Ex. no: 1 VERIFICATION OF KVL AND KCLDate:

AIM

To Verify Kirchhoff’s voltage and current laws for a given circuit.

APPARATUS REQUIRED

S.No. Description Type Range Quantity1 Regulated Power

SupplyVariable (0-30)V 1

2 Resistor Carbon 560Ω 33 Ammeter Moving Coil (0-30)mA 34 Voltmeter Moving Coil (0-10)mV 35 Bread Board 16 Connecting wires

THEORY:

OHM’S Law

In electrical circuits, Ohm's law states that the current through a conductor

between two points is directly proportional to the potential difference or voltage across the two

points, and inversely proportional to the resistance between them

The mathematical equation that describes this relationship

Where V is the potential difference measured across the resistance in units of volts; I is the

current through the resistance in units of amperes and R is the resistance of the conductor in units

of ohms.

Kirchhoff’s Current law

At any node (junction) in an electrical circuit, the sum of currents flowing into that node

is equal to the sum of currents flowing out of that node.

The current entering any junction is equal to the current leaving that junction. i1 + i4 = i2 + i3

Kirchhoff’s Voltage Law

The directed sum of the electrical potential differences a round any closed circuit must be zero

The sum of all the voltages around the loop is equal to zero. v1 + v2 + v3 + v4 = 0

PROCEDURE

Ohms Law

1. Connections are made as per the circuit diagram

2. Using the RPS, Source voltage is set

3. Connect the ammeter in series with the resistors and measure the deflection of current.

Measure the value of I1,I2,I3

4. Compare the measured value of current to the theoretical value. The Ohms law is

verified by v = IR. The combined resistance measured from terminals A and B is given

by Rab =r1+r2. Resistors in parallel is measured across terminals A and B is given by

I/Rab = I/R1+I/R2. Equivalently Rab = R1.R2/(R1+R2)

5. The above procedure is repeated by varying source voltage in steps at 5V to 30V

KIRCHOFFS CURRENT LAW

1. Connections are made as per the circuit diagram

2. Using the regulated power Supply, Source voltage is set to 5V

3. Deflections are shown in all the three ammeters

4. Observe the readings of ammeter in each branch

5. The kirchoffs current law is verified by I total = I1+I2

6. The above procedure is repeated by varying source voltage in steps at 5v to 30V

Kirchoff’s Voltage Law

1. Connections are made as per the circuit diagram

2. Using the regulated power Supply, Source voltage is set to 5V

3. Readings shown in all the three voltmeters are tabulated

4. Kirchhoff’s Voltage law is verified by V= V1+v2

5. Measure the voltage across the each branch and tabulate the reading

6. The above procedure is repeated by varying source voltage in steps at 5V to 30V

RESULT:

Thus KVL and KCL are verified theoretically and practically

CIRCUIT DIAGRAM

KIRCHOFF’S CURRENT LAW

(0-30)V 1

A+(0

-10

)mA

560 ohms R 1A+

(0-1

0)m

A

560 ohms R 2

56

0 o

hm

s R

3

A+

I2

KIRCHOFF’S VOLTAGE LAW

(0-30)V 1

560 ohms R 2560 ohms R 1

V+

(0-1

0)V

V+

(0-1

0)V

V+

(0-1

00

V

560 ohms R 3

TABULATIONKCL

S.No Input voltage

Itotal I1 I2 I1+I2 Theoretical value

I1 I2 I1+I2

V mA mA mA mA mA mA mA mA

KVL

S.No Input voltage

V1 V2 V3 V1+V2+V3 Theoretical value

V1 V2 V3 V

V V V V V V V V V V

Ex.no:2 VERIFICATION OF THEVENIN AND NORTON THEOREMSDATE:

AIM

To Verify Thevenin theorem and Norton theorem practically for given circuit

APPARATUS REQUIRED

S.No. Description Type Range Quantity1 Regulated Power

SupplyVariable (0-30)V 1

2 Resistor Carbon 560Ω,680Ω,1kΩ 1,2,13 Ammeter Moving Coil (0-10)mA 14 Voltmeter Moving Coil (0-30)mV 15 Decade

resistance box1

6 Bread Board 1

7 Connecting wires8 Multimeter

THEORY

THEVENIN'S THEOREM

Any combination of batteries and resistances with two terminals can be replaced by a single voltage source e and a single series resistor r. The value of e is the open circuit voltage at the terminals, and the value of r is e divided by the current with the terminals short circuited.

Thévenin's theorem states that at a pair of terminals a network composed of lumped, linear circuit elements may, for purposes of analysis of external circuit or terminal behavior, be replaced by a voltage source V(s) in series with a single impedance Z(s).

Norton's Theorem

Any collection of batteries and resistances with two terminals is electrically equivalent to an ideal current source i in parallel with a single resistor r. The value of r is the same as that in the Thevenin equivalent and the current i can be found by dividing the open circuit voltage by r.

Norton's theorem for linear electrical networks, states that any collection of voltage sources, current sources, and resistors with two terminals is electrically equivalent to an ideal current source, I, in parallel with a single resistor, R.

PROCEDURE

1. Connections are made as per circuit diagram2. Vary RPS and set input voltage of 1V3. Note down voltmeter and ammeter reading4. Switch off supply and make the connection5. Measure Rth. Rth= Thevenin and Norton resistance6. Set an input voltage 10V in RPS and note down voltmeter reading7. Switch off supply and make connection 48. Set an input voltage 10V in RPS and note down voltmeter reading 9. Draw the Thevenin equivalent circuit and Norton equivalent circuit10. Calculate the IL value using the formula 11. IL = Vth/(Rth+Rl)12. Il = In*Rn/(Rn+Rl)

RESULT

Thus Thevenin and Norton’s theorem are verified practically and theoretically

Theoretical Value = ------------

Practical Value =_______

TO MEASURE IL

680 ohms R 1 560 ohms R 2

R4

1k

680

ohm

s R

3V+

(0-30)V(0-30)V 1

A+

(0-10)mA

TO MEASURE VTH

680 ohms R 1 560 ohms R 2680 o

hm

s R

3

V+

(0-30)V(0-30)V 1

V+

(0-30)V

TO MEASURE RTH

680 ohms R 1 560 ohms R 2

680

ohm

s R

3

+ Multimeter 1

680 ohms R 1 560 ohms R 2

680

ohm

s R

3

A+(0-10)mA(0-30)V 1

THEVENIN EQUIVALENT CIRCUIT

900 ohms Rth 1

1K

RL 1

5V 1

NORTON EQUIVALENT CIRCUIT

A+2.5mA

900

ohm

s R

1

1K R

L 1

TABULAR COLUMNTO MEASURE IL

TO MEASURE Rth

TO MEASURE Vth or Voc TO MEASURE IN or Isc

V1(V) IL(Ma)

V1(V) IL(Ma) V1(V) IL(Ma)

Ex.no:3 VERIFICATION OF SUPERPOSITION THEOREMDATE:

AIM:

To Verify Superposition theorem for a given circuit

APPARATUS REQUIRED:

S.No. Description Type Range Quantity1 Regulated Power

SupplyVariable (0-30)V 2

2 Resistor Carbon 1kΩ,2.2kΩ 2,23 Ammeter Moving Coil (0-50)mA 14 Bread Board 1

5 Multimeter

THEORY:

Theorem is designed to simplify networks containing two or more sources. It states that in a network containing more than one source, the current at any one point is equal to the algebraic sum of the currents produced by each source acting separately.

The superposition theorem for electrical circuits states that the response (Voltage or Current) in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone, while all other independent sources are replaced by their internal impedances.

To ascertain the contribution of each individual source, all of the other sources first must be "turned off" (set to zero) by:

1. Replacing all other independent voltage sources with a short circuit (thereby eliminating difference of potential. i.e. V=0, internal impedance of ideal voltage source is ZERO (short circuit)).

2. Replacing all other independent current sources with an open circuit (thereby eliminating current. i.e. I=0, internal impedance of ideal current source is infinite (open circuit).

This procedure is followed for each source in turn, then the resultant responses are added to determine the true operation of the circuit. The resultant circuit operation is the superposition of the various voltage and current sources.

PROCEDURE:

1. Connections are made as per circuit diagram2. The ammeter readings are noted down which are I1 &I23. Figure 1 shows a circuit with two sources V1 and V24. Take the reading current I’ through load R5. Now switch off V2 and Short circuit the 2 Terminals6. Measure the current I’’, through the load R.7. Insert V2 and switch off V1, by short circuit the 2 terminals and again measure the

current and verify I=I’+I’’

RESULT:

Thus the superposition theorem is verified practically and theoretically.

CIRCUIT DIAGRAMStep 1

R1 1k R2 1k

R4 2

.2k

R3 2

.2k

A+AM1

(0-30)V 1(0-30)V 2

Step II

R1 1k R2 1k

R4 2

.2k

R3 2

.2k

A+AM1

(0-30)V 1

Step III

R1 1k R2 1k

R4

2.2k

R3

2.2k

A+

(0-30)mA(0-30)V 2

TABULAR COLUMN

Vs1 active and Vs2 short circuit (II)

Vs2 active and Vs1 short circuit (III)

Total current(mA)

IL from TAB(mA)

Vs1(V) IL(mA) Vs1(V) IL(mA)

Values I1(mA) I2(mA) I(mA)

Theoretical

Practical

Vs1(V) Vs2(V) IL(mA)

Ex. no: 4 VERIFICATION OF MAXIMUM POWER TRANSFER

DATE: THEOREM

AIM:

To Verify Maximum power transfer theorem for a given circuit

APPARATUS REQUIRED:

S.No. Description Type Range Quantity

1 Regulated Power

Supply

Variable (0-30)V 2

2 Resistor Carbon 1kΩ,2.2kΩ 2,2

3 Ammeter Moving Coil (0-50)mA 1

4 Bread Board 1

THEORY:

Maximum power transfer states, the maximum amount of power will be dissipated by a

load resistance when that load resistance is equal to the Thevenin/Norton resistance of the

network supplying the power. If the load resistance is lower or higher than the Thevenin/Norton

resistance of the source network, its dissipated power will be less than maximum. The theorem

was originally misunderstood (notably by Joule) to imply that a system consisting of an electric

motor driven by a battery could not be more than 50% efficient since, when the impedances were

matched, the power lost as heat in the battery would always be equal to the power delivered to

the motor. In 1880 this assumption was shown to be false by either Edison or his colleague

Francis Robbins Upton, who realized that maximum efficiency was not the same as maximum

power transfer. To achieve maximum efficiency, the resistance of the source (whether a battery

or a dynamo) could be made close to zero. Using this new understanding, they obtained an

efficiency of about 90%, and proved that the electric motor was a practical alternative to the heat

engine.

PROCEDURE:

1. Connections are given as per the circuit diagram

2. Switch on the power supply RPS 1 and set voltage v

3. By increasing the load resistance RL corresponding load current value is noted

4. Note the power values from the noted load current

5. Plot RL Versus Power

6. From the graph RL, corresponding to maximum power transmitted is noted

7. Maximum power transmitted is calculated

8. Thevenin equivalent resistance is calculated using circuit

9. This value Rth is compared with RL observed from the graph

10. The graph is shown drawn between RL in X-axis and power transmitted in y – axis

RESULT:

Thus the maximum power transfer theorem is verified theoretically and practically

CIRCUIT DIAGRAM:

VERIFICATION OF MAXIMUM POWER TRANSFER THEOREM

560 ohms R 2330 ohms R 1

470

ohm

s R

3

A+

(0-1

00)

mA

(0-30)V 1

RL/

DR

B753 ohms R 4

A+

(0-1

00

)mA

(0-30)V 1

RL

/DR

B

EQUIVALENT CIRCUIT:

330 ohms R 1 560 ohms R 2

470

ohm

s R

3TABULATION V=

S.No.RL (Ω)

IL(mA) I^2*RL(w)

Rth(Ω) Pmax (theoretical) (mW)

RL(Ω) PmaX(prac)=I^2*RL(w)

Ex. no: 5 VERIFICATION OF RECIPROCITY THEOREM

DATE:

AIM

To Verify Reciprocity theorem for a given circuit

APPARATUS REQUIRED

S.No. Description Type Range Quantity1 Regulated Power

SupplyVariable (0-30)V 1

2 Resistor Carbon 1kΩ,2.2kΩ 3,33 Ammeter Moving Coil (0-100)mA 14 Bread Board 1

THEORY

The reciprocity theorem states that if an voltage in one branch of a reciprocal network produces a current I in another, then if the voltage is moved from the first to the second branch, it will cause the same current in the first branch, where the emf has been replaced by a short circuit. It is sometimes phrased as the statement that voltages and currents at different points in the network can be interchanged. More technically, it follows that the mutual impedance of a first circuit due to a second is the same as the mutual impedance of the second circuit due to the first.

PROCEDURE

1. Connections are given as per the circuit diagram2. Switch on the power supply RPS 1 and set voltage v, and measure the current which is

connected with 2.2kΩ3. The ammeter & RPS position is interchanged4. Then the voltage sis changed using RPS and ammeter reading is noted5. It is found that the current through the branch is same as the previous value6. Thus the theorem is proved

RESULT:

Thus the Reciprocity theorem is verified theoretically and practically

CIRCUIT DIAGRAM

Circuit I

0-30 V 1

1K R 1 1K R 3 1K R 5

2.2K

R 2

2.2K

R 4

A+

0-30mA

2.2K

R 6

Circuit II

1K R 1 1K R 3 1K R 5

2.2K

R 2

2.2K

R 4

2.2K

R 6

A+

0-30mA

0-30 V 1

TABULATION

S.No. Voltage(V) Iout(mA) R= V/Iout(kΩ)

S.No. Voltage(V) Iout(mA) R= V/Iout(kΩ)

Values I1(mA) I2(mA)

Theoretical

Practical

Ex. no: 6 FREQUENCY RESPONSE OF SERIES AND PARALLEL DATE: RESONANCE CIRCUITS

AIM

To study the frequency response of a series and parallel RLC circuit

APPARATUS REQUIRED

S.No. Description Type Range Quantity1 Function

Generator1

2 Decade resistance Box

(0-100kΩ) 1

3 Decade inductance Box

(0-100)H 1

4 Decade Capacitor Box

(0-1000)µF 1

5 Ammeter Moving Coil (0-50)mA 16 Bread Board 1

7 Connecting wires

THEORY:

A circuit is said to be resonance when the applied voltage and source current are in phase. Thus at resonance the power factor of the circuit is unity and the circuit acts as a purely resistive.

SERIES RESONANCE:

At resonance the power factor is being unity Z= R.The reactive part of the complex impedance must be zero. (i.e. XL- XC =0).

XL= XC

ωL = 1/ ωc , ω= 1/(LC) 1/2

PARALLEL RESONANCE:

At resonance the reactive part is zero, 1/ XC -1/XL= 0.

ω0C-1/ ω0L =0.

2πf0 =1/ (LC) ½

f0=1/2π (LC) ½

PROCEDURE:

1. The connections are made as per the circuit diagram.2. The required values of resistance, inductance and capacitance are set in DRB,DIB ,DCB.

3. Vary the frequency in the function generator in regular interval.

4. As frequency is increased, the current is noted in mA.

5. The graph shown between frequency and current is drawn.

6. Resonance frequency is noted from the graph.

RESULT

Frequency response of series and parallel resonance circuit is studied and the value of Fo is found to be --------Hz

CIRCUIT DIAGRAM:

R1 1kOhm L1 1mH C1 1uF+

10v A+

0-25mA

MODEL GRAPH:

T

frequency(HZ)

0 1

load

cur

rent

(mA

)

0

1

TABULATION

Frequency (Hz) IL (mA)

CIRCUIT DIAGRAM

R1 1kOhm

L1 1mH

C1 1uF

+ 10 V A+

(0-25)mA

MODEL GRAPH

T

frequency(HZ)

0 1

load

cur

rent

(mA)

0

1

TABULATION

Frequency (Hz) IL (mA)

Ex. no: 7 STATIC CHARACTERISTICS OF SEMICONDUCTOR

Date: (PN) DIODE

AIM:

To Study the Forward and reverse characteristics of the PN diode

APPARATUS REQUIRED:

S.No. Description Type Range Quantity

1 Diode In4001 2

2 Regulated Power

Supply

Variable (0-30)V 1

3 Resistor Carbon 330Ω 1

4 DC Ammeter Moving Coil (0-30)mA,(0-

100)µA,

1,1

5 DC Voltmeter Moving Coil (0-30)V,(0-1)V 1,1

6 Bread Board 1

7 Multimeter

THEORY:

A modern semiconductor diode is made of a crystal of semiconductor like silicon that has

impurities added to it to create a region on one side that contains negative charge carriers

(electrons), called n-type semiconductor, and a region on the other side that contains positive

charge carriers (holes), called p-type semiconductor. The diode's terminals are attached to each

of these regions. The boundary within the crystal between these two regions, called a PN

junction, is where the action of the diode takes place. The crystal conducts conventional current

in a direction from the p-type side (called the anode) to the n-type side (called the cathode), but

not in the opposite direction.

PROCEDURE:

FORWARD BIASING:

1. Connect the circuit as per the circuit diagram

2. Vary the power supply voltage in steps of 0.1

3. Note down the corresponding readings

4. Plot the graph V Against I

5. Find the dynamic resistance r which is given by

R = V/ I

REVERSE BIASING:

1. Connect the circuit as per the circuit diagram

2. Vary the power supply voltage in steps of 0 .1

3. Note down the corresponding readings

4. Plot the graph V Against I

RESULT:

Thus the diode characteristics and reverse saturation current, dynamic resistance is

determined in forward and reverse bias.

Forward resistance=

Reverse resistance=

CIRCUIT DIAGRAM

STATIC CHARACTERISTICS OF SEMICONDUCTOR DIODE

FORWARD BIAS

(0-30)V 1

A+

(0-3

0)m

A

V+

(0-1)V

D1

1N

40

01

330 ohms R 1

REVERSE BIAS

330 ohms R 1

A+

(0-100)uA

(0-30)V V 1 V+

(0-30)V

D1

1N40

01

MODEL GRAPH:

TABULAR COLUMN:

FORWARD BIAS:

S.NO Vf (V) If (mA)

REVERSE BIAS:

S.NO Vr (V) Ir (mA)

Ex.no:8 CHARACTERISTICS OF ZENER DIODEDATE:

AIM:

To Study the Forward and reverse characteristics of the PN and Zener diode

APPARATUS REQUIRED

S.No. Description Type Range Quantity

1 Diode In4001 2

2 Zener diode FZ8V2 2

3 Regulated Power

Supply

Variable (0-30)V 1

4 Resistor Carbon 330Ω 1

5 DC Ammeter Moving Coil (0-30)mA,(0-

100)µA,

1,1

6 DC Voltmeter Moving Coil (0-30)V,(0-1)V 1,1

4 Bread Board 1

5 Multimeter

THEORY:

Zener doide is a special diode with increased amounts of doping. This is to compensate

for the damage that occurs in the case of a pn junction diode when the reverse bias exceeds the

breakdown voltage and thereby current increases at a rapid rate. Applying a positive potential to

the anode and a negative potential to the cathode of the zener diode establishes a forward bias

condition. The forward characteristic of the zener diode is same as that of a pn junction diode i.e.

as the applied potential increases the current increases exponentially. Applying a negative

potential to the anode and positive potential to the cathode reverse biases the zener diode.

As the reverse bias increases the current increases rapidly in a direction opposite to that of the

positive voltage region. Thus under reverse bias condition breakdown occurs. It occurs because

there is a strong electric filed in the region of the junction that can disrupt the bonding forces

within the atom and generate carriers. The breakdown voltage depends upon the amount of

doping. For a heavily doped diode depletion layer will be thin and breakdown occurs at low

reverse voltage and the breakdown voltage is sharp. Whereas a lightly doped diode has a higher

breakdown voltage. This explains the zener diode characteristics in the reverse bias region. The

maximum reverse bias potential that can be applied before entering the zener region is called the

Peak Inverse Voltage referred to as PIV rating or the Peak Reverse Voltage Rating (PRV rating).

PROCEDURE

PN Junction diode and Zener diode (Forward Biasing)

1. Connect the circuit as per the circuit diagram2. Vary the power supply voltage in some steps of .13. Note down the corresponding readings4. Plot the graph V Against I5. Find the dynamic resistance r which is given by6. R = V/ I

PN Junction diode (Reverse Biasing)

1. Connect the circuit as per the circuit diagram2. Vary the power supply voltage in some steps of .13. Note down the corresponding readings

RESULT:

Thus the characteristic of Zener diode is studied under forward and reverse bias

conditions.

The breakdown voltage= v

CIRCUIT DIAGRAM:

FORWARD BIAS

330 ohms R 1A+

(0-3

0)m

A

(0-30)V 1V+

(0-1)V

Z1

1N2

804

REVERSE BIAS

330 ohms R 1

(0-30)V 1

A+

(0-3

0)m

A

Z1 1

N28

04

V+

(0--30)V

MODEL GRAPH:

TABULATION:Forward Bias:

S no. INPUT VOLTAGE(v)

OUTPUT VOLTAGE(v)

REVERSE BIAS

S No. INPUT VOLTAGE(v)

OUTPUT VOLTAGE(v)

Ex.no:9 CHARACTERISTICS OF CE CONFIGURATIONDATE:

AIM:

1. To study CE configuration

2. To draw the characteristics and find out hybrid parameters graphically.

APPARATUS REQUIRED:

S.NO NAME RANGE QUANTITY

1. DC power supply (0-50)V 1

2. Ammeter (0-50)mA 1

3. Voltmeter (0-50)V 1

4. Bread board 1

5 Connecting wires

THEORY:

In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous field-effect transistor circuit is the common-source amplifier.

Here the emitter terminal is common to both the input and output signal. The arrangement is the same for a PNP transistor. Used in this way the transistor has the advantages of medium input impedance, medium output impedance, high voltage gain and high current gain.

PROCEDURE:

INPUT CHARACTERISTICS:

1. Set VCE=5V, vary input voltage VBE and tabulate the corresponding input current IB.

2. Repeat the step to VCE=2V and VCE=4V.

3. Plot graph between IB and VBE.

4. Calculate the hybrid parameters.

OUTPUT CHARACTERISTICS:

1. Set I=20µA. vary the input voltage VBE and tabulate the corresponding Ic

2. Plot the graph between Ic and VCE

3. Calculate the hybrid parameters.

FORMULA:

GAIN:

Gain= , VCE=constant

RESULT:

Thus the characteristic of CE configuration is studied.Thus gain hfe=----------

CIRCUIT DIAGRAM:

T1 BC107A+

(0-100)uA Ib

V+

0-10V

R1 1k

(0-30)V 1

A+

0-30mA

V+

0-30V

R2 1k

0-30V 2

MODEL GRAPH:

INPUT CHARACTERISTICS

T

Input voltage

0 1

Out

put

0

1

OUTPUT CHARACTERISTICS:

TABULAR COLUMN:INPUT CHARACTERISTICS:

VCE (V)= VCE(V)=

T

Output voltage

0 1

Out

put

Cur

ren

t

0

1

VBE(V) IB(µA) VBE(V) IB(µA)

OUTPUT CHARACTERISTICS:

IB = IB = VCE(V) IC(mA) VCE(V) IC(mA)

Ex.no:10 CHARACTERISTICS OF UJTDATE:

AIM:

To plot the emitter characteristics of UJT and to determine

a) Peak voltage

b) Valley voltage

c) Peak voltage

d) Valley point current

FORMULA:

Intrinsic stand off ratio

Where

VP =peak voltage

VD=diode voltage

Vbb=drop between base B1 and B2

THEORY:

It is essentially a bar of N type semiconductor material into which P type material has been diffused somewhere along its length. The contacts are referred to as the emitter, base1 and base 2 respectively.

RBB is known as the interbase resistance, and is the sum of RB1 and RB2:

RBB = RB1 + RB2 (1)

VRB1 is the voltage developed across RB1; this is given by the voltage divider rule:

RB1

VRB1 = (2) RB1 + RB2

Since the denominator of equation 2 is equal to equation 1, the former can be rewritten as: RB1

VRB1 = x VBB (3) RBB

The ratio RB1 / RBB is referred to as the intrinsic standoff ratio and is denoted by (the Greek letter eta).

If an external voltage Ve is connected to the emitter, the equivalent circuit can be redrawn as shown in Fig.5.

If Ve is less than VRB1, the diode is reverse biased and the circuit behaves as though the emitter was open circuit. If however Ve is increased so that it exceeds VRB1 by at least 0.7V, the diode becomes forward biased and emitter current Ie flows into the base 1 region. Because of this, the value of RB1 decreases. It has been suggested that this is due to the presence of additional charge carriers (holes) in the bar. Further increase in Ve causes the emitter current to increase which in turn reduces RB1 and this causes a further increase in current. This runaway effect is termed regeneration. The value of emitter voltage at which this occurs is known as the peak voltage VP and is given by: VP = AVVBB + VD (4)

As the emitter voltage is increased, the current is very small - just a few microamps. When the peak point is reached, the current rises rapidly, until at the valley point the device runs into saturation. At this point RB1 is at its lowest value, which is known as the saturation resistance.

The simplest application of a UJT is as a relaxation oscillator, which is defined as one in which a capacitor is charged gradually and then discharged rapidly. The basic circuit is shown in Fig.7; in the practical circuit of Fig.8 R3 limits the emitter current and provides a voltage pulse, while R2 provides a measure of temperature compensation. Fig. 9 shows the waveforms occurring at the emitter and base 1; the first is an approximation to a sawtooth and the second is a pulse of short duration.

PROCEDURE:

1. Connections are given as per the circuit diagram.

2. To begin with VBB is maintained at a constant value for a convenient value.

3. Then VBE is increased from 0 in steps of small value and corresponding IC values are noted in each stage

4. This procedure is repeated for another convenient values for VBB the values VP, IP and Vv from the graph.

RESULT:The Emitter characteristics of UJT is plotted.

CIRCUIT DIAGRAM:

2N 2646 XUJT

0-30V 1

R1 1k

A+

0-30mA

V+

0-30V V+

0-30V

R2 1k

0-30V 2

MODEL GRAPH:

TABULATION:

S.NO Emitter voltage VEB(V) Emitter current IE(mA)

Ex.no:11 CHARACTERISTICS OF SCRDATE:

AIM:

To study the characteristics of SCR

THEORY:

The Silicon Controlled Rectifier (SCR) is a semiconductor device that is a member of a family of control devices known as Thyristors. The SCR has become the workhorse of the industrial control industry. Its evolution over the years has yielded a device that is less expensive, more reliable, and smaller in size than ever before. The SCR is a three-lead device with an anode and a cathode (as with a standard diode) plus a third control lead or gate. As the name implies, it is a rectifier which can be controlled - or more correctly - one that can be triggered to the “ON” state by applying a small positive voltage ( VTM ) to the gate lead.· Once gated ON, the trigger signal may be removed and the SCR will remain conducting as long as current flows through the device. · The load to be controlled by the SCR is normally placed in the anode circuit.

RESULT:

Thus the characteristics of SCR is studied.

SYMBOL:

U1 2N1595A K

G

CIRCUIT DIAGRAM:

CHARACTERISTICS CURVE:

Ex.no:12 CHARACTERISTICS OF JFETDATE:

AIM:

To study the operation of JFET to draw its characteristics and finding out its parameters graphically.

THEORY:The junction gate field-effect transistor (JFET or JUGFET) is the simplest type of

field effect transistor. It can be used as an electronically-controlled switch or as a voltage-controlled resistance. Electric charge flows through a semiconducting channel between "source" and "drain" terminals. By applying a bias voltage to a "gate" terminal, the channel is "pinched", so that the electric current is impeded or switched off completely.

The JFET is a long channel of semiconductor material, doped to contain an abundance of positive charge carriers (p-type), or of negative carriers (n-type). Contacts at each end form the source and drain. The gate (control) terminal has doping opposite to that of the channel, which it surrounds, so that there is a P-N junction at the interface. Terminals to connect with the outside are usually made ohmic.

PROCEDURE:DRAIN CHARACTERISTICS:

1. Connections are given as per the circuit diagram2. Set the gate voltage as 13. Vary the drain voltage in steps and tabulate the corresponding drain current.4. Repeat the steps for various values of the gate voltage.5. Graph is plotted for drain voltage vs. drain current for constant gate voltage.

TRANSFER CHARACTERISTICS:

1. Connect the circuit as per the diagram2. Set the gate voltage as 1V3. Vary the gate voltage in steps of 1V and tabulate the current reading.4. Graph can be plotted for gate voltage vs. drain current for constant values of drain

voltage.

RESULT:

CIRCUIT DIAGRAM:

T1 BF256A

V1 2 V2 2

R1 10k

V+

0-10V

V+

0-30V

A +

0-10mAR2 1k

MODEL GRAPH:TRANSFER CHARACTERISTICS DRAIN CHARACTERISTICS

TABULAR COLUMN:

Gate voltage= Gate voltage= Gate voltage=

VDS(V) ID(mA) VDS(V) ID(mA) VDS(V) ID(mA)

TRANSFER CHARACTERISTICS:

VDS (V)=

S.NO VGs(V) ID(mA)

Ex.no:13 CHARACTERISTICS OF MOSFFETDATE:

AIM:To study the characteristics of MOSFET

THEORY:The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or

MOS FET) is a device used for amplifying or switching electronic signals. The basic principle of the device was first proposed by Julius Edgar Lilienfeld in 1925. In MOSFETs, a voltage on the oxide-insulated gate electrode can induce a conducting channel between the two other contacts called source and drain. The channel can be of n-type or p-type (see article on semiconductor devices), and is accordingly called an NMOSFET or a PMOSFET (also commonly nMOS, pMOS). It is by far the most common transistor in both digital and analog circuits, though the bipolar junction transistor was at one time much more common

RESULT:

Thus the characteristics of MOSFET are studied

SYMBOL:

CIRCUIT DIAGRAM:

MOSFET CHARACTERISTICS:

TRANSFER CHARACTERISTICS DRAIN CHARACTERISTICS

Ex.no:14 CHARACTERISTICS OF TRIAC AND DIACDATE:

AIM:

To study the characteristics of DIAC, TRIAC.

THEORY:

DIAC:

DIAC is a three layer; two terminal semiconductor devices.MT1 and MT2 are the two main terminals which are interchangeable .It acts as a bidirectional avalanche diode. It does not have any control terminal. It has two junctions J1 and J2 resembles a bipolar transistor, the central layer is free from any connection with the terminals. It acts as a switch in both directions.

TRIAC

Triacs are notorious for not firing symmetrically. This means these usually won't trigger at the exact same gate voltage level for one polarity as for the other. Generally speaking, this is undesirable, because unsymmetrical firing results in a current waveform with a greater variety of harmonic frequencies. Waveforms that are symmetrical above and below their average enter lines are comprised of only odd-numbered harmonics. Unsymmetrical waveforms, on the other hand, contain even-numbered harmonics (which may or may not be accompanied by odd-numbered harmonics as well).

PROCEDURE:

1. Connect the millimeter, DIAC, Voltmeter to the circuit.

2. Switch on the power supply.

3. Increase the supply voltage in steps; note the corresponding currents and voltages for each step.

4. Plot the graph of VI characteristics.

5. Reverse the terminal of DIAC. Increase the supply voltage in steps, note the corresponding currents and voltages for each step

6. Plot the graph of VI characteristics.

RESULT:

TRIAC SYMBOL AND CIRCUIT DIAGRAM:

VI CHARACTERISTICS:

SYMBOL:

CIRCUIT DIAGRAM OF DIAC

CHARACTERISTICS CURVE OF DIAC:

TABULAR COLUMN:

o/p voltage(V)

Current(mA)

o/p voltage(V)

Current(mA)

Ex.no:15 CHARACTERISTICS OF PHOTODIODE AND HOTOTRANSISTOR

DATE:

AIM:

To study the characteristics of photo diode and photo transistor.

APPARATUS REQUIRED:

1. Photodiode & Phototransitor2. Resistor3. Voltmeter(0-30)V4. Multimeter

THEORY:

PHOTODIODE:

Photodiode is used for detecting light at the receiving end in optical communication. Light photons incident on the photodiode gets absorbed in the absorption region which leads to the generation of electron-hole pairs. These charge carriers present in the depletion region drift under the influence of existing electric field ,i.e set up due to applied reverse bias. The reverse current flowing in the external circuit increases linearly with the level of illumination .The Large width in the depletion region results in achieving high quantum efficiently.

PHOTOTRANSISTOR:

Like diodes, all transistors are light-sensitive. Phototransistors are designed specifically to

take advantage of this fact. The most-common variant is an NPN bipolar transistor with an

exposed base region. Here, light striking the base replaces what would ordinarily be voltage

applied to the base -- so, a phototransistor amplifies variations in the light striking it. Note that

phototransistors may or may not have a base lead (if they do, the base lead allows you to bias the

phototransistor's light response. The photodiodes also can provide a similar function, although

with much lower gain (i.e., photodiodes allow much less current to flow than do

phototransistors).

SYMBOL:

PROCEDURE:

PHOTODIODE:

1. Connect the multimeter.2. Plot photodiode reverse current upon different level of illumination.3. Draw Dc load line for the circuit and determine the diode current and voltages at different

levels of illumation.

PHOTOTRANSISTOR:

1. Connect the multimeter across transistor.2. Using Light source by varying the scale, different voltages are noted in multimeter.3. A graph is plotted between distance and voltage.

RESULT:Thus the characteristic of Photodiode and Photodiode is studied.

CIRCUIT DIAGRAM:PHOTO DIODE:

R1 10k

V+

0-30V

FT1 !NPN

Vcc

PHOTO TRANSISTOR

FD1 BP104S

R1 10k

V+

0-30V

Vcc

MODEL GRAPH:PHOTO DIODE

T

distance

0 1

Out

put

volta

ge

0

1

PHOTO TRANSISTOR

T

distance

0 1

Out

put

volta

ge

0

1

TABULAR COLUMN

Distance(mm) Photo diode(mV) Phototransistor(V)