like a spark plug. Inside you will find a piezo element ( little ceramic block) which is struck mechanically as you press the trigger. This produces a high voltage spike, enough to jump a spark gap.
Its a bit difficult to operate the trigger remotely with these. And it would certainly be safer to push a button while ducking behind a brick wall in order to fire a propane filled potato gun :D
At least, until one is *very* sure the barrel chosen can take the explosive punishment
:wink:
Klaus
 

L3wis

New Member
hummm good idea with the bbq lighter. But i think i prefer the safer method of the electronic approach. How would i go about wiring things if i used a car battery as my electrical source? Could i put that straight into the spark plug? and where can i get a decent switch that will hold lots of amps?
 

trikebuilder

New Member
Lewis,
Your making this thing too hard! a simple lever will allow you press the BBQ button easily, and the spark it makes is very dependable. Make sure the spark contacts are clean, and the peizo unit works very well. (used on on a spud gun for nearly a year, and never had a failure. I even ganged two BBQ units to the trigger lever and had insured ignition. It takes about 25,000 volts to jump a 1/4" air gap. You would need a battery, a coil, and some way to break the primary circuit to produce a nice spark on a spark plug. The BBQ units are easier and lighter!
 
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