help on ignition

[koolaid]

I am trying to make a electronic igniter form a disposable camera and then hook it up to some steel wool. How would I do this? thank you in advance for your help.

[pudidotdk]

http://members.misty.com/don/kflashmp.gif

Cut over one of the capasitors (C2) legs creating to poles. Hook each pole to the poles of a female minijack.

Remove the little square (S1) that is fastened with tape, underneath you will see two poles, hook them up to a charging button.

Locate the firing poles (S2) (usually a copper and a silver colored), each is a pole, hook it to a ignition switch.

Unsolder the LED and solder two wires to it and solder to the place where the LED was.

 

Use a hobbybox...

 

(It ain't difficult)

[BombBuilder]

Actually there easier to search if you use the correct name of project box. Radioshack has a variety fo em.

[jacob]

You aren't the same person as cannon creator on spudfiles are you? your avatar is exactly the same. just wondering.

[Boomer]

Might I add that these work at 300 volts, with much more current (short time) than a mains socket? Not healthy if you don't know what you're doing....

[NightHawkInLight]

Yeah they will give you quite a zap. I have made a simple ignition system out of one of these boards just by connecting two wires straight to the capacitor with a light switch breaking one. Charge with the button and flip the switch.

 

Christmas light bulbs filled with a 50/50 mix of kno3 flash and BP and sealed with a wad of wax paper work well for igniters.

 

Now that I look at the top post it looks like this thread is rather old and I'm probably achieving nothing but wearing down my keys typing this.

[BombBuilder]

You aren't the same person as cannon creator on spudfiles are you? your avatar is exactly the same. just wondering.

Ya I am CC from spudfiles. Oand afterI finish my Det Box I will post a tutorial, maybe evenwith a vid to help everyone out.

[jacob]

I knew it, welcome to the forum.

[rev.redneck]

I do not understand why you need that type of power for igniter? If it is say, 300 V. it will not have any amps. if you want a lot of volts just get a bug zapper and remove the step up transformer. it will give somthing like 1500 V. Why would you use that circuit, hmm i dont understand. could someone explain?

[they call me 9 fingers]

theis type work great for igniting gas ( i.e spudguns) they will spark a spark plug no problem. Plus they are free, go to any one hour photo and ask for them, the have boxs of already developed disposable cameras. You might get some funny looks but they will usually give you as many as you want. They also work well for a mini coil gun I have found the most reliable way to wire them is remove the flash bulb and just solder the leads where the flash bulb used to be. One word of caution through when working on these things always take a screwdriver and short out the capaciter until no more sparks come out(looks cool) trust me you dont want to short it out with your hand when working on it, not fun, I still have the scar.

[EEguy]

Since no one has addressed the electrocution hazard here, I will take the liberty.

 

It looks like that capacitor is 160uF. Charged to 300V, that's over 7 joules of energy! DC currents as low as 300mA can cause ventricular fibrillation of the heart. With moist skin, the hand to hand resistance of a human body can be as low as 1,000 ohms. This means that if the capacitor were charged to 300V, then potentially 300mA would pass through the body. Since the capacitor discharges exponentially and Ohm's law is a linear equation; the current will also decay exponentially with a time constant of about 160ms. Basically, electrocution is possible under very wet conditions, but unlikely since the current is not constant. Also, those with weak hearts have an increased risk. This particular circuit of discussion would definitely give a good, frightful jolt to someone connecting the leads with their hands, through their chest. Most commonly, injury from this kind of accident is caused by violent muscle contractions, making the victim hit themselves or a near by object.

 

A capacitive discharge launch controller should be under 60V, which is below what international CE-safety standards consider high voltage. A half joule at 50V is plenty to fire most electric matches over very long cables if the bridge wire is 38 awg or smaller. For high current igniters like Estes, you simply need to add more capacitance; after all, they are designed to ignite from a 12v car battery.

 

NichroPulse has video demonstrations of 50V launch controller system over 500ft of 22 AWG wire with only 1/2 joule in the demo version:

http://www.youtube.com/watch?v=5nTYCGMO2MU

http://www.youtube.com/watch?v=BYPo9RGVviM

 

Good luck, and remember to be careful around high voltage charged capacitors. 7 joules can also cause burns if shorted through a low resistance path the you are touching.

[QED4803]

Since no one has addressed the electrocution hazard here, I will take the liberty.

 

It looks like that capacitor is 160uF. Charged to 300V, that's over 7 joules of energy! DC currents as low as 300mA can cause ventricular fibrillation of the heart. With moist skin, the hand to hand resistance of a human body can be as low as 1,000 ohms. This means that if the capacitor were charged to 300V, then potentially 300mA would pass through the body. Since the capacitor discharges exponentially and Ohm's law is a linear equation; the current will also decay exponentially with a time constant of about 160ms. Basically, electrocution is possible under very wet conditions, but unlikely since the current is not constant. Also, those with weak hearts have an increased risk. This particular circuit of discussion would definitely give a good, frightful jolt to someone connecting the leads with their hands, through their chest. Most commonly, injury from this kind of accident is caused by violent muscle contractions, making the victim hit themselves or a near by object.

 

A capacitive discharge launch controller should be under 60V, which is below what international CE-safety standards consider high voltage. A half joule at 50V is plenty to fire most electric matches over very long cables if the bridge wire is 38 awg or smaller. For high current igniters like Estes, you simply need to add more capacitance; after all, they are designed to ignite from a 12v car battery.

 

NichroPulse has video demonstrations of 50V launch controller system over 500ft of 22 AWG wire with only 1/2 joule in the demo version:

http://www.youtube.com/watch?v=5nTYCGMO2MU

http://www.youtube.com/watch?v=BYPo9RGVviM

 

Good luck, and remember to be careful around high voltage charged capacitors. 7 joules can also cause burns if shorted through a low resistance path the you are touching.

 

 

Actually it looks like that cap is 350uFd @ 160V. Since electrolytics are typically used at only about 50% of their rated voltage, it's unlikely that it will ever charge above a hundred volts. While I agree that caution is always indicated in messing with high potentials (or potentially high potentials, as it were), I doubt that it would be likely to get more than a good tickle out of the capacitor itself. Disconnect the power source and discharge the capacitor (preferably through a 1K-ohm or so resistor rather than with a screwdriver, which may damage the capacitor) before tinkering, and keep one hand in your pocket.

 

Where, BTW, does that 1K-ohm hand-to-hand resistance number come from? That sounds awfully low to me.

[EEguy]

Actually it looks like that cap is 350uFd @ 160V. Since electrolytics are typically used at only about 50% of their rated voltage, it's unlikely that it will ever charge above a hundred volts. While I agree that caution is always indicated in messing with high potentials (or potentially high potentials, as it were), I doubt that it would be likely to get more than a good tickle out of the capacitor itself. Disconnect the power source and discharge the capacitor (preferably through a 1K-ohm or so resistor rather than with a screwdriver, which may damage the capacitor) before tinkering, and keep one hand in your pocket.

 

Where, BTW, does that 1K-ohm hand-to-hand resistance number come from? That sounds awfully low to me.

 

 

 

If you look closer, it is 350V and 160uF (not 350uF 160V). 300V is common in flash circuits. And often in cheaper cameras, they charge to over the rated voltage by a little bit, not under. I am not sure where you are getting that 50% rule for an infrequent DC charge of a cap.

[QED4803]

If you look closer, it is 350V and 160uF (not 350uF 160V). 300V is common in flash circuits. And often in cheaper cameras, they charge to over the rated voltage by a little bit, not under. I am not sure where you are getting that 50% rule for an infrequent DC charge of a cap.

 

 

You're right on the values--I had to blow the picture up to actually see the labels. The 50% rule of thumb is generally applied to continuous duty (e.g. power supply filters); still I'm surprised that they would actually exceed the rated voltage, but I reckon the bloody thing only has to charge a couple dozen times in a disposable camera.

[EEguy]

You're right on the values--I had to blow the picture up to actually see the labels. The 50% rule of thumb is generally applied to continuous duty (e.g. power supply filters); still I'm surprised that they would actually exceed the rated voltage, but I reckon the bloody thing only has to charge a couple dozen times in a disposable camera.

 

 

Yes, I have heard of the 50% rule of thumb in SMPS design. I think it is for reliability, to allow for line burst (EFT) and surges from the mains as well as other faults. Reliability in power supplies and instrumentation seems to be taken more seriously than in flash charge circuits. I think your right; these circuits often have a short life span, especially in disposable cameras. And they only charge once in a while during their life. Which makes me wonder if using a disposable camera flash circuit for ignition is a good idea to begin with. Just how reliable are they? In my designs, I keep the DC charge voltage at or within the rated voltage of the cap, but the ripple may go over slightly.

 

And I forgot to address your query about 1k ohm seeming low for hand-to-hand resistance. It does seem low, but I was making a worst case scenario in wet conditions. This value will vary greatly between people. Often women and children have a much lower resistance than men due to thinner skin on the hands. So, a young girl with wet hands might be the worst reasonable case. Anyhow, back to flash circuits for ignition.....

[Arthur]

In commercial blasting it is usual to have high voltages so that many fuses can be shot in series. Commercial machinery seems to rely on insulated wire and terminals. The NATO approved exploder has a detection cct to ensure that the load cct is 400 ohms or less before it will actually fire This means that if there is a cap on the line it will fire but if only a person is holding it then it will not fire.

 

In fireworks it should be plenty to have 50v available to fire cues and this can often come from a sensible battery and a DC to DC converter -which is a single chip!

[snow]

i wouldnt recomend that, the camera give high power for small time for short steelwool it will just burn before it will get the BP hot enough to start burning

though with some expirince you can ignite the bp useing a spark you can get from the camera (best working with very fine and dry BP or flash powders)

[EEguy]

i wouldnt recomend that, the camera give high power for small time for short steelwool it will just burn before it will get the BP hot enough to start burning

though with some expirince you can ignite the bp useing a spark you can get from the camera (best working with very fine and dry BP or flash powders)

 

 

 

Yes, I doubt that many would light BP directly from this circuit. Use a more sensitive pyrogen and make an e-match to light the BP from the lower energy cap circuits.

[quicksilver]

Ive worked with "no bridgewire" and exploding bridgewire ignition for a bit and suggest that the more professional you make your "b-box" the better. Both of the previous are a bit safer that using something like steel-wool for a bridge. This can be exposed to salts of other materials which can either sever it or ignite it.. While the use of a "no bridgewire" or EBW unit needs a very specific, specially made unit to ignite it; things like static have much less of a chance to make a problem.

Capacitors designed for flash units in camera have a limited life. They are not the "self healing" type meant for high energy. They work; but they are not designed to work for an extended period. Depending on what you're doing you may want to consider an ignition system that really cannot self-ignite under almost any conditions except for a very specifically designed box.

Just food for thought.....the flash camera systems work fine for most applications but I would re-consider the TYPE of bridgewire and stay away from steel wool. It is easily oxidized, can be reactive, and inconsistently constructed in diameter, design, width & thickness,& have virtually no resistance. For actual bridgewire applications, resistance wire offers a great many features that maintain safety and consistency.