[Diy_efi] RE: Diy_efi Digest, Vol 24, Issue 34

[James Holland]

> 
> I agree with Adam.  The cost of military-grade parts is small compared
> to the time and expense troubleshooting a thermal or design margin
> problem.   Unless you are GM, making electronics by the millions, a few
> extra bucks for parts is no big deal.  I work at the other end of the
> scale; designing electronics for space applications where we build a few
> (or one).  In that case, reliability and design margin are everything.
> I always use the best parts I can get because I've had some bad
> experiences when I didn't.  As a wise engineer once told me when I
> remarked on the extra size, weight and cost of additional design margin:
> "The only thing margin saves is your ass."
> 
> -- Dave
> 

My experience is different. I am in a similar situation, designs can be one
offs or just a few. Full MIL Spec parts, 883 and similar, tend to be high
cost are not available in 'modern' packages and have long lead times and/or
high Minimum Order Quantities. Nearly all our stuff for the military is now
built using extended temperature range parts. Military requirements have
changed over the last 10 yrs or so and the temperature ranges have reduced
for a lot of it. Most requirements now state a power up time from cold and
external equipment is fitted with heaters to bring the ambient level up to a
'safe level'. I can see that this approach wouldn't work too well in designs
for Space applications were the heater draw would be an issue.
Here in the UK parts rated at -40 to +85 or above aren't that difficult to
source. Farnell and RS stock a massive range.