to

1
Introduction to Electronic and
Digital Measurement
2
Performance Attributes of Measurement
3
Ideal Instrument
Reference Electronic Instrument Handbook
(Figure 4.1)
4
The Signal Flow of Electronic Instruments
Operator
Instrument
Display and Controls
Information interface
Measurement Information
Digital Information Processing Calibration
Digital Data
Analog to Digital Conversion
Analog Data
Analog Signal Processing Reference
Electrical Signal
Sensor or Actuator
Physical Sensing or Stimulus
DUT
Reference Electronic Instrument Handbook
(Figure 4.4)
5
The Instrument Block Diagram
6
Measurement Systems
7
Measurement Systems
8
Multiple Computers in a Measurement System
Reference Electronic Instrument Handbook
9
Multiple Computers in a Measurement System
Embedded Real-Time Computer
General-Purpose Computer
10
Analog Electronic VOM Meter
Electronic Instrumentation and Measurements DAVID
A.BELL Prentice-Hall International, Inc. ISBN
0-13-288317-1
11
Important limitations
Reference Electronic Instrumentation and
Measurement, DAVID A.Bell, P.86 Chapter 4
cannot measure very low voltage resistance
is to low for measurements in high-impedance
circuitry
http//www.allaboutcircuits.com/vol_1/chpt_8/3.htm
l
12
Important limitations
Reference Modern Electronic Instrumentation and
Measurement Techniques, Albert D.Helfrick and
William D.Cooper, P.132-133 Chapter 6
13
Important limitations
Sensitivity
Input Impedance
The sensitivity of a VOM, given in the unit
ohm/volt, has been described earlier as the
reciprocal of the meter movements full-scale
current.
Example.. A 50-µA movement used with a
multiplier resistor to make a voltmeter has a
sensitivity of 1/5 x 10-5, or 20,000 ?/V.
On low voltage ranges, then, the impedance of
such an instrument tends to be low. In the
case of the 20,000 ?/V meter with 0-to-0.5-V
range, the input impedance is only (0.5 V)(20,000
?/V), or 10 k?
Reference Elements of Electronic
Instrumentation and Measurement, Joseph J. Carr,
P.152 Chapter 7
14
Transistor Voltmeter (Emitter follower)
Calculate the meter current when E 10 V
Determine the voltmeter input resistance with and
without the transistor
With the transistor
Without the transistor
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.87-88 Chapter 4
15
Transistor Voltmeter (Emitter follower)
Calculate the meter current when E 10 V
5 V is not 50 of Full-scale, WHY ?
Determine the voltmeter input resistance with and
without the transistor
With the transistor
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.87-88 Chapter 4
16
Dual Transistor with Adjust base bias
Adjust base biased voltage control
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.89 Chapter 4
17
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.92 Chapter 4
18
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.92 Chapter 4
19
Determine the meter reading
20
HOMEWORK
21
Op-Amp Voltage-Follower Voltmeter
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.95 Chapter 4
22
Non-Inverting Amplifier Voltmeter
Maximum 20 mV, Op-Amp input Current 0.2 µA Im100
µA FSD Rm10 k?
High Input Impedance Low Output Impedance High
Voltage Gain
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.96 Chapter 4
23
Non-Inverting Amplifier Voltmeter (V-to-I)
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.96 Chapter 4
24
AC Electronic Voltmeters
Source of Error, WHY ?
Block DC
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.104 Chapter 4
25
AC Electronic Voltmeters
Error is corrected, WHY ?
Block DC
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.104 Chapter 4
26
AC Electronic Voltmeters
Error is corrected, WHY ?
Block DC
What ?
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.104 Chapter 4
27
AC Electronic Voltmeters
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.106 Chapter 4
28
Series OHM Meter
Reference Electronic Instrumentation and
Measurements, David A.Bell, P.99 Chapter 4
29
Shunt OHM Meter
Current Measurement
Reference Electronic Instrumentation and
Measurements, David A.Bell
Reference Electronic Instrumentation and
Measurements, David A.Bell
30
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