Re: Ambient temperature control

On Tue, 02 Jul 2024 10:24:58 -0400, legg <legg@nospam.magma.ca> wrote:

On Mon, 01 Jul 2024 07:46:52 -0700, john larkin
<jlarkin_highland_tech> wrote:
>

On Mon, 01 Jul 2024 10:34:46 -0400, legg <legg@nospam.magma.ca> wrote:
>

On Sun, 30 Jun 2024 18:14:32 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:
>

Assuming you can keep a device in its "normal operating (temperature)
range", how advantageous is it (think MTBF) to drive that ambient
down?  And, is there a sweet spot (as there is a cost to lowering the
temperature)?
>

If all you're thinking of is MTBF, adding the complexity of an active
cooling element is a big step in the wrong direction for the system.
>
Reducing the thermal impedance of the source, to ambient is the
usual way to go, when addressing a specific aging factor.
>
https://ve3ute.ca/2000a.html
>
If you're thinking of performance, It's cheaper and more reliable
to concentrate on reducing the temperature of the point source, not
the rest of the planet.
>
RL

>
Tubes? The cathodes fail eventually. Reduce filament voltage and
suffer the reduced gain. Better yet, don't use tubes.
>
But for most parts that dissipate power, the big win is to have some
air flow. A fan can reduce the theta of your parts by 2:1.
>
Nowadays, parts are very good, with failure rates in the ballpark of
one failure per billion hours, the Bellcore and MIL217 FITS numbers.

>
This was an example of a demonstrated and documented failure mode
in a specific component (glass electrolysis) that is/was largely
ignored by the general user.
>
If you know what the specific aging mechanism is that you're
trying to address, your methods of improving mtbf will be more
effective.
>
RL

Given non-junk products from you-know-where, most electronics failures
are not from classic parts failure. Few real products, in the field,
get close to the standard-calculated-method MTBF rates. They die from
bad design, bad packaging and soldering, or external effects like ESD.

Sometimes one of our customers will ask for a calculated MTBF, so we
dutifully crank one out. We both know that the number is prfetty much
fantasy.