Graham North wrote:
>
> Dear all,
>
> I have a few circuits that are kept in water proof boxes, but while in
> storage (in not the most ideal place in the word) they seem to get damp.
>
> My question is not how to prevent this, as I have sealed the boxes as well
> as is humanly possible, and have put sachets of silica gel in the boxes
> also.
>
> My question is would a crystal or RC res circuit (in am currently using
> cheap resonator) startup more reliabily in these conditions?
>
> Has anyone come across this problem before?
>
> I know electronics should not be subjected to these environmments, but we
> all live in the real world don't we!
>
> Thanks for your valuble time and comments,
>
> Regards
>
> Graham North


Graham, one word; Encapsulate! Set up your hardware to use
ICSP for upgrades, then set the whole lot in a chunk of plastic.
If you do it right you can run the thing submerged in saltwater
for years and it won't care. Microchip make it easy with the simple
ICSP on the flash chips, and I have found you can use the PicstartPlus
for ICSP with no probs, saving some bucks there if that is an issue
for you.

Most big hardware stores have cheap polyester (fibreglass) resin,
play with this until you are comfortable with the whole thing and
your molds etc, then order some higher quality electrical resin
from anyone in the yellow pages. Normally you can "pot" the
device in a cheap plastic hobby box with just the wires hanging
out the top. I was trained in encapsulating elec devices many
years ago in industry, it has numerous adantages including
tamperproofing and mechanical strength. Our current product can
be run-over repeatedly by a car with no affect on performance.
Not many electronic products can claim that! :o)
-Roman

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