[PSUBS-MAILIST] Depth Gage

[Alec Smyth via Personal_Submersibles]

Hi Alan,

My current gauge has no lighting at all, so I have to turn on the cabin
lights to see it. I would certainly prefer it to stay on indefinitely, but
on the other hand it lights up with the press of a button so I guess it's
better than what I have now. If it turns out to be a pain, I guess I could
rig some little lights strategically - it should be easier to place a few
adhesive LED strips in the vicinity than to hack the gauge. There is also
at least one other instrument I would like to see that has no lighting at
all. I've ordered one, so let's see what it's like once in hand.


Best,

Alec

On Mon, Sep 14, 2015 at 7:01 PM, Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Alec,
> looks a good gauge; I am tempted to buy one :)
> It has an auto shut off after an hour, but this can be disengaged.
> The backlight goes out after 2 minutes which may be a nuisance, but as it
> works off a small battery I guess this has to happen to preserve them.
> I would be interested to see if you think this is going to be a problem.
> A solution would be to wire the backlight LED to an external power source
> if you can get at it.
> Cheers Alan
>
>
> ------------------------------
> *From:* Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Tuesday, September 15, 2015 1:02 AM
> *Subject:* Re: [PSUBS-MAILIST] Depth Gage
>
> Coincidentally I just spent yesterday afternoon selecting one of those. I
> would normally prefer an analog gauge because I try to minimize electronics
> to maximize reliability. However, on a 1,000 foot sub the needle would
> barely move on shallower dives, so digital display is the only way to go.
> The accuracy of these instruments is measured as a percent of full scale,
> and a cheap one is accurate to 1% FS. For a thousand foot sub, that means
> the smallest depth change it could measure is 10 feet - not good! Well, let
> me rephrase that. I'm fine knowing my depth to within 10 feet, but what I
> really want to know if whether my depth is increasing or decreasing, and
> I'd like to know that before I've traveled 10 feet.
>
> I settled on the Dwyer DPG-100, because it has this:
>
> - 0.25% FS accuracy
> - Displays pressure directly in feet of water
> - Wetted elements are 316 SS
> - IP66 enclosure (waterproof to "hose-down" standard)
> - Lighted display
> - Battery powered, so no need to wire it into the sub power (battery life
> 2000 hrs)
> - Reasonably priced ($185)
>
> It also records the max depth, hardly a necessity but cool for unmanned
> depth tests. For testing my K250 I just strapped a dive computer outside,
> but that wouldn't work for a test to over 1,000 feet.
>
> Here is a link: https://www.dwyer-inst.com/PDF_files/A_34.pdf
>
> If you want to go the Arduino or PLC route with a touch screen and all
> that, you can step up to the Dwyer DPG-200 because it transmits a process
> signal. The nice thing compared to the normal pressure transducers is if
> your Arduino, PLC, or display screen failed, you could still see the depth
> directly on the gauge. The DPG-200 also has high and low programmable
> alarms with NC and NO switches, so you could use it for example to
> automatically turn on your scrubber when going past ten feet, or to wake
> you up with a klaxon if you are going past your max depth.   However, it
> has cables coming out the back that make it a little less compact, and it
> needs an external power feed. Dwyer also offers low-cost screens that you
> can plug the DPG-200 depth gauge into directly without any processor.
>
> https://www.dwyer-inst.com/PDF_files/A34A_low.pdf
>
>
> I opted for the DPG-100 because my focus is on simplicity, but depending
> on your priorities one or the other of these two should make a good
> instrument.
>
>
>
> Best,
>
> Alec
>
>
>
> On Sun, Sep 13, 2015 at 8:56 PM, Jon Wallace via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
>
>
> SSI technologies P51 family, but Honeywell MLH500PGL01G
> <http://media.digikey.com/Photos/Honeywell%20Micro%20&%20Precision%20Sensors/MLH500PGL01G.jpg>
> is about the same price and has better accuracy.  I use combination of
> arduino, raspberry pi, and processing for my project.  See
> http://www.subdb.info/cgi/database/showvessel/albums/index.cgi?A=1320788990&B=1439139327&C=&D=Submarine%20Environment%20Monitor%20Software
>
> Jon
>
> On 9/13/2015 7:35 PM, Christopher Cave via Personal_Submersibles wrote:
>
> I'm looking to buy an electronic depth gauge. Any suggestions for a brand,
> software etc...
>
> Thanks,
> Christopher
>
>
>
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