As I previously mentioned, this cannon won't be hand-held, and it will be on a mount I've only recently started to make (I had to finish the cannon itself first).
Here's what I'll show ya tonight. On the very top are two cable-hiders, I will be using the large one to mount my fan on and to mount the spark strip on. It'll also double as, well, its intended use as a wire-hider inside.
The smaller one may be used outside as a conduit where needed -- not sure on this one yet though.Just below that is my concept spark gap using copper circuit tape -- works great, will touch back on that later. Next to that is my measuring square, no big deal. Just giving you an idea of scale.
Below that, is my actual system. My 80mm x 38mm/80CFM Delta fan, my control box (made out of a PVC conduit L box, VERY nice for what I used it for!), and my power source, a 12V AGM battery yanked out of a snowmobile. I'm not sure of the amperage but I imagine it's at least 10Ah. This puppy will last a while before needing a new charge
Close-up of my spark gap concept. The electric tape is where I temporarily aped the sparker wires so I got an idea of how far I can get away with gaps. With a piezo igniter, I could only close one gap, and the second one did too if I helped close it a bit more using something metallic. The copper tape looks crappy, but it'll look nicer when acutally implemented -- this was just to get an idea of what to expect when I actually implemented it.
Ah, the rat's nest of my control box. I used a 6x2 terminal strip as the center. Wiring was pretty tricky (and yeah, I confess it's incredibly messy. I'm sure there could have been a more efficient way of doing this). There's two toggle switches -- one's a master power switch and the other's the fan switch. Right now, the firing mechanism is totally independent. But when I get a better sparking device that'll actually work with 12V, I'll incorporate it with that. Notice my liberal use of crimp connectors. They do work, though the ones I used totally suck. At least I did ok crimping.
A shot of the whole system lined up. The battery wires are connected by.. gravity! I didn't feel like adding temporary alligator clips and it's only for testing.
My system when turned on. Pretty green LED
My system with the fan turned on as well. You can kinda see the fan spinning, though it's at 5700rpm so it's hard to see it sometimes in photos. The fan's so powerful I had to place my square behind it to keep itself from moving. If I killed the master switch, it'd kill power to everything; I designed it this way so when I incorporate a better sparking device, it'll be an additional safety factor. Not to mention with that fan being able to chip skin off my fingers like they were potato skin shavings, I highly prefer to be able to kill the fan quickly. (I'll be adding a fan guard though, to minimize this as well)
Note there's some space to the left of the ignition button (In the previous picture, it's actually displayed upside down; the LEDs are technically on the right side of the panel, and the piezo on the left) -- I plan on adding a volt meter there to monitor the battery voltage, and a control button for propane injection. That's for the future though, and I need to finish my mount first.
Oh yeah, and those two half-assed holes below the toggle switches will be covered up. Those were my first attempt to add the LEDs, but my drill press had issues on my first attempt. Doh!
So there ya have it, I'm not proud of the wiring but it does work and is quite reliable. I ensured there's as little chance of shorting as possible, and I've tested it by shaking and pounding the outside pretty hard.
If anyone can think of a more efficient way of wiring, I'll post a schematic of what I did and maybe someone can improve on it. This system works, but I bet it can work better.
