[time-nuts] White LED's

[Dave Martindale]

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.
>
>