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Camera Flash Circuit Questions & Comments

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: mark.f » Sat Sep 29, 2007 5:54 am

You're right. In the setup you see above, the ionization electrode is the bottom one, and is placed below the spark electrodes, (90* to each other).

I believe it has more to do with the surface area of the ionization electrode than the placement, though. A few tests with a copper plate, (cut from some tubing), would confirm or deny this.
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Unread postAuthor: CpTn_lAw » Sat Sep 29, 2007 6:00 am

I'd recommand we try to wire a few capacitors in parallels, so that we see if the spark gap can be even bigger.
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Unread postAuthor: jimmy101 » Sat Sep 29, 2007 6:22 pm

More caps in parallel won't increase the voltage, just the power. You'll get a bigger bang in the gap but you won't be able to use a bigger gap.

Pretty impressive what the cheapo flash board and a 1.5V battery will do isn't it! When the trigger only voltage jumps it makes little or no noise and a barely visible spark. When the full 300V@120uF (5.4 Joules) jumps it sounds like a small firecracker.
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Unread postAuthor: irishguy » Sun Sep 30, 2007 1:16 am

one or two more questions i blew five boards today am i suppose to be using an anti static strap and how do you test a capacitor to see if its working
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Unread postAuthor: CpTn_lAw » Sun Sep 30, 2007 6:47 am

I got shocked yesterday. Took the 6 joules and god it hurts!!
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Unread postAuthor: Mr.Russ » Sun Sep 30, 2007 8:00 am

ive been reading about these for a while, and im not good with all the names of electric parts.

ive heard of making tazers out of disposable cameras. is this like what your doing?

you have the camera, take the case off and rip the flash bulb thingy out. then do you solder a wire to each side, and connect them to screws in a chamber?



the tazers i have read about just have 2 wires sticking out, you charge the flash and then touch the 2 wires to the person you want to taze. is this similar to the way you are using it for ignition?

sorry im a noob with this stuff.
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Unread postAuthor: CpTn_lAw » Sun Sep 30, 2007 8:09 am

Well, let's explain this a little.
You have current, stuck in the positive lead of your capacitor, and waiting for something to make the contact with the negative lead in order to close the circuit. Touching the two leads between themselves short circuits the capacitor and is bad for it. So you need to come across something else for the current to travel. Disposable cameras are in fact equipped with a high-voltage lead coming from a little transformator, that basically ionises the gas in the bulb of the flash. Ionised gas has a very very little resistance enabling the current to travel through it, exciting the atoms and generating light.
The air has a much more higher resistance than argon or krypton in the flash bulbs, so you still need to ionise the air between the capacitor leads. When you trigger your project, the HV lead ionises the air reducing instantly its resistance and allowing the current to "jump" from the positive wire to the negative one of the capacitor. this is the spark gap, basically a lightning-fast stream of high energy particles.

And, after yesterday, i believe a tazer can be made from those circuits...
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Unread postAuthor: Mr.Russ » Sun Sep 30, 2007 8:16 am

CpTn_lAw wrote:Well, let's explain this a little.
You have current, stuck in the positive lead of your capacitor, and waiting for something to make the contact with the negative lead in order to close the circuit. Touching the two leads between themselves short circuits the capacitor and is bad for it. So you need to come across something else for the current to travel. Disposable cameras are in fact equipped with a high-voltage lead coming from a little transformator, that basically ionises the gas in the bulb of the flash. Ionised gas has a very very little resistance enabling the current to travel through it, exciting the atoms and generating light.
The air has a much more higher resistance than argon or krypton in the flash bulbs, so you still need to ionise the air between the capacitor leads. When you trigger your project, the HV lead ionises the air reducing instantly its resistance and allowing the current to "jump" from the positive wire to the negative one of the capacitor. this is the spark gap, basically a lightning-fast stream of high energy particles.

And, after yesterday, i believe a tazer can be made from those circuits...


okay well..

i did not understand one word of that.

sorry, for being stupid but i have one question.


can you hook the camera up to 2 or 3 bolts in your chamber, charge the flash and press the button on the camera, and make a spark in your chamber? without buying and other parts.
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Unread postAuthor: CpTn_lAw » Sun Sep 30, 2007 8:18 am

no you can't., you have to understand what you are doing as you are dealing with near-lethal current. and it's three bolts when the mounting is complete.
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Unread postAuthor: Mr.Russ » Sun Sep 30, 2007 8:24 am

okay ill just stick to bbq igniters then
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Unread postAuthor: TurboSuper » Sun Sep 30, 2007 4:02 pm

I has a question:

The ignition coil appears to be designed for use with 12V. So could you just hook it up to a 12V source, and avoid the camera flash alltogether? I'm sure the spark would be considerably shorter...but it should still work, rite?
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Unread postAuthor: CpTn_lAw » Mon Oct 01, 2007 11:10 am

i didn't quite get your point sorry...?
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Unread postAuthor: Fnord » Mon Oct 01, 2007 11:22 am

I has a question:

The ignition coil appears to be designed for use with 12V. So could you just hook it up to a 12V source, and avoid the camera flash alltogether? I'm sure the spark would be considerably shorter...but it should still work, rite?


You could, but the spark will be very small. For a normal cannon it should work, but for a hybrid it won't. I would use the camera flash if I had one avalible, as it doesn't take that much extra work and you can make tons of spark gaps with it.
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Unread postAuthor: jimmy101 » Mon Oct 01, 2007 4:06 pm

_Fnord wrote:
I has a question:

The ignition coil appears to be designed for use with 12V. So could you just hook it up to a 12V source, and avoid the camera flash alltogether? I'm sure the spark would be considerably shorter...but it should still work, rite?


You could, but the spark will be very small. For a normal cannon it should work, but for a hybrid it won't. I would use the camera flash if I had one avalible, as it doesn't take that much extra work and you can make tons of spark gaps with it.

Yep, a 12V power source, a switch and the coil will work. It works great in a car which is an ~8x hybrid with a single spark gap of ~0.03".

You need a pretty serious 12V supply, 8 AA batteries in series won't supply enough current. A 12V wall wart might work if it will supply at least a couple amps. A 12V car battery charger will work, as will a car battery or one of those car emergency batteries. At the required current levels you have to be careful, 12V from a car battery will knock you on your ass if you touch the wrong thing.

The switch needs to be pretty beefy. A generic little toggle switch or push button from Radioshack will get fried pretty quick. A standard 120VAC, 15Amp wall switch will last much longer. You can get one for a buck or two from any hardware store.

The coil will spark when you disconnect the power.
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Unread postAuthor: mark.f » Mon Oct 01, 2007 5:42 pm

Jimmy, we've used 8 AA's in series to power an outboard motor's coil before. Now, we use a motorcycle battery. I didn't see much difference in spark, but I guess that's a matter of opinion. Since the voltage across the secondary coil is a function of the instantaneous rate of change of current in the primary coil, I'd want to work on my switching system before adding amperage to my 12 volts. I've heard that switching your primary coil after the - electrode going to the ground of your battery gives you the best voltage in the primary. I guess you'd have to test that to prove it, though.
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