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Re: [PSUBS-MAILIST] Water depth sensing?
Dang. I used a motorola absolute pressure transducer
that was cake to interface to (bridge circuit I
believe), and it was under $30! I believe I bought it
from www.digikey.com
Warren.
--- Michael Wright <mwright@smallip.com> wrote:
> For a depth sensor you really want absolute.
>
> The downside to using gauge pressure is that it
> gives you the pressure
> relative to the inside of the ROV (or electronics
> bottle). This is only
> a problem if you're using hull vaccume to hold the
> end caps in (as done
> on DOE vehicles).
>
> This is simple enough to solve by implementing a
> means to zero the depth
> reading in software.
>
> Desert Star Systems http://www.desertstar.com has
> something listed on
> their web page that might be useful, though it might
> be OMG expensive.
>
> IIRC good quality pressure transmitters cost between
> $500 and $1000 so
> they might be cost competitive.
>
> Given the choice I would use a 0-5V Absolute and
> interface it to
> Netmedia BX24. In a time crunch I've had ok
> experience with 0-5V gauge
> sensors and 4-20 mA sensors, though we only saved a
> two week order lead
> time since the pricing was the same.
>
> The BX 24 gives you an easy way to interface an SPI
> or serial compass
> module as well.
>
> let me know if you need any pointers :)
>
> mike
>
>
> Warren Greenway wrote:
>
> > The only real difference is the point of reference
> for
> > the sensors. You would want an absolute sensor for
> > sensing depth/pressure for a sub. Gauge often
> means
> > the same thing as absolute, differential will have
> two
> > sensor inputs and read the difference between the
> two.
> > Try the datasheets for the sensor you are
> interested
> > in. Usually the datasheet will have some standard
> > interface circuits and information. Also, get TI
> > application notes book for the MSP430...Even if
> you
> > are
> > using any MCU. It has great circuits and
> algorithms
> > for reading various common sensors.
> >
> > Warren.
> >
> > normaly means that there will be t
> > --- steve <steve@kobol.worldonline.co.uk> wrote:
> >
> >>another question on the subject if i may.
> >>i have heard there are three different types of
> >>sensor available: absolute,
> >>differential and gauge.
> >>i have an idea what the differential type does but
> >>what about the other two?
> >>what should i be looking for to get a linear 0 -
> 5v
> >>or 0 - 10v output i can
> >>feed to an A to D converter?
> >>
> >>Best Regards
> >>
> >>Steve Bosworth
> >>UK
> >>
> >>----- Original Message -----
> >>From: "Steven Mills" <cirtemoeg@juno.com>
> >>To: <personal_submersibles@psubs.org>
> >>Sent: Saturday, February 21, 2004 7:41 AM
> >>Subject: Re: [PSUBS-MAILIST] Water depth sensing?
> >>
> >>
> >>
> >>>Steve, here are a few links that I recall.
> >>>
> >>>http://members.cox.net/igalysh/pressure.html
> >>>
> >>>
> >>>
> >>
> >
>
http://www.parallax.com/html_pages/resources/custapps/app_underwater.asp
> >
> >>>I have many more sources, but the case and hinge
> >>
> >>on my laptop cracked a
> >>
> >>>few
> >>>months ago [ no video ] so I'm starting over with
> >>
> >>the searches/sources
> >>
> >>>[and
> >>>everything else ! ]
> >>>When I come across anything significant I'll post
> >>
> >>it.
> >>
> >>>--Steve
> >>>
> >>>
> >>>On Sat, 21 Feb 2004 02:16:40 -0000 "steve"
> >>><steve@kobol.worldonline.co.uk> writes:
> >>>
> >>>>anything helps, thanks.
> >>>>i had originally considered the low tech
> >>
> >>approach but as the project
> >>
> >>>>progresses i keep moving the boundaries. in one
> >>
> >>way i actually know
> >>
> >>>>it
> >>>>could be done visually but where is the
> >>
> >>challenge?
> >>
> >>>>steve
> >>>>
> >>>>----- Original Message -----
> >>>>From: "Al Secor" <wreckdiver@usadatanet.net>
> >>>>To: <personal_submersibles@psubs.org>
> >>>>Sent: Friday, February 20, 2004 12:42 PM
> >>>>Subject: Re: [PSUBS-MAILIST] Water depth
> >>
> >>sensing?
> >>
> >>>>
> >>>>>Steve,
> >>>>>
> >>>>>I'm using a pressure sensor from Digikey
> >>
> >>(www.digikey.com) for my
> >>
> >>>>rebreather
> >>>>
> >>>>>controller which uses a PIC processor. Mine is
> >>
> >>a 0-250 psi sensor
> >>
> >>>>which
> >>>>will
> >>>>
> >>>>>measure down to about 600 feet but you can get
> >>
> >>them that measure
> >>
> >>>>0-100
> >>>>psi.
> >>>>
> >>>>>The particular sensor I'm using is a
> >>
> >>Measurement Specialties
> >>
> >>>>2000519. It
> >>>>
> >>>>>has a .5-4.5v ratiometric output voltage and
> >>
> >>runs on 5 vdc and a
> >>
> >>>>1/4" NPT
> >>>>
> >>>>>pressure port. The downside is they are
> >>
> >>somewhat pricey....about
> >>
> >>>>$100.00.
> >>>>
> >>>>>Hope this helps....Al
> >>>>>
> >>>>>Al Secor ARS: WA3PWX Scuba Instructor SSI
> >>
> >>PDIC TDI
> >>
> >>>>>http://www.geocities.com/SubDiverI
> >>>>>----- Original Message -----
> >>>>>From: "steve" <steve@kobol.worldonline.co.uk>
> >>>>>To: <personal_submersibles@psubs.org>
> >>>>>Sent: Friday, February 20, 2004 3:37 AM
> >>>>>Subject: Re: [PSUBS-MAILIST] Water depth
> >>
> >>sensing?
>
=== message truncated ===
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