RE: [CAD_CAM_EDM_DRO] Re:BEI encoder replacement

> Hmm-I would like to point out that the40,000 hour life of the lamp is
> NOT a guarantee-it is sort of an "average" lifespan for that particular
> lamp, and is arrived at through testing and extrapolation.
>
> What it really means is that if you run a statistically significant
> number of lamps at their rated current, after 40,000 hours half of them
> will have failed, and half will still be working.

Ah, the wonderful MTBF (mean time between failure) number, aka something we
made up after lunch.

Much grumbling (particularly in the computer industry) about how useful it
actually is. I suspect it applies equally well to light bulbs.

On the other hand, I don't ever recall seeing an LED actually fail in normal
use. The oft-quoted 100,000 hour lifetime (11 years) is a bit misleading
(not in a bad way), it means the point when the LED is at 50% brightness
after continuous operation at the specified current. It's still working,
just not as brightly.

If you run the LED under it's specified rating (eg at 10mA rather than the
usual 20mA), it'll probably run forever. I've got a 25 year old clock
radio, it still works fine.

For the OP, if he can get the replacement bulb easily enough, then I'd just
use that. Finding the right LED is a bit too much mucking about. I'd buy a
few spare bulbs though, and tape them up inside the encoder. When it blows
again you won't be able to buy new ones.

Tony