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Figure 10 Balanced Bridge Circuit | Up
Instrumentation and Control Volume 1 of 2 | Next
Temperature Compensation |
TEMPERATURE DETECTION CIRCUITRY
Temperature Detectors
Temperature Detection Circuit
Figure 11 is a block diagram of a typical temperature detection circuit. This represents a
balanced bridge temperature detection circuit that has been modified to eliminate the
galvanometer.
Figure 11 Block Diagram of a Typical Temperature Detection Circuit
The block consists of a temperature detector (RTD) that measures the temperature. The detector
is felt as resistance to the bridge network. The bridge network converts this resistance to a DC
voltage signal.
An electronic instrument has been developed in which the DC voltage of the potentiometer, or
the bridge, is converted to an AC voltage. The AC voltage is then amplified to a higher (usable)
voltage that is used to drive a bi-directional motor. The bi-directional motor positions the slider
on the slidewire to balance the circuit resistance.
If the RTD becomes open in either the unbalanced and balanced bridge circuits, the resistance
will be infinite, and the meter will indicate a very high temperature. If it becomes shorted,
resistance will be zero, and the meter will indicate a very low temperature.
IC-01
Page 14
Rev. 0
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