Chris Loiacono wrote:
>
> Just one more thought on this for me today...
>
> I have seen commercial dive computers that have no port, tube or balloons
> visible, and yet they are amazingly accurate in sensing depth. I have
> searched and phoned sensor makers, foguring that someone must have a
> chip-scale sensing element, but have found nothing of the sort. Has anyone
> ever seen what I'm talking about? Know a way to sense pressure or depth
> without porting water or bagging air? This thread has me thinking of
> re-inventing my own rather small wheel...

Probably a slightly flexible casing and a small
strain gauge to measure casing compression.
You could do the same on the sub, have a
diaphragm (or special hull section) etc that
has known compression at depth, you can sense
deformation with something as simple as a
trans/receive opto interrupter. Aim for 2mm
max deflection and run the opto in the linear
range, with software compensation. Should
give 8 bit accuracy, total depends on mechanical
error. A quality spring attached to your
diaphragm will help repeatability and I think
you could chuck one together pretty quick and
cheap.
-Roman

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body