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Thread: Ck12

  1. #11
    #keepittea ebt's Avatar
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    A23 12v batteries....

    ....and never use miltons on dive kit unless you like replacing gear. I use trigene from a vets suppliers, although Virkon is slightly better.

    ps. paul, a display with no sensor will *not* read 0.00 unless you put a resistor/short across the input to the meter.

  2. #12
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    Quote Originally Posted by ebt View Post

    ps. paul, a display with no sensor will *not* read 0.00 unless you put a resistor/short across the input to the meter.
    I don't have a Kiss display to test anymore but my homemade one displays 0.

    No current = no voltage, multiply that by zero and you'll get zero volts. The meter is not using the cell to complete the circuit, it's just a voltmeter seeing zero volts, so will display 0.

    As I say, I've not had mine for several years now, perhaps the OP could indulge me with a little experiment when he gets the correct batteries.

    Actually, just re-read your comment, are you saying that the display will be blank or that it will display some sort of floating voltage with no cell?

    I think that despite there being resistors in the cell itself as I think that's how the temperature compensation works, there's still a resistor across the contacts of the meter, so with no cell it'll read zero.

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  3. #13
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    From the manual:

    PPO2 READ OUT IS ZERO OR‐1:
    If the read out is‐1 then sea water has come in contact with the circuit board and/or meter.Any parts that have
    come in contact with sea water must be replaced.
    If the read out is zero, then it could also be a dead sensor.

    Granted not entirely conclusive.

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  4. #14
    #keepittea ebt's Avatar
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    Its just a DVM, if you float the inputs the amp will generate a small reading... (like 0.01x, depending on how the impedance matching is done)

    the only way you get a real zero is to short the pins, hence the comment about the flooding you saw.
    Last edited by ebt; 22-10-2017 at 10:50 PM.

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    Just fitted correct batteries and units are working, not booked up to cells yet but with power on the readout in each is -.000

  6. #16
    #keepittea ebt's Avatar
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    interesting!! my generation of displays floated....

    guess I'll owe paul a pint then.

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    Nicotine, valium, vicodin... notdeadyet's Avatar
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    Quote Originally Posted by Turbanator View Post
    In it's simplest form, you could measure the output of the cell across a resistor (It's a current course,not a voltage source) and multiply the milivolts by a constant to give PO2, the resistor bridge just prevents you having to do sums underwater.
    I did this for a while after I flooded a display and had to replace a meter. It's just a Lascar DPM but there is a (tiny) surface mount resistor that has to be desoldered from the board to make it work as a PPO2 meter. I couldn't be arsed (i.e. I knew I'd fuck it up) so just installed it as it came out of the bag as a pure voltmeter. R22D cells output in mV is almost half of what the O2 content is in % (eg. 100% oxygen at the surface would read ~50mV on the display, use the trim pot to get it bang on). It wasn't a hard calc to do underwater, just double the reading and move the decimal point to get ppo2. I dived it for a long time (years) like that. I only ever bothered fixing it when I went to sell it.
    Caliph Hamish Aw-Michty Ay-Ya-Bastard, Spiritual leader of Scottish State in England

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    Quote Originally Posted by ebt View Post
    interesting!! my generation of displays floated....

    guess I'll owe paul a pint then.
    Mine was 146, so had mk2 displays I think.
    They had optional backlights, but still required a plug rather than the twistable disk to trim.
    Thty were all screwed to a perspex sheet rather than the 'chocolate block' style.


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  9. #19
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    Quote Originally Posted by ebt View Post
    Its just a DVM, if you float the inputs the amp will generate a small reading... (like 0.01x, depending on how the impedance matching is done)

    the only way you get a real zero is to short the pins, hence the comment about the flooding you saw.
    Depends if they have a load resistor in the handset, if there is a load resistor in there then that will clamp the meter reading down to zero.


 
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