I'm in need of a physically small, high power, short duration light source, such as a xenon flash or a high power LED for high speed photography purposes in a crammed volume.
My experimentation with a 12V 10W LED driven at 15V at a few hundred microseconds proved satisfactory, but the LED is perhaps a bit on the large side (20 x 20 mm).
I've found a xenon flash module used in Nokia Lumia phones, such as this one: http://www.ebay.com/itm/OEM-Xenon-Flash-Light-Module-Replacement-for-Nokia-Lumia-1020-/171670955706?hash=item27f862e6ba
It might prove to be better suited. I haven't ordered it yet, just wanted to ask if anybody here has experience with messing with it or a similar xenon flash module. My concern is that I will not know how to control it, since I have found no datasheet for it, or even the pinout. From what I can see on the pictures it has at least 7 contacts. Any guesses on how it might be controlled?
I have not used that module but I did build a stroboscope using a Xenon tube back in the 60s and the basic principle will be the same.
Basically across the tube you capacitor, this is charged up to a high voltage by an inverter circuit. The trigger consists of a thin wire laid along side the tube. When the capacitor is charged you apply a high voltage to this trigger by means of an induction coil rather like the spark plugs worked in a car.
You need to get the capacitor value and the voltage you charge it up to right to supply the maximum power ( but no more ) to the tube.
I imagined that all those (capacitor, high voltage inverter and high voltage trigger/switch) are included in the module itself, with the mobile phone only dealing with low voltage control signals and the power being supplied directly from the battery (with some sort of a power switch, of course).
You can extract the flash unit from many disposable cameras; frequently available for free from photo-processors. It may be difficult to make it smaller than your LED, though; usually they need a relatively substantially sized HV capacitor. (that nokia module is tiny, and there are some smaller ones.)
You wouldn't believe how hard those things are to find over here.
My cousin owns a photo processing business and they get those once in a blue moon, and then forget to contact me to come and get them, so those disposable cameras just get thrown out.
Shpaget:
You wouldn't believe how hard those things are to find over here.
My cousin owns a photo processing business and they get those once in a blue moon, and then forget to contact me to come and get them, so those disposable cameras just get thrown out.
Very difficult in the uk now as well, ederyone has gone digital and jessops is no more
A search on the net will find a supplier of the components in israel.
Shpaget:
Isn't the silver cylinder the cap? Устройства - 4PDA
Page 24 shows the phone opened up. I don't see anything else there that might be the cap.
The strobe circuit can be made smaller (though the cap tends to stay pretty big.)
Here's the guts of a fuji disposable, and the reconstructed (for a model rocket) repeating strobe version.
But probably you should reexamine your LED solution; I doubt that a 20W LED is needed or optimal; there are some specialized LEDs (for camera strobe applications) designed for higher "intermittent" output in smaller packages. http://www.lumileds.com/products/flash-leds/luxeon-flash Driving them won't be trivial in a small circuit, and I'm somewhat disturbed that you talked about driving them with a higher voltage rather than a higher current...
FYI, a typical "passive" Xenon strobe burst is in the 1,000 uS range. Is that fast enough for you? Only the thyristor driven circuits can achieve better than 1/2000 s.
Don't hammer on me if you find circuits that use something other than an actual thyristor to do the same thing. It's a photographic industry term.
But a Xenon can achieve much higher peak light intensity than any LED that I'm aware of. The shorter the burst, the more important that is.
But a Xenon can achieve much higher peak light intensity
Do you have numbers? Lumens per Joule (input) or something? (or maybe something time-related; Joules (W-s) are just the easy number to calculate for Xenon, since the duration tends to be relatively constant.
(and does the O.P. have required intensity numbers?)
I don't have a required intensity numbers. The project is in its infancy.
What I need it to do is to stop the motion of a spinning (around 200 rpm) barrel (around 60 mm inside diameter, 50mm deep). Camera, flash/LED and possibly some transportation mechanism for the camera and flash need to fit inside the barrel shape, so there is very little space to work with.
Power supply, drivers, triggers etc. can be placed outside this barrel.
From my measurements of xenon flashes for cameras (the big things you mount on a DSLR), they have a fast ramp up, a plateau, and then much slower rampdown. The duration of the plateau is a influenced by the power setting of the flash and on this particular flash I'm using 1/128 and getting a 40us plateau with a 3000 us rampdown where the drop is sharp at first and then slows down, so the most intense afterglow is in the fist 200 or 300 us, after which, I believe, the faint glow is not an issue.
It provides very good results, so my aim is to get as close to that as possible and the plan was to either use the mobile phone xenon flash or LEDs which I'd drive with some fast MOSFETs.
westfw, I understand your concern about overdriving the LEDs, but how do I shove more current than the LED will take without increasing voltage? The thing takes 800 mA at 12V and no more.
Shpaget:
From my measurements of xenon flashes for cameras (the big things you mount on a DSLR), they have a fast ramp up, a plateau, and then much slower rampdown. The duration of the plateau is a influenced by the power setting of the flash and on this particular flash I'm using 1/128 and getting a 40us plateau with a 3000 us rampdown where the drop is sharp at first and then slows down, so the most intense afterglow is in the fist 200 or 300 us, after which, I believe, the faint glow is not an issue.
plateau width can be controlled down to 10 us or so by the use of a quench tube, this is how high speed flash works.
It also gives a sharp cutoff with little ramp down
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Shpaget:
Camera, flash/LED and possibly some transportation mechanism for the camera and flash need to fit inside the barrel shape,
Could you not use a mirror or prism to mount your gubbins outside the barrel.
Or use fibre optics for the flash like keyhole surgery gear.
Mouser do flexible light pipes for leds, if one of those fits, using led is probably the easiest.
Led can be any size then.
Shpaget:
Power supply, drivers, triggers etc. can be placed outside this barrel.
No they cant.
The tube will not fire if too far distant from the cap and coil..
Not sure but i think the problem is with the trigger coil.
Available ones are not man enough ,
Its possible to wind your own but they get very bulky that way.
However i have ordered from that supplier before. Delivery is about 2 to 3 weeks.
Its the only supplier worldwide i have been able to find that will sell retail.
Product is described as a trigger transformer and may be getting interest from customs.
I don't think I'll be making the xenon flash if I can purchase an off the shelf module. I know enough about xenon flashes to realize I'm not up to the task, which is reflected by the "outside the barrel" comment. Thanks Boardburner.
When I said the barrel will rotate at 200 rpm, I didn't mean I need the flash to go off 200 times per minute. I need a single flash and then a pause for several hours before the next flash.
I mentioned the rotation to give a general idea of how short the light duration has to be to avoid motion blur. Sorry if it was confusing.
Yes, perhaps I will need to put everything outside and use mirrors/prisms. I will make that decision when I receive the camera module (which should have already arrived, maybe I should contact the seller about that, hmm) and see how it performs and how I'm able to mount it.
Shpaget:
Yes, perhaps I will need to put everything outside and use mirrors/prisms. I will make that decision when I receive the camera module (which should have already arrived, maybe I should contact the seller about that, hmm) and see how it performs and how I'm able to mount it.
If you can get it apart without damage and post a micrograph of the circuit i will assist with the connections if i can.
