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~50KV from 1 CR123 3V Battery

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Ash Small

Fri Aug 12 2011, 05:30PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Alex1M6 wrote ...

Awesome!

BTW what camera did you use?

Hotwired wrote ...

.
First you need the capacitor charging circuit from a disposable camera. Any will do but the easiest way is to get a Kodak Fun Saver camera. The Wedding and Custom Kodak cameras are the same thing by the way.

Get the battery out of it, and short out the capacitor before removing the circuit:

.

Nah

Fri Aug 12 2011, 10:37PM

Registered Member #3567 Joined: Mon Jan 03 2011, 10:49PM
Location: USA, 1960s
Posts: 260

I would use a neon discharge tube, used in relaxsation oscillators.

Fnord

Sat Aug 13 2011, 12:25AM

Registered Member #2004 Joined: Sat Feb 28 2009, 11:43PM
Location:
Posts: 39

Ha! I see you here Hotwired.

Half an hour is a hell of a long time given your power source... impressive.

You should be pretty safe touching it, given camera flash circuits only run at about 1-2 watts output. A small crt FBT with a simple driver puts out way more and is generally not lethal(I just tested a big one sitting on my desk... it's using about 6-10 watts with a single trans driver).
The 350vt side of the circuit is rather unpleasant, though.

I'd throw a couple more caps on there in parallel and see if you can brighten up those sparks any.

Hotwired

Sat Aug 13 2011, 03:04AM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

Hi Fnord,

I'm not testing it on myself anyway :P

No, this is for gas ignition which it does well, each spark is about 13mJ and you can see how fast it throws those out. The capacitor could be half the 0.22uF it is and still have enough energy for ignition.

I've got a 500mJ spark version in mind (1KV 1uF capacitor), It'll require a voltage doubling circuit and possibly a second power circuit. Heck, maybe two of each driving it. Still, it'll charge faster than the stock 100-150uF electrolytic which hold about 10J.

Now that is power hungry overkill for gas ignition but that hasn't stopped anyone using commercial stunguns for spudgun ignition yet.

I'll be doing that just to see how it could be done.

I'll be testing a GDT replacement later today. Got a bag of 330V SIDACs in. I have a suspicion they won't be able to run for half an hour....

Fnord

Sat Aug 13 2011, 02:10PM

Registered Member #2004 Joined: Sat Feb 28 2009, 11:43PM
Location:
Posts: 39

You may not need a voltage doubler.
I think a common practice on here is to run two FBTs with the secondaries wired in series to get roughly double the output voltage. You'll probably have to glue the cores together for proper magnetic coupling.
Of course I'm not really the person to ask here since I've never done it and don't know how well multiple drivers would work together in such a circuit.

Tetris

Sat Aug 13 2011, 06:14PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

LOL Homemade tazer. Its like, I know how to make a tazer. Do not make me actually make one to make you stop teasing me. Otherwise teasing will qickly turn to tazing. "No teacher, this isn't a taser! Its my Kodak! *hides taser in kodak* I must have been charged with static! Anyways, that is a win. I didn't think you can get that much out of a camera flash board.

H8erade

Sun Aug 14 2011, 08:27PM

Registered Member #3451 Joined: Sun Nov 28 2010, 11:13PM
Location: United States
Posts: 100

I was interested in your oscillator, so I looked up a few camera charging diagrams. Many of them seem to require a small capacitor, but I see your version doesn't. Do you have a schematic for that particular cut-out?

Hotwired

Sun Aug 14 2011, 09:32PM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

smcerm wrote ...

I was interested in your oscillator, so I looked up a few camera charging diagrams. Many of them seem to require a small capacitor, but I see your version doesn't. Do you have a schematic for that particular cut-out?

Most camera circuits are full of redundant parts.

The small capacitor you talk of is the trigger capacitor which is dumped into a tiny transformer to create a few thousand volts on an ionising wire near the the flash tube and thus allow the large electrolytic to arc between the flash tube terminals.

There is no reason for that to be on this circuit.

The BARE MINIMUM to charge capacitors is this:

Tmpi

Took that several years ago by putting the component->component soldered circuit on a scanner. Battery input on the red wires, few hundred volts come out between the two free ends top and right.

One resistor
One transistor
One transformer
One diode

However the circuit square I show in the guide also contains +1 resistor and a LED. It glows when the output voltage is above XXX volts which is when the original electrolytic had enough charge to do a decent flash. Kinda redundant now since these capacitors charge in a fraction of a second but it also functions in a roundabout way as a power on indicator since these capacitors are such low capacitance the output voltage stays high enough for it to be on all the time.

You can chop off the LED and extra SMD resistor by taking off a corner of the circuit board but it barely matters power wise.

As for a proper circuit diagram, no I never did one but it's fairly simple stuff with just those handful of components.

However HowStuffWorks has... http://electronics.howstuffworks.com/camera-flash3.htm

H8erade

Sun Aug 14 2011, 09:41PM

Registered Member #3451 Joined: Sun Nov 28 2010, 11:13PM
Location: United States
Posts: 100

Okay, thanks for the explanation. In that picture though, the transformer has five pins. If I come across one with six, will the setup still work if I just ignore the middle pin (on the secondary side)?

Hotwired

Sun Aug 14 2011, 10:22PM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

smcerm wrote ...

Okay, thanks for the explanation. In that picture though, the transformer has five pins. If I come across one with six, will the setup still work if I just ignore the middle pin (on the secondary side)?

Definitely maybe.

Every transformer on a flash board I've seen and I've seen maybe a dozen models uses 5 pins even if it physically has 6 or even 8 pins.

The wiring is not guaranteed in any pattern if you use a transformer from a different circuit so you may need to play about and check which pins go where first if you're thinking of removing a transformer from a board to use it.

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