signal conditioning: attenuation, amplification, addition …€¦ · general characteristics of...
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![Page 1: Signal Conditioning: Attenuation, Amplification, Addition …€¦ · General Characteristics of Signal Amplification (p. 35) Gain is the relationship between change in input and](https://reader031.vdocuments.site/reader031/viewer/2022022508/5acf16207f8b9a6c6c8cafdc/html5/thumbnails/1.jpg)
Signal Conditioning:Attenuation, Amplification, Addition and Subtraction
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General Characteristics of Signal Amplification (p. 35)
Gain is the relationship between change in inputand change in output voltages,
Gain can be large (1000 or more)Gain can be less than 1
___________ in this case
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What is the “gain” for this data?
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 1 2 3 4 5 6 7 8 9 10
Input Voltage, mV
Out
put V
olta
ge, V
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Example #1: Miniature Shaker
Given: Miniature piezoelectric shakerInput: ±100 VOutput: 0.004 lb/V (0.018 N/V)
How do you measure the voltage applied to the shaker?
100 V WELL beyond the range of standard data acquisition systems
Function Generator Amplifier Shaker
Attenuate the signalAttenuate the signal
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Example #1 Continued
Scale the ±100 V down to ±10 VUse a ____________
±100 V COM
Make sure that your measuring circuit does not draw too much current!→ Make it’s impedance HIGH
→Make the input impedance of the circuit measuring Vouteven higher!
Limitation: you can only ________ with a voltage divider.
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Operational Amplifier (op-amp)
Note the hole
741
4
1
2
3
5
6
7
8
Positive power supply (+12V)
Positive powersupply (+12V)
Negative powersupply (-12V)
Inverting input
Non-inverting inputNon-invertinginput (V+) +
-Output (Vo)
Invertinginput (V-)
Output
Negative power supply (-12V)
Integrated Circuit8 Pin DIP (Dual In-line Package)
Electrical SchematicSymbol
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Single Input, Inverting amp
note Vi connected to inverting input (-)
+
-+12 V
-12 V
R1 R2
-Vi
+ (Eq. 3.17)=0V
Vo-
+
Inverting op-amp amplifier
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Single-input, Inverting Amplifier
-10
-8
-6
-4
-2
0
2
4
6
8
10
-3 -2 -1 0 1 2 3
Input, volts
Out
put,
volts
What is the gain of the op-amp that has this input/output?
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To Maintain Ideal Relationships for all Op-amp Circuits!
Input resistance R1 should be fairly large
R1 > 10kΩ in most casesminimizes current drawn from input side of op-amp circuit
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Op-Amp Saturation (±12V power)
-15
-10
-5
0
5
10
15
-6 -4 -2 0 2 4 6
Input, volts
Out
put,
volts
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Multiple input, summing amplifier
=oV
V1
+R1
-
V2
+-
R1
+
-
Vo
+
-
R2
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Multiple input, summing amp
-12-10-8-6-4-202468
1012
-3 -2 -1 0 1 2 3
Input E1, volts
Out
put E
o, v
olts
E2 = 0 voltsE2 = +0.75 voltsE2 = -1 volt
What is the gain of the op-amp that has this input/output?
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Single input, non-inverting amplifierR2R1
=oV
+
-
+
Note connection-
VoVi
+
-
See anything interesting? Any limitation here?
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Single input, non-inverting amp
-12-10
-8-6-4-202468
1012
-4 -3 -2 -1 0 1 2 3 4
Input E1, volts
Out
put E
o, v
olts
What is the gain of the op-amp that has this input/output?
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What op-amp circuit does this? #1
-3
-2
-1
0
1
2
3
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Time, sec
Vol
tage
InputOutput
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In-Class Exercise #1
Design an op-amp circuit to give the input/output relationship shown in #1
make ALL necessary connections to op-amp chipinput connection is yellow, output is orange
use the following resistors - 20kΩ, 56kΩ
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In-class Exercise #1+12V
Com
Out
Vi
-
+
Vo
+
Build a single input,inverting amplifier,gain of 2.8
R2 = 56 kΩ(Gr-Blue-Or) In 741
-R1 = 20 kΩ(Red-Blk-Or)
-12V
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-3
-2
-1
0
1
2
3
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Time, sec
Vol
tage
InputOutput2
What op-amp circuit does this? #2
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In-Class Exercise #2
Design an op-amp circuit to give the input/output relationship shown in #2
make ALL necessary connections to op-amp chipinput connection is yellow, output is orange
use the following resistors - 20kΩ, 56kΩ
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In-Class Exercise #2 Build a single input, non-inverting amplifier,
gain of 1.36 You have 20 kΩ and 56 kΩ resistors
R1
+
R2
-
+Vo+
Vi --
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Single input, non-inverting amplifierR2R1
=oV
+
-
+
Note connection-
VoVi
+
-
What happens if…
This is called a _____________.
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Dual input, difference amplifier
E2
E1
-i2 R2
i-
i1
+
R1
+
R4
-
i+
Eo
-
+
R3
i3
=oE assuming R4=R3 and R2=R1
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Dual input, difference amp
-12-10-8-6-4-202468
1012
-30 -20 -10 0 10 20 30
Input (E2-E1), millivolts
Out
put E
o, v
olts
What is the gain of the op-amp that has this input/output?
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Integrator
+
CR
-
+=oV
-Vi
(Eq. 3.32)+
Vo
-
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Differentiator
+
RC
-
+=oV
-Vi
(Eqn 3.33)+
Vo
-
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Comparatorreference voltage
input voltage to be compared
-
- +
+
+
-+12V
-12V+Vref
VoVi -
=oV
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Instrumentation Amp
-
+
R2 -Vo
+
-
+
R3
-
+
R3
+ R2R1V1
RGR1
-
Figure 3.14
=oV Note – Formula in text is incorrect
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“Buffered” Voltage Divider
+12V “low” impedancePotentiometer
-+ +
+VpotVpot “high”
impedance --
-12V
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Potentiometer - Schematic
1
2
3
“wiper”Variable
ResistanceR1-2
VariableResistance
R2-3
FixedResistance
R1-3
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Potentiometer - Physical
Wiper Adjustment