Digital pH Meter Signal Conditioner with Pulse/Frequency Output

A signal conditioner for pH meter probe is required to have high input impedance. The signal conditioning of the pH meter probe is done by providing a buffer with gain, offset, and volatge to frequency converter. High input impedance requirement for pH probe while maintaining low cost constraint is given by 3130 CMOS opamp. Output of probe, is amplified by the op-amp. The configuration of the op-amp provides gain and offset adjustment to calibrate the drift caused by temperature variation of solution measured by the probe. This amplifier produce DC signal ranging from positive voltage for low pH to 0 V for pH 7 and negative voltages for high pH values. Output of opamp can be fed directly to center-scale milliammeter through 100K calibrating pot for analog reading. In digital display, 0V output representing pH 7, then pH output is converted to calibrated current for summing with stable offset current equal to 700 counts. This converter convert fed to current to frequency and very suitable for digital display. Here is the schematic diagram of the circuit:

DIGITAL pH METER circuit schematic diagram

This entry was posted in Test and Measurement and tagged , . Bookmark the permalink.,
Possibly Related to "Digital pH Meter Signal Conditioner with Pulse/Frequency Output" Circuits

  • Digital pH Meter Signal Conditioner
    A pH meter circuit is basically an amplifier to boost a voltage signal which is produced by a pH probe. The pH probe itself is equal to a battery cell when submersed in the measured solution, producing a weak voltage … Continue reading →...
  • Simple pH Meter Circuit, A Low Cost Adapter for Your Digital Voltmeter
    What is A pH Meter? A pH meter is actually a precise voltmeter  that measures the generated voltage of a pH electrodes. The requirement of such meter is high input impedance and has the gain of  voltage-pH conversion. The standard … Continue reading →...
  • Inductance Meter Adapter Circuit, Turns Your Digital Voltmeter to Inductance Meter
    Measuring inductance is important in making your hand-made inductors, especially when you do-it-yourself (DIY) your coil winding. An inductance meter adapter circuit would be helpful since you can measure inductance using your general purpose digital voltmeter (DVM). This circuit cost … Continue reading →...
  • Temperature Probe for Digital Multi Meter
    This is a simple temperature measurement probe circuit. This circuit measures temperature either on a PC board or at the probe tip to which contains the temperature sensor. It can be used for debugging and troubleshooting electronic circuits. Here is … Continue reading →...
  • Digital Sample And Hold
    If you need to hold an analog signal for infinite period then this digital sample and hold circuit is the solution.  This circuit uses a Exar XR-2240 programmable timer/counter as main component. The Exar XR-2240 is triggered when strobe input … Continue reading →...

Comments are closed.