White LEDs for strobing?

I was thinking about making a little battery powered strobe using one of the really bright white LEDs now available. But I don't know how long the phosphor glows after the LED turns off. Anybody here know? Thanks, Eric

Reply to
etpm
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What phosphor? LED is a semiconductor which produces light while active.

Reply to
Daniel Pitts

Daniel Pitts wrote in news:mvhgs.6562$ snipped-for-privacy@newsfe10.iad:

active.

Yes, but no white light. For white light you have a blue or ultrviolet LED, and a phosphor to convert that to white light. Also there are leds made out of three chips, each supplying a primary color. Philips did quite some reseach/development in that. There is no monochrome white light. Regarding the strobing, the white leds are not very suitable for that, the phosphor has a very large turn-off time. A green led would do quite well, producing a bright beam. I would modify a green laser pointer for your strobe.

Reply to
Sjouke Burry

Or he could use an RGB led which makes (apparent) white light and has no phosphors

Reply to
David Eather

Another great idea shot down. I did think about then RGB LEDs. All the ones I have seen have a diffuser lens to blend the colors so that the light spreads a lot. Fine for under counter lighting but maybe not for focused light. I have seen some white LEDs that have a pretty narrow beam. I have a green laser and while bright enough it is pretty temperature sensitive. I know that the IR laser in the things can switch plenty fast enough for me but don't know if the KTP crystals in them have any kind of lag. Eric

Reply to
etpm

Why?

Reply to
Michael A. Terrell

Reading Don Klipstein's website he reports that one of his fans measured the rise and fall times of white LEDS and found thes times to be less than a microsecond! I doubt this. Mr Klipstein didn't do the actual measurement so he can't verify these times. I guess I'll just have to order some LEDs, build a circuit, and see for myself. Eric

Reply to
etpm

So you can throw away (more than) 2/3s of the energy in the filters.

Reply to
krw

Because we perceive the correct mix of red, green, and blue light as white. And because LEDs can be made to turn on and off quickly.

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Tim Wescott 
Control system and signal processing consulting 
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Reply to
Tim Wescott

On Fri, 19 Oct 2012 17:33:17 -0700, snipped-for-privacy@whidbey.com wrote as underneath my scribble :

A couple of years ago I made a strobe using 7 white LED in a circle, works fine but this wasnt the really high powered heat sinked modern types which you may want to use, I calibrated it 1 Hz to 600 KHz in 9 ranges but it tested to 1 mHz, I didnt bother to go further. C+

Reply to
Charlie+

Greetings Charlie, From reading about the phosphors used the higher powered LEDs may actually make the phosphor decay faster. And 1 Mhz equals 1 microsecond which is what you got. So it turns out that I'll just have to build the damn thing to see if I can make something that works for me. Thanks, Eric

Reply to
etpm

What filters?

Reply to
David Eather

Look harder

Reply to
David Eather

The ones from the stop light (missed the subject change when reading).

Reply to
krw

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