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14ec2005- Edc Lab Manual

Jul 18, 2016

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lab manual

EX.NO.1 CHARACTERISTICS OF PN DIODE AND ZENER DIODEA. Characteristics of PN Diode

Objective To obtain the V-I characteristics of a PN Diode.

EquipmentsS.NOAPPARATUSRANGEQUANTITY

1Regulated Power supply(0-30)V,2A1

2Voltmeter(0-1)V /(0- 30)V1

3Ammeter(0-50) mA,(0-500)A1

4DiodeIN40071

5Resistor1 K ohm, W1

6Breadboard, Connecting Wires --

Theory

Forward Bias In PN junction diode, electrons are the majority carrier in n- region; holes are the majority carrier in p- region. When voltage is applied to a forward biased pn diode, electrons diffuse from the n region to the p region and are captured by holes in the p region. These captured electrons are attracted towards the positive terminal of the voltage source. In the forward biased condition, majority carrier moves across the junction and leaves less immobile ions in the depletion region. So the width of the depletion region is very small and the resulting current is large. It is measured in terms of mA. The forward cut in voltage is generally 0.6 V.Reverse Bias During the reverse bias condition, the majority carrier moves away from the junction and leaves many immobile ions in the depletion region. So the width of the depletion region increases which results in very little current. It is measured in terms of A.

Circuit Diagram

Model Graph

ObservationForward CharacteristicsS.NOFORWARD VOLTAGE - Vf( VOLTS)FORWARD CURRENT - If(mA)

Reverse CharacteristicsS.NOREVERSE VOLTAGE Vr ( VOLTS)REVERSE CURRENT - Ir (A)

Procedure

Connections are made as shown in Fig 1.1 and Fig 1.2. By adjusting the RPS, voltage and current are measured from the voltmeter and ammeter respectively. Then the readings are tabulated. V-I characteristics of the pn junction diode is drawn on the graph by taking voltage on the X- axis and current on the Y axis.

ResultThus the V-I characteristics of a pn junction diode is obtained and plotted on the graph.

B. Characteristics of Zener Diode

ObjectiveTo obtain the V-I characteristics of a Zener diode.EquipmentsS.NOAPPARATUSRANGEQUANTITY

1Regulated Power supply(0-30)V,2A1

2Voltmeter(0-1)V ,(0- 10)V1

3Ammeter(0-50) mA1

4Zener Diode6.2 V, 250mW1

5Resistor1 K ohm, W1

6Breadboard, Connecting Wires --

Circuit Diagram

Model Graph

ObservationForward Characteristics

S.NOFORWARD VOLTAGE Vf( VOLTS)FORWARD CURRENT - If(mA)

Reverse Characteristics

S.NOREVERSE VOLTAGE Vr( VOLTS)REVERSE CURRENT - Ir(mA)

TheoryDiodes, which are designed to operate in the breakdown region, are called Zener diode. In zener diode, direct rupture of covalent bonds takes place because of the strong electric field at the junction. The new electron hole pair so created increase the reverse current. Thus large change in the diode current by variation in load current or supply voltage results small change in diode voltage. In forward bias condition, Zener Diode acts as an ordinary pn diode and in the reverse bias breakdown occur at 6.2 V. At this voltage, the current increases very rapidly and limited by Rs only.

ProcedureThe Forward Bias and Reverse Bias connections are made as shown in Fig 1.3 and Fig 1.4. By varying the RPS, Vr and Ir, Vf and If readings are noted and tabulated. The V-I characteristics are plotted on the graph.

ResultThus the V- I characteristics of Zener Diode is obtained and the graph is plotted.

EX.NO.2CHARACTERISTICS OF PHOTODIODE

ObjectiveTo obtain the V-I characteristics of the Photodiode.Equipments

S.NOAPPARATUSRANGEQUANTITY

1Regulated Power supply(0-30)V,2A1

2Digital Voltmeter(0-10)V1

3Ammeter(0-500) A1

4Photo DiodeTIL811

5Resistor100 K ohm, 1/4 W1

6Breadboard, Connecting Wires -1

Circuit Diagram

Fig 2.1 CHARACTERISTICS OF PHOTODIODEModel Graph

Observation

Light with high intensityLight with medium intensityLight with low intensity

Vd (volts)Id( A)Vd (volts)Id( A)Vd (volts)Id( A)

TheoryPhotodiode is a reverse biased PN junction semiconductor device. It converts light energy into electrical energy (current). It permits light to fall on one side of the device across the junction, keeping the remaining sides unilluminated. When light falls on the junction, carriers are generated which contribute photocurrent. This current is proportional to the incident light.

ProcedureConnections are made as shown in Fig 2.1. First, keep the photodiode at some fixed distance from the light then vary the RPS and note down the voltmeter and ammeter readings in the light 1 column. Next decrease the distance between the light and the photodiode and repeat the above procedure. Depending upon the incident light, current flows through the device. Plot the voltage on the X-axis and current on the Y-axis on the graph.

ResultThus the V_I characteristics of a photodiode is obtained and plotted on the graph.

EX.NO.3CHARACTERISTICS OF BJTObjective

To obtain the input and output characteristics of a transistor under common emitter configuration.

ApparatusS.NOAPPARATUSRANGEQUANTITY

1Regulated Power supply (0-30) V,2A2

2Digital Voltmeter(0-1)V1

3DC Voltmeter(0-30) V1

4DC Ammeter(0-500) A & (0-50)mA1

5Resistor1 K ohm,100 Kohm1

6TransistorBC107/SL1001

7Breadboard and Connecting Wires

Circuit Diagram

Fig 3.1 CE Configuration

Model GraphInput Characteristic

Output Characteristic

Tabulation:

Input CharacteristicsS.NoVCE=0VVCE=5V

VBE(V)IB(A)VBE(V)IB(A)

Output characteristics S.NoIB=20AIB=80A

VCE(V)Ic(mA)VCE(V)Ic(mA)

Theory Transistor can be made to work in any of the three configurations1. Common base (CB) configuration2. Common emitter (CE) configuration3. Common collector (CC) configurationIn CE configuration, input signal is fed between the base and emitter. The output is developed between the emitter and collector.Input characteristics:This characteristic relates the input current with the input voltage, for a given value of output voltage VCE. The curve is just like the diode characteristic in forward bias region.Output characteristicsThis characteristic relates the output current with the output voltage for a given value of input current IB. The curve indicates the way in which the collector current varies with the change in collector to emitter voltage with the base current IB kept constant.

ProcedureConnections are given as per Fig 3.1. By keeping the collector-emitter voltage at different constant levels, readings are tabulated for the input characteristics. Again by keeping the base current at different constant levels, readings are tabulated for the output characteristics. Finally, the tabulated readings are plotted on the graph.

Result

Thus the input and output characteristics of a transistor under CE configuration are obtained and plotted on the graph.

EX.NO.4 CHARACTERISTICS OF JFET

ObjectiveTo obtain the drain characteristics of JFET.Equipments

S.NOAPPARATUSRANGEQUANTITY

1Regulated Power supply(0-30)V,2A2

2Voltmeter(0-10)V / (0-30)V1

3Ammeter(0-50) mA1

4JFETBFW101

5Resistor1 K ohm,1/2 W1

6Breadboard -1

Circuit Diagram

Model Graph

Observation

S.NoVds(volts)Vgs = 0VVgs = - 1VVgs = - 2V

Id(mA)Id(mA)Id(mA)

Theory

FET consists of three terminals namely source, drain and gate. Source is the terminal through which the majority carriers enter the substrate. Drain is the terminal through which the majority carriers leave the substrate. Gate is nothing but a heavily doped p-region. Space between two p-region is called channel. Reverse bias is applied to the gate terminal. When Vgs = 0, width of the channel is large. So it conduct large amount of carriers, which results in large Id current. When Vgs is increased from 0, i.e., when the channel reverse bias is increased, the conducting portion of the channel begins to constrict. So it results in fewer Ids current.

Procedure

Connections are made as shown in the Fig.4.1. By adjusting RPS I, Vgs is fixed to a value. Then by varying RPS II, Vds and Id values are noted. Taking Vds on the X-axis and Id on the Y-axis graph is plotted

ResultThus the drain characteristics of a JFET is obtained and plotted on the graph.

EX.NO.5CHARACTERISTICS OF UJT

ObjectiveTo obtain the characteristics of a UJT.Equipments

S.NOAPPARATUSRANGEQUANTITY

1Regulated Power supply(0-30)V,2A1

2Digital Multimeter/Voltmeter(0-10)V /(0- 30)V1

3Ammeter(0-10) mA1

4UJT2N26461

5Resistor4.7 K,1 K 1/4W1

6Breadboard --

Circuit Diagram

Model Graph

Observations

VB1B2 = 0 VVB1B2 = 5VVB1B2 = 10 V

VB1E (volt)IE (mA)VB1E (volt)IE (mA)VB1E (volt)IE (mA)

Description

UJT has a unijunction. It consists of three terminals namely emitter, base1 and base2. UJT is also called double base diode. UJT operates when the emitter is forward biased. Voltage Vb1b2 is applied between base1 and base2. If an external voltage is a

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