[time-nuts] White LED's

[Brooke Clarke]

Hi Dave:

LEDs are used on many cell phone cameras in just that way.  The data 
sheets for the LEDs have the pulse use specs.

At:  http://www.sd36.bc.ca/sulhts/departments/elx/p/elec.html
scroll down to the "Boy Scout Motor" and notice a common LED held by two 
wires that's being used as a strobe light.

Have Fun,

Brooke Clarke
http://www.PRC68.com


Dave Martindale wrote:
> Hmm.  Has anyone built a strobe light using LEDs instead of a xenon 
> flash tube?  I can see the appeal of building something that doesn't 
> need high voltage to fire or trigger the tube.  Yes, you probably 
> couldn't get as much light as a big Xenon tube, but there are 
> applications where you don't need to illuminate a large area.  (Recent 
> example of where I wished I had a stroboscope: looking at the balance 
> wheel of a pocket watch).
>
> How high can you push the drive current of a LED if the pulse is 
> short?  Of course you have to keep the average dissipation below what 
> the device is rated for, but there must be a peak current limit too.
>
>     Dave
>
> On 30/01/2010 01:17, Robert Atkinson wrote:
>> Hi,I'm late to the thread (as usual), but have looked at these LED's 
>> in the past. It was for a biotech imaging application. There are two 
>> types, a red/green/blue cluster or a blue / near UV LED with a white 
>> phosphor. These phosphors seem to have a fairly continuous spectrum, 
>> at least compared to fluorescent lamps and HID lamps. What surprised 
>> me was the speed. We had a strobe application for which a xenon 
>> strobe was proposed. I tried LED's (our optics "expert" said even 
>> normal LED's would not be fast enough). I knew normal LED's are fast 
>> enough but was unsure about the phosphor types. To my surprise they 
>> where faster than the xenon tube! They were faster than my detector. 
>> This has has an impact on the mill illumination in that you can get 
>> strobe effects that could cause you to think the spindle was 
>> stationary when it was not. This is more of a problem in a noisy 
>> environment than a home shop with only one machine running.  Robert 
>> G8RPI.
>>
>
>
>
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