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Using camera flash cricuits as an igniton source for a combution cannon can be extremely tricky, but if you having a general idea of what your doing it will save you a alot of time and frustration. After many fail attemts with a BBQ ignitor (The things always broke for me). I set out to try and find a cheap reliable ignition source. After three years of fooling around, I figured out that the flash circuit from a disposable camera was an extremly cheap and very effective igniton source and and i could make a almost fall proof ignition setup.
The way the flash works is that a small capacitor discharges into a hv transformer which ionizes the air in the flash to tube making the air resistance almost zero, which then alows the larger capacitor to disharge and create the flash. so basically all you have to do is replace the flash tube with a spark gap, like this one.
the wire in the middle is connected to HV transformer and the other to bent wires are conneted to the leads of the capacitor. so when you discharge the small capacitor it will go into the HV trans and this will result in the air be ionized beteewn the center wire and the two bent ones which then allows the large capacitor to discharge. the gap between the bent wires and middle wire has to be very small but it will still result in a discharge of the capacitor and ignition.
heres a pick of a camera flash circuit bored i have (I fried it though)
the trans circuled in red is the hv trans which you should connect to the middle wire on the spark gap. the wires circuled in green connect to the main flash capacitor and should be connected to the bent wires separatly.
the cap ciculed in blue is the samll capacitor that discharges into the hv trans. the switch to trigger the smal cap to discharge is on the back of the bored.
But wait, what if your circuit boared is different then the one here? First make sure the camera flash works before dismantling tha camera. then make figure out how the flash works before you pull it out of the camera. Usually, the circuit bored is not ment to last a long time, so the companies use these cheap little switch things which you can replce with almost any decent switch. the down side though is that it usually takes a coouple seconds for the capacitor to charge up, but 95% of the time you'll get ignition the first time. Also, discharge the main capacitor (short the two wires coming out of the capacitor with something medlle, which will probably result in a lot of sparks). when you done cover the back of the circuit boared and electronics with elctrical tape so the thing won't short out and fry it self.
hope this helps
Last edited by Killjoy on Thu Jan 11, 2007 10:39 pm, edited 1 time in total.
These sparks are usually pretty hot! They're MUCH hotter than your standard BBQ igniter, (more current), and they give a nice pop when firing.
BUT, I still haven't had a piezoelectric igniter fail on my yet. Usually, the issues I see people having with those is that the spark is shorting somewhere outside the chamber, or they're trying to run it through a freaking 1/2" spark gap!
DO YOU HAVE TO USE ALL CAPS?
hmmm, what do you think? I think it may result in more complete combustion of the fuel, so yeah, probably works a little better, but nothing significant.
Persistence is a measure of faith in yourself
Theres no real noticable increase in power, I just use this setup cause its cheap and I have access to everything I need to make it.
I have another setup though that uses a camera flash circuit which does have a noticable increase in power of the cannon, its still being tested though so I'll put it up here when im through with the tests.
Camera flash circuits are more difficult to wire up because the circuit boards are rarely the same between builders unless you make a point of getting an identical camera.
Not to mention the gap has to be dam small for it to arc ~1mm.
Piezos just need 2 wires about 5mm apart.
A combusted mix can't tell the difference ^_^
you don't want to go touching this one...its in the deadly zone from what i know (amperage wise)
I have a few of these boards in the electronics bin. ill have to try this one some time.
hotwired, yes they may be a little more chalenging to wire, but though their circuit boards may be different, they all work the same, and its not that hard to figure out how to wire one. This setup also alows you to to add all sorts of bells and whistles (switchs, lights), which you can't really do with a bbq lighter. And its cheaper for me to get the camera flash circuit board then it is to get a bbq lighter.
You can aslo discharge the capacitor from a camera flash circuit through an ignition coil which will result in an extremly hot and large spark (ive gotten sparks over 1 inch in length)
That is a good idea i dont no why i dident think of it myself and yes it would realy hurt if u thouched it its like a eletric shock
Ah well. I'd still go for the battery free convenience of a peizo. Eventually you'll spend more on the batteries
I've got a capacitor bank of 12 flash caps for a coilgun and they eat batteries. The spark from that lot is louder than my cannon
In that case, your coil has far too little resistance.
A coilgun should be nowhere near as loud as that.
Novacastrian: How about use whatever the heck you can get your hands on?
frankrede: Well then I guess it won't matter when you decide to drink bleach because your out of kool-aid.
...I'm sorry, but that made my year.
dam small spark gap...or do you have them just barley toucing to make the spark??
if they are touching then it would eventualy run out of wire...
and did u make a switch for it to charge the camera before flash? you can't just chrge then it goes cuz it would just have a small connection and while there is only a small amount of energy that goes through.
if anyone could draw ou how it works (a.k.a mabey a tutorial to make it) or if you could post pics of it hooked to your cannon i would loooooooove that
Just so everyone knows, I was trying my hand at this and I had the capacitor dump it's charge into me... The amps aren't high enough to do damage, but the voltage was at 330 and quite unpleasant. I am now wearing dishwashing gloves...
i am trying to wire up something like this only its gonna be like a camera stun gun..it dumped 2 times on me..it hurts..bad..im not feeling to good right now i have a damn bad headache and i couldnt move my legs for a bit...but anyway where should i hook my wires to? like on each side of the light thingy?? mine looks nothing like the one in the tutorial..im confused..
4" piston valved cannon-half done..( i spilt my cement...)
Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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