CN0359 4 Wire Conductivity Help

What do the Track-Hold Setup Time and Track-Hold Hold Time settings do? I looked on the wiki, but still did not fully understand. What Excitation voltage/frequency settings would be best for measuring conductivity in the range of 0-200 mS? I am also experiencing an extremely slow response time, especially at higher conductivity levels. The system will reach ~95% of the final value very quickly, but then may take 10+ minutes to reach the final value. Any idea on what could be causing this, or how to get around it? 

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  • Hi Ntroise,

    Sorry for the late response.

    The track-hold setup time is the time interval before the input voltage is sampled for each tracking cycle in the PWM signals driving the ADG1211 switches. The track-hold hold time the time interval after sampling before the hold cycle begins. You can see them in the timing diagram below:

    It is generally accepted that measurements in the mS range for NaCl and KCl solutions use an excitation frequency from 1 kHz to 10 kHz. The excitation voltage depends on the conductivity probe you are using. Be careful not to set this high enough as it will damage the probes.

    I need more details to check for the slow response time you are using. What excitation voltage and frequency are you using. Also, can you tell me the cell constant and model of the conductivity probe you are using?

    Regards,

    Nikko

Reply
  • Hi Ntroise,

    Sorry for the late response.

    The track-hold setup time is the time interval before the input voltage is sampled for each tracking cycle in the PWM signals driving the ADG1211 switches. The track-hold hold time the time interval after sampling before the hold cycle begins. You can see them in the timing diagram below:

    It is generally accepted that measurements in the mS range for NaCl and KCl solutions use an excitation frequency from 1 kHz to 10 kHz. The excitation voltage depends on the conductivity probe you are using. Be careful not to set this high enough as it will damage the probes.

    I need more details to check for the slow response time you are using. What excitation voltage and frequency are you using. Also, can you tell me the cell constant and model of the conductivity probe you are using?

    Regards,

    Nikko

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