Temp. resistance measuring cct. - has only one voltage supply and negligible measuring errors

摘要

The circuit uses a temperature-dependent measuring resistor and comprises a voltage supply, a constanct current supply and a voltmeter with a differential amplifier on the input side, whereby a constant measuring current is passed through the resistor via a feed wire and a return wire and the voltage drop at the resistor is measured by the voltmeter through first and second measuring wires. An inverting compensating high gain amplifier has one input connected to the end of the return wire, a second input connected to a central neutral wire and its output connected to the end of the second measuring wire. The second input of the voltmeter or differential amplifier is connected to the neutral wire but not directly to the end of the second measuring wire.