Signal Conditioning: Attenuation, Amplification, Addition ...

[Pages:30]Signal Conditioning: Attenuation, Amplification, Addition and Subtraction

General Characteristics of Signal Amplification (p. 35)

Gain is the relationship between change in input and change in output voltages,

Gain can be large (1000 or more) Gain can be less than 1

___________ in this case

What is the "gain" for this data?

Output Voltage, V

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

0

1

2

3

4

5

6

7

8

9 10

Input Voltage, mV

Example #1: Miniature Shaker

Given: Miniature piezoelectric shaker

Input: ?100 V Output: 0.004 lb/V (0.018 N/V)

Function Generator

Amplifier

Shaker

How do you measure the voltage applied to the shaker?

100 V WELL beyond the range of standard data

acquisition systems

AAtttteennuuaatteetthheessiiggnnaall

Example #1 Continued Scale the ?100 V down to ?10 V

Use 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 Vout even higher! Limitation: you can only ________ with a voltage divider.

Operational Amplifier (op-amp)

Note the hole

Positive power supply (+12V)

Inverting input (V-)

-

Output (Vo) Inverting input

Non-inverting input (V+)

+

Non-inverting input Negative power

supply (-12V)

Negative power supply (-12V)

1

8

2

741

7

Positive power supply (+12V)

3

6 Output

4

5

Electrical Schematic Symbol

Integrated Circuit 8 Pin DIP (Dual In-line Package)

Single Input, Inverting amp

note Vi connected to inverting input (-)

R1

R2

+ Vi

+12 V -

V0 =

-

+

+

-12 V Vo -

(Eq. 3.17)

Inverting op-amp amplifier

Single-input, Inverting Amplifier

Output, volts

What is the gain of the op-amp that has this input/output?

10

8

6

4

2

0

-2

-4

-6

-8

-10

-3

-2

-1

0

1

2

3

Input, volts

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