{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

0132130084_ism09 - CHAPTER 9 Exercises E9.1 The equivalent...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
347 CHAPTER 9 Exercises E9.1 The equivalent circuit for the sensor and the input resistance of the amplifier is shown i Figure 9.2 in the book. Thus the input voltage is in sensor in sensor in R R R v v + = We want the input voltage with an internal sensor resistance of 10 k to be at least 0.995 times the input voltage with an internal sensor resistance of 5 k . Thus with resistances in k , we have in in sensor in in sensor R R v R R v + + 5 995 . 0 10 Solving, we determine that R in is required to be greater than 990 k . E9.2 (a) A very precise instrument can be very inaccurate because precision implies that the measurements are repeatable, however they could have large bias errors. (b) A very accurate instrument cannot be very imprecise. If repeated measurements vary a great deal under apparently identical conditions, some of the measurements must have large errors and therefore are inaccurate. E9.3 V 2 . 0 5 . 5 7 . 5 2 1 = = = v v v d V 6 . 5 ) 7 . 5 5 . 5 ( ) ( 2 1 2 1 2 1 = + = + = v v v cm E9.4 The range of input voltages is from -5 V to +5 V or 10 V in all. We have 256 2 2 8 = = = k N zones. Thus the width of each zone is 1 . 39 10 = = N mV. The quantization noise is approximately 3 . 11 3 2 rms = q N mV. E9.5 Look at Figure 9.14 in the book. In this case, we have f s = 30 kHz and f = 25 kHz. Thus, the alias frequency is f alias = f s - f = 5 kHz. E9.6 The file containing the vi is named Figure 9.17.vi and can be found on the CD that accompanies this book.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
348 Problems P9.1 The elements of a computer-based instrumentation system include sensors, signal conditioners, analog-to-digital converters, a computer, and suitable software. P9.2* The equivalent circuit of a sensor is shown in Figure 9.2 in the book. Loading effects are caused by the voltage drop across R sensor that occurs when the input resistance of the amplifier draws current from the sensor. Then the input voltage to the amplifier (and therefore overall sensitivity) depends on the resistances as well as the internal voltage of the sensor. To avoid loading effects, we need to have R in much greater than R sensor . P9.3 The equivalent circuit for a sensor for which the short-circuit current is proportional to the measurand is In this case we want the short-circuit current to flow into the amplifier (which is often a current-to-voltage converter). Thus we need to have R in much smaller than R sensor . P9.4* The equivalent circuit for the sensor and the input resistance of the amplifier is shown in Figure 9.2 in the book. Thus the input voltage is in sensor in sensor in R R R v v + = We want the overall sensitivity to be affected by less than 1% by loading. Thus we require 99 . 0 + in sensor in R R R Using the fact that R sensor = 1 k and solving we determine that we need k 99 in R .
Image of page 2
349 P9.5* We need a current-to-voltage converter that converts the short- circuit current into a voltage that can be applied to an analog-to- digital converter. The equivalent circuit is: The input current to the converter is in sensor sensor sensor in R R R I i + = Furthermore we want the overall sensitivity to change by no more than 1% as R sensor
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern