ph electrode circuit

Posted on Feb 6, 2014

A pH electrode measures hydrogen ion (H+) activity and produces an electrical potential or voltage. The operation of the pH electrode is based on the principle that an electric potential develops when two liquids of different pH come into contact at opposite sides of a thin glass membrane. This is a design circuit for the measurement. This is the

ph electrode circuit
Click here to download the full size of the above Circuit.

figure of the circuit. Amplifier U1 off sets the pH electrode by 512 mV. This is achieved by using National`s LM4140A-1. 0 precision micro power low-dropout voltage reference that produces an accurate 1. 024V. That voltage is divided in half to equal 512 mV by the 10 k © resistor divider. The output of amplifier U1, which is set up in a unity-gain configuration, biases the reference electrode of the pH electrode with the same voltage, 512 mV, at low impedance. The pH-measuring electrode will produce a voltage which rides on top of this 512 mV bias voltage. In effect, the circuit shifts the bipolar pH-electrode signal to a uni-polar signal for use in a single-supply system. The second amplifier U2 is set up in a unity-gain configuration and buffers the output of the pH electrode. Again, a high-input impedance buffer between the pH electrode and the measurement instrument allows the circuit to interface with a greater variety of measurement instruments including those with lower input impedance. In most applications, the output voltage of the pH electrode is high enough to use without additional amplification. If amplification is required, this circuit can easily be modified by adding gain resistors to U2.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    400-Volt 60-watt push-pull power supply
    Electronics Circuits Reference Archive Audio LED VU meter
    Fire Fighting Robot (AT89S52)
    ir remote control extender mark 5
    build good audio buffer
    LM4610 Dual Dc Operated Tone/volume/balance Circuit With National 3-d Sound - National Semiconductor
    How to Control Electronic Circuits Using a Computer and the BASIC Programming Language
    Automatic UPS system wiring circuit diagram for Home or Office (New Design With One Live Wire)
    Plans for the Next MP3 Player
    Overvoltage protection circuit diagram
    Fill light indoor photography circuit