Need help with pH meter

Discussion in 'The Projects Forum' started by dphil, Jul 3, 2008.

  1. dphil

    Thread Starter New Member

    Jul 3, 2008
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    I have been stuck with a problem in my pHmeter expt for almost a month. I searched the net and found many pH circuits and tried many but none are working.I have attached my circuit diagram with this.The problems i face are-1)There is lot of 'noise' present in the output of the TL081. Even if I touch the BNC of the electrode noise can be seen in CRO, 2)the voltage values don't seem to be constant.it keeps on changing with time.if for acid to base i get 800mV change,at the next instant i get 400mV change. What can i possibly do to make my project working??
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. dphil

    Thread Starter New Member

    Jul 3, 2008
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    Thankyou for the reply. I will definitely try out ideas mentioned in the sites you have recommended. Will let you know the improvements too.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The TL081 IC has more noise than the TL071, LF351, and many other opamps.

    While most of your noise is probably occurring due to external sources, having a low-noise opamp will help by reducing noise caused within the amplifier itself.
     
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