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Thread: Volt meter modifications for o2 sensor display

  1. #1

    Volt meter modifications for o2 sensor display

    Hi does anyone know the electric scheme to build diy o2 display? I know volt meter might be used for o2 display after some small modifications, I've seen one of those diy box working well but can't find open source electric scheme to modify one of my volt meters - for now I want to build o2 display for surface like regular o2 analysers
    I appfeciate your informations and opinion

  2. #2
    RBW Member Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse's Avatar
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    Re: Volt meter modifications for o2 sensor display

    You need to modify the board so you can "recalibrate it". As it it there should be a pot that allows calibration over a small range. But you need to be able to recalibrate it so 9-13mv will show as 20.9mv.


    Here is the info on how to do it on a couple of DPM's

    Airspeed Updates

    If I recall correctly the KISS used the Lascar DPM 2AS-BL and this required no modifications except the addition of a load resistor across the input (10k?)
    Mind you the pot is a surface mount one and not robust enough for regular use. Remove it and run wires for an external 10 turn pot.


    The other way to do it is to add an operational amp to the DPM and set the Op Amp up as a non inverting gain amplifier.
    There is a little more involved in this method but probably worth it.
    You can then use any DPM with out modification. google non inverting amplifier

  3. #3

    Re: Volt meter modifications for o2 sensor display

    thank you very much for explanation Packhorse,
    I see it will be a bit bigger effort to make it than I expected ;)

  4. #4
    RBW Member jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk has a reputation beyond repute jkaterenchuk's Avatar
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    HammerMeg

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    Re: Volt meter modifications for o2 sensor display

    Look around this site and you might find something useful.

    Welcome to PPO2.COM

    John

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    RBW Member mike_123 will become famous soon enough mike_123 will become famous soon enough mike_123 will become famous soon enough mike_123's Avatar
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    Classic KISS #336

    Re: Volt meter modifications for o2 sensor display

    I can't remember the exact details but I bought one of these dirt cheap meters.

    Inside is a calibration potentiometer.

    Lift one of the end legs (which one = 50/50 trial and error) and add a multiturn potentiometer (I think I used 10k) in series with a new calibration potentiometer (470ohms ?) into the circuit.

    Also, solder a 10k resistor across the +/- terminals to correctly load the sensor.

    Set the meter to the 200mV DC range. Connect your o2 sensor and adjust the multiturn pot so that the new calibration pot can vary the indication around the true value.

    Check it in air and O2 before use, as you would any analyser.

    And be careful not to select any of the meter's resistance ranges or you might damage the o2 sensor.

    Not a recommendation as such, but it's worked fine for me for a couple of years now.

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