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Feature request - rebreather solenoid signal

Discussion in 'Shearwater Research' started by doctormike, Jul 8, 2019.

  1. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    No, the NERD is a monitor, why would it need to be a controller for this application?

    The NERD would get the signal from the DiveCAN bus that the solenoid was either (1) getting a command to fire, or (2) actually firing (which might be difficult from an engineering point of view, as mentioned).

    But the signal only makes sense if it's coming to you continually through a HUD. If the signal can be delivered through DiveCAN, I'm assuming that this information can be displayed on either the controller display or the NERD display. Why would you need to rewire anything? Isn't that the point of DiveCAN?
     
  2. rjack321

    rjack321 Captain

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    Didn't realize you had a divecan unit, had assumed you had a fisher connection.

    Most of this discussion has focused on the actual analog signal at the solenoid ie "voltage has been applied". I don't know how the divecan signal is converted to ~5-12V solenoid power.

    Having this light in your secondary monitor vs in your controller just makes it one more step removed from the actual solenoid plunger opening.
     
  3. hroark2112

    hroark2112 Tech Instructor

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    All this reminds me of why I chose an mCCR as my first unit :D
     
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  4. broncobowsher

    broncobowsher Solo Diver

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    Not what I want. Just a visual indicator of the command is enough. If that command starts going into a strange rhythm it is an indicator that something needs addressing. I'm not asking (nor do I want) more complexity in actually trying to monitor actual flow. You are starting to sound like the engineers I work with that take something very simple, turn it into something that is so overly complex it will never work anywhere near what your dreams are. Surprised someone hasn't suggested adding an oxy meter to the blood stream and Bluetooth link it back to the controller.

    No extra hardware, no extra complexity. The controller (Petrel, NERD) is giving the command (DIVCAN?) to fire. That is ALL there should be any monitoring of. If that isn't working right, time to get out of the water and figure the problem. And that problem better not be the O2 flow monitoring system isn't working right. You do realize that a manual rebreather works based on simplicity, not complexity. Any of the real electronic rebreathers should be able to be dived manually (that is simply) and without added BS. If you want the added BS, may I suggest a Poseidon or a Liberty. They appear to enjoy pissing off the diver with all the extra features.
     
  5. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    Yeah, this .^^ is the important point.

    I'm not suggesting this to replace PO2 monitoring. I'm not suggesting that hearing the solenoid means that everything is fine.

    I'm just saying that a normally functioning eCCR fires the solenoid at a regular rhythm, based on O2 consumption. And if that firing rate suddenly gets much faster or slower, it's one simple sign to alert the diver that something has changed. If the people with normal hearing have that advantage, I would just like to have it as well.
     
  6. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    There would be no point of having this light on the controller, so not sure why that's an issue. Either the information can or can't be transmitted to the NERD. That's the only place that it would do any good.
     
  7. hroark2112

    hroark2112 Tech Instructor

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    Just for me, any blinking lights in my face kicks my ADHD into high gear, which would likely explain why this idea is a "no" in my mind. Although if it were added, as long as it can be turned off I'd be totally OK with it.
     
  8. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    Here, I made a little mockup of what I had in mind.

     
  9. jgttrey

    jgttrey Barracuda

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    Yeah.... I didn't actually ask for any of that stuff if you read my posts.

    I was simply suggesting, semi-tongue in cheek, a workaround for a diver, not me or apparently you, who can't hear his solenoid and would like some way to get feedback.

    My unit does indicate when voltage is sent to the solenoid as you suggest, but it's not a very useful feature. Harmless, but of limited use because it tells you nothing about whether the solenoid is actually working. For that you need to watch PO2, which of course you should be doing anyway, begging the question of why the indicator would be needed to begin with.
     
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  10. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    Once more, this isn't an idea to replace PO2 monitoring. Not sure why that straw man keeps being brought up.

    Yes, an indicator of when the solenoid is being instructed to fire isn't the same as an indicator of when the solenoid is actually firing, which in turn isn't the same as an indicator of when O2 is actually being added to the loop. But, as mentioned several times, a rebreather diver who notices that the solenoid is suddenly firing faster or not firing at all (or suddenly getting faster commands to fire, or not getting those commands at all) would be alerted that something has changed with the functioning of the unit (examples upthread).

    We all are taught that if for some reason we find ourselves breathing faster, feeling anxious, or any other subtle CHANGE in our baseline state, that we should do a dil flush or bail out. Now none of those things are the same as an end tidal CO2 monitor, but that doesn't mean that they are useless information. And someday when we DO have end tidal CO2 monitors, you can be sure that the same recommendation will be made, because it's one more channel of useful information.
     

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