PPO2 monitor.

[divetheworld]

Been chatting over with the Draeger boys, this is the conversation;

Originally Posted by Kerry McKenzie

Analog is by far the better option and this is one of the reasons digital watches fell from favour eg going to work 7:45am still registers a 7 :00 am
in the brain and not quarter to eight as you see it on an analog screen.
Most airlines still use all analog reading instruments even though they are
digital driven displays.

Right now the only analog meters are being used on the mk15 and the prism and are jeweled movement , extremely expensive and subject to damage. While lcd are cheap and robust and are very acuate, more bang for your buck.(edited)

I suggested these;

http://www.lascarelectronics.com/products.cfm?STOCKNO=SP%205%2D1710%2DBL&CFID=67686 72&CFTOKEN=38591763

or

http://www.lascarelectronics.com/products.cfm?STOCKNO=EMA%201710&CFID=6768672&CFTOK EN=38591763

Any comments?

I'm thinking of making a monitor with analogue and digital in it. Problem is, you use 3 cells to avoid failure problems. Replacing one DPM with analogue would require some thinking to avoid defeating the object.

[narked at 90]

hello brent i was looking at these a wile ago more for the novelty than any thing else

i've just about finished some new displays which are very funky! there just being anodized and pressure tested then i'll post some pics

the problem i can see with these displays from lascar is there is no option on the boards to increase the gain not even with mods, so the display will read very low all the time and you will have problems calibrating, i guese you could use it as a quik visual guide if you can get the gain up( or you'll have to use an amp) but you'll still have the problem with calibrating
and to loose one of your cells so you can use this display i think would be taking away safty not adding.
but i could be wrong mate
best regards john

[divetheworld]

Your probably right, and it is a novelty to me too. Look cool though!

[narked at 90]

what do ya think, we should stick it to the front of are masks with doudle sided tape and call it a A'HUD Anolog Heads Up Display!
regards john routley

Originally Posted by divetheworld

Your probably right, and it is a novelty to me too. Look cool though!

[divetheworld]

If we remove the grey backing, the LCD element is transparent. We could stick it directly over the mask lens!
If your really clever you can whop your PO2 up and down so quick it looks like windscreen wipers!

[Drmike]

Improvised HUD I made last week using primary display, duct tape and a hose clamp.

Big and ugly but fine as a temp measure.


http://www.yorkshire-divers.co.uk/ga...p-pics/ffmmk15
http://www.yorkshire-divers.co.uk/ga.../me_mk15_coron

[Duncan Price]

Originally Posted by divetheworld

I'm thinking of making a monitor with analogue and digital in it. Problem is, you use 3 cells to avoid failure problems. Replacing one DPM with analogue would require some thinking to avoid defeating the object.

I looked into using real moving coil ammeters instead of battery powered LCD displays. The problem is that the current is quite small from a cell and it was difficult to source the correct milliammeter. The PRISM and Mk15 one's are quite expensive because they are bespoke meters.

[The Purist]

Like the idea of analogue displays - in my first dive club we had a guy who designed instrumentation for power stations and he was adamant that it was quicker and more reliable to check that a bunch of needles were pointing the right way than it was to read a bunch of numbers.

Not familiar with the way the Prism/Mk15 displays work - are they configured to read full scale directly from the cells (ie. 0 to 2ish PO2) or so that the set-point is on the centre of the scale with deviations shown as +/-?

[Drmike]

Originally Posted by The Purist

Like the idea of analogue displays - in my first dive club we had a guy who designed instrumentation for power stations and he was adamant that it was quicker and more reliable to check that a bunch of needles were pointing the right way than it was to read a bunch of numbers.

Not familiar with the way the Prism/Mk15 displays work - are they configured to read full scale directly from the cells (ie. 0 to 2ish PO2) or so that the set-point is on the centre of the scale with deviations shown as +/-?

I liked them too until last week when mine started telling me from all cells that I was breathing a ppo2 of over 2 bar!

No such thing as 'truly independent' electronics unless you have independent cells.

Set point was maintained correctly - but secondary display was indicating wrong ppo2

[Simon A]

Originally Posted by Duncan Price

I looked into using real moving coil ammeters instead of battery powered LCD displays. The problem is that the current is quite small from a cell and it was difficult to source the correct milliammeter. The PRISM and Mk15 one's are quite expensive because they are bespoke meters.

Duncan
You may want to have a look at steammachines website. they are selling off a bunch of new prism jewel meters with the scale marked in ppO2 for $150 each.

Simon A