Electrolytic cap in high-discharge application

It might not like the peak current. Flash capacitors aren't that super-duper expensive:

Not sure if you guys in India still use film cameras. In the US there used to be these disposable cameras where you could take xx photos, then give the whole camera to a processing place. Which was usually located inside a drugstore. The cameras were collected in a box there and (hopefully) recycled. Some people were able to get some of those if they knew the folks behind the counter well enough. The motivation was often to pry out that photo-flash capacitor for free :-)

That's what I'm afraid of.

That's a steal at $1 but alas, there's no way I can order it from here. It's not the price I'm concerned about. It's finding a source. It's not just that I'm in India, I'm in a remote corner of the country. Indian companies ignore emails 9 times out of 10. If I call them, they're likely to say "Yes sir, we have just what you want" and then send the wrong one or simply ignore the order. :-(

The ratio of die-hard film users to digitals is probably roughly the same here as in the US.

I've heard about those disposable cameras, but I don't think it caught on in India - if, indeed, they were introduced at all.

Capacitors made for the purpose are marked 'photoflash'. Reason is that a xenon strobe is much akin to short circuiting the fully charged capacitor. A VERY high current flows while the stored energy is dissipated in about a microsecond or so. Good for making a plasma in the strobe tube but just as likely to make a loud noise (and smoke) if the cap isn't up to the task. You can add a series inductance to the discharge circuit to widen the discharge time and moderate current rise - air core recommended. Make sure that you don't exceed the limits of the strobe tube. Too much energy on each flash and too high a flash rate can kill the tube from over-temperature.

I used to do a lot of flashtube stuff using caps from old TV sets. They seemed to work fine.

John

"Pimpom"

There is a reason why camera lashes take a few seconds between each full power discharge.

.... Phil

The lifetime of the bulb will depend on the ratio of the flash energy to the explosion energy of the flashlamp. (That's how lamps are specified, believe it or not.)

If you stay below about 10% of the explosion energy, you should get at least a million shots. Start with a cap about a quarter of the size of the one in the flash.

As Phil A points out, you also have to keep the tube reasonably cool.

Cheers

Phil Hobbs

Yes, I've had second thoughts about the frequency-energy combination I first proposed. Maybe ~1Hz with a smaller cap. However, I'd say that the cycling times of camera flashes have as much to do with charging limitations as with the need to protect the tube. Some flashguns are rated to fire several times a second.

But they'll sure use bigger tubes, just like the strobes above a fancy disco dance floor do. My camera also lets off several flashes in one second but the first ones are of limited energy.

Wow, best stay away from the later ones. ;-)

"Pimpom"

.... Phil

Good points. Thanks. I doubt this unit will have to go through much more than 1000 flashes before it's discarded and replaced with something else. It's to be a temporary solution that's unlikely to be used for more than a couple of years at the rate of perhaps 10-20 flashing sequences an hour, 3-4 hours a day, 1 or 2 days a year.

My original question was about the capacitor. Which is not to say that an expansion of the topic is not admissible, but that does not mean that the OP of a thread is under obligation to treat each reply as gospel.

"Oppie

The only thing that harms electros is getting too hot - which could happen in a strobe flashing rapidly for long periods.

Ones rated for camera flash use have low ESRs and long life expectations - low ESR electros are almost the norm these days.

.... Phil

"Pimpompous"

Go look the terms up if you have no clue what they refer to.

Dickhead.

..... Phil

The old GR stroboscopes ran at KHz rates. Just keep the average power down so you don't melt the flashtube.

If a tube is rated for X joules single-flash, firing it 5 times at X/5 joules should be fine.

Things get fun at a couple of hundred joules per flash. THoooopp! 1Kj is definitely interesting.

John

Have you done the math? According to the back of my "envelope", your biggest problem might be charging the cap in the half second between flashes.

Here in the states, you can buy used one-time-use cameras with flash and good batteries for 20-cents each. If I were doing this, I'd mount 5 flashes side by side, charge 'em with a 3V supply and fire 'em sequentially.

Whew! That's a relief. For a moment there, I thought you were losing your touch.

BTW, I'm quite familiar with those terms. Though, as a non-native user of English, I'm not as fluent in _using_ colloquial terms as in understanding them.

"mike"

BTW

I once made myself a simple "ring flash" by mounting 3 such units around a hole in a piece of cardboard.

The hole was just big enough to poke my SLR camera lens through and the whole kaboodle hung onto the lens using a large electro capacitor mounting bracket.

Fired simultaneously, it worked like a charm for taking close up shots of small items.

... Phil

"Pimpompous"

Piss head.

.... Phil