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can you use a spark plug for a potato cannon? Answered

i have a spark plug at home and have no idea how it works, all i know is it makes a spark



Best Answer 6 years ago

You'd be better off with a grill igniter like this.

Connect the positive lead of a 12V battery to the end where the spark plug cable goes and the ground to the threaded end and you will have a spark jumping across the prongs. But you need to use a good sized battery like a car battery that offers allot of amps.

You can certainly adapt it for a potato gun.

Spark plugs no make spark? Next you're going to be telling me a raincoat won't make rain. Or that I can't grow birds from birdseed. ;-)

Jack...Jack, how can I break this to you ?

You know all about the stork, right ?

The spark plug is just the last part of the spark chain. To go along with it you need something that will generate 7,000 to 20,000 volts. That's what creates the spark. You could do that by hooking a car spark coil up to the spark plug then powering the spark coil with a 12 volt battery. All you need for control is a momentary push button to turn the battery on then off.

So the answer is "yes" but there are easier ways.

You can use it as a spark gap, but you will need a high enough voltage to create the spark. You could use an automotive coil, but that is a lot of unnecessary complication and cost unless you have one about. A better option is to use a piezo igniter out of an old BBQ.

You're really not kidding about having "no idea how" a spark plug works.

However I think I have an analogy to improve your understanding.

A spark plug plays the same role in an ignition system that a coffee cup in a coffee system.  A coffee cup does not make coffee.Rather a coffee cup is a convenient place to put the coffee, which is made by a coffee maker.

Similarly a spark plug does not make spark. It is simply a convenient place to put spark. It is a spark container.  In contrast, the spark itself, also called a "high voltage pulse", is made by some other part of the ignition system.

So using a spark plug for your potato gun is a good idea. A spark plug is a good place to put spark. But you still need some contrivance to actually make the spark to put there.

So, how does one make spark?  How does one make high voltage pulse? There are a number of ways to do this.

One sort of quick, and too easy, way to make spark is by using one of those piezo sparker modules from a barbeque lighter.  There are a few pictures of such a module in this instructable:

You don't have to put it in a pen body. In fact the enclosure it comes in already has a big plastic trigger, so that's convenient.  Mostly you just need some wires to connect it to your spark plug.

But I said this method is too easy, and what I meant by that is the piezo module is kind of a weak source of spark, and it only produces one pulse per trigger pull, and in my experience trying to get one to ignite a potato gun is kind of a swing-and-miss game.  Not every trigger pull causes the gun to fire. It's more like: Click. Click. (Try again.) Click-Boooom! Oh! So that one worked. ;-P

A superior way to ignite a potato gun, is to actually build a circuit to drive a "spark coil" (also called "ignition coil") on and off, at a frequency of maybe a few tens or hundreds of times per second. That way, as long as the trigger is held down, you've got spark in the spark plug.

There are few instructables on building such a spark-making ignition coil driver.