Low-Drift High-Impedance JFET DC Voltmeter


Posted on Feb 4, 2014

The voltmeter shown in the schematic diagram below has very high impedance. The range selector uses conventional voltage divider resistors, but since the following pre amplifier uses JFET, the divider can be designed using very high resistance series resistors. This DC voltmeter circuit also featured with low drift. This circuit uses a pair JFETs,


Low-Drift High-Impedance JFET DC Voltmeter
Click here to download the full size of the above Circuit.

which is configured in a balanced-bridge source-follower amplifier circuit. The Q2 and Q1 must be matched within 10% for Idss that will maintains bridge balance over temperature. Here is the schematic diagram of the circuit:




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    12 volt power supply (7812)
    2x30W audio amplifier (STK465)
    Stud-finder
    Keyboard Matrix Interface
    Positive And Negative Voltage Switching Supply
    Simple RS 232 Level Converter
    Poddwatt: Class-A Stereo Push-Pull EL84 (6BQ5) Vacuum Tube Amplifier
    Digital Controlled Precision Amplifier Circuit PCB
    IN4148 Silicon Epitaxial Planar Switching DIODE
    1 A LAMP FLASHER
    Medical call with lighting signal receiver circuit diagram



    Top