I want to be able to make a new spark system for my potato cannon since the barbeque starter and spark plug are inadequate (even the battery powered starter with the AA battery). I'm wondering if I can make a bigger case by myself and use one of those huge 4"x2.5" batteries with the terminals on top across a homemade transformer to make a larger current? I just need a bigger spark across the sparkplug...
What you want is a higher VOLTAGE, not a higher current. If you want to use a larger battery, why bother winding your own transformer. Use an old automotive ignition coil from a junkyard.
Well I want to be able to have my potato cannon portable and without some fuckin car battery hangin off the side of it. And we have no junkyards around here, I'd have to order it... I'd rather just make something small and powerful... A stungun is out of the question. I figure taking the idea that has been already implemented into my electric starter and running with that idea is the best way to go... Can't you just buy small transformers from Radio Shack (The Source).
You wouldn't need a "fuckin car battery", just a 12V battery, such as the gel-cells used for burglar alarm panels, emergency lights, etc. Certainly one of the 4"x2.5" ones you mentioned would have enough capacity for many, many shots before recharging. If you don't have a junkyard, how about an auto parts store? You want a generic old style ignition coil, from the days before electronic ignition. I have one around here from a early 70s Mopar slant 6 which works great for such applications. Shouldn't cost more than $20 or so to buy one like it new. Other than a stungun, there aren't too many other devices around that take low voltage DC in and output high voltage sparks. If you could use AC power, my first suggestion would be an igniter module from a gas oven or furnace, but I doubt you want to be tethered to an extension cord. Your best bet is going to be some kind of homebrew setup, and by using a premade HV transformer in the form of an ignition coil, you avoid the hassle of winding and insulating the thing properly. If all you want is a single spark at a time, a heavy switch in series with the primary winding is all you need. If you want something a bit sexier, an electronic driver like these would be even nicer: http://www.geocities.com/capecanaveral/lab/5322/coildrv.htm http://www.powerlabs.org/igncoildrivers.htm Another possibility would be a salvaged horizontal sweep transformer ("flyback transformer") from a discarded TV set or computer monitor. This would take a bit more electronic knowledge to get going, though. Here's a good starting point: http://members.misty.com/don/samflyhv.html Not sure about Canada, but Radio Shack here in the states has long-ago ceased to be a serious source for anything more than cell phones and overpriced patch cords. Certainly nothing like a high voltage pulse transformer to be had.
What about a rocket ignition? They are small batteries and seem to set off the rocket engines pretty good. Get it at the local toy store.
