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Disposable camera innards Answered

I was taking apart a disposable camera today and found this thing. It looks like it is probably a coil of some sort, and it has a little brother hanging out on another part of the circuitboard. The big one is about 1 cm across, and the little one is about 5mm. What, precisely is it, what does it do, how does it do it, and if I replaced it with a bigger one, what would happen? In idiot-english, please, I'm not well-versed on electrical devices. The little one, especially, reminds me of an ultra-small high-tension coil. Is that what it is? Does it perform precisely the same duty in this circuit?

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1-0_1-6 (author)2008-12-28

"item in question" is the inverter which steps up the voltage from the battey to charge up the capacitor ( about 330V). When the flash is going to be fired, the capacitor discharges and its voltage goes to "its' little bro". This is the transformer that steps up the voltage from 330V to about 1-2kV. This is significant to fire the xeon lamp.

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unum (author)1-0_1-62011-05-04

That would Explain why my homemade tazer would not fire any of the zenon tubes! Thanks!

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AnarchistAsian (author)2008-08-09

sort of tesla coil, i think, look it up on wikipedia, a tesla coil increases voltage/decreases amperage, (look up)

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Big Bwana (author)2008-06-24

And the big black capacitor, you might want to discharge it if your going to be handling it, or you will have a shocking experience, they can actually be very painful, however once you get shocked, your brain should remind you not to do that again....(( wish mine would do that more often ))

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AnarchistAsian (author)Big Bwana2008-08-09

s'not that bad, i don't mind getting shocked

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Rishnai (author)Big Bwana2008-06-24

Ah, yes, I learned young, don't touch capacitors. I shorted it with my insulated pliers before touching anything else, and it made an incredibly loud popping noise and melted some solder onto my pliers, and continued to have enough charge for another five small sparks. A very good sign, since it was one of the bits I intend to salvage, and implies it will be able to supply the burst of current I'm hoping it will. Mwahahahaha!

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NachoMahma (author)Rishnai2008-06-25

. You can avoid melting things if you will use a "big" (1-10Mohm, 1W or greater) resistor to short out the cap. Not as much fun, but it saves your tools.

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Rishnai (author)NachoMahma2008-06-25

Good idea. I wish I'd thought of that, since a very loud explosion noise was not part of the plan, especially late at night.

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westfw (author)Rishnai2008-06-25

I've opined that you can drain the cap (slowly) by shorting the trigger leads together. According to The Schematic, this effectively puts a 1M resistor (plus the primary of the trigger xformer) across the big cap. It should discharge to small values in a couple hundred seconds.

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gmoon (author)Big Bwana2008-06-25

One more word of caution: ultimately, the amount of current this thing can supply in a short burst is dictated by the capacitor, not the transformer. I.E., insert a humongous cap here and even a tiny current source will eventually charge it to saturation. The resulting discharge wouldn't be harmless anymore....

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mikemmcmeans (author)2008-06-27

does anyone have any of these boards they would like to pass along to me, for some kind of reward.

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Rishnai (author)mikemmcmeans2008-06-27

You could just ask at a one-hour photo place. They're usually keen to get them gone, at least around here.

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westfw (author)Rishnai2008-06-27

And you can always buy the camera and take all the pictures. At that point (unlike a conventional film camera) all the film will have been wound INTO a somewhat standard 35mm cartridge, which you can take out and have processed normally while you keep the camera body for your own nefarious purposes. Disposable cameras take surprisingly good pictures, and it's not an awful idea to throw one in your car, purse, or backpack to have with you all the time. That way if one of your classmates runs amok at school, you can snap pictures and get rich selling pictures to the press (or your surviving family can...) They can be fun at parties and weddings and such too; have a bunch lying around for random people to take pictures with... I have a slight preference for Fuji cameras; they're cheaper and have more consistent internal electronics (I've found at least three different versions of flash boards inside Kodak Max camers...) The board is smaller, too...

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Rishnai (author)westfw2008-06-28

One thing to mention, though, about choosing a disposable camera to buy, use, and then take apart: don't get Polaroid. Apparently they've gotten out of the instant-picture racket and ran headlong into difficult-to-use, very cheap cameras. I picked up a few to snap pictures with on vacation recently, and the shutter button is iffy at best, the number displayed does NOT coincide with the actual number of pictures on the roll (Every picture I wound for moved the dial 1.5 numbers and a couple of times didn't move it at all), the flash was disappointing, and the cameras actually seemed to funtion better after I had gotten a large amount of sand into them. I like Fuji in every way. They have consistent performance, and the Fujifilm has an amazing green response.

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westfw (author)2008-06-24

The item in question is the "inverter transformer" for the electronic flash. It (with the help some of the other components) converts the 1.5V battery to about 300V.

The smaller item is the "trigger transformer", which converts a bit of the 300V from the rest of the circuit into an approximately 4kV "pulse" that triggers the actual flash event.

Almost everything you could ever want to know about camera strobes, including basic principles of operations AND actual schematics of the strobe you have there (from a Kodak MAX camera, right?) is in Sam's Strobe FAQ
There are also several instructables on using such camera guts for other purposes...

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Rishnai (author)westfw2008-06-24

As a matter of fact, it is from that precise camera. 4kV, eh? This could work better than I thought. Thanks for clarifying things!

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westfw (author)Rishnai2008-06-24

note the size of that second transformer. 4kv perhaps, but the ENERGY and power it's capable of converting is quite small. That's true of the inverter as well; you figure it's putting out enough current to charge the ~100uF cap to 300V (about 5 Joules) in about 10 seconds, for a whopping power of 0.5J/second == 0.5W. It even sorta looks about the right size for a half-watt transformer...

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Rishnai (author)westfw2008-06-24

But if I had, say, a lot of free camera guts, and strung together a lot of these, would I be able to get, say 24 watts/second? Or would I just fill my workshop with the smell of burnig electronics?

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westfw (author)Rishnai2008-06-25

Maybe. I think there are even some strobe kits that achieve a higher flash rate and more convenient power supply by running several inverter transformers with their primaries in series (~6V instead of 1.5) and their secondaries in parallel (4x the current.) (can't find it now, though. IIRC, it was advertised as being configurable for several possible input voltages.)

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Rishnai (author)westfw2008-06-25

Mostly, I'm looking for an incredibly huge spark off of a 6v or 12v supply. Primaries in series and secondaries in parallel is a configuration I wouldn't have thought of. That does present a challenge, though, in terms of wiring the two seperately.

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westfw (author)Rishnai2008-06-25

I have a project in mind using a Cheap stun gun to create a Jacob's ladder. I don't know if that's within your budget, but a $20-30 "stun gun" is cheaper than the average neon sign transformer.

Another interesting idea is to set up a circuit like a Marx Generator, replacing the spark gaps with xenon tubes. My theory is is that this gives you a "low voltage" Marx Generator, capable of generating pulses of a couple thousand volts (and significant (FATAL) energy) from ~300V input, rather than the typical 100kVs from 10kV inputs. And it would be easily triggerable...

But I'd rather finish my Radial Dirod; more fun, less fatal...

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