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random stun gun sparking

Posted: Thu May 01, 2008 6:00 pm
by Big D
This is my first post here but i've been browsing for a while now but i have ran into a bit of a problem. A little background before i start is in order i suppose.

My gun is an advanced over-under combustion with:
Chamber - 36" of 3" pvc
Barrel - 60" of 2" pvc
Chamber fan and 2" Ball valve for quick venting
Metered MAPP currently
350V Stun gun with 3 spark gaps

I have no issues with firing when the stun gun actually sparks but often it doesn't. It will usually work until i fire it once and try to spark it again. It usually will not do anything at all or sound likes its fizzling. Sometimes after a minute or so of venting it will began to fizzle then spark like normal. It might be evident but the gaps are wired in series exactly like on advancedspuds.com.

I have changed the battery countless times in the stun gun and have checked to see if the default gap works. (it does) I have rewired it countless times and am using 12g wire. The gaps in the chamber are made like normal with screws with are insulated after they are screwed in. I have taken the screws out, changed them and cleaned them before.

I can not find any visible shorts or hear them. This seemed to have started when i switched from MAPP to propane but i do not believe this is the propblem because i have tried using propane since it has stopped working and it does not.

I think thats all, feel free to ask for extra information i may have forgetten. I am out of ideas on what too try to fix this problem, any help will be greatly appreciated. Thanks.

Posted: Thu May 01, 2008 6:07 pm
by pat123
How far apart are the gaps?

Posted: Thu May 01, 2008 6:08 pm
by jrrdw
Post pics of all the components so we can get a look. A video of the malfuntion would be great if you can.

Posted: Thu May 01, 2008 6:14 pm
by Big D
I would love to post a pic if i could but i do not have a decent camera at all. The gaps are very small, maybe 1/16 of an inch but i have scaled them up to as big as all 3 can be while still sparking until shot. The inside of the chamber is just 6 screws in pairs of 2 drilled into the chamber, thats all that is inside the chamber; no wires or anything else except for the chamber fan screws.

Posted: Thu May 01, 2008 6:48 pm
by pat123
will they spark withoout propane in the chamber?

Posted: Thu May 01, 2008 7:12 pm
by Big D
It will until i shoot it, then it will usually take a while almost like it has to air out before it will spark again. When it begins to spark, it will continue to spark until shot again.

Posted: Thu May 01, 2008 7:23 pm
by pat123
try it with the gaps about 1/4" apart. 1/16" maybe too small of a gap to ignite the mix and if you have it at the absolute largest distance in air then it wouldn't light with propane in it.

Posted: Thu May 01, 2008 7:32 pm
by bigbob12345
I dont think it is the sparker that is the problem, i think you dont have a chamber fan to exhaust the spent gasses inside the chamber and they interfere with the propane igniting properly.
So if you dont already have one get a chamber fan and a ball valve vent

Posted: Thu May 01, 2008 7:58 pm
by Big D
Pat:
When the stun gun sparks it has no problem igniting the mix and the sparks are set at about 1/8inch for each.

Bob:
I do have a fan and a ball valve for venting already but my question is, can the spent gasses actually interfere with sparking? That is almost what seems to be the problem because it works after it vents generally.

And thanks for responding so quickly and trying to help :)

Posted: Thu May 01, 2008 8:05 pm
by starman
Big D wrote:Pat:
When the stun gun sparks it has no problem igniting the mix and the sparks are set at about 1/8inch for each.

Bob:
I do have a fan and a ball valve for venting already but my question is, can the spent gasses actually interfere with sparking? That is almost what seems to be the problem because it works after it vents generally.

And thanks for responding so quickly and trying to help :)
Make sure your fan is sucking fresh air into the ball valve vent and exhausting out the barrel. If you try to blow exhaust out the vent, it just pulls gases back down the barrel and into the chamber...not nearly as efficient a process.

Yes spent gases can interfere with sparking. However you said you had a 350 v stungun?? Are you sure that's correct...sounds way low. Modern ones are usually 50k volts and much higher.

Posted: Thu May 01, 2008 8:06 pm
by Big D
Yep, the fan is definetly sucking fresh air in.

Posted: Thu May 01, 2008 8:15 pm
by starman
We really need to see you spark setup and placement to help you much further. Try to find a digital camera to get some shots. Maybe this is the moment you've been waiting for to run over to Walmart and pick one up...basic ones really are quite affordable these days.

Posted: Thu May 01, 2008 8:54 pm
by Big D
Could the paint on the gun short the spark where the wires are connected to the screws? I am not really sure whats in paint but when i look into the chamber and spark the stun gun, i see blue rings around the two leads where the screws are.(I took the MAPP off before looking into the chamber for safety) It was painted before but still worked so i don't think thats the problem but i'm throwing it out there.

I managed to get a camera but the pictures are 3x the size they should be. I've never worked with pictures on a computer, is there any way to resize them? (Their about 1.2mb each)

Posted: Thu May 01, 2008 9:02 pm
by starman
Big D wrote:Could the paint on the gun short the spark where the wires are connected to the screws? I am not really sure whats in paint but when i look into the chamber and spark the stun gun, i see blue rings around the two leads where the screws are.(I took the MAPP off before looking into the chamber for safety) It was painted before but still worked so i don't think thats the problem but i'm throwing it out there.

I managed to get a camera but the pictures are 3x the size they should be. I've never worked with pictures on a computer, is there any way to resize them? (Their about 1.2mb each)
You'll need a basic photo editor to scale them down some. There's a good chance there was one included with the camera. I personally use an old copy of Paint Shop Pro. Go to www.downloads.com and find yourself something that will do the job.

Posted: Thu May 01, 2008 9:27 pm
by Big D
Image

This is of the stungun with a pushbutton switch instead of the rocker it came with.

Image

Just a picture of the gun for reference. The duct tape is holding 5 couplings together which are used as a sliding breech for easier loading.

Image

This was about the best picutre i could get of the 3 pairs of screws for spark gaps, other than the screws for the fan, this is the only thing in the chamber. (at the back of the chamber is some excess potato garbage i need to dump out)

Image

The fan and ball valve

Image

This is of the screws and wires. The screws have black tape over the top of them and the wires to insulate them a bit more. It is a bit sloppy because the angle of the holes doesnt allow them to be put all the way in without touching. Ill be grabbing more screws sometime soon for the aesthetics issue.

When i discconect the leads from the screws and use the pushbutton switch, the spark takes the default gap so i know that is not the problem.