# REVISION ANALOG ELECTRONICS

Semiconductor

Nov 2, 2013 (4 years and 6 months ago)

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REVISION
ANALOG
ELECTRONICS

Prepared by: Cesar Mendoza

Applied Technology Teacher

Revison
:

1.
Module 1: Semiconductor

Diode

2.
Module 2: BJT Transistor

3.
Module 3: Operational Amplifier

4.
Module 4: Application of Semiconductor

5.
Module 5: Project

Project
-

automatic fan controller

Operational
Amplifier

What is Operational Amplifier?

Operational Amplifier
is an electronic devices
which amplifies small ac or dc signal and perform
multiplication and so on.

Fig. Operational amplifier (LM741)

Operational Amplifier

_

+

V
in1

V
in2

+V

-
V

V
out

Op Amp has 2 inputs

Inverting
Input

Non
-
Inverting
Input

Voltage Output

Inverting Input
-

the input where output will change to
the opposite sign.

Non
-
Inverting Input
-

the input where output will not change
to the opposite sign.

Operational Amplifier

_

+

V
in1

V
in2

+V

-
V

V
out

Op Amp has voltage supply,
+V and
-
V

Negative (
-
)
supply voltage

Positive (+)
supply voltage

OP
-
AMP is an IC or Integrated Circuit made of many components

Operational Amplifier

Characteristic of Operational
amplifier…….

1.
High input impedance

2.
Output impedance is zero

3.
Open loop gain is high (10,000x)

What is the use of Operational
Amplifier?

Operational Amplifier
-
amplifies small AC or DC
Signal.

Operational Amplifier
can also do basic
operation : add, subtract, multiply (amplify) etc.

_

+

V
in1

V
in2

+V

-
V

V
out
= A x (V
in2

V
in1
)

Gain (A) =
V
out

V
in

V
out

Open Loop Gain = 100,000 x

Op Amp as Comparator.

Op Amp compares Vin1 and Vin2:

If Vin 2 > Vin1

therefore:

V out = +V

If Vin1 > Vin2

V out =
-
V

Op Amp as Comparator.

Example: The +V= 15V and; If

Vin1= 4mV and

V =
-
15V

Vin2 = 6 mV

Therefore: Vin2 > Vin2 So,
Vout
= 15V

Op Amp compares Vin1 and Vin2:

If Vin 2 > Vin1 therefore: V out = +V

If Vin1 > Vin2

V out =
-
V

Project
-

automatic fan controller

Operational
Amplifier

Pin Number or Configuration

Fig. LM 311 Op Amp IC

Fig. LM 741 Op Amp IC

Pin Number or Configuration

Pin Configuration is the assignment of Pin number with
the corresponding use.

Pin

1

and

Pin

5
:

Offset

null

input
;

used

to

remove

the

Offset

voltage

(a

small

DC

voltage

that

exists

at

the

op
-
amp

inputs

that

will

contribute

to

a

significant

error

at

the

output)
.

Pin

2
:

Inverting

input

(
-
VIN)
;

signals

at

this

pin

will

be

inverted

at

output

Pin

6
.

Pin

3
:

Non
-
inverting

input

(+VIN)
;

signals

at

pin

3

will

be

processed

without

inversion
.

Pin

4
:

Negative

power

supply

terminal

(
-
VCC)
.

Pin

6
:

Output

(VOUT)

of

the

Op
-
Amp

Pin

8
:

No

connection

(N
\
C),

it

is

just

there

to

make

it

a

standard

8
-
pin

package

Pin Number or Configuration

Other uses of Op Amp.

1.
Inverting Amplifier

2.
Non inverting amplifier

3.
Summing Amplifier

4.
Differential amplifier

5.
Voltage follower

6.
Integrator

7.
Differentiator

Revision Question

1.
________________
is an electronic devices which
amplifies small ac or dc signal and perform basic
operation as addition, subtraction multiplication and so
on.

2.
________________
-

input of Op Amp where the output
is changed to opposite sign.

3.
________________ the open loop gain of Op Amp.

4.
________________ use of an Op Amp with no feedback.
where it compares Vin2 and Vin2.

5.
________________ the arrangement of Pin of an
integrated circuit of IC.

6.
________________

is the Pin number of the output of a
LM741 operational amplifier.

Application of Op amp.

Project
-

automatic fan controller

Do you understand now the purpose of the operational amplifier
in this circuit?
Answer: To Compare input pin 3 and pin 2.

What is the Input in Pin 3 and Pin 2?

Voltage Divider
Circuit
(Reference)

What is the Input in Pin 3 and Pin 2?

Voltage Divider
Circuit
(Sensor)

Voltage Divider…

Potentiometer of
Variable Resistor

A

B

C

A

B

C

R
1

R
2

Vcc

So, V
in2

could be from 0
-
12V?

And Vin1 depends on the value of NTC?

What is NTC?

NTC is a
Thermistor

or Thermal Resistor that converts Temperature to Change in
Resistance.

It has two (2) types; NTC and PTC

NTC

Negative Temperature Coefficient. As temp
increses
, resistance Decrease.

PTC

Positive Temperature Coefficient. As
tempincrease
, resistance increases.

Temperature, deg C

Temperature, deg C

Resistance , ohm

Resistance , ohm

NTC

PTC

Voltage Divider…

A

B

C

R
1

The voltage V
C

changes the
resistance of the
Thermistor

changes.

V
B

=
V
cc

x

R
NTC

.

R
1

+ R
NTC

Vcc

Revision Question

6.
________________ a circuit that divided the voltage
proportionally with the value of resistors connected in
series.

7.
_______________ a thermal resistor that converts
temperature in change in resistance.

8.
_______________ use of an Op Amp with no feedback.
where it compares Vin2 and Vin2.

9.
________________ the arrangement of Pin of an
integrated circuit of IC.

Voltage Divider…

A

B

C

R
1

V
c

=
V
cc

x

R
NTC

.

R
1

+ R
NTC

Vcc

If R1 = 10,000

R
NTC

= 10,000 @ 30 deg C

VB = 10V x ( 10,000/20,000)

VB = 5V

Voltage Divider…

A

B

C

R
1

Vcc

= 10V

If R1 = 10,000

R
NTC

= 10,000 @ 30 deg C

VB = 10V x ( 10,000/20,000)

VB = 5V

If R
NTC

= 8,000 @ 50 deg C

VB = 10V x (8,000/ 18,000)

VB = 4.44 V

So, V
in2

could be from 0
-
12V?

Potentiometer.

B

C

A

Vcc
= 10V

IF
V
cc

= 10 V

Therefore: V
BC

= 0V

10 V

V

Potentiometer.

B

C

A

Vcc
= 10V

V
BC

= 0V

V

B

C

A

Vcc
= 10V

V
BC

= 10V

V

Potentiometer.

B

C

A

Vcc
= 10V

So, in the middle V
BC

= 5V

V

I will combine potentiometer circuit and
the Voltage divider circuit with NTC

B

C

A

Vcc
= 10V

A

B

C

R
1

Vcc

So, this 2 circuit is the input to the
operational amplifier

So, this 2 circuit is the input to the
operational amplifier

So, if V
in2

> V
in3

=
V
out

= +12V

IN THIS
FIGURE
ONLY

So, if V
in2

> V
in3

=
V
out

= +12V

IN THIS
FIGURE
ONLY

Voltage Output

The
V
out

= +12V will activate the Driver Transistors

What is Transistor? BJT?

BJT

-

is a three
-
terminal semiconductor device, whose
operation depends upon the flow of electric charge
carriers within the solid.

Transistor

is derived from the combination of two words,
“Transfer
-
Resistance”. It means that it is a device, which
transfers a low resistance into a circuit having high
resistance

Transistor…

Transistor ID.

Low Power

Small Packages

Medium Power

Medium Packages

High Power

big Packages

Transistor Action…

The base is 0.7V (or slightly more) positive of its emitter

The base is 0.7V (or slightly more) positive of its emitter

The base is 0.7V (or slightly more) positive of its emitter

Its emitter is its negative terminal.

The collector is several volts positive of its emitter.

The base is 0.7V (or slightly more) positive of its emitter

Use of Transistor.

Transistor is used as:

1.
Switch

2.
Amplifier.

Small Base
Current

Will Turn
ON the
Transistor

Transistor as switch…

When switch is
closed
:

1.
Small base current is applied
to the base.

2.
LED B is DIM (small current)

3.
Transistor is turned ON
allowing emitter
-
collector
current which is bigger.

4.
LED C will have a bright light
(big current)

So, if V
in2

> V
in3

=
V
out

= +12V

IN THIS
FIGURE
ONLY

Voltage Output

The
V
out

= +12V will activate the Driver Transistors

R
Base

So if the output of the OP Amp is Hi, it will provide base current
to the transistor making it ON thus Energizing the Relay.

What is a Relay?

Relay

an electrically operated switch. It
is made of coil and set of contacts, NO NC.

R
Base

Small Current

Big current

Med
Current

AC
power
Supply

Conclusion

1.
Application of Semiconductor Devices:
transistor diode, etc..

2.
Learned the operation of transistor

3.
WE learn operational amplifier and it uses.

4.
We make use of LED as indicator of
current
.

Thank You
For
Listening

What is voltage divider circuit?