spudcannon project help

[kamikaze33]

hey guys just found this forum through google haha
anyways
im really interested in electronics n what not, dont know why im not going into a related profession but w.e. anyways i can solder stuff and thats about it. ive taken apart tonnes of **** and stockpiled a bunch of parts for use when i eventually understand this stuff, thank god i found this forum now i can finally get to it

anyways

im making a spud cannon, and instead of the conventional bbq push-start ignition id like to rig a joystick to the ignition and use the trigger from that to fire it. i have no clue how to do this however, and am just taking a shot in the dark. can it be done? im sure everyone already knows on here but if someone doesnt know how a bbq lighter works its basically just a short circuit that ignites butane i believe. if thats wrong sorry im a r00K
help/input/links would be greatly appreciated

 

[ormo]

The traditional combustion spud launcher isn't very powerful. My advice would be not to bother with any of the combustion models and do some research on the pneumatic models.

 

[Hero999]

A BBQ igniter generates a high voltage pulse by firing a metal pin at a piece of piezo crystal. The pulse has a fairly low energy so it feels no worse than a static shock and can't kill a human but I've zapped insects with a piezo igniter before.

 

[kamikaze33]

A BBQ igniter generates a high voltage pulse by firing a metal pin at a piece of piezo crystal. The pulse has a fairly low energy so it feels no worse than a static shock and can't kill a human but I've zapped insects with a piezo igniter before.

haha ya i shocked myself a few times on it. would there be a way to just rig a short circuit somehow then so i can still have it fire via joystick?

 

[Ankulake]

Hey Kamikaze, I'm new to this site as well, but I can do a little more than just solder stuff. So let's see if I can help you.

Sure, the pneumatic cannons are more powerful, but you want to make combustion; I can appreciate that.

So you want to have some remote button of some sort that will ignite the gas in your combustion chamber. So you need an arc of some sort, just like what's in the BBQ behind the house. If we want to do this with the piezo-electric idea, you'd likely be looking at using the switch to start a motor that would load then release a spring to smack the piezo crystal. So this is still using the ignitor from the BBQ, but with an unnecessary step in there.

I think what you are looking for would be something strictly electronic, without the physical motion, right? If that's the case, I think something with a capacitor discharging would do the job. Let me get out the old electronics kit and see what I can get going here.

 

[Hero999]

haha ya i shocked myself a few times on it. would there be a way to just rig a short circuit somehow then so i can still have it fire via joystick?

I don't know what you're talking about, a short circuit is an unwanted connection which stops something from working. If the piezo igniter is working properly there won't be a short circuit.

 

[crutschow]

It wouldnt be a joystick, but you could use a BBQ type igniter remotely. Just run a high voltage wire and a ground wire from the ignitor to a sparkplug in the cannon.

If you want the ignitor to be electronic then you could use an ignition coil to fire the sparkplug. A 1uF cap charged to a 100V or so and discharged through the coil primary by an SCR will generate the spark.

 

[kamikaze33]

oh sorry i thought thats how the piezo was working cuz when i took mine apart only one of the wires went to the end of the butane hose
yes id like to have it electronic as opposed to mechanical. i have enough knowhow with my paintball guns that i could probably make a pneumo one but combustion seems to be the cheapest option for starting atm anyways
and thanks a bunch ankulake i was thinking of using a capacitor as well. i also thought about spark plugs, but like cruts said id prefer it to use the joystick

 

[kamikaze33]

got it working! its primitive but it gets the job done! ill post pics when i finish the cannon!
heres the circuit and such
**broken link removed**

 

[Hero999]

The 300V from a capacitor isn't high enough to create a spark, the trigger transformer might do it but it certainly doesn't produce much energy. The best way of producing the spark is to use a automotive ignition coil.

 

[kamikaze33]

ya good point. it works but im not sure itll work well enough to actually ignite a large volume of gas. ill look into the coil this weekend thanks!