PRESSURE DETECTION CIRCUITRYPressure DetectorsPRESSURE DETECTION CIRCUITRYAny of the pressure detectors previously discussed can be joined to an electricaldevice to form a pressure transducer. Transducers can produce a change inresistance, inductance, or capacitance.EO 1.6 EXPLAIN how a strain gauge pressuretransducer produces an output signal including:a. Method of detectionb. Method of signal generationEO 1.7 Given a basic block diagram of a typical pressuredetection device, STATE the purpose of the followingblocks:a. Sensing elementb. Transducerc. Pressure detection circuitryd. Pressure indicationResistance-TypeTransducersIncluded in this category of transducers are strain gauges and moving contacts (slidewire variableresistors). Figure 3 illustrates a simple strain gauge. A strain gauge measures the external force(pressure) applied to a fine wire. The fine wire is usually arranged in the form of a grid. Thepressure change causes a resistance change due to the distortion of the wire. The value of thepressure can be found by measuring the change in resistance of the wire grid. Equation 2-1shows the pressure to resistance relationship.(2-1)RKLAwhereR = resistance of the wire grid in ohmsK = resistivity constant for the particular type of wire gridL = length of wire gridA = cross sectional area of wire gridIC-02 Page 6 Rev. 0
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