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Large chamber spark

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Large chamber spark

Unread postAuthor: pat123 » Tue Apr 15, 2008 4:10 pm

I was wondering what you guys thought would be a good ignitor for a 510 in3 8X hybrid? I was thinking about an electric bbq ignitor but I have never made a gun this big so I don't know if this is sufficient.
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Unread postAuthor: SpudFarm » Tue Apr 15, 2008 4:12 pm

camera capacitor and a ignition coil.

any specs?
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Unread postAuthor: psycix » Tue Apr 15, 2008 4:26 pm

Camera ignition? Blah too much trouble I think.
Take the easy way.
This gives enough volt doesnt it?
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Re: Large chamber spark

Unread postAuthor: Hubb » Tue Apr 15, 2008 4:35 pm

From my understanding, each atm that is added will essentially cut the spark in half. This means that if the spark, at normal pressure, is 1 inch, then in a 2x mix, the spark will be 1/2 inch, and so on.

I haven't tested this, but if it is true, then at 8x, you will need a spark from a 1 inch spark producer that is 1/128 inch. Now, I'm sure that is not entirely accurate, but that may be a good start.

If the above is true, and I was only able to produce a spark from my new electric BBQ igniter of 1/2 inch, which means your spark gap will need to be 1/256 inch.

In my hybrid, which is considerably smaller in size (but I'm not totally convinced that the size of the chamber is affected by spark size, just as long as there is a spark), my spark gap, using a stun gun (1" spark) is about 1/16 inch, and I have successfully fired it at 8x.

SpudWiki wrote:The ignition of a hybrid gun is more difficult than a normal combustion, as the length of a spark is roughly inversely proportional to the density of the gas. This necessitates the use of high-powered ignition source such as a stungun, flyback, or other high-voltage source; grill igniters frequently won't jump a spark gap in pressurized fuel/air environments.
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Unread postAuthor: DYI » Tue Apr 15, 2008 4:36 pm

It depends how long the chamber is.

And a camera + coil ignition is a lot easier than waiting a month for a stungun from BCARMS.

A quick tutorial, much simpler (and more effective) than the one in the Wiki:

1. Test the flash to see that it actually works. If it doesn't, take it back.
2. Take the case apart carefully, until you only have the circuits left.
3. Test again, by using the switch on the board.
4. Solder wires onto the positive and negative terminals of the capacitor, and run them to the appropriate terminals on the ignition coil.

You should now have a working sparker. You could rig more capacitors in parallel with the first one to get a hotter spark, but that really isn't necessary (unless you build your own charging circuit and use so many capacitors that the ignition spark actually adds to the overall power of the gun). :twisted:
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Unread postAuthor: STHORNE » Tue Apr 15, 2008 4:38 pm

you can just buy a stun gun from bcarms for $15.00 (+s&h). I'm planning on getting one from there myself.
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Unread postAuthor: DYI » Tue Apr 15, 2008 5:06 pm

The spark length is inversely proportional to the pressure.

So at 8x, a spark that was a maximum of 1" long at atmospheric will be a maximum of 1/8" long.

Hubb had some pretty faulty logic there, but it happens to the best of us :roll:

It probably doesn't happen to everyone, but I've waited more than a month now for my stungun, and it's never arrived. If you live in the US, that problem likely won't arise.
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Unread postAuthor: STHORNE » Tue Apr 15, 2008 5:10 pm

DYI wrote:It probably doesn't happen to everyone, but I've waited more than a month now for my stungun, and it's never arrived. If you live in the US, that problem likely won't arise.


did you order it from bcarms. and yeah, it probably takes longer to deliver to anywhere besides the U.S., as they are shipped from the U.S.
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Unread postAuthor: JDP12 » Tue Apr 15, 2008 5:14 pm

sorry STHORNE, you won't be able to get one...... stun guns are illegal in WI
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Unread postAuthor: STHORNE » Tue Apr 15, 2008 5:20 pm

yeah, but they will just take it out of the box and send it as a "high voltage circuit". it says that on bcarms.
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Unread postAuthor: Blitz » Tue Apr 15, 2008 5:22 pm

ilovetoblowthingsup wrote:sorry STHORNE, you won't be able to get one...... stun guns are illegal in WI


Actually, it's the housing that'd make it illegal, and if I remember right, BCARMS disassembles them prior to shipping to circumvent this and make it legal.

EDIT: meh, too slow. thanks sthorne. :P
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Last edited by Blitz on Tue Apr 15, 2008 5:27 pm, edited 1 time in total.
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Unread postAuthor: Hubb » Tue Apr 15, 2008 5:23 pm

Hubb had some pretty faulty logic there, but it happens to the best of us


But my number sounds better...

JK I knew it was something like that. Could you explain the math behind it? I tend to grasp things better that way.
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Unread postAuthor: pat123 » Tue Apr 15, 2008 5:37 pm

I don't want to spend too much money on it. I got the chamber for free and just the barrel and meter was $80. I might try a camera flash.
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Unread postAuthor: STHORNE » Tue Apr 15, 2008 5:39 pm

that would be your best bet if you wanted to go as cheap as possible.

get a camera flash, an old ignition coil, and wala! Spark Gap!
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Unread postAuthor: JDP12 » Tue Apr 15, 2008 6:59 pm

sweet! time to order one from BCARMS...
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