SIGNAL CONDITIONING Part 2

1
CHAPTER 5
SIGNAL CONDITIONING (Part 2)
2
Structure For Chapter 5

• INTRODUCTION TO SIGNAL CONDITIONING
• BRIDGE WHEATSTONE BRIDGE
• Balanced Condition
• Unbalanced Condition
• AMPLIFIER
• PROTECTION
• FILTERS Low Pass, High Pass Band Pass

3
Amplifier

• An amplifier is any device that changes, usually
  increases, the amplitude of a signal.

Amplifier
4
Operational Amplifier

• OP-AMP
• symbol

Properties for ideal Op-Amp
(Infinite gain)
(Infinite input resistance)
(Zero output resistance)
For idealized model
5
Amplifier circuit

• Inverting amplifier
• Non-inverting amplifier
• Voltage follower/buffer
• Voltage summing/summer

6
Inverting Amplifier

• The formula Rf/R1 shows that the input signal
  is inverting
• Any inputs will give 180 phase shifted

7
Non-inverting amplifier

• The formula 1(Rf/R1) shows that the input
  signal is non-inverting
• The output is in phase with the input

8
Voltage follower/buffer

• When Non-inverting amplifier circuit gives, Rf0
  and R1 8 it will produce Vo Vi
• This circuit is called voltage follower
• The function is can be used in isolating one
  circuit from loading effects of another

9
Voltage Summing/Summer
n input,
10
Gain of Cascade Circuit
11
Example
Determine the total gain produced by the network
below. Then, determine the output voltage, Vout
12
Protection

• So, what can we do?

Problem A unit after a sensor has a possibility
of damage by a high current or high voltage
High Current
High Voltage

• a series resistor to limit the current to
  an acceptable level
• a fuse to break if the current does exceed a safe
  level.

• the use of a Zener diode circuit

13
Filter
Signal Noise
FILTER
Signal
FILTER - to remove unwanted frequency components
from the signal or to enhance wanted ones
14
Filter

• Low Pass Filter (LP Filter)
• High Pass Filter (HP Filter)
• Band Pass Filter (BP Filter)

15
Low Pass Filter

• A filter designed to pass all frequency below a
  given cut-off frequency

The Bode Plot or Frequency Response Curve
16
High Pass Filter

• A filter designed to pass all frequency above a
  given cut-off frequency
• High-pass filters invert the frequency
  characteristics of low-pass filters

The Bode Plot or Frequency Response Curve
17
Band Pass Filter

• Designed to pass all frequency that fall between
  fc1 and fc2
• High pass filter followed by Low pass filter

Centre Frequency Equation
Where, r is the resonant or centre frequency
L is the lower -3dB cut-off frequency point H
is the upper -3db cut-off frequency point
18
Band Pass Filter
The Bode Plot or Frequency Response Curve
19
END OF CHAPTER 5GOOD LUCK FOR YOUR FINAL
EXAMSOALAN FINAL SUSAH TAPI SENANG KALAU TAHU
PAHAM