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EDAYATHANGUDI G.S.PILLAY ENGINEERING COLLEGE NAGAPATTINAM DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING LAB MANUAL Subject Code : EC6211 Subject Name : CIRCUITS AND DEVICES LAB Year/Semester : I/II ECE Name:_____________________________________ Reg no:____________________________________ 0 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) LIST OF EXPERIMENTS CYCLE I 1. Verification of KVL and KCL 2. Verification of superposition Theorem. 3. Verification of Thevenin and Norton Theorems. 4. Characteristics of PN junction diode. 5. Characteristics of Zener diode and regulator using Zener diode. 6. Characteristics of Clipper, Clamper & FWR 7. Characteristics of CE configuration CYCLE II 8. Characteristics of CB configuration 9. Characteristics of SCR 10. Characteristics of JFET and MOSFET 11. Verification of Maximum power transfer and reciprocity theorems. 12. Frequency response of series and parallel RLC resonance circuits. 13. Transient analysis of RL and RC circuits.. 1 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-KIRCHOFF’S VOLTAGE LAW TABULATION VOLTMETER READING SUPPLY VOLTAGE IN VOLTS V in volts THEORITICAL VALUE PRACTICAL VALUE V1 in volts THEORITICAL VALUE PRACTICAL VALUE V2 in volts THEORITICAL VALUE PRACTICAL VALUE 5V 10 V 15 V 2 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: 01 VERIFICATION OF KIRCHOFF’S LAWS A.KIRCHOFF’S VOLTAGE LAW AIM: To verify the Kirchhoff’s Voltage law for the given circuit. APPARATUS REQUIRED: S.NO 1. 2. APPARATUS RPS Resistors 3. 4. 5. Voltmeter Bread Board Connecting wires RANGE (0-30) V 5.6 kΩ 4.7 kΩ (0-30)V - QUANTITY 1 1 1 2 1 few THEORY: KIRCHOFF’S VOLTAGE LAW: In a closed circuit, the sum of potential drops is equal to the sum of the potential rises. PROCEDURE: 1. The connections are made as per the circuit diagram. 2. Supply voltage from the RPS is varied and the corresponding voltmeter readings are noted down. 3. The same procedure is repeated for various values of supply voltage. 4. Compare the theoretical value with the practical value. 3 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 4 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: Supply voltage given V = ______________ Volts. Total Resistance of the circuit, Req R1 R2 =_____________Ω. Total Current in the circuit, I Where, V = ________ Volts & V ( A) Req Req = ______Ω. I = _____________A Voltage drop across the resistor R1 V1 I * R1 = V1 =_____________V Voltage drop across the resistor R2 V2 I * R2 = V2 _____________V The Total Voltage V V1 V2 = V _____________V RESULT: Thus, the Kirchhoff’s voltage law was verified. 5 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-KIRCHOFF’S CURRENT LAW TABULATION AMMETER READING SUPPLY VOLTAGE IN VOLTS I (A) THEORITICAL VALUE I1 (mA) PRACTICAL VALUE THEORITICAL VALUE PRACTICAL VALUE I 2 (mA) THEORITICAL VALUE PRACTICAL VALUE 5V 10 V 15 V 6 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) B.KIRCHOFF’S CURRENT LAW AIM: To verify the Kirchhoff’s current law for the given circuit. APPARATUS REQUIRED: S.NO 1. 2. APPARATUS RPS Resistors 3. 4. 5. Ammeter Bread Board Connecting wires RANGE (0-30) V 1.5 kΩ 1 kΩ 2.2 kΩ (0-30) mA - QUANTITY 1 1 1 1 3 1 few THEORY: KIRCHOFF’S CURRENT LAW: In any electrical network, the sum of the currents flowing towards a junction is equal to the sum of the currents flowing away from it. PROCEDURE: 1. The connections are made as per the circuit diagram. 2. Supply voltage from the RPS is varied and the corresponding reading is noted. 3. The corresponding ammeter readings are noted down and the values are tabulated. 4. The same procedure is repeated for various values of supply voltage. 5. Compare the theoretical value with the practical value. 7 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 8 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: Total resistance of the Req R1 Total Current in the circuit, I R2 R3 R2 R3 V ( A) Req Where, V = ________ Volts & Req = ______Ω. I = _____________A Current flowing through R2 resistor, I1 I * R3 R2 R3 I1 = ____________A Current flowing through R3 resistor, I 2 I * R2 R2 R3 I 2 = ___________A Total current in the circuit, I I1 I 2 RESULT: Thus, the Kirchhoff’s current law was verified. 9 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-THEVENIN’S THEOREM: TO FIND VTH : TO FIND RTH : 10 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: VERIFICATION OF THEVENIN’S THEOREM AIM: To verify the Thevenin’s theorem for the given circuit. APPARATUS REQUIRED: S.NO 1. APPARATUS RPS 2. Resistors 3. 4. 5. 6. 7. 8. Variable resistance box Voltmeter Ammeter Bread Board Connecting wires Multimeter RANGE (0-30) V 470 Ω 100 Ω 220 Ω (0-30)V (0-30) mA - QUANTITY 1 1 2 1 1 1 1 1 few 1 THEORY: THEVENIN’S THEOREM: Any two-terminal network containing resistances and voltage sources or current sources may be replaced by a single voltage source in series with a single resistance. FORMULA: Load current, I L VTH RTH RL I L Load current in amperes. 11 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TO FIND I L : TABULATION: SUPPLY VOLTAGE (Volts) OPEN CIRCUIT VOLTAGE ( VTH in Volts) THEVENIN’S RESISTANCE( RTH in Ohms) THEORITICAL VALUE THEORITICAL VALUE PRACTICAL VALUE PRACTICAL VALUE I LOAD CURRENT L (mA) THEORITICAL VALUE PRACTICAL VALUE 10 V 15 V 20 V 12 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) VTH Thevenin’s voltage (or) open circuit voltage in volts. RTH Thevenin’s resistance in ohms. RL Load resistance in ohms. PROCEDURE: 1. The connections are made as per the circuit diagram. 2. Remove the load resistance across the terminals AB and measure open circuit voltage across it. This voltage is called thevenin’s voltage represented as Vth . 3. Remove the voltmeter from the terminals. 4. The voltage source is removed and short circuit the terminal and by using the multimeter measure the looking back resistance (or) thevenin’s resistance. 5. Then calculate the current flowing through the removed load resistance using the formula, I L RL by VTH . RTH RL 6. Repeat the same procedure for various value of supply voltage and tabulate the readings. 13 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 14 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: Theoretical value of VTH in Volts: To find VTH : Total Resistance of the circuit, Req R1 R2 =_____________Ω. Total Current in the circuit, I Where, V = ________ Volts & V ( A) = Req Req = ______Ω. I = _____________A The open circuit voltage (or) thevenin’s voltage VTH = I * R2 = VTH Theoretical value of RTH = _____________Volts in Ohms: To find RTH : Thevenin’s resistance, RTH R1 * R2 R3 = R1 R2 RTH = _____________Ω Theoretical value of I L in Amps: To find I L : Load current, I L VTH = RTH RL I L = _____________mA RESULT: Thus, the thevenin’s theorem for the given circuit was verified. The theoretical and the practical values are found to be approximately equal. 15 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-NORTON’S THEOREM: TO FIND I SC : TO FIND Rn : 16 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: VERIFICATION OF NORTON’S THEOREM AIM: To verify the Norton’s theorem for the given circuit. APPARATUS REQUIRED: S.NO 1. APPARATUS RPS 2. Resistors 3. 4. 5. 6. 7. Variable resistance box Ammeter Bread Board Connecting wires Multimeter RANGE (0-30) V 470 Ω 100 Ω 220 Ω (0-30) mA - QUANTITY 1 1 2 1 1 1 1 few 1 THEORY: NORTON’S THEOREM: Any two-terminal network containing resistances and voltage sources or current sources may be replaced by a single current source in parallel with a single resistance. Load current, I L I SC X Rn Rn RL I L Load current in amperes. I SC Short circuit current in Amps. 17 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TO FIND I L : TABULATION: SUPPLY VOLTAGE (Volts) SHORT CIRCUIT NORTON’SRESISTANCE I ( Rn in Ohms) CURRENT( SC in Amps) THEORITICAL VALUE PRACTICAL VALUE THEORITICAL VALUE PRACTICAL VALUE I LOAD CURRENT L (mA) THEORITICAL VALUE PRACTICAL VALUE 10 V 15 V 20 V 18 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Rn Norton’s resistance in ohms. RL Load resistance in ohms. PROCEDURE: 1. The connections are made as per the circuit diagram. 2. Remove the load resistance and short circuit the output terminals. 3. Measure the current flowing through the short circuited path using an ammeter, for a particular value of the supply voltage. Let this current be short circuit current ( I SC ). 4. To find the Norton’s equivalent resistance, remove the load resistance and replace all the sources by its internal resistance and measure the equivalent resistance between the open output terminals by using a multimeter. 5. Then calculate the current flowing through the removed load resistance using the formula, I L RL by I SC X Rn . Rn RL 6. Repeat the same procedure for various value of supply voltage and tabulate the readings. 19 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 20 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: I SC Theoretical value of in Amps: To find I SC : Total Resistance of the circuit, Req R1 V ( A) = Req Total Current in the circuit, I Where, V = ________ Volts & R2 * R3 _____________Ω. R2 R3 Req = ______Ω. I = _____________A The short circuit current, I SC Theoretical value of I SC I * R3 R2 R3 = _____________mA Rn in Ohms: To find Rn : Norton’s resistance, Rn R2 R1 * R3 R1 R3 Rn = _____________Ω Theoretical value of I L in Amps: To find I L : Load current, I L I SC X Rn = Rn RL I L = _____________mA RESULT: Thus, the Norton’s theorem for the given circuit was verified. The theoretical and practical values are found to be approximately equal. 21 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-SUPERPOSITION THEOREM: TO FIND I L : When both the sources 22 V1 & V2 are acting together: DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: VERIFICATION OF SUPERPOSITION THEOREM AIM: To verify the Superposition theorem for the given circuit. APPARATUS REQUIRED: S.NO 1. APPARATUS Dual RPS 2. Resistors 3. 4. 5. Ammeter Bread Board Connecting wires RANGE (0-30) V 330 Ω 100 Ω 220 Ω (0-100)mA - QUANTITY 1 1 1 1 1 1 few THEORY: SUPERPOSITION THEOREM: In a network containing more than one source of voltage (or) current, the current through any branch is the algebraic sum of the currents produced by each source acting independently. While one source is applied, the other sources are replaced by their respective internal resistances. To replace other sources by their respective internal resistances, the voltage sources are short circuited and the current sources are open circuited. 23 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TO FIND I L1 : When V1 is acting alone: TO FIND I L 2 : When 24 V2 is acting alone: DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE: Step 1: [When both the sources V1 & V2 are acting] 1. The connections are given per the circuit diagram. 2. V1 Voltage and V2 Voltage are given to the circuit from both the regulated power supplies. 3. Note down the current flowing through 100 Ω resistor by using an ammeter. Step 2: [When supply voltage V1 is acting alone] 1. The connections are given per the circuit diagram. 2. Remove the supply voltage 3. Supply voltage V1 V2 and replace it by its internal resistance. is given to the circuit and the current flowing through 100 Ω resistor is noted down using the ammeter. Step 3: [When supply voltage V2 is acting alone] 1. The connections are given per the circuit diagram. 2. Remove the supply voltage 3. Supply voltage V2 V1 and replace it by its internal resistance. is given to the circuit and the current flowing through 100 Ω resistor is noted down using the ammeter. 25 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TO FIND I L : When both the sources V1 & V2 are acting together: I SUPPLY VOLTAGE(Volts) V1 in Volts V2 in volts 10 V 10 V LOAD CURRENT L (mA) THEORITICAL VALUE PRACTICAL VALUE I L (mA) I L (mA) TO FIND I L1 : When V1 is acting alone: I LOAD CURRENT L1 (mA) SUPPLY VOLTAGE V1 (Volts) THEORITICAL VALUE PRACTICAL VALUE I L1 (mA) I L1 (mA) 10 V TO FIND I L 2 : When V2 is acting alone: SUPPLY VOLTAGE V2 (Volts) LOAD CURRENT THEORITICAL VALUE IL2 (mA) IL2 (mA) PRACTICAL VALUE IL2 (mA) 10 V 26 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: Theoretical value of I L in Amps: [When both the sources V1 & V2 are acting] To find I L : Apply KVL to the circuit (2): Loop ABEFA 10 330I1 100I 2 0 330 I1 100 I 2 10 -------> (1) Loop BCDEB 220( I1 I 2 ) 10 100I 2 0 220I1 220I 2 10 100I 2 0 220 I1 320 I 2 10 --------> (2) Apply Cramer’s rule, I I 330 100 D 11 12 I 21 I 22 220 320 D 127600 I V 330 10 D2 11 1 I 21 V2 220 10 D2 5500 IL I2 D2 5500 43.1mA D 127600 I L 43.1 mA I L I 2 43.1mA 43.1X 103 A 27 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 28 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Theoretical value of I L1 in Amps: [When supply voltage V1 is acting alone] To find I L1 : By Ohm’s law, I Here I V R R2 * R3 V ( A) ----> Req R1 R2 R3 Req Req 330 I 100 X 220 398.75 100 220 10 25mA 398.75 By using current division rule, I * R3 (25 X 103 ) X 220 I L1 R2 R3 100 220 I L1 17mA Theoretical value of IL2 in Amps: [When supply voltage V2 is acting alone] To find I L 2 : By Ohm’s law, I V R R1 * R2 V R R ( A) ----> eq 3 Here I R1 R2 Req Req 220 29 330 X 100 296.75 330 100 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 30 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) I 10 33mA 296.75 By using current division rule, I * R1 (33 X 103 ) X 330 I L2 R1 R2 330 100 I L 2 25mA By the statement of superposition theorem, I L I L1 I L 2 43.1mA 17mA 25mA 43.1mA 42mA 43.1mA 42mA OBSERVATION: OUTPUT I L (mA) I L1 (mA) I L 2 (mA) THEORITICAL VALUE PRACTICAL VALUE RESULT: Thus, the superposition theorem was verified. The theoretical and practical values are found to be approximately equal. 31 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-MAXIMUM POWER TRANSFER THEOREM: TO FIND VTH : TO FIND RTH : 32 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: VERIFICATION OF MAXIMUM POWER TRANSFER THEOREM AIM: To verify the Maximum power transfer theorem for the given circuit. APPARATUS REQUIRED: S.NO 1. APPARATUS RPS 2. Resistors 3. 4. 5. 6. 7. 8. Variable resistance box Voltmeter Ammeter Bread Board Connecting wires Multimeter RANGE (0-30) V 470 Ω 330 Ω 390 Ω (0-30)V (0-10)mA - QUANTITY 1 1 1 1 1 1 1 1 few 1 THEORY: MAXIMUM POWER TRANSFER THEOREM: In a linear lumped bilateral electric circuit, maximum power is transferred from source to load, when the load resistance ( RL ) is equal to the thevenin’s resistance ( RTH ). PROCEDURE: 1. The connections are made as per the circuit diagram. 2. Remove the load resistance ( RL ) across the terminals AB and measure open circuit voltage across it by using the voltmeter. This voltage is called thevenin’s voltage represented as Vth . 3. Remove the voltmeter from the terminals. 33 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TO FIND I L : TABULATION: LOAD RL (Ω) OPEN CIRCUIT VOLTAGE ( VTH in Volts) THEORI TICAL VALUE PRACTIC AL VALUE THEVENIN’S RESISTANCE ( RTH in Ohms) THEORITIC AL VALUE PRACTICAL VALUE I LOAD CURRENT L (mA) THEORITIC AL VALUE PRACTICA L VALUE LOAD POWER P(mW) THEORITIC AL VALUE 200 Ω 400 Ω 583 Ω 600 Ω 34 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PRACTICAL VALUE 4. The voltage source is removed and short circuit the terminal and by using the multimeter measure the looking back resistance (or) thevenin’s resistance. 5. Then calculate the current flowing through the removed load resistance RL by using the formula, IL VTH . RTH RL For maximum power transfer theorem, RTH RL 6. To calculate the power through RL by using the formula, RL RTH P I L 2 * RL 35 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH: 36 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: To find VTH : For voltage V =_________Volts. Total Resistance of the circuit, Req R1 R2 =_____________Ω. Total Current in the circuit, I V ( A) = Req I = _____________A The open circuit voltage (or) thevenin’s voltage VTH = I * R2 = VTH = _____________Volts To find RTH : Thevenin’s resistance, RTH R1 * R2 R3 = R1 R2 RTH = _____________Ω To find I L : RL RTH Load current, I L VTH = RTH RL I L = _____________mA To find P: Load power, P I L 2 * RL P = _____________mW. RESULT: Thus, the maximum power transfer theorem for the given circuit is verified. The maximum power _________ is occurred at _______ Ω resistance. 37 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-RECIPROCITY THEOREM: 38 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: VERIFICATION OF RECIPROCITY THEOREM AIM: To verify the Reciprocity theorem for the given circuit. APPARATUS REQUIRED: S.NO 1. APPARATUS RPS 2. Resistors 3. 4. 5. 6. Voltmeter Ammeter Bread Board Connecting wires RANGE (0-30) V 470 Ω 220 Ω 330 Ω (0-30)V (0-10)mA - QUANTITY 1 1 1 1 1 1 1 few THEORY: RECIPROCITY THEOREM: Reciprocity theorem states that “In a linear, bilateral network a voltage source V volts in a branch gives rise to a current I in another branch, the ratio V/I is constant when the positions of V and I are interchanged. PROCEDURE: 1. The connections are made as per the circuit diagram. 2. Supply from the RPS is varied and the corresponding values in the voltmeter and ammeter are noted down. 3. Tabulation is made by these readings. 4. The same procedure is repeated for various values of supply voltage. 39 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION: STEP 1 SUPPLY VOLTA GE IN VOLTS AMMETER READING (mA) THEORITIC AL VALUE PRACTICA L VALUE STEP 2 R1 V1 / I1 (kΩ) THEORITIC AL VALUE PRACTICAL VALUE SUPPLY VOLTA GE IN VOLTS 3V 3V 5V 5V 7V 7V 40 AMMETER READING (mA) THEORITIC AL VALUE PRACTICAL VALUE R2 V2 / I 2 (kΩ) THEORITIC AL VALUE DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PRACTICAL VALUE 5. Then the reciprocity theorem should be verified both theoretically and practically. 6. By changing excitation and response, the value must be equal and should be verified. MODEL CALCULATION: To find I1 : For voltage V1 =_________Volts. Total Resistance of the circuit, Req R1 Total Current in the circuit, I1 R2 R3 =_____________Ω. R2 R3 V1 ( A) = Req I1 = _____________mA To find I L1 : I L1 I1 * R2 R2 R3 I L1 = _____________mA To find I 2 : For voltage V2 =_________Volts. Total Resistance of the circuit, Req R3 Total Current in the circuit, I 2 I2 41 R1 * R2 =_____________Ω. R1 R2 V2 ( A) = Req = _____________mA DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 42 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) To find I L 2 : I L2 I 2 * R2 R2 R3 I L 2 = _____________mA To find R1 : By Ohm’s law, V=I*R ----> V V ------> R R I V1 = I1 Here, R1 R1 I = _____________kΩ To find R2 : By Ohm’s law, V=I*R ----> Here, R2 R2 I V V ------> R R I V2 = I2 = _____________kΩ OBSERVATION: OUTPUT R1 (kΩ) R2 (kΩ) THEORITICAL VALUE PRACTICAL VALUE RESULT: Thus, the reciprocity theorem was verified. 43 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-SERIES RESONANCE CIRCUIT: 44 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: FREQUENCY RESPONSE OF SERIES RESONANCE CIRCUIT AIM: To verify the series resonance condition for a series RLC circuit. APPARATUS REQUIRED: S.NO 1. 2. 3. 4. 5. 6. 7. APPARATUS Function generator (or) Signal generator Resistor Decade inductance box Capacitor CRO Bread Board Connecting wires RANGE - QUANTITY 1 1 kΩ 1 µF - 1 1 1 1 1 few THEORY: It is an important phenomenon in electric circuit containing both capacitor and inductor. Resonance is defined as a phenomenon which occurs in any physical system, when a fixed amplitude forcing function is applied. It produces a response of minimum amplitude. Following is the list of few system in which resonance occurs. 45 Electrical. Mechanical. Hydraulic. Acoustic. DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION: 46 S.NO FREQUENCY (Hz) 1 300 Hz 2 400 Hz 3 500 Hz 4 600 Hz 5 700 Hz 6 800 Hz 7 900 Hz 8 1000 Hz 9 1100 Hz 10 1200 Hz 11 1300 Hz 12 1400 Hz 13 1500 Hz 14 1600 Hz 15 1700 Hz VOLTAGE (V) DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Following are the characteristics of series resonant circuit. Input impedance is purely resistive. Applied voltage and current are in phase. Circuit current is maximum. Power factor is unity. Voltage across the inductor and capacitor are equal in magnitude and opposite in phase. PROCEDURE: 1. Connect the various elements R, L, C as shown in the circuit diagram. Set the decade boxes to obtain the required values of R, L and C as given in the circuit diagram. 2. Switch on the supply and set function generator to a low frequency of say 300 Hz and note the corresponding voltage in the CRO. 3. Repeat the same procedure for different values of frequency. 4. Tabulate the observations. 5. Note down the resonance frequency from the table. 6. Draw the graph of frequency in Hz Vs voltage in volts. 47 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH: 48 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: The resonant frequency of a series RLC circuit is given by, fs 1 2 L * C Where, L 50mH 50 X 103 C 1 f 1X 106 fs 1 2 (50 X 103 )*(1X 106 ) f s 712.12Hz OBSERVATION: OUTPUT fs (Hz) THEORITICAL VALUE PRACTICAL VALUE RESULT: Thus, the frequency response of series resonance circuit was verified. 49 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-PARALLEL RESONANCE CIRCUIT: 50 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: FREQUENCY RESPONSE OF PARALLEL RESONANCE CIRCUIT AIM: To verify the series resonance condition for a parallel RLC circuit. APPARATUS REQUIRED: S.NO 1. 2. 3. 4. 5. 6. 7. APPARATUS Function generator (or) Signal generator Resistor Decade inductance box Capacitor CRO Bread Board Connecting wires RANGE - QUANTITY 1 1 kΩ 1 µF - 1 1 1 1 1 few THEORY: A parallel circuit is said to be in resonance when applied voltage and resulting current are in phase that gives unity power factor condition. The resonant frequency of a parallel RLC circuit is given by, fp 51 1 2 L * C DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION: 52 S.NO FREQUENCY (Hz) 1 300 Hz 2 400 Hz 3 500 Hz 4 600 Hz 5 700 Hz 6 800 Hz 7 900 Hz 8 1000 Hz 9 1100 Hz 10 1200 Hz 11 1300 Hz 12 1400 Hz 13 1500 Hz 14 1600 Hz 15 1700 Hz VOLTAGE (V) DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE: 1. Connect the various elements R, L, C as shown in the circuit diagram. Set the decade boxes to obtain the required values of R, L and C as given in the circuit diagram. 2. Switch on the supply and set function generator to a low frequency of say 300 Hz and note the corresponding voltage in the CRO. 3. Repeat the same procedure for different values of frequency. 4. Tabulate the observations. 5. Note down the resonance frequency from the table. 6. Draw the graph of frequency in Hz Vs voltage in volts. 53 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH: 54 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL CALCULATION: The resonant frequency of a series RLC circuit is given by, fp 1 2 L * C Where, L 50mH 50 X 103 C 1 f 1X 106 fp 1 2 (50 X 103 )*(1X 106 ) f p 712.12 Hz OBSERVATION: OUTPUT fp (Hz) THEORITICAL VALUE PRACTICAL VALUE RESULT: Thus, the frequency response of parallel resonance circuit was verified. 55 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 56 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) ELECTRONIC DEVICES EXPERIMENTS 57 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-FORWARD BIAS: PN JUNCTION DIODE-SYMBOL PN JUNCTION DIODE (IN 4007) -PIN CONFIGURATION P 58 N DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF PN JUNCTION DIODE AIM: (i) To plot the forward and reverse V-I characteristics of given PN-junction diode. (ii) To find the dynamic forward and reverse resistance offered by the PNdiode. APPARATUS REQUIRED: S.NO 1. 2. 3. 4. APPARATUS RPS PN junction diode Resistor Voltmeter 5. Ammeter 7. 8. Bread Board Connecting wires RANGE (0-30) V IN 4007 1 kΩ (0-1) V (0-10) V (0-10) mA (0-500) µA - QUANTITY 1 1 1 1 1 1 1 1 few THEORY: The V-I characteristics is a graph drawn between the voltage applied across the terminals of a device and the current that flows through it. The characteristics of PN junction diode are classified as, 59 Forward V-I characteristics (Forward bias). Reverse V-I characteristics (Reverse bias) DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION: S.NO FORWARD VOLTAGE VF (V ) FORWARD CURRENT I F (mA) 1 2 3 4 5 6 7 8 9 10 60 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) FORWARD BIAS: In forward bias, the positive terminal of the battery is connected with P side (anode) of the diode and the negative terminal of the battery is connected with the N side (cathode) of the diode. When a diode is connected in the forward bias, the electrons of the N material and holes of the P material are repelled by the negative and positive terminals of the battery respectively towards the junction. Some of the electrons and holes enter into the depletion region and they are recombines with each other. This reduces the width as well as height of the potential barriers. As a result of this, more majority carriers diffuse across the junction. Therefore it causes a large current to flow through the PN junction. The forward voltage at which the diode starts to conduct is called cut-in voltage, knee voltage (or) threshold voltage. Normally the cut-in voltage for silicon diode is 0.7V and the germanium diode is 0.3V.so we can say the diode conducts the signal only in forward bias. In other words, the diode is ON in forward bias. REVERSE BIAS: In reverse bias, the negative terminal of the battery is connected with P side (anode) of the diode and the positive terminal of the battery is connected with the N side (cathode) of the diode. When a diode is connected in reverse bias, the electrons of the N material and holes of the P materials are attracted by the positive terminal and negative terminal of the battery respectively. If we increase the reverse voltage, the depletion region width and the height of the potential barrier is increased. Therefore there is no possibility of majority charge carrier current can flow across a reverse-biased junction. The minority carriers generated on each side can still cross the junction. Electrons in the p-side are attracted across the junction to the positive voltage on the n-side. Holes on the n-side may flow across to the negative voltage on the p-side. Since only a very small reverse current can flows through the junction. 61 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-REVERSE BIAS: TABULATION: S.NO REVERSE VOLTAGE VR (V ) REVERSE CURRENT I R ( A) 1 2 3 4 5 6 7 8 9 10 62 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) The reverse voltage at which the diode starts to conduct is called breakdown voltage. So, we can say the diode won’t conduct the signal in its reverse bias. In other words the diode is OFF in reverse bias. PROCEDURE: PN-JUNCTION DIODE FORWARD BIAS 1. The connections are given as per the circuit diagram. 2. Vary the supply voltage from RPS in steps and note down the voltmeter readings. 3. The corresponding current is noted from Ammeter and tabulated. 4. Plot the graph between forward voltage VF (V ) and forward current I F (mA) . 5. From the graph calculate the Forward dynamic resistance using the formula, Dynamic resistance, ri 1 Slope of the forward characteristics Slope ri 63 I F VF V Change in voltage F Resulting change in current I F DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH: V-I CHARACTERISTICS OF PN JUNCTION DIODE 64 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE: PN-JUNCTION DIODE REVERSE BIAS 1. The connections are given as per the circuit diagram. 2. Vary the supply voltage from RPS in steps and note down the voltmeter readings. 3. The corresponding current is noted from Ammeter and tabulated. 4. In reverse bias only limted current flows through the diode. 5. Plot the graph between reverse voltage VR (V ) and reverse current I R ( A) . 6. From the graph calculate the Reverse dynamic resistance using the formula, Dynamic resistance, ri Slope ri 65 1 Slope of the reverse characteristics I R VR V Change in voltage R Resulting change in current I R DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 66 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) RESULT: Thus the V-I characteristics of PN-junction diode were drawn for both forward and reverse bias. 1. Dynamic forward resistance was found to be_____________Ω. 2. Dynamic reverse resistance was found to be_____________Ω. 67 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-ZENER DIODE-FORWARD BIAS: ZENER DIODE -SYMBOL ZENER DIODE (IN 2646C) -PIN CONFIGURATION P 68 N DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF ZENER DIODE AIM: (i) To plot the forward and reverse V-I characteristics of the given Zener diode. (ii) To find the dynamic forward resistance offered by the Zener diode. (iii) To find the reverse breakdown voltage of the given Zener diode. APPARATUS REQUIRED: S.NO 1. 2. 3. 4. APPARATUS RPS Zener diode Resistor Voltmeter 5. 7. 8. Ammeter Bread Board Connecting wires RANGE (0-30) V IN 4007 1 kΩ (0-1) V (0-10) V (0-10) mA - QUANTITY 1 1 1 1 1 2 1 few THEORY: A Zener diode is a properly doped crystal diode which has a sharp breakdown voltage. When the reverse bias on a crystal diode is increased, a critical voltage called breakdown voltage is reached where the reverse current increases sharply to a high value. When the doping is heavy, even the reverse voltage is low, the electric field at barrier will be so strong thus the electrons in the covalent bonds can break away from the bonds. This effect is called Zener effect. Zener diode is available with breakdown voltages 0f 4.7 V, 6.2 V, 8.2 V, 12 V. 69 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION: S.NO FORWARD VOLTAGE VF (V ) FORWARD CURRENT I F (mA) 1 2 3 4 5 6 7 8 9 10 70 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Breakdown occurs due to the avalanche multiplication between the thermally generated ions as a chain of collisions are called Avalanche breakdown. The Zener diode with breakdown voltages of less than 6V operates predominantly in Zener breakdown. The Zener diode with breakdown voltages greater than 6V operates predominantly in Avalanche breakdown. PROCEDURE: ZENER DIODE FORWARD BIASED: 1. The connections are given as per the circuit diagram. 2. Vary the supply voltage from RPS in steps and note down the voltmeter readings. 3. The corresponding current is noted from Ammeter and tabulated. 4. Plot the graph between forward voltage VF (V ) and forward current I F (mA) . 5. From the graph calculate the Forward dynamic resistance using the formula, Dynamic resistance, ri Slope ri 71 1 Slope of the forward characteristics I F VF V Change in voltage F Resulting change in current I F DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-REVERSE BIAS: TABULATION: S.NO REVERSE VOLTAGE VR (V ) REVERSE CURRENT I R ( A) 1 2 3 4 5 6 7 8 9 10 72 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE: ZENER DIODE REVERSE BIASED: 1. The connections are given as per the circuit diagram. 2. Vary the supply voltage from RPS in steps and note down the voltmeter readings. 3. The corresponding current is noted from Ammeter and tabulated. 4. Plot the graph between reverse voltage 5. From the graph calculate the Reverse dynamic resistance using the formula, Dynamic resistance, ri 1 Slope of the reverse characteristics Slope ri VR (V ) and reverse current I R ( A) . I R VR V Change in voltage R Resulting change in current I R 6. From the graph also find the reverse breakdown voltage. 73 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH: V-I CHARACTERISTICS OF ZENER DIODE 74 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) RESULT: Thus the V-I characteristics of Zener diode were drawn for both forward and reverse bias. 1. Dynamic forward resistance was found to be_____________Ω. 2. Dynamic reverse resistance was found to be_____________Ω. 3. The reverse breakdown voltage was found to be____________V. 75 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-CE CONFIGURATION: BJT –NPN TRANSISTOR -SYMBOL BJT (BC 107)-PIN CONFIGURATION 76 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF BJT IN CE CONFIGURATION AIM: To plot the input and output characteristics of BJT in CE configuration. APPARATUS REQUIRED: S.NO 1. 2. 3. APPARATUS Dual RPS NPN Transistor Resistor 4. Voltmeter 5. Ammeter 7. 8. Bread Board Connecting wires RANGE (0-30) V BC 107 1 kΩ 10 kΩ (0-1) V (0-10) V (0-10) mA (0-500) µA - QUANTITY 1 1 1 1 1 1 1 1 1 few THEORY: A transistor consists of two PN junctions. They are formed by sandwiching P type (or) N type semiconductor layer with a pair of PN junction. It has three junctions called Emitter, Base, Collector labeled as E, B, C respectively. There are two types of transistors called NPN and PNP. When transistor is connected in a circuit one terminal is considered to be common for input and output. According to the common terminal the transistor is configured as common emitter, common base, and common collector. The configuration in which emitter is common to the input and output is known as common emitter configuration. 77 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR INPUT CHARACTERISTICS OF BJT IN CE CONFIGURATION VCE VCE = 2V = 4V S.NO VBE (V) I B (µA) VBE (V) I B (µA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-INPUT CHARACTERISTICS OF CE CONFIGURATION 78 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) There are two types of transistor characteristics namely, (i) Input characteristics. (ii) Output characteristics. INPUT CHARACTERISTICS: Input characteristics gives the relation between input current and input voltage at constant output voltage .In CE configuration this curve is drawn between base current ( I B ) and the base-emitter voltage (VBE ) at constant collector emitter voltage (VCE ) . When I B increases VBE increase. When VCE increases the width of the base region increase and reduces the base current. This phenomenon is known as early effect. OUTPUT CHARACTERISTICS: Output characteristics give the relation between output current and output voltage at constant input current. In CE configuration this curve is drawn between collector current ( I C ) and the collector - emitter voltage (VCE ) at constant base current ( I B ) . The output characteristics are divided as active region, cut-off region and saturation region. The characteristic obtained when the collector current ( I C ) is nearly zero is known as cut-off region. It is obtained when both the PN junctions are reverse biased. The saturation region characteristic is obtained when both the junctions are forward biased. The collector current ( I C ) in this region is independent of base current ( I B ) . In the active region the collector current ( I C ) increases linearly with the increase in collector - emitter voltage (VCE ) . 79 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR OUTPUT CHARACTERISTICS OF BJT IN CE CONFIGURATION I B =15µA I B =20µA S.NO VCE (V) IC (mA) VCE (V) IC (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-OUTPUT CHARACTERISTICS OF CE CONFIGURATION 80 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE 1. The connections are given as per the circuit diagram. 2. For input characteristics VCE voltage is kept at a fixed value. increased gradually and the changes in 3. This process is repeated for various 4. For output characteristics I B is gradually and the changes in VBE Voltage is I B are noted down and tabulated. VCE values. kept at a fixed value. VCE Voltage is increased I C are noted down and tabulated. 5. This process is repeated for various I B values. 6. Graphs are drawn. RESULT: Thus, the input and output characteristics of given transistor was done under common emitter configuration. 81 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-CB CONFIGURATION: BJT –NPN TRANSISTOR -SYMBOL BJT (BC 107)-PIN CONFIGURATION 82 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF BJT IN CB CONFIGURATION AIM: To plot the input and output characteristics of BJT in CB configuration. APPARATUS REQUIRED: S.NO 1. 2. 3. APPARATUS Dual RPS NPN Transistor Resistor 4. Voltmeter 5. 7. 8. Ammeter Bread Board Connecting wires RANGE (0-30) V BC 107 1 kΩ 10 kΩ (0-1) V (0-10) V (0-10) mA - QUANTITY 1 1 1 1 1 1 2 1 few THEORY: A transistor consists of two PN junctions. They are formed by sandwiching P type (or) N type semiconductor layer with a pair of PN junction. It has three junctions called Emitter, Base, Collector labeled as E, B, C respectively. There are two types of transistors called NPN and PNP. When transistor is connected in a circuit one terminal is considered to be common for input and output. According to the common terminal the transistor is configured as common emitter, common base, and common collector. The configuration in which base is common to the input and output is known as common base configuration. There are two types of transistor characteristics namely, (i) Input characteristics. (ii) Output characteristics. 83 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR INPUT CHARACTERISTICS OF BJT IN CB CONFIGURATION VCB VCB = 2V = 4V S.NO VEB (V) I E (mA) VEB (V) I E (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-INPUT CHARACTERISTICS OF CB CONFIGURATION 84 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) INPUT CHARACTERISTICS: Input characteristics gives the relation between input current and input voltage at constant output voltage .In CB configuration this curve is drawn between emitter current ( I E ) and the emitter-base voltage (VEB ) at constant collectorbase voltage (VCB ) . When I B increases VEB increase. When VCB increases the value of IE decrease for a particular VEB . OUTPUT CHARACTERISTICS: Output characteristics give the relation between output current and output voltage at constant input current. In CB configuration this curve is drawn between collector current ( I C ) and the collector – base voltage (VCB ) at constant emitter current ( I E ) . The output characteristics are divided as active region, cut-off region and saturation region. The characteristic obtained when the collector current ( I C ) is nearly zero is known as cut-off region. It is obtained when both the PN junctions are reverse biased. The saturation region characteristic is obtained when both the junctions are forward biased. The collector current ( I C ) in this region is independent of emitter current (IE ) . In the active region the collector current ( I C ) increases linearly with the increase in collector-base voltage (VCB ) . 85 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR OUTPUT CHARACTERISTICS OF BJT IN CB CONFIGURATION I E =1.5 mA I E =2 mA S.NO VCB (V) IC (mA) VCB (V) IC (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-OUTPUT CHARACTERISTICS OF CB CONFIGURATION 86 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE 1. The connections are given as per the circuit diagram. 2. For input characteristics VCB voltage is kept at a fixed value. increased gradually and the changes in 3. This process is repeated for various 4. For output characteristics I E is gradually and the changes in VBE Voltage is I E are noted down and tabulated. VCB values. kept at a fixed value. VCB Voltage is increased I C are noted down and tabulated. 5. This process is repeated for various I E values. 6. Graphs are drawn. RESULT: Thus, the input and output characteristics of given transistor was done under common base configuration. 87 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-JFET: N- CHANNELJFET SYMBOL D G S JFET (BFW 10)-PIN CONFIGURATION 88 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF JFET AIM: To plot the drain and transfer characteristics of JFET. APPARATUS REQUIRED: S.NO 1. 2. 3. 4. 5. 7. 8. APPARATUS Dual RPS FET Resistor Voltmeter Ammeter Bread Board Connecting wires RANGE (0-30) V BFW10 470 Ω (0-10) V (0-10) mA - QUANTITY 1 1 2 2 1 1 few THEORY: Field effect transistor is one type of transistor having three terminals namely gate, source and drain. The current conduction in this device is only due to majority carriers. In the normal operation of FET, gate source junction is always reverse biased. DRAIN CHARACTERISTICS: Drain characteristics is the curve between drain current ( I D ) and drain to source voltage (VDS ) at constant gate to source voltage (VGS ) . The current increases linearly with voltage and remains constant at its maximum voltage. When the voltage is further increased rapidly leading to the breakdown of the device. This characteristic is used to find drain resistance of FET. 89 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR DRAIN CHARACTERISTICS OF JFET VGS VGS = - 2V = - 3V S.NO VDS (V) I D (mA) VDS (V) I D (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-DRAIN CHARACTERISTICS OF JFET 90 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TRANSFER CHARACTERISTICS: Transfer characteristics are the curve between drain current and gate to source voltage at constant drain to source voltage. When gate to source voltage is zero, the depletion regions are small and the drain current will be maximum. When the voltage is increased, the depletion region increases and reduces the current. This voltage is called pinch-off voltage. From this characteristic, we can find the transconductance of FET. DC DRAIN RESISTANCE It is also called the static or ohmic resistance of the channel and is given by the ratio of voltage to drain current. AC DRAIN RESISTANCE It is also called dynamic drain resistance and is the ac resistance between the drain and source terminal, when the JFET is operating in the pinch-off voltage of saturation region. It is given by the ratio of small change in drain to source voltage to the corresponding change in drain current for a constant gate to source voltage. It is the resistance from drain to source terminals. Since drain voltage is the output resistance of JFET. It may also be expressed as output admittance. 91 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR TRANSFER CHARACTERISTICS OF JFET VDS =1 V VDS =2V S.NO VGS (V) ID (mA) VGS (V) ID (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-TRANSFER CHARACTERISTICS OF JFET 92 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE DRAIN CHARACTERISTICS 1. The connections are given as per the circuit diagram. 2. For drain characteristics set VGS to a constant value. 3. The drain to source voltage VDS is varied from “0” volt, in steps of 1 V and in each step the corresponding drain current is noted by using the ammeter. VDS is also noted by using voltmeter. This is conducted till the drain current becomes constant. 4. This process is repeated for various VGS values. 5. Plot the drain characteristics. PROCEDURE TRANSFER CHARACTERISTICS 1. The connections are given as per the circuit diagram. 2. For transfer characteristics set VDS to a constant value. 3. The gate to source voltage is varied in steps of 1 V and in each steps VGS and drain current is noted down. This is continued till the drain current becomes zero. 4. This process is repeated for various VDS values. 5. Plot the transfer characteristics. RESULT: Thus, the drain and transfer characteristics of given JFET was obtained. 93 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-MOSFET: N- CHANNEL MOSFET SYMBOL MOSFET (IR 740)-PIN CONFIGURATION 94 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF MOSFET AIM: To plot the drain and transfer characteristics of MOSFET. APPARATUS REQUIRED: S.NO 1. 2. 3. 4. 5. 7. 8. APPARATUS Dual RPS MOSFET Resistor Voltmeter Ammeter Bread Board Connecting wires RANGE (0-30) V IR 740 470 Ω (0-10) V (0-10) mA - QUANTITY 1 1 2 2 1 1 few THEORY: MOSFET is an improved version of JFET and is widely used in many circuit applications. The input impedance of MOSFET is much more than that of JFET because of very small gate leakage current. It has 3 terminals namely source, gate and drain. The output characteristic of MOSFET is the plot of drain to source voltage (VDS ) against the drain current The threshold voltage ( I D ) at constant gate to source voltage (VGS ) . (VT ) is the minimum voltage for forming virtual channel between drain and source. If VGS is increased beyond VT , the drain current (drain to source current) begins to flow. There are three regions in the V-I characteristic of MOSFET namely 95 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR DRAIN CHARACTERISTICS OF MOSFET VGS VGS = - 2V = - 3V S.NO VDS (V) I D (mA) VDS (V) I D (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-DRAIN CHARACTERISTICS OF MOSFET 96 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) (i) Cut-off region, where VGS <= VT .there will not be any drain current flow due to the absence of virtual channel. The MOSFET is said to be in OFF state. (ii) Pinch-off (or) saturation region, Where off occurs when VDS = VGS VT .the VDS >= VGS VT .The Pinch- drain current remains almost constant for any increase in the value of VDS . (iii) Linear region, Where VDS <= VGS VT .The drain current I D varies proportion to the VDS . DRAIN CHARACTERISTICS Drain characteristics is the plot of drain to source voltage current ( I D ) at constant gate to source voltage Until the threshold voltage (VDS ) against drain (VGS ) . (VT ) is reached there won’t be any drain current and the device is in OFF state. TRANSFER CHARACTERISTICS: Transfer characteristics are the plot of gate to source voltage (VGS ) against drain current ( I D ) at constant drain to source voltage (VDS ) . 97 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR TRANSFER CHARACTERISTICS OF MOSFET VDS =1 V VDS =2V S.NO VGS (V) ID (mA) VGS (V) ID (mA) 1 2 3 4 5 6 7 8 9 10 MODEL GRAPH-TRANSFER CHARACTERISTICS OF MOSFET 98 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE DRAIN CHARACTERISTICS 1. The connections are given as per the circuit diagram. 2. Keep the gate to source voltage (VGS ) at a particular voltage and vary the drain to source voltage (VDS ) till the MOSFET gets turn on and note down the voltmeter, ammeter readings and tabulate. 3. Further increase the drain to source voltage (VDS ) and note the drain current ( I D ) . 4. The above process is repeated for different values of gate to source voltage (VGS ) . 5. Plot the drain characteristics. TRANSFER CHARACTERISTICS 1. The connections are given as per the circuit diagram. 2. Keep the drain to source voltage the gate to source voltage (VDS ) at a particular voltage and vary (VGS ) till the MOSFET gets turn on and note down voltmeter, ammeter readings and tabulate. 3. Further increase the gate to source voltage (VGS ) and note the drain current ( I D ) . 4. The above process is repeated for different values of drain to source voltage (VDS ) . 5. Plot the transfer characteristics. RESULT: Thus, the drain and transfer characteristics of given MOSFET was obtained. 99 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-SILICON CONTROLLED RECTIFIER(SCR) SCR SYMBOL 100 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: CHARACTERISTICS OF SCR AIM: To plot anode (VAK I A ) forward conduction characteristics including the measurement of holding and latching currents. APPARATUS REQUIRED: S.NO 1. 2. 3. APPARATUS Dual RPS SCR Resistor 4. 5. Voltmeter Ammeter 7. 8. Bread Board Connecting wires RANGE (0-30) V TYN 1006 1 kΩ 10 kΩ (0-10) V (0-10) mA (0-500) µA - QUANTITY 1 1 1 1 1 1 1 1 few THEORY: A silicon controlled rectifier is a semiconductor device that acts as a true electronic switch. It can change ac into dc and at the same time can control the amount of power fed to the load. It combines the features of a rectifier and transistor. It is sometimes called as thyristor. It contains three terminals namely anode, cathode and gate. It is a unidirectional device.SCR conducts only where the anode is positive with respect to cathode with proper gate current.SCR can turn ON and OFF by two methods. 101 i. TURN ON METHODS ii. TURN OFF METHODS DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION FOR CHARACTERISTICS OF SCR IG IG S.NO VAK (V) I A (mA) VAK (V) I A (mA) 1 2 3 4 5 102 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) APPLICATIONS OF SCR: Power control. Over light detector. Static contactor. PROCEDURE: 1. The connections are given as per the circuit diagram. 2. Keep the gate current ( I G ) at a certain value (5mA). 3. Now slowly increase the anode-cathode voltage (VAK ) till the thyristor gets turned on. 4. Note down ammeter current ( I A ) , voltmeter (VAK ) readings. 5. Now find out the break over voltage (VBR ) and latching current ( I A ) . 6. Increase the anode-cathode voltage (VAK ) till the thyristor turns off and measure the holding current ( I H ) . 7. For various gate currents take the readings and tabulate them. 103 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH Forward current in mA IA IH VBO Forward voltage in Volts 104 VAK DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) RESULT: Thus the forward conduction characteristic was obtained along with the measurement of holding and latching currents. The break down voltage of the SCR is also obtained. 105 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 106 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: Clippers,Clampers and Full wave rectifier A. Clippers AIM: To obtain the output and transfer characteristics of diode clippers. APPARATUS REQUIRED: THEORY Clippers 107 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION: Output characteristics: Sl.no Input voltage Output voltage Amplitude Time Transfer characteristics: 108 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 109 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Thus the output and transfer characteristics of diode clippers are obtained. 110 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM-CLAMPERS POSITIVE CLAMPER 111 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: Clampers AIM To obtain the output characteristics of diode clampers. APPARATUS REQUIRED S.NO 1. 2. 3. 4. 5. 6. 7. 8. APPARATUS RPS PN junction diode Resistor Capacitor Voltmeter CRO Bread Board Connecting wires RANGE (0-30) V IN 4007 1 kΩ 10 µF (0-10)V - QUANTITY 1 1 1 1 1 1 1 Few THEORY A circuit that places either the positive or negative peak of a signal at a desired D.C level is known as a clamping circuit. A clamping circuit introduces (or restores) a D.C level to an A.C signal. Thus a clamping circuit is also known as D.C restorer, or D.C reinserted or a baseline stabilizer. The following are two general types of clamping. 1. Positive clamping occurs when negative peaks raised or clamped to ground or on the zero level In other words, it pushes the signal upwards so that negative peaks fall on the zero level. 2. Negative clamping occurs when positive peaks raised or clamped to ground or on the zero level In other words, it pushes the signal downwards so that the positive peaks fall on the zero level. 112 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION Sl No Input Voltage(v) Amplitude(v) 113 Time(ms) Output voltage(v) Positive clamping Negative clamping Amp(v) Time(ms) Amp(v) Time(ms) DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) In both cases the shape of the original signal has not changed, only there is vertical shift in the signal wave form. POSITIVE CLAMPER During the negative half cycle of the input voltage, the diode conducts heavily and behaves as a closed switch At the negative peak, the capacitor is charged to maximum voltage V slightly beyond the negative peak, the diode is shunt off and the capacitor charged to Vm behaves as a battery during the positive half cycle of the input signal. The diode is reversed biased and the output voltage will be equal to Vm + V this gives positive clamped voltage and is called positive clamper circuit. NEGATIVE CLAMPER If we change the polarity of the diode and the capacitor then the circuit become negative clamper. PROCEDURE 1. Connect the circuit as per circuit diagram shown in figure. 2. Obtain a sine wave of constant amplitude 8 V p-p from function generator and apply as input to the circuit. 3. Observe the output wave form and note down the amplitude at which clamping occurs. 4. Draw the observed output waveforms. RESULT: Thus the output characteristics of diode clampers are obtained. 114 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUIT DIAGRAM- FULL WAVE RECTIFIER WITH FILTER WITHOUT FILTER 115 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: FULL WAVE RECTIFIER AIM: To determine the output characteristics of full wave rectifier with and without filter. APPARATUS REQUIRED S.NO 1. 2. 3. 4. 5 7. 8. APPARATUS Step down transformer PN junction diode Resistor Capacitor CRO Bread Board Connecting wires RANGE 230/9 Volts IN 4001 10 kΩ 4.7µF - QUANTITY 1 2 1 1 1 1 few THEORY It converts an a.c voltage into a pulsating d.c voltage using both half cycles of the applied a.c voltge. It uses two diodes of which one conducts during one half cycle while the other diode conducts during the other half cycle of the applied a.c voltage. There are two types of full wave rectifies viz(i) Full wave rectifier with center tapped transformer and (ii) Full wave rectifier without transformer(Bridge rectifier) During positive half of the input signal,anode of diode D1 becomes positive and at the same time the anode of diode D2 becomes negative. Hence,D1 conducts and D2 does not conduct. The load current flows through D1 and the voltage drop across RL will be equal to the input voltage. During the negative half cycle of the input signal,anode of diode D1 becomes negative and at the same time the anode of diode D2 becomes positive. Hence,D1 does not conduct and D2 conducts. The load current flows through D2 and the voltage drop across RL will be equal to the input voltage. 116 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) MODEL GRAPH TABULATION INPUT OUTPUT(WITHOUT FILTER) OUTPUT(WITHOUT FILTER) AMPLITUDE(V) TIME(MS) 117 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) PROCEDURE 1. Connect the circuit as per circuit diagram shown in figure. 2. Observe the output wave form and note down the amplitude. 3. Draw the observed output waveforms. MODEL CALCULATION Rectification efficiency: 𝑃𝑑𝑐 Ƞ= 𝑃𝑎𝑐 (𝑉𝑑𝑐)2 𝑅𝑙 = (𝑉𝑟𝑚𝑠)2 𝑅𝑙 = (𝑉𝑑𝑐)2 (𝑉𝑟𝑚𝑠)^2 2𝑉𝑚 [ 𝜋 ]^2 = 𝑉𝑚 [ ]^2 = √2 8 𝜋^2 = 0.812 = 81.2%. Ripple factor: 𝛤 = √[[ Vrms = 𝑉𝑟𝑚𝑠 2 𝑉𝑚 √2 𝛤 = √[[ 118 𝑉𝑑𝑐 ] − 1] ; Vdc= 𝑉𝑚 √2 2𝑉𝑚 𝜋 2𝑉𝑚 𝜋 2 ] − 1 = √[ 𝜋2 8 − 1]= 0.482. DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) RESULT Thus the output characteristics of full wave rectifier with and without filter is determined. 119 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) R-L SERIES CIRCUIT CIRCUIT DIAGRAM MODEL GRAPH 120 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) R-C SERIES CIRCUIT: CIRCUIT DIAGRAM MODEL GRAPH 121 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) TABULATION R-L SERIES CIRCUIT S.NO T(ms) I(t)Amps R-C SERIES CIRCUIT: S.NO 122 T(ms) V(t)volts DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Ex. No: Date: TRANSIENT CIRCUITS AIM: To find the transient response of R-C and R-L source free and source driven network. APPARATUS REQUIRED: S.No 1 2 3 4 5 6 Components Regulated power supply SP-ST(single pole-single throw single throw switch) Resistor capacitor Stop watch DPST Type/Range (0-15)V Quantity 2 Nos 1 Nos 100Ω 0.01µF 2 Nos 1 Nos 1 Nos 1 Nos THEORY: If a network contains energy storage elements, with change in excitation, the current and voltages change from one state to other state. The behaviour of the voltage (or) current when it is changed from one state to another state is called transient state. Whenever a circuit is switched from one condition to another either by a change in the applied source (or) change in the circuit elements there is a transitional period during which the branch currents and voltage change from their values to new ones, this period is called transient. PROCEDURE: 1. Charge on capacitor is ‘0’ initially. 2. If there is a charge in it, short circuit the terminal then the charge will be dissipated. 3. Close the switch at t=0 4. Simultaneously switch on the stop watch. 5. For every 2 seconds note down the voltage across capacitor until voltmeter reaches 5 V. 123 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 6. After reaching 15 V allow 10 sec for it. THEORETICAL VERIFICATION R-L CIRCUIT 𝑑𝑖 V= Ri+L𝑑𝑡 15/S=R I(s)+L S I(s) I(s)= 15 (100+500𝑥10−3 𝑠) 15 = 50𝑥10^−3(𝑠+2000)𝑠 300 𝐴 𝐵 = + 𝑠(𝑠+2000) 𝑆 𝑆+200 0.15 0.15 = − 𝑆 𝑠+2000 I(t)=0.15-0.15e^-2000t. =0.15(1-e ^-2000t) R-C CIRCUIT 1 V=Ri+𝐶 ∫ 𝑖𝑑𝑡 15 A=0.15,B=0.15 108 =I(s)((100 + 𝑠 ) 𝑆 15⁄ 15 𝑆 I(s) = = 8 (100𝑆 +|10 )/𝑠 100𝑗+108 0.15 I(s)=𝑠+106 I(t)=0.15e^ − 106𝑡 6𝑡 V(t)=i(t)R1=0.15𝑒 −10 x100=0.15𝑒−106𝑡. RESULT: Thus ,the transient response of RC-RL obtained for source free and source drive methods. 124 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) CIRCUITS AND DEVICES LAB Viva questions & Answers (Electrical) 1. What is charge? The charge is an electrical property of the atomic particles of which matter consists. The unit of charge is the coulomb. 2. Define current. The flow of free electrons in a metal is called electric current. The unit of current is the ampere. Current (I) = Q/t, Where Q is total charge transferred & T is time required for transfer of charge. 3. What is voltage? The potential difference between two points in an electric circuit called voltage. The unit of voltage is volt. It is represented by V OR v. Voltage = W/Q = work done/Charge 4. Define power. The rate of doing work of electrical energy or energy supplied per unit time is called the power. The power denoted by either P of p. It is measured in Watts(W). Power = work done in electric circuit/Time P dw dw dq dt dq dt P = V*I 125 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 5. What is network? Interconnection of two or more simple circuit elements is called an electric network. 6. Distinguish between a branch and a node of a circuit. A part of the network which connects the various points of the network with one another is called a branch. A point at which two or more elements are jointed together is called node. 7. Define active and passive elements. The element which delivers energy is called active elements. Example: voltage source, current source. The element which stores or dissipates energy is called passive element. Example: Resistor, Inductor, Capacitor. 8. Define unilateral and bilateral elements. In unilateral element, voltage – current relation is not same for both the direction. Example: Diode, Transistors. In bilateral element, voltage – current relation is same for both the direction. Example: Resistor 126 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 9. Define linear and non-linear elements. If the element obeys superposition principle, then it is said to be linear elements. Example: Resistor. If the given network is not obeying superposition principle then it is said to be non linear elements. Example: Transistor, Diode. 10. Define Lumped and distributed elements. Physically separable elements are called Lumped element. Example: Resistor, Capacitor, Inductor. A distributed element is one which is not separable for electrical purpose. Example: Transmission line has distributor resistance, capacitance and inductance. 11. Distinguish between a mesh and a Loop of a circuit. A mesh is a loop that does not contain other loops. All meshed are loops. But all loops are not meshes. A loop is any closed path of branches. 12. How the electrical energy sources are classified? The electrical energy sources are classified into: 1. Ideal voltage source 2. Ideal current source. 127 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 13. Define an ideal voltage source. The voltage generated by the source does not vary with any circuit quantity. It is only a function of time. Such a source is called an ideal voltage source. 14. Define an ideal current source. The current generated by the source does not vary with any circuit quantity. It is only a function of time. Such a source is called as an ideal current source. 15. What are independent source? Independent sources are those in which, voltage and current are independent and are not affected by other part of the circuit. 16. What are dependent sources? Dependent sources are those in which source voltage or current is not fixed, but is dependent on the voltage or current existing at some other location in the circuit. 17. What are the different types of dependent or controlled sources? i. Voltage Controlled Voltage Sources (VCVS) ii. Current Controlled Voltage Sources (CCVS) iii. Voltage Controlled Current Sources (VCCS) iv. Current Controlled Current Sources (CCCS) 128 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 18. What is resistance? It is the property of a substance which opposes the flow of current through it. The resistance of element is denoted by the symbol “R”. It is measured in Ohms. R V I 19. Define Ohm’s law. The current flowing through the electric circuit is directly proportional to the potential difference across the circuit and inversely proportional to the resistance of the circuit, provided the temperature remains constant. 20. Define Kirchoff’s current law. Kirchhoff’s current law states that in a node, sum of entering current is equal sum of leaving current. ∑ I at junction point = 0 (Total current around a closed loop = 0) 21. Define Kirchoff’s voltage law. Kirchhoff’s Voltage Law (KVL) states that the algebraic sum of the voltages around any closed path is zero. Around a closed path ∑ V = 0. 129 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 22. Distinguish between a cycle, time periods and frequency. One complete set of positive and negative instantaneous values of the Voltage or current is called cycle The time taken by an alternating quantity to complete one cycle is called time period (T). The number of cycle that an alternating quantity completed per second is known as frequency. It is measured in Hz. 23. What are peak value and peak to peak value? The peak value of the sine wave during positive or negative half only. The sum of positive and negative value is called a peak to peak value. The peak to peak value of a sinusoidal alternating voltage is equal to two times the peak value. 24. What is mesh analysis? Mesh analysis is one of the basic techniques used for finding current flowing through the loop in a network. Mesh analysis is applicable if the given network contains voltage sources. If there exists current sources in a circuit, then it should be converted into equivalent voltage sources. 130 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 25. What is nodal analysis? Nodal analysis is one of the basic techniques used to finding solution for voltage drop across the nodes in a given circuit. Nodal analysis is applicable if the given network contains current sources. If there exists voltage sources in the given circuit, then it can to be converted into equivalent current sources. 26. State superposition theorem. Any electric circuit (linear, lumped, bilateral), is energized by two or more sources, the response in any element in the network is equal to the algebraic sum of the responses caused by individual sources acting separately. 27. State Thevenin’s Theorem. A complex network having linear, bilateral, lumped elements with open circuited output terminals can be reduced by a simple circuit consisting of a single voltage source in series with a impedance. 28. State Norton’s theorem. Any electrical network (linear, lumped, bilateral) with short circuited terminals can be reduced by a simple circuit consisting of a single current source in parallel with a Thevenin’s equivalent resistance. 29. State Maximum power transfer theorem. Power transferred from source to load will be maximum, when source resistance is equal to load resistance looking back from its load terminals. 131 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 30. Define duality. Two electrical networks which are governed by the same type of equations are called duality. 31. What is transient state? If a network contains energy storage elements, with change in excitation, the current and voltages change from one state to other state. The behavior of the voltage or current when it is changed from one state to another state is called transient state. 32. What is transient time? The time taken for the circuit to change from one steady state to another steady state is called transient time. 33. What is natural response? If we consider a circuit containing storage elements which are independent of sources, the response depends upon the nature of the circuit, it is called natural response. 34. What is transient response? The storage elements deliver their energy to the resistances, hence the response changes with time, gets saturated after sometime, and is referred to the transient response. 132 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 35. Define resonant circuit. The circuit that treat a narrow range of frequencies very differently than all other frequencies. These are referred to as resonant circuit. The gain of a highly resonant circuit attains a sharp maximum or minimum as its resonant frequency. 36. When the circuit is said to be in resonance? 1. A network is in resonance when the voltage and current at the network input terminals are in phase. 2. If inductive reactance of a network equals capacitive reactance then the network is said to be resonance 37. What is resonant frequency ? The frequency at which resonance occurs is called resonance frequency. fr 1 1 2 LC 38. Define bandwidth. The bandwidth (BW) is defined as the frequency difference between upper cut-off frequency (f2) and lower cut-off frequency (f1) Bandwidth 133 = f 2 f1 . DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 39. Define selectivity. Selectivity is defined as the ratio of bandwidth to the resonant frequency of resonant circuit. Selectivity = Bandwidth Resonant frequency 40. Define quality factor. The quality factor is defined as the ratio of maximum energy stored to the energy dissipated per cycle. Maximum energy stored per cycle Q 2 * Quality factor, Energy dissipated per cycle 134 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) Viva questions & Answers (Electronics) 1. Give the value of Charge, Mass of an electron. Charge of an electron – 1.6 x 10 -19 coloumbs & Mass of an electron – 9.11 10 -31 Kgs. 2. Define Potential. A potential of V volts at point B with respect to point A, is defined as the work done in taking unit positive charge from A to B , against the electric field. 3. Define Current density. It is defined as the current per unit area of the conducting medium. J=I/A 4. Define Electron volts. If an electron falls through a potential of one volt then its energy is 1 electron volt. 1 eV 5. 1.6 X 1019 Joules What is the relation for the maximum number of electrons in each shell? Ans: 2𝑛2 6. What are valence electrons? Electron in the outermost shell of an atom is called valence electron. 135 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 7. What is forbidden energy gap? The space between the valence and conduction band is said to be forbidden energy gap. 8. What are conductors? Give examples? Conductors are materials in which the valence and conduction band overlap each other so there is a swift movement of electrons which leads to conduction. Ex: Copper, silver. 9. What are insulators? Give examples? Insulators are materials in which the valence and conduction band are far away from each other. So no movement of free electrons and thus no conduction. Ex: glass, plastic. 10. What are Semiconductors? Give examples? The materials whose electrical property lies between those of conductors and insulators are known as Semiconductors. Ex: germanium, silicon. 11. What are the types of Semiconductor? 1. Intrinsic semiconductor 2. Extrinsic semiconductor. 136 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 12. What is Intrinsic Semiconductor? Pure form of semiconductors are said to be intrinsic semiconductor. Ex: germanium, silicon. 13. Define Mass – action law. Under thermal equilibrium the product of free electron concentration (n) and hole concentration (p) is constant regardless of the individual magnitude. 14. What is Extrinsic Semiconductor? If certain amount of impurity atom is added to intrinsic semiconductor the resulting semiconductor is Extrinsic or impure Semiconductor. Ex: Arsenic. 15. What are the types of Extrinsic Semiconductor? 1. P-type Semiconductor 2. N- Type Semiconductor. 16. What is P-type Semiconductor? The Semiconductor which are obtained by introducing pentavalent impurity atom (phosphorous, antimony) are known as P-type Semiconductor. Ex: Boron, aluminum. 137 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 17. What is N-type Semiconductor? The Semiconductor which is obtained by introducing trivalent impurity atom (gallium, indium) is known as N-type Semiconductor. Ex: Antimony, Phosphorous. 18. What is doping? Process of adding impurity to an intrinsic semiconductor atom is doping. The impurity added is called dopant. 19. Define drift current? When an electric field is applied across the semiconductor, the holes move towards the negative terminal of the battery and electron move towards the positive terminal of the battery. This drift movement of charge carriers will result in a current termed as drift current. 20. Give the expression for drift current density due to electron. J n qnn E Where, J n --> drift current density due to electron. q- Charge of electron, n - Mobility of electron. 138 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 21. Give the expression for drift current density due to holes. J p qp p E Where, J p --> drift current density due to holes. q- Charge of holes. p - Mobility of holes. 22. Define the term diffusion current? A concentration gradient exists, if the number of either electrons or holes is greater in one region of a semiconductor as compared to the rest of the region. The holes and electron tend to move from region of higher concentration to the region of lower concentration. This process is called diffusion and the current produced due this movement is diffusion current. 23. Define mean life time of a hole or an electron. The electron hole pair created due to thermal agitation will disappear as a result of recombination. Thus an average time for which a hole or an electron exists before recombination can be said as the mean life time of a hole or electron. 139 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 24. Define the term transition capacitance? When a PN junction is reverse biased, the depletion layer acts like a dielectric material while P and N –type regions on either side which has low resistance act as the plates. In this way a reverse biased PN junction may be regarded as parallel plate capacitor and thus the capacitance across this set up is called as the transition capacitance. CT A W Where CT - Transition capacitance. A - Cross section area of the junction. W – Width of the depletion region. 25. What are break down diodes? Diodes which are designed with adequate power dissipation capabilities to operate in the break down region are called as break down or zener diodes. 26. What is break down? What are its types? When the reverse voltage across the pn junction is increased rapidly at a voltage the junction breaks down leading to a current flow across the device. This phenomenon is called as break down and the voltage is break down voltage. The types of break down are 140 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 1. Zener break down 2. Avalanche breakdown 27. What is Zener breakdown? Zener break down takes place when both sides of the junction are very heavily doped and consequently the depletion layer is thin and consequently the depletion layer is tin. When a small value of reverse bias voltage is applied, a very strong electric field is set up across the thin depletion layer. This electric field is enough to break the covalent bonds. Now extremely large number of free charge carriers are produced which constitute the zener current. This process is known as zener break down. 28. What is avalanche break down? When bias is applied, thermally generated carriers which are already present in the diode acquire sufficient energy from the applied potential to produce new carriers by removing valence electron from their bonds. These newly generated additional carriers acquire more energy from the potential and they strike the lattice and create more number of free electrons and holes. This process goes on as long as bias is increased and the number of free carriers gets multiplied. 141 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) This process is termed as avalanche multiplication. Thus the break down which occurs in the junction resulting in heavy flow of current is termed as avalanche break down. 29. How does the avalanche breakdown voltage vary with temperature? In lightly doped diode an increase in temperature increases the probability of collision of electrons and thus increases the depletion width. Thus the electrons and holes need a high voltage to cross the junction. Thus the avalanche voltage is increased with increased temperature. 30. How does the zener breakdown voltage vary with temperature? In heavily doped diodes, an increase in temperature increases the energies of valence voltage is sufficient to knock or pull these electrons from their position in the crystal and convert them in to conduction electrons. Thus zener break down voltage decreases with temperature. 31. What is a transistor (BJT)? Transistor is a three terminal device whose output current, voltage and /or power are controlled by input current. 32. What are the terminals present in a transistor? Transistor contains three terminals. 1. Emitter. 2. Base. 3. Collector. 142 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 33. What is FET? FET is abbreviated for field effect transistor. It is a three terminal device with its output characteristics controlled by input voltage. 34. Why FET is called voltage controlled device? The output characteristics of FET is controlled by its input voltage thus it is voltage controlled. 35. What are the two main types of FET? 1. JFET 2. MOSFET. 36. What is JFET? JFET- Junction Field Effect Transistor. 37. What are the terminals available in FET? FET contains three terminals. 1. Drain, 2. Source 3. Gate 38. What are the types of JFET? N- Channel JFET and P- Channel JFET 39. What are the two important characteristics of JFET? 1. Drain characteristics 2. Transfer characteristics. 143 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 40. What is transconductance in JFET? It is the ratio of small change in drain current to the corresponding change in drain to source voltage. 41. What is amplification factor in JFET? It is the ratio of small change in drain to source voltage to the corresponding change in Gate to source voltage. 42. Why the transistor is called a current controlled device? The output characteristics of the transistor depend on the input current. So the transistor is called a current controlled device. 43. Define current amplification factor? It is defined as the ratio of change in output current to the change in input current at constant. 44. When does a transistor act as a switch? The transistor acts as a switch when it is operated at either cutoff region or saturation region 45. What is biasing? To use the transistor in any application it is necessary to provide sufficient voltage and current to operate the transistor. This is called biasing. 144 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg) 46. Explain about the various regions in a transistor? The three regions are 1. Active region. 2. Saturation region 3. Cutoff region. 47. Explain about the characteristics of a transistor? Input characteristics: it is drawn between input voltage & input current while keeping output voltage as constant. Output characteristics: It is drawn between the output voltage &output current while keeping input current as constant. 145 DEPARTMENT OF ECE /EGSPEC / I YEAR- CIRCUITS AND DEVICES LAB MANUAL (2013 reg)