Field ignition ...

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pezman
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Field ignition ...

Post by pezman » Sat May 07, 2005 9:12 pm

I was just fidling with a hacked together ignition system that might be of general interest. It costs under 15$ and can be knocked together in a few minutes.

Basically, the device consists of a transformer from a bug-zapper ($14) and a kodak Super-Max flash camera. Note that you can substitute any other disposable flash camera.

Once the camera is done, you can crack the case open. BE VERY CAREFUL DOING THIS. There is a capacitor in there and it may be charged to over 200 volts. At the very least, it can zap you badly enough to make you regret it. If you are unlucky and careless, it can injure you. Under freak circumstances, it could kill you.

Find the large capacitor (http://repairfaq.ece.drexel.edu/sam/kflashmp.gif) and discharge it using the blade of a junk screw-driver. Make a hole in the case that allows you to access the capacitor terminals safely. Here's a schematic: http://repairfaq.ece.drexel.edu/sam/kflashm.gif

When you are ready to rock, hook one side of the bug-zapper transformer to ground and then touch the other terminal of the primary to the capacitor's "+" terminal. A high voltage spark will jump agross the secndary leads if they are close enough. In this case, close enough is about 7/16", which corresponds to a voltage of about 12kv (http://www.kronjaeger.com/hv/hv/msr/spk/index.html). Be careful triggering this -- a discharge from the secondary might be quite dangerous. The voltage is definitely high enough to drive a lethal current through your body and the cap has enough W/S stored up to ensure that it flows for a relatively long time.

With a smaller cap, you can fire the spark more frequently, but my guess is that the output voltage will drop a bit. On the other hand, there is a corresponding reduction in lethality.

Advantages: Cheap (the camera is essentially free), easy to make and the whole unit can run in the field on a AA battery.

Disadvantages: Potentially dangerous if mis-handled

Jmitchell
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re: Field ignition ...

Post by Jmitchell » Sat May 07, 2005 10:19 pm

You can do this more sophisticatedly (sp?) using a ignition coil, a camera flash and a SIDAC which is a device that triggers when a certain voltage is reached across it. With a small capacitor ~1µF and a 240v SIDAC along with an ignition coil and camera flash, you can get a reliable ignition system that can run on batteries.

pezman
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re: Field ignition ...

Post by pezman » Sat May 07, 2005 11:08 pm

Yeah, I was actualy thinking abotut that (it's mentioned here: http://members.misty.com/don/kmaxhack.html).

My interest in hacking the cameras stems from getting a bunch of cheap strobes for high-speed analysis of a pulse. I plan to use solid-state relays controlled by a small computer to ignite a pulse and trigger the flashes at certain, precisely selected times.

Jmitchell
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re: Field ignition ...

Post by Jmitchell » Sun May 08, 2005 2:20 am

Here's a schematic I drew of a sparker. The values aren't really critical except for voltage. The resistor values have some slop to them, but I haven't tested anything, 10K might not be enough to prevent explosions of components :).
Attachments
sprker.GIF
sprker.GIF (5.28 KiB) Viewed 3191 times

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