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Thread: Pondering simplicity: analog o2 monitoring?

  1. #11
    Thinker n Tinkerer Sparedone is an unknown quantity at this point Sparedone's Avatar
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    Re: Pondering simplicity: analog o2 monitoring?

    Good catch, thank you. I was getting hasty in my search.

    Secondly, thanks for pointing out the missing resistor. I have PSR-11-33-NM 25mv cells on the way (mk15) and would I be right to assume I'm safe with minimum 10 kOhms resistor in line regardless of the additional meter impedance?

    Again thanks, Cameron

  2. #12
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    Re: Pondering simplicity: analog o2 monitoring?

    I think that it's important to separate nostalgia from other things.

    Fifteen components with an aggregate probability of failure that multiply out less than one less reliable component means that the more complex system is still more reliable and that's what you're looking at here.

    No way is an electromechanical display going to ever be more reliable than an electronic path.

    If you want to do it because it's oldskool fully sick, go for it.
    If you want to do it because you lack the skills and knowledge to do the electronic version, go for it.
    But don't kid yourself that it's going to be more reliable.

  3. #13
    Thinker n Tinkerer Sparedone is an unknown quantity at this point Sparedone's Avatar
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    Re: Pondering simplicity: analog o2 monitoring?

    Guess the old days aren't what they use to be. I'm a tad young myself for nostalgia but I do like the process of reinventing the wheel as a way of learning how life rolls.

    Without some decent sampling I'll withhold option on the aggregated failure rates analog vs digital. You are most likely are right I'd imagine.

    I will own the second possible suggestion. A nice clean lcd ppo2 monitor is beyond my tinkering abilities at this point, especially if I would expect it to be less failure prone. My camera housing designs and flashlight encounters have proved this over the years.


    In way of update... Thanks for the various inputs. Without horribly good reasons not to I'm going for it for kicks and giggles, since arguably ppo2 monitoring on an o2 breather isn't critical anyway it shouldn't hurt to drag them along.

    Placed the order for four 45mm 200mv 10Ω voltmeters this evening. Now the fun part.

    I'd appreciate heads up on some signs of failure to watch for as well from the mk15, topaz crowd if some of you stumble across this thread. ...for that matter I am in the market for a mcc as much as I enjoy bench time

    Well, thanks for tolerating my whim, I'll update on the build as it develops, keeping in this thread to avoid clutter.
    Last edited by Sparedone; 20th June 2016 at 05:27.

  4. #14
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    Re: Pondering simplicity: analog o2 monitoring?

    Don't get me wrong:

    "For sh its and giggles", "bow ties are cool" and my favourite: "because I want to" are some of the very best reasons to embark on a project like this.

    And I suspect you'll have your PPO2 meter up and running a heck of a lot quicker than mine :)

  5. #15
    Thinker n Tinkerer Sparedone is an unknown quantity at this point Sparedone's Avatar
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    Re: Pondering simplicity: analog o2 monitoring?

    Might just have something to do with my 'revolutionary' design is lacking any parts that need an electron microscope to see and butterflies fart to solder.

    If you happen to sweep up under your desk I'll buy whatever happens to have fallen forgotten there though. And I've been following your thread, looking forward to the next batch of updates.

    Oh, since I somewhat have you stopped buy... can I at least expect a binary failure when the electromechanical gauge goes wonky on me? Eg. Will the wheels fall off my wagon or just wobble till get a headache?

    And a brief google does show up the studies which includes reliability as why aviation has moved to solid state gauges. My dream is officially crushed... but hey, I'll be the only kid on my block.

  6. #16
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    Re: Pondering simplicity: analog o2 monitoring?

    Quote Originally Posted by Sparedone  View Original Post
    Without horribly good reasons not to I'm going for it for kicks and giggles, since arguably ppo2 monitoring on an o2 breather isn't critical anyway it shouldn't hurt to drag them along.
    .. I assume this is a typo..?
    www.rEvo-rebreathers.com
    ...."Yes you have to pre-breathe to activate the scrubber sorb, anyone who says different doesn't know what they are talking about!"...
    .... to get more accurate CO2 injection in the breathing machine we put 2 mass flow controllers in series ...
    .... The noise is a few tens of nano-volts, so DL were able to reduce the output voltage ...
    .... radial scrubbers give longer dwell time than axials...
    .... the earth is flat and ...

  7. #17
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    Re: Pondering simplicity: analog o2 monitoring?

    Quote Originally Posted by Sparedone  View Original Post
    Placed the order for four 45mm 200mv 10Ω voltmeters this evening. Now the fun part.
    .

    you do understand why this will never work with an O2 sensor?
    www.rEvo-rebreathers.com
    ...."Yes you have to pre-breathe to activate the scrubber sorb, anyone who says different doesn't know what they are talking about!"...
    .... to get more accurate CO2 injection in the breathing machine we put 2 mass flow controllers in series ...
    .... The noise is a few tens of nano-volts, so DL were able to reduce the output voltage ...
    .... radial scrubbers give longer dwell time than axials...
    .... the earth is flat and ...

  8. #18
    Thinker n Tinkerer Sparedone is an unknown quantity at this point Sparedone's Avatar
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    Re: Pondering simplicity: analog o2 monitoring?

    Quote Originally Posted by paulraymaekers  View Original Post
    you do understand why this will never work with an O2 sensor?
    Sadly not... an impedance issue if I were to hazard a guess. Give a man a fish?

    And yes, thankfully the irrelevance of ppo2 comment was tongue in cheek.

  9. #19
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    Re: Pondering simplicity: analog o2 monitoring?

    Quote Originally Posted by Sparedone  View Original Post
    Sadly not... an impedance issue if I were to hazard a guess.
    then better not to try to make life support electronics!
    warm regards
    www.rEvo-rebreathers.com
    ...."Yes you have to pre-breathe to activate the scrubber sorb, anyone who says different doesn't know what they are talking about!"...
    .... to get more accurate CO2 injection in the breathing machine we put 2 mass flow controllers in series ...
    .... The noise is a few tens of nano-volts, so DL were able to reduce the output voltage ...
    .... radial scrubbers give longer dwell time than axials...
    .... the earth is flat and ...

  10. #20
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    Re: Pondering simplicity: analog o2 monitoring?

    The Jewell Gauges that we had made for the Mark 15/15.5's cost us, in 1996, $110 each in lots of 50 minimum. They are VERY fragile.

    I remember when I moved into my shop here in Pennsylvania - my oldest son was around 2 at the time, and I had been teaching him how to play catch.

    Sure enough, he grabbed one of these precious gauges and said "Papa!" and threw it (poorly, I might add, sheesh!), and it hit the floor a good 6 feet away from me.

    I told his mother at the time I would have had more enjoyment lighting a cigar with a $100 bill...



    Kevin Juergensen
    Juergensen Marine, Inc.

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