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Thread: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

  1. #21
    Darlene Starr - DIY Diva Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen's Avatar
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Snusmumrik  View Original Post
    Great work, Darlene!!!
    Nice looking thing ;)
    Which sensors you are use as depth sensor and as buttons?

    The switches are model: F73NYA from these guys: Piezo Switch Development, Inc.- Providence, Rhode Island, USA

    I use these as they are smaller in diameter and have a smaller thread (15/32-32) than most others with the M16 thread.

    On the depth sensors;

    For analog systems I use the Intersema, MS5212

    For digital; MS5535


    Darlene

  2. #22
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Scuba_Vixen  View Original Post
    Here's the pic of the handset with the display as it's currently programmed:

    Darlene
    Impressive, excellent piece of work.

  3. #23
    Darlene Starr - DIY Diva Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen's Avatar
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Scuba_Vixen  View Original Post
    Been playing with the code for the last 7 hours or so from an older project that I did some hacks on the analog processing board to to see if it'll make a good base for this project, and I'm quite encouraged.

    I'm also running on the processor board from the same project with a few hacks, all of which and then some are on the processor board specifically for this project. I'll try to get the new processor / I/O board running tomorrow, since I believe I have enough parts on hand to build it out.

    The nice thing about having the processor and I/O functions on a seperate board, is that it allows for a processor change really easily. Only that board to redesign to accommodate the different pin-out of the new processor. All the other hardware can stay the same, it doesn't care what kind of MCU you have.


    I'll post a pic of the Primary Handset / display pod tomorrow, so you can get an idea of how the display is laid out.


    Darlene

    I did get the new processor board built and running.

    This new board supports the 9 led HUD as I described at the start of the thread.

    I updated the code to accomodate it, as well as made several new improvements.

    Since it's sort of a "beta" version of the processor board, I made it capable of running the 9 LED HUD program or the old 3 LED HUD program.

    It's also vibe alarm motor capable; you can choose to include one or not.

    I also finished the layout of the new analog processing board, and made one up ready to put parts in; will be ordering from Digikey this week.

    The depth monitoring versus the battery voltage monitoring and having the cell outputs read in 1/10 millivolt resolution is going to be an either/or situation. There's just not enough variable space in the MCU.

    Depth is the lesser important issue on a simple controller system. It's nice to have Auto Setpoint switching tied to depth, and solenoid "on time" tied to depth, but it's not essential.

    Instead, I'll redesign the "cells in" pcb to use some of these new zero offset op amps and have some "dead nuts accurate" actively isolated outputs.

    Here's a piccie showing the primary handset, the secondary display, and the HUD in operation. The HUD is sitting above the primary handset, and that's a stand alone vibe alarm module next to the secondary.


    The setpoint is user settable in the options menu in 0.05 increments from 0.60 to 1.40. You can see it's at 1.05 in the pic.


    Darlene
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    Last edited by Scuba_Vixen; 28th June 2010 at 02:01.

  4. #24
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    Question Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Do you cast your own acrylic or do you get blocks and mill them please?

    (Nice work, by the way!)

  5. #25
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Scuba_Vixen  View Original Post
    The switches are model: F73NYA from these guys: Piezo Switch Development, Inc.- Providence, Rhode Island, USA

    I use these as they are smaller in diameter and have a smaller thread (15/32-32) than most others with the M16 thread.

    On the depth sensors;

    For analog systems I use the Intersema, MS5212

    For digital; MS5535


    Darlene

    So how do you go about waterproofing the sensors?
    Thanks.
    John

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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Do you have any schematics?

    What op-amp do you use? How is it connected?

    What is the digital potentiometer model? Looks like there is 10-bit models with easy control. Nice idea to use these for calibration.

  7. #27
    Darlene Starr - DIY Diva Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen's Avatar
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Mdemon  View Original Post
    Do you cast your own acrylic or do you get blocks and mill them please?

    (Nice work, by the way!)

    I start with a BOB (big ol' block) from McMaster Carr, cut the outside dimensions (also cut the lid while the saw is set, so they are the exact same size) , mill out the recess and o-ring groove, then mate the lid and drill and tap, then lastly, cut the big chamfers on the bottom edges that make them much more ergonomic, sand and polish.

    One of the keys here is working backwards from the ID of standard o-ring sizes to get the inner circumference, and then matching up the o-ring groove dimensions so that a standard sized o ring can be used.

    First, I look at the minimum dimensions I need for the recess, add 1/16" all around for the lip, then see what the perimeter measures out at.

    They divide by Pi to get an inner diameter and pic the closest (usually larger, unless it's really, really close) o ring, multiply that ID by Pi and adjust your o-ring groove dimensions to match.

    Using 1/8" cross sectional O rings, the diameter sizes increment by 1/8", which translated to ~3/8" increments in circumference. That's about an increment of 1/8" in length and 1/16" in width between O ring sizes.



    Darlene

  8. #28
    Darlene Starr - DIY Diva Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen's Avatar
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by DepthCharge  View Original Post
    So how do you go about waterproofing the sensors?
    Thanks.
    John

    I'm off to work in a moment, but when I get home, I'll post a pic of my test mule. A pic can be worth a lot of words.

    Briefly, if you looked on the Intersema site and saw the sensors, they have a nice polished metal ring surrounding them and are mounted on a ceramic substrate.

    I made a small pcb (about .75" by 1.25") that the sensor solders on to, so I can have a breakout for the connections and holes to put fixing screws thru.

    The metal ring will fit snugly into a shallow .375" hole with 2 orings. (same size as on a second stage 9/16 reg fitting) The screws then hold it in place. The .375 hole is only as deep as the metal ring is tall, it's connected to the pressure to be measured with a smaller 1/16" hole.


    Darlene

  9. #29
    New Member DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge is a jewel in the rough DepthCharge's Avatar
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Scuba_Vixen  View Original Post
    I'm off to work in a moment, but when I get home, I'll post a pic of my test mule. A pic can be worth a lot of words.

    Briefly, if you looked on the Intersema site and saw the sensors, they have a nice polished metal ring surrounding them and are mounted on a ceramic substrate.

    I made a small pcb (about .75" by 1.25") that the sensor solders on to, so I can have a breakout for the connections and holes to put fixing screws thru.

    The metal ring will fit snugly into a shallow .375" hole with 2 orings. (same size as on a second stage 9/16 reg fitting) The screws then hold it in place. The .375 hole is only as deep as the metal ring is tall, it's connected to the pressure to be measured with a smaller 1/16" hole.

    Darlene
    Thought that might be a way of doing it. I was a bit concerned about how to fix the sensor so that the pressure wouldn't dislodge it, and still have an easy way to hook it up.
    Thanks again,
    John

  10. #30
    Darlene Starr - DIY Diva Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen has a brilliant future Scuba_Vixen's Avatar
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    Re: Let's Build a PO2 Monitor / Setpoint Controller For a Homebuild mCCR

    Quote Originally Posted by Scuba_Vixen  View Original Post
    I'm off to work in a moment, but when I get home, I'll post a pic of my test mule. A pic can be worth a lot of words.

    Briefly, if you looked on the Intersema site and saw the sensors, they have a nice polished metal ring surrounding them and are mounted on a ceramic substrate.

    I made a small pcb (about .75" by 1.25") that the sensor solders on to, so I can have a breakout for the connections and holes to put fixing screws thru.

    The metal ring will fit snugly into a shallow .375" hole with 2 orings. (same size as on a second stage 9/16 reg fitting) The screws then hold it in place. The .375 hole is only as deep as the metal ring is tall, it's connected to the pressure to be measured with a smaller 1/16" hole.


    Darlene
    Here's the pics.

    I put a Schrader valve on the test mule here so that I could pressure it up thru a variable regulator with a gage, and track the output. It also was to see how well this mounting plan worked out. The space between the sensor and the valve is filled with water, so I could easily detect any leaking. It's never leaked a drop.

    In actual dive versions, I use a 4 screw mounting because the screws are shorter, since the housings are much thinner than that test block of acrylic.

    Also pictured is the little do-dad that can be clamped to a housing with a sensor mounted in it to calibrate the zero and span adjustments on the instrument amp that interfaces it to the ADC.


    Darlene
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