Simplify circuit design; Resistance temperature device (RTD) measurements.

The DPV-3 can be used to significantly reduce the complexity of external circuits required to handle many sensors.

For example RTDs usually require complex circuits to eliminate the offset created by the nominal resistance of the RTD sensor. In the circuit below, all that is required is a 1mA current source, an amplifier set for a gain of 70 , a 100 ohm Pt RTD, and a DPV-3.

• 0 °C output = 100 ohms X 1 mA X 70 = 7.00 volts
• 100 °C output = 138.5 ohms X 1 mA X 70 = 9.66 volts

None of the parameters are critical and need not be held to tight tolerances. There are no separate adjustments required in the external circuit. Both offset and span are done by the DPV-3.

The RTD sensor can placed in a stirred ice batch (0 °C) and the DPV-3 adjusted to display 00.0 °C. Next the RTD sensor is placed in boiling water (100 °C) and the DPV-3 is adjusted to display 100.0 °C.

This even eliminates RTD sensor interchangeability. In addition the °C annunciator on the DPV-3 can be enabled.

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