On Tue, Dec 20, 2005 at 10:38:07PM -0800, William Chops Westfield wrote:
> 
> > It's gotta be off the shelf and documented, so that in 10 years when 
> > the laser craps out it'll be easy to replace with another one.
> >
> 
> 
> "off the shelf and documented" is an entirely different problem than
> "the same part will still be available in 10 years."  The latter is
> MUCH harder to find.  This is a major PITA when trying to use OTS
> PCs or PC components for an embedded design with a long lifetime;
> THOSE parts tend to disappear in a year or two, never to be seen
> again, perhaps with any driver SW that existed disappeared as well.
> 
> I don't think that red laser modules have enough 'real' applications
> that there's been any standardization of form factors or pin-outs or
> any of that; you'll just have to take your chances...

Actualy I disagree on that. Practically every laser module I've seen has
a number of things in common:

Cylindrical case > 5mm in dia < 30 mm in dia.

I can handle this by making the mount have a removable liner to adapt to
the size of the pointer. If a new one needs to be made, chances are in
10 years 3d printing technology will make that job much easier than it
is now!

Minimum voltage required from 3V to 6V

So I'll just put a easilly adjustable pot to change that as needed.
Current is always less than 500mA and probably will be for any eye-safe
laser!

Pin-outs? You mean one wire is black and one is red?

Seriously, they are all simple power devices. Some of the odder ones
have adjustable brightness with a third lead, but I think
non-adjustables will always be available.


Nah, the laser doesn't worry me too much, other then the annoying issue
of them probably burning out after 10,000 hours. In the very long term
flash memory is going to die which means that we run into the fun issue
of drive SW and dev kit availability as you so accurately mentioned.
That's the real killer. The one that will force an expensive
reimplementation of the elctronics is 30-50 years time. 

I'll probably be alive too to regret all the dumb choices I made when I
get the warrenty call. :)

-- 
pete@petertodd.ca http://www.petertodd.ca
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