SELECTEDMEASURING-SYSTEM COMPONENTS AND EXAMPLES Operational Amplifiers Operational amplifiers [] used in measuring systems have the basic configuration shown in Fig. . The operational amplifier is composed of a high-gain voltage amplifier coupled with both input and feedback impedances. | STANDARD HANDBOOK OF MACHINE DESIGN FIGURE Frequency response of strip-chart recorder of Example 4. Input frequency co rad s Amplitude V Phase angle lag Input Output 0 0 5 10 10 20 15 30 20 45 25 90 It follows that 10 cos 5t - cos 10t - cos 20i - SELECTED MEASURING-SYSTEM COMPONENTS AND EXAMPLES Operational Amplifiers Operational amplifiers used in measuring systems have the basic configuration shown in Fig. . The operational amplifier is composed of a high-gain voltage amplifier coupled with both input and feedback impedances. The characteristics of MEASUREMENT AND INFERENCE FIGURE Operational amplifier circuit a General h voltage amplifier c charge amplifier d integrator e differentiator. e eio o e0 the operational amplifier depend on the feedback impedance Zf and input impedance Z selected according to Eq. e Z The relations between input and output voltage for the specific configurations shown in Fig. are as follows Voltage amplifier - Ri Charge amplifier Integrator 1 ff eo - e dt eo 0 Kil_f A STANDARD HANDBOOK OF MACHINE DESIGN Differentiator n det e RfCi 3-24 Piezoelectric Crystal Piezoelectric crystals are specific crystals of such materials as quartz barium titinate and lead zirconate which when properly heated and quenched demonstrate the piezoelectric phenomenon. The piezoelectric phenomenon is that the crystal when stressed produces an electric charge on its surfaces. If the crystal is a wafer of thickness t and its surfaces are coated with or touching conductive plates the plates become a capacitor of plate area A spacing t and dielectric property e of the piezoelectric material. The voltage developed from the piezoelectric crystal from any input force pressure acceleration stress etc. is eo Sex where S voltage sensitivity and x input variable. The voltage sensitivity depends .
