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Thread: Analog electronic controller.

  1. #11
    RBW Member Bottom Dollar Diver is an unknown quantity at this point Bottom Dollar Diver's Avatar
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    Classic Inspiration

    Re: Analog electronic controller.

    Quote Originally Posted by anarchista  View Original Post
    Exactly cut it short inclusions are unnecessary and consume a solenoid mechanically draw too much energy.

    greet rc
    Hi,
    The translation to english is poor. I think I understand your point: The very short solonoid openings are not necessary and consume power and wear out the solonoid.

    Maybe, except I defer to the engineers at Inspiration Headquarters and I assume that the Inspiration was well designed and tested. They easily could have elimited short solonoid openings if they wanted to.

    I think the reason for very short solonoid openings is to improve the setpoint holding specification. it probably has no meaning in practical diving situations.
    Regards,
    Mark Thompson

  2. #12
    RBW Member Bottom Dollar Diver is an unknown quantity at this point Bottom Dollar Diver's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by lizardland  View Original Post
    You can't really see much on the pod as the whole thing is potted. There's a copy of the manual posted somewhere on here, it has the circuit diagrams in it.
    Hi,
    Thanks, I will try to get that.
    Regards,
    Mark Thompson

  3. #13
    RBW Member anarchista is an unknown quantity at this point anarchista's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by Bottom Dollar Diver  View Original Post
    Hi,
    The translation to english is poor. I think I understand your point: The very short solonoid openings are not necessary and consume power and wear out the solonoid.

    Maybe, except I defer to the engineers at Inspiration Headquarters and I assume that the Inspiration was well designed and tested. They easily could have elimited short solonoid openings if they wanted to.

    I think the reason for very short solonoid openings is to improve the setpoint holding specification. it probably has no meaning in practical diving situations.
    Translation is not as bad as usual.
    I just do not know what I say.

    What you have here electro valve
    http://www.rebreathers.pl/forum/download.php?id=2
    CMF is at 12-16l/min oxygen dosis. Opening at 1 s is not very effective for changes ppO2. This gives a dose of 0,23l l of oxygen resulting in a change of 0.01 ppO2 loop, with a volume of about 20l (included here rigid and flexible capacity.) The inclusion of a short play with noise. For this purpose, the systems with hysteresis. If you want to enter the upper limit dosage of oxygen is a threshold system can reduce the amount of energy consumed. To open the valve you need more power than its maintenance.

    Completely understood what was going on, in accelerating the setting ppO2 ascent. You do not know the subject. The problem was solved by J.B.Morrison

    greet rc
    Last edited by anarchista; 25th June 2011 at 07:44.

  4. #14
    RBW Member Bottom Dollar Diver is an unknown quantity at this point Bottom Dollar Diver's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by anarchista  View Original Post

    You do not know the subject.

    greet rc
    Hi,
    Yes, you are right about that! I am not a rebreather design expert. That is why I plan to exactly emulate the original Inspiration controller. That way I can be assured that it will work properly.

    I understand your points about noise and the need for hysteresis in the system. This would be one reason for the 6 second hold off time, to prevent rapid opening and closing of the valve. It can only open once between each 6 second delay.

    I am not thinking about power consumption. I will give my new controller plenty of battery capacity. Also the circuitry is not "state of the art" in low power consumption. I am using well proven, simple circuitry.
    Regards,
    Mark Thompson

  5. #15
    RBW Member anarchista is an unknown quantity at this point anarchista's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by Bottom Dollar Diver  View Original Post
    That is why I plan to exactly emulate the original Inspiration controller. That way I can be assured that it will work properly.

    I understand your points about noise and the need for hysteresis in the system. This would be one reason for the 6 second hold off time, to prevent rapid opening and closing of the valve. It can only open once between each 6 second delay.

    I am not thinking about power consumption. I will give my new controller plenty of battery capacity. Also the circuitry is not "state of the art" in low power consumption. I am using well proven, simple circuitry.
    You can see the size dependence of the deviation from setpoint and valve opening time of dose CMF.
    Look for Pat Martin Parker in particular for links, is more information than they know trainee instructors in using this design.
    espacenet - Bibliographic data
    Cited documents: View all

    greet rc
    Last edited by anarchista; 25th June 2011 at 16:46.

  6. #16
    RBW Member Bottom Dollar Diver is an unknown quantity at this point Bottom Dollar Diver's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by anarchista  View Original Post
    You can see the size dependence of the deviation from setpoint and valve opening time of dose CMF.
    Look for Pat Martin Parker in particular for links, is more information than they know trainee instructors in using this design.
    espacenet - Bibliographic data
    Cited documents: View all

    greet rc
    Hi
    OK, I will read all this information. Thanks for the references.

    Also, you are correct. Rebreather training is weak about the "servo" aspects of the loop ppO2 control. I am familier with feedback and servo systems in other areas of electronics.
    Regards,
    mark Thompson

  7. #17
    RBW Member Mike_Eitel is an unknown quantity at this point Mike_Eitel's Avatar
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    Re: Analog electronic controller.

    HI

    I'm wondering to do my own controler since a few years...
    I don't think that you shoud do it without microcontroler.

    I have very fast teldyne cells. The respond much faster than AI. Also the new narked at 90 is very fast.

    With these cells I can see what happems in my manual injected CCR.

    After I press the button and I have to breat AT LEAST three to four times, before the meassured ppO2 is "balanced" in my system. Means that you have to use quite a big "intergral compensation". Not so easy to do in analog. I think that i must use something like a "programmed regulator" that needs "timed ppO2 compensation by measured injection time".

    Mike

  8. #18
    RBW Member moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund is a glorious beacon of light moribund's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by Bottom Dollar Diver  View Original Post

    I am not thinking about power consumption. I will give my new controller plenty of battery capacity. Also the circuitry is not "state of the art" in low power consumption. I am using well proven, simple circuitry.
    Regards,
    Mark Thompson
    Keep in mind that there are newer versions of many devices that are lower power and more efficient than the originals. Since a RB has to carry it's power with it (hmmmm...saltwater, dissimilar metals, am I thinking really self-contained, green energy RB here? Well, that's a separate topic!) you always want to go for the lowest power option if possible. No reason not to stay with proven and simple circuitry.

  9. #19
    RBW Member anarchista is an unknown quantity at this point anarchista's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by Mike_Eitel  View Original Post
    I'm wondering to do my own controler since a few years...
    I don't think that you shoud do it without microcontroler.
    ....
    Not so easy to do in analog. I think that i must use something like a "programmed regulator" that needs "timed ppO2 compensation by measured injection time".
    It is simple in the analog variant.

    greet rc

  10. #20
    RBW Member Bottom Dollar Diver is an unknown quantity at this point Bottom Dollar Diver's Avatar
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    Re: Analog electronic controller.

    Quote Originally Posted by Mike_Eitel  View Original Post
    HI



    After I press the button and I have to breat AT LEAST three to four times, before the meassured ppO2 is "balanced" in my system. Means that you have to use quite a big "intergral compensation". Not so easy to do in analog. I think that i must use something like a "programmed regulator" that needs "timed ppO2 compensation by measured injection time".

    Mike
    Hi,
    I think fast responding cells will be ok. The circuit that I'm working on uses a sampling method. It works like this:

    The amplified cell voltage is compared to a precision voltage reference (the set point) and a positive or negative voltage results. This "error" voltage is positive if O2 is needed, negative if O2 is above the set point. It is exactly proportional to the amount of O2 needed.

    At the end of the 6 second "hold off" period the "error" voltage is sampled by a milli-second gate. The sampled voltage is stored in a capacitor. This capacitor then discharges at a calibrated rate back to zero volts. The solonoid valve opens during the discharge time. When the capacitor returns to zero volts another 6 second "hold off" begins.

    Of course the solonoid only opens if the "error" voltage is positive!

    The interval of the solonoid opening is proportional to the amount of O2 needed at the sample time. That is the only time that the cell output is considered. The 6 second interval allows the O2 level to stabalize before the next measurement sample.

    This is the basic "loop". I also will add warning and monitoring circuits.
    Regards,
    Mark Thompson

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