Spark rail issue

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alkapwn1
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Sun Oct 12, 2008 10:08 pm

Ok, I've built a spark rail for my first combustion cannon but it seems when i try to test the whole rail together it doesn't work.
I have 3 spark gaps on it.
I'm using a wooden dowel with 3 small PVC rings attached to it. (Each ring has a spark gap)
I'm using screws for the prongs and some small wire to connect each gap and the ignition source.
My ignition source is a simple click BBQ igniter (non-electric)

The rail sparked fine when i connected the ignitor to each gap individually, but when I wired them all together and tried to spark them all together they dont spark.

I have it wired correctly, im damn sure of it but I think its because my ignitor doesnt have sufficient power to light all three at once. I think it might be the size of the gaps thats the problem. They are 4-5 mm apart each.

If anyone could help me out I'd be very appreciative. Thanks
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jook13
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Sun Oct 12, 2008 10:43 pm

I'm no expert but I believe your spark gap has to shrink when you make multiple gaps. try shrinking that gap? If that isnt it perhaps some pics and/or diagrams are in order?
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Pilgrimman
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Sun Oct 12, 2008 10:57 pm

Your gaps are definitely too far apart. Just find the max spark length that your ignitor will do, and divide it by 3 to get your gap size for each individual spark. For most ignitors, you will get a total of about 1/2", so your gaps should be 1/6".
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starman
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Sun Oct 12, 2008 11:05 pm

Here's my PVC "rail". Gaps are as small as I could get them with a dremel cutting wheel, roughly 1/16" each.

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mark.f
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Mon Oct 13, 2008 9:05 am

First, take the cannon into a dark room and trigger the sparker to make sure there are no shorts outside the launcher.

If there are none, then shorten the spark gaps.
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psycix
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Mon Oct 13, 2008 1:35 pm

4-5mm each, 3 gaps? Too large.
That comes down to 3x5=15mm
A good spark system has less then 5mm in total.
Make sure that every gap is 1mm or less and it will spark just fine.
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alkapwn1
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Mon Oct 13, 2008 4:11 pm

ok thanks all of you for helping, I just have to find the correct lengths of screws to put into it
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mrbadexample
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Mon Oct 13, 2008 5:18 pm

hopefully, you'll use propane as a fuel, hair spray and deoderants have water in them and would foul those tiny gaps over time. maybe later you could move up to a stun gun ignition system.
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