Rectifiers and Filters

Experiment No. : 1 Rectifiers and Filters Date: / / Aim : To design and testing of Full wave centre tapped transformer type and Bridge type rectifier circuits with and without Capacitor filter. Determination of ripple factor, regulation and efficiency Apparatus Required : Sl. No. Particulars Range Quantity 1. Transformer As per design 01 2. Diode (BY 127) - 04 3. Resistors & Capacitors As per design - 4. Multimeter - 01 5. CRO Probes - 2 Set 6. Spring board and connecting wires - - Theory: Rectifier is a circuit which converts AC to pulsating DC. Rectifiers are used in construction of DC power supplies. There are three types of rectifiers namely Half wave rectifier, Center tap full wave rectifier and bridge rectifier. In half wave rectification, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, it is very inefficient if used for power transfer. A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the input waveform to DC (direct current), and is more efficient. Fullwave rectification can be obtained either by using center tap transformer or by using bridge rectifier. The output of a rectifier is not a smooth DC it consists of ac ripples therefore to convert this pulsating DC in to smooth DC we use a circuit called filter. There are many types of filters like C filter, L filter, LC filter, multiple LC filter, filter etc.. of all these C filter is the most fundamental filter. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 1

Circuit Diagram: Full wave rectifier a) Center tap FWR without filter b) Center tap FWR with C filter D2 a) Bridge Rectifier without filter b) Bridge Rectifier with C filter Vi Vm 2 t Vo without filter Vm VDC 2 t Vo with C filter Vm VDC Vrpp 2 t Dept. of EEE, CIT, Gubbi, Tumkur 572 216 2

Design : a) Center Tap Full Wave Rectifier / Bridge Rectifier Without filter VDC = 2Vm / for FWR ( both center tap and bridge rectifier ) For the given VDC calculate Vm and Vrms = Vm / 2 Procedure : 1. Components / Equipment are tested for their good working condition 2. Connections are made as shown in the circuit diagram 3. Observe different waveforms on CRO 4. Measure VDC using multimeter in dc mode and Vm on CRO 5. Calculate Vrms from Vm using formula Vrms = Vm / 2 for Half wave rectifier Vrms = Vm / 2 for full wave rectifier 6. Calculate the efficiency, ripple factor and regulation. Compare the results with the theoretic values. Result : Without filter : Type of rectifier - theoretical - practical - theoretical - practical Center tap full wave rectifier Bridge Rectifier 0.48 81.2 % 0.48 81.2 % With filter : Type of rectifier theoretical practical % Regulation Center tap full wave rectifier Bridge Rectifier 0.006 0.006 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 3

Choose the transformer of rating Vrms 0 Vrms / IDC for Center tap full wave rectifier and 0 Vrms / IDC for Bridge rectifier The value of load resistance, RL = VDC / IDC, PRL = VDC 2 / RL b) Full Wave Rectifier with C filter VDC = Vm ( IDC / 4fC ) = 1 / ( 4 3 fcrl ) ( f = 50 Hz ) For the given value of VDC and IDC Calculate RL = VDC / IDC, PRL = VDC 2 / RL For the given Calculate the value of capacitor C For the given value of VDC and IDC Calculate Vm and Vrms = Vm / 2 Choose the transformer of rating, Vrms 0 Vrms / IDC for Center tap full wave rectifier and 0 Vrms / IDC for Bridge rectifier Choose the capacitor of value C / Vm Example - 1: Design an FWR for an output DC voltage of 10 V and load current of 10 ma. (Bridge and Center tap rectifier) VDC = 10 V Vm = (VDC X ) / 2 = 15.7 V Vrms = Vm / 2 = 11.1 V 12 V Choose a transformer of rating 12V 0 12V / 10 ma for Center tap full wave rectifier Choose a transformer of rating 0 12V / 10 ma for Bridge rectifier RL = VDC / IDC = 1 K PRL = VDC 2 / RL = 0.1 W Choose RL = 1 K / 0.1 W Example 2 : Design a full wave rectifier for VDC = 16 V, IDC = 16mA, = 0.006 (Bridge and center tap rectifier) RL = VDC / IDC = 1 K, PRL = VDC 2 / RL = 0256 W From = 1 / ( 4 3 fcrl ), C = 481 f, ( 470 f ) ( f = 50 Hz ) From VDC = Vm ( IDC / 4fC ), Vm = 16.17 V, Vrms = 11.43 V, ( 12 V ) Choose transformer of rating 12V - 0 12V / 16mA for center tap full wave rectifier and 0 12V / 16mA for bridge rectifier Choose RL = 1 K / 0.256 W, C = 470 f / 16.17V Dept. of EEE, CIT, Gubbi, Tumkur 572 216 4

Tabular Column : Without filter Circuit VDC Vm Vrms =VDC 2 / Vrms 2 = (Vrms 2 / VDC 2 )-1 Center tap full wave rectifier Bridge Rectifier Note : Vrms = Vm / 2 for Half wave rectifier Vrms = Vm / 2 for full wave rectifier With filter : Circuit Center tap full VDC full load Vrpp Vrrms VDC no load % Regulation = Vrrms / VDC wave rectifier Bridge rectifier Note : Vrrms = Vrpp / 2 3 % Regulation = ( VDC no load VDC full load ) / VDC full load Dept. of EEE, CIT, Gubbi, Tumkur 572 216 5

Experiment No. : 2 Date: / / Simplification and Realization of Boolean Expression using logic gates/universal gates Aim: Simplify and realize the given Boolean expressions using Logic Gates/Universal Gates Apparatus: Theory: Sl No Particulars Quantity 1 IC 7408,IC 7432 2 each 2 IC 7400,IC 7402 2 each 3 IC 7410 1 Canonical Forms (Normal Forms): Any Boolean function can be written in disjunctive normal form (sum of min-terms) or conjunctive normal form (product of max-terms).a Boolean function can be represented by a Karnaugh map in which each cell corresponds two minterm. Sum of minterms Product of maxterms : Sum Of Product (SOP) : Product Of Sum (POS) Procedure: 1. Verify that the gates are working. 2. Construct a truth table for the given problem. 3. Draw a Karnaugh Map corresponding to the given truth table. 4. Simplify the given Boolean expression manually using the Karnaugh Map. A. Implementation Using Logic Gates 1. Realize the simplified expression using logic gates. 2. Make connections as per the logic gate diagram. 3. Apply the different combinations of input according to the truth tables. 4. Verify that the results are correct. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 6

1) Y1=(A+BC)(B+A C ) using Basic Gates Simplification: Y1=(A+BC)(B+A C ) ( Given Expression) = AB+ A C +BC (Using basic gates) = AB + AC + BC = AB. BC. A C (Using NAND Gates) Y1= ( A+BC)(B+ A C ) = (A+B)(A+C)(B+A)(B+C ) = ( A C)( A B)( B C) = ( A C) + ( A B) + ( B C) (Using only NOR gates) A B C Y1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 7

B. Implementation Using Universal Gates 1. Convert the AND-OR logic into NAND-NAND and NOR-NOR logic. 2. Implement the simplified Boolean expressions using only NAND gates, and then using only NOR gates. 3. Connect the circuits according to the circuit diagrams, apply inputs according to the truth table and verify the results. Using Only NAND gates A B C Y1 Using only NOR gates A B C Truth Table A B C Y1 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 1 1 1 1 1 Y 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 8

2) Z= A B C +AB C + A B C+ABC = A B (C+C )+AB(C+ C ) = A B +AB (using Basic Gates) Z= A B + AB ( Using only NAND Gates) Z= (A+ B )+( A +B) ( Using only NOR Gates) Using NAND Gates Only A B Z Using NOR Gates only A B Z Dept. of EEE, CIT, Gubbi, Tumkur 572 216 9

Circuit Diagram : A. Series Clippers : 1. To pass positive peak above V level A A K K 10 V p-p 500 Hz Vi Vo V Vm Vo 2 t V Vi 2 t 2. To pass positive peak above some reference level ( VR +V ) Vo 10 V p-p 500 Hz VR +V Vi Vi VR+V Vo Vm 2 t 2 t Dept. of EEE, CIT, Gubbi, Tumkur 572 216 10

Experiment No. : 3 Date: / / Testing of diode clipping and Clamping circuits Aim : To design and study the series and shunt clipping circuits using diodes. Apparatus Required : Theory: Sl. No. Particulars Range Quantity 1. Diode ( 1N4007 / BY 127 ) - 02 2. Resistor As per design - 3. Multimeter - 01 4. CRO Probes - 3 set 5. Spring Board and Connecting wires - - A clipper is a circuit that removes either positive or negative portion of a waveform. This kind of processing is useful for signal shaping, circuit protection and communications. The clippers are usually constructed by using diodes and resistors and some times to adjust the clipping level DC power supplies are also used. There are two types of clippers namely series clippers and shunt clippers. If the clipping element (diode) is in series with the source then we call it as series clippers and if the clipping device is in parallel with the source then we call such circuit as shunt clippers. Further based on the portion of a waveform clipped the clippers can be classified as positive clippers, negative clippers and two level clippers (combination clippers). Procedure: 1. Components / Equipment are tested for their good working condition. 2. Connections are made as shown in the circuit diagram 3. Apply a sine wave of amplitude greater than the designed clipping level with frequency 500 Hz. 4. Observe the output wave form on the CRO 5. Observe the transfer characteristic curve on CRO by applying input waveform to channel X and output waveform to channel Y. 6. Measure the clipped voltage and compare with the designed value. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 11

3. To pass negative peak above -V level Vo 10 V p-p 500 Hz - V Vi Vi Vo Vm -V 2 t 2 t 4. To pass negative peak above some reference level (-VR - V ) Vo 10 V p-p 500 Hz - VR - V Vi Vi Vm Vo 2 t -VR-V 2 t Dept. of EEE, CIT, Gubbi, Tumkur 572 216 12

5. To pass positive peak above some reference level (VR1+V ) and negative peak above some reference level -VR2 - V Vo -VR2- V 10 V p-p 500 Hz VR1+ V Vi Vi VR1+V Vm 2 t -VR2-V Vo 2 t Result: A. Series Clippers Designed Sl. Circuit Clipping level No. (Theoretical) 1. To pass positive peak above V level V = 0.7V 2. To pass positive peak above some reference level VR +V VR +V = 2.5+0.7 3. To pass negative peak above -V level -V = -0.7V 4. 5. To pass negative peak above some reference level -VR - V To pass positive peak above some reference level (VR1+V ) and negative peak above some reference level -VR2-V =3.2V -VR -V = -3-0.7 = -3.7V VR1+V = 2+0.7=2.7V -VR2 - V =-2-0.7 =-2.7V Observed Clipping level in CRO(Practical) Dept. of EEE, CIT, Gubbi, Tumkur 572 216 13

B. Shunt Clippers 6. To remove positive peak above V level Vo 10 V p-p 500 Hz V Vi Vi V Vm 2 t Vo V 2 t 7. To remove positive peak above some reference level (VR +V ) Vo 10 V p-p 500 Hz VR+ V Vi Vi VR+V Vo Vm 2 t VR+V 2 t Dept. of EEE, CIT, Gubbi, Tumkur 572 216 14

8. To remove negative peak above -V level Vo 10 V p-p 500 Hz -V Vi Vi Vo Vm -V 2 t -V 2 t 9. To pass positive peak above some reference level (VR-V ) Vo 10 V p-p 500 Hz VR- V Vi Vi VR-V Vo VR-V Vm 2 t 2 t Dept. of EEE, CIT, Gubbi, Tumkur 572 216 15

10. To remove positive peak above some reference level (VR1+V ) and negative peak above some reference level (-VR2-V ) Vo 10 V p-p 500 Hz Vo VR1+V -VR2-V Vi Vi VR1+V Vm 2 t -VR2-V Vo VR1+V -VR2-V 2 t Design : Example 1 : Design a clipping circuit to pass the positive peak above the reference level 2V (Circuit 2) VR + V = 2V Assume the diode to be silicon make then V = 0.6 V Then VR = 2 0.6 = 1.4 V Assume Rr = 100 K and Rf = 10 Then R = Rr Rf = 1 K Example 2 : Design a clipping circuit to remove positive peak above + 3 V negative peak above 4 V (Circuit 12) VR1+V = + 3 V Assume the diode to be silicon make then V = 0.6 V VR1 = 3 0.6 = 2.4 V -VR2-V = - 4 V -VR2 = - 4 + 0.6 = - 3.4 V Dept. of EEE, CIT, Gubbi, Tumkur 572 216 16

VR2 = 3.4 V Assume Rr = 100 K and Rf = 10 Then R = Rr Rf = 1 K Result: Sl. No. Circuit B. Shunt Clippers 6. To remove positive peak above V level V = 0.7V 7. To remove positive peak above some reference level (VR +V ) Designed Clipping level (Theoretical) (VR +V )=2+0.7=2.7V Observed Clipping level in CRO(Practical) 8. To remove negative peak above -V level -V =-0.7V 9. 10. To pass positive peak above some reference level (VR-V ) To remove positive peak above some reference level (VR1+V ) and negative peak above some reference level (-VR2-V ) VR-V =3-0.7=2.3V VR1+V =2+.7=2.7V -VR2-V =-3-0.7 =-3.7V Dept. of EEE, CIT, Gubbi, Tumkur 572 216 17

Circuit Diagram: Positive Clampers: 1. Negative peak clamped to -V level Vi Vo V t -V V t 2. Negative peak clamped to positive reference level (VR-V ) Vi Vo V t VR-V V t 3. Negative peak clamped to negative reference level (-VR-V ) Vi Vo V t V Dept. of EEE, CIT, Gubbi, Tumkur 572 216 18

Clamping Circuits Aim : To design a clamping circuit for the given specification. Apparatus Required : Sl. No. Particulars Range Quantity 1. Diode ( 1N4007 / BY 127 ) - 01 2. Resistors & Capacitors As per design - 3. CRO Probes - 3 set 4. Spring board and connecting wires Theory : Clamper is a circuit which adds DC level to an AC waveform. There are two types of clampers namely positive clampers and negative clampers. In positive clampers positive DC level will be added to the AC waveform or the negative peak will be clamped to some other level. In Negative peak clampers negative DC level will be added to the AC waveform or the positive peak will be clamped to some other level. Clampers are very much used in communication systems for example clampers are used in analog television receivers for the purpose of restoring the dc component of the video signal prior to its being fed to the picture tube. Procedure : 1. Components / Equipment are tested for their good working condition. 2. Connections are made as shown in the circuit diagram 3. Apply a square wave / triangular wave / sine wave input of amplitude 10 V peak to peak and frequency of 1 khz 4. Observe the input and output waveform keeping CRO in DC position 5. Measure the clamping level and compare with the designed value Design : For a clamper RC T let RC = 10 T Assume f = 1 KHz, hence T = 1 ms, choose C = 1 f Then R = 10 K Dept. of EEE, CIT, Gubbi, Tumkur 572 216 19

Negative Clampers : 4. Positive peak clamped to V level Vi Vo V V t V t 5. Positive peak clamped to positive reference level (VR+V ) Vi Vo VR+V V V t t 6. Positive peak clamped to negative reference level (-VR+V ) Vi Vo -VR+V V V t t Dept. of EEE, CIT, Gubbi, Tumkur 572 216 20

Result: A. Positive Clampers Sl. No. Circuit Designed Clipping level (Theoretical) 1. Negative peak clamped to -V level - V =-0.7V Observed Clipping level in CRO(Practical) 2. Negative peak clamped to positive reference level (VR-V ) Negative peak clamped to negative 3. reference level (-VR-V ) VR-V =2-0.7 =1.3V -VR-V =-3-0.7 =-3.7V B. Negative Clampers 4. Positive peak clamped to V level V =0.7V 5. Positive peak clamped to positive reference level (VR+V ) VR+V = 4+0.7 =4.7V 6. Positive peak clamped to negative reference level (-VR+V ) -VR+V = -3+0.7=-2.3V Example 1 :Design a clamping circuit to clamp the negative peak to +3V ( Circuit 2 ) VR - V = 3 V Let the diode be silicon make then V = 0.6 V VR = 3 + 0.6 = 3.6 V 2.Negative peak clamped to negative reference level (-2V) -VR-V = -2, VR=1.4V Dept. of EEE, CIT, Gubbi, Tumkur 572 216 21

Half Adder: a) Half Adder using Basic gates A B S= A B C= AB b) Half Adder using NAND Gates A S=A B B C=AB Truth Table A B SUM CARRY (S) (C) 0 0 0 0 0 1 1 0 1 0 1 0 1 1 0 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 22

Experiment No. : 4 Date: / / Realization of half/full adder and Half/Full Subtractors using logic gates Aim: (i) To realize half/full adder using Logic gates & NAND gates (ii) To realize half/full Subtractor using Logic gates & NAND gates Components Required: Sl no Particulars Quantity 1 IC 7400 3 2 7404,7486,7408,7432 1 Theory: Half-Adder: A combinational logic circuit that performs the addition of two data bits, A and B, is called a half-adder. Addition will result in two output bits; one of which is the sum bit S, and the other is the carry bit, C. The Boolean functions describing the half-adder are: S =A B C = A.B Full-Adder: The half-adder does not take the carry bit from its previous stage into account. This carry bit from its previous stage is called carry-in bit. A combinational logic circuit that adds two data bits, A and B, and a carry-in bit,cin,is called a full-adder. The Boolean functions describing the full-adder are: S = A B Cin C = A.B+ Cin (A B) Half Subtractor: Subtracting a single-bit binary value B from another A (i.e. A -B) produces a difference bit D and a borrow out bit Br. This operation is called half subtraction and the circuit to realize it is called a half subtractor. The Boolean functions describing the half-subtractor are: D =A B Br= A.B Full Subtractor: Subtracting two single-bit binary values, B, Cin from a single-bit value A produces a difference bit D and a borrow out Br bit. This is called full subtraction. The Boolean functions describing the full-subtractor are: D = A B Cin, Br= A.B + A.Cin + B.Cin Procedure: 1. Verify that the gates are working. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 23

2. Make the connections as per the circuit diagram for the half adder circuit, on the trainer kit. 3. Switch on the VCC power supply and apply the various combinations of the inputs according to the respective truth tables. 4. Verify that the outputs are according to the expected results. 5. Repeat the procedure for the full adder circuit, the half subtractor and full subtractor circuits. 6. Verify that the sum/difference and carry/borrow bits are according to the expected values. FULL ADDER: a) Full Adder using Basic Gates A B C S= A B C C= AB+C(A B) b) Full Adder using NAND Gates only A S= A B C B C C= AB+C(A B) Truth Table: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 24

A B C Sum Carry 0 0 0 0 0 0 0 1 1 0 0 1 0 1 0 0 1 1 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 0 1 1 1 1 1 1 SUM= S= A B C C= AB+C(A B) Half Subtractor: a. Half Subtractor using Basic gates A B D= A B Bo= AB b. Half Subtractor using NAND Gates A D=A B B C= A B Dept. of EEE, CIT, Gubbi, Tumkur 572 216 25

Truth Table A B Diff(D) Borrow (B) 0 0 0 0 0 1 1 1 1 0 1 0 1 1 0 0 Full Subtractor: c. Full Subtractor using Basic Gates A B C D= A B C d. Full Subtractor using Nand gates Bo= A B+C(A B) Truth Table: Diff= A B C B0 = A B+C(A B) A B C Diff Borrow 0 0 0 0 0 0 0 1 1 1 0 1 0 1 1 0 1 1 0 1 1 0 0 1 0 1 0 1 0 0 1 1 0 0 0 1 1 1 1 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 26

Circuit Diagram: RC coupled Single stage BJT amplifier: C IR1 B 0.1 F VR2 0.1 F E SL100 or CL100 Design : Given, VCE = 5 V and IC = 2 ma Assume = 100 VCC = 2VCE = 2 X 5 = 10 V Let VRE = 10% VCC = 1 V RE = VRE / ( IC + IB ) IB = IC / = 2mA / 100 = 20 A RE = 1 / ( 2m + 20 ) = 495 Choose RE = 470 Apply KVL to collector loop VCC IC RC VCE VE = 0 RC = (VCC VCE VE) / IC = (10 5 1) / 2 m RC = 2 K Choose RC = 1.8 K Let IR1 = 10 IB = 10 X 20 A = 200 A VR2 = VBE + VE = 0.6 + 1 = 1.6 V ( Since transistor is silicon make VBE = 0.6 V ) R2 = VR2 / ( IR1 IB ) = 1.6 / ( 200 A - 20 A ) R2 = 8.8 K Choose R2 = 8.2 K R1 = ( VCC VR2 ) / IR1 = ( 10 1.6 ) / 200 A R1 = 42 K Choose R1 = 47 K XCE < < RE XCE = RE / 10 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 27

Experiment No. : 5(a) Date: / / RC Coupled Single Stage BJT Amplifier Aim: To conduct an experiment to plot the frequency response of an RC coupled amplifier and to find the half power points, bandwidth, input impedance, output impedance. Apparatus Required: Theory : Sl. No. Particulars Range Quantity 1. Transistor SL 100-01 2. Resistors & Capacitors As per design - 3. CRO Probes - 3 Set 4. Multi meter - 01 5. DRB - 01 6. Spring board and connecting wires - - An amplifier is a circuit which increases the voltage, current or power level of i/p signal where the frequency is maintained constant from o/p to i/p signal. The common emitter amplifier is basically a current amplifier ( I C = I b ) where I B is input current and I C is output current and is a non unity value, in turn it provides voltage amplification. The ratio of collector current to base current is noted as the current amplification factor and is denoted as i.e.[ = I C /I b ], is very large. In RC coupled CE amplifier R1, R2 and RC are selected in such a way that transistor operates in active region and the operating point will be in the middle of active region. RE is used for stabilization of operating point. Coupling capacitors CC1 and CC2 are used to block dc current flow through load and the source. The emitter by-pass capacitor CE is connected to avoid negative feedback. Input signal increases base current and the collector current increases by a factor. [i.e. Ic = I b ]. Hence output voltage is large compared to input voltage which is known as amplification An amplifier in which resistance-capacitance coupling is employed between stages and at the input and an output point of the circuit is known as RC coupled amplifier. A capacitor provides a path for signal currents between stages, with resistors connected from each side of the capacitor to the power supply or to ground. 1 / ( 2 f CE ) = 470 / 10 Let f = 100 Hz CE = 33 F Choose CE = 47 F Choose CC1 = CC2 = 0.1 F Dept. of EEE, CIT, Gubbi, Tumkur 572 216 28

Tabular Column : Vi = V F in Hz Vo in Volt AV = Vo / Vi Gain in db = 20*log AV Procedure : 1. Components / Equipment are tested for their good working condition. 2. Connections are made as shown in the circuit diagram. 3. By keeping the voltage knobs in minimum position and current knob in maximum position switch on the power supply. 4. By disconnecting the AC source measure the quiescent point (VCE and IC = VRC / RC) To find frequency response : 1. Connect the AC source. Keeping the frequency of the AC source in mid band region (say 10 khz) adjust the amplitude to get the distortion less output. Note down the amplitude of the input signal. 2. Keeping the input amplitude constant, Vary the frequency in suitable steps and note down the corresponding output amplitude. 3. Calculate AV and gain in decibels. Plot a graph of frequency Vs gain in db. From the graph calculate f L, f H and band width. 4. Calculate figure of merit. To find the input impedance ( Zi ) : 1. Connections are made as shown in the diagram. 2. Keeping the DRB in its minimum position, apply input signal at mid band frequency (say 10kHz) and adjust the amplitude of the input signal to get distortion less output. Note down the output amplitude. 3. Vary the DRB until the output amplitude becomes half of its previous value. The corresponding DRB value gives the input impedance. To find the output impedance ( Zo ) : 1. Connections are made as shown in the diagram. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 29

2. Keeping the DRB in its maximum position, apply input signal at mid band frequency (say 10kHz) and adjust the amplitude of the input signal to get distortion less output. Note down the output amplitude. 3. Vary the DRB until the output amplitude becomes half of its previous value. The corresponding DRB value gives the output impedance. Circuit to find input impedance ( Zi ) : Circuit to find output impedance ( Zo ) : Ideal Graph : Gain db 3dB Band width f in Hz f L f L = Lower cutoff frequency f H f H = Higher cutoff frequency Dept. of EEE, CIT, Gubbi, Tumkur 572 216 30

Result: 1. Quiescent point : VCE = V, IC = ma 2. Voltage Gain ( AV ) = ( in mid band region ) 3. Bandwidth (BW) = Hz 4. figure of merit ( FM = AV * BW ) = Hz 5. Input impedance (Zi) =, Output Impedance (Zo) = Experiment No. : 5(b) Date: / / RC Coupled Single Stage FET Amplifier Aim: To conduct an experiment to plot the frequency response of an RC coupled FET amplifier and to find the half power points, bandwidth, input impedance, output impedance Apparatus Required: Sl. No. Particulars Range Quantity 1. FET BFW 10-01 2. Resistors & Capacitors As per design - 3. CRO Probes - 3 Set 4. Multi meter - 01 5. DRB - 01 6. Spring board and connecting wires - - Theory: An amplifier is a circuit which increases the voltage, current or power level of i/p signal where the frequency is maintained constant from o/p to i/p signal. In FET amplifier the output current (ID) is a function of input voltage VGS. That is as VGS varies the drain current varies. VGS varies as input signal varies in turn the drain current varies hence amplification takes place. In RC coupled FET amplifier RD and RS are selected in such a way that FET operates in active region and the operating point will be in the middle of active region. Coupling capacitors CC1 and CC2 are used to block dc current flow through load and the source. The source by-pass capacitor CS is connected to avoid negative feedback. An amplifier in which resistance-capacitance coupling is employed between stages and at the input and output point of the circuit is known as RC coupled amplifier. A capacitor provides a path for signal currents between stages, with resistors connected from each side of the capacitor to the power supply or to ground. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 31

5b) Circuit Diagram : G D Substrate S BFW 10 Design : Given V DD = 10V, V GS (off) = -4V I DSS (max) = 12mA R G = 2 M Formulae I D = I DSS.(1 V GS / V GS (off)) 2 -------------------------------------(1) When V G = 0, Then V S = -V GS Applying KVL to output circuit But V S = I D. R S V DD = I D. R D + V DS + I D.R S When V G = 0, I D = I DSS R D = (10 5 4.6 x 10-3 x 330) / 4.6 x 10-3 V S = I DSS.R S R D = 756 I DSS.R S = -V GS (off) Choose R D = 820 R S = -(-4) / 12mA = 333 XCS < < RS Choose R S = 330 XCS = RS / 10 From (1) 1 / ( 2 f CS ) = 470 / 10 Let f = 100 Hz I D = I DSS.(1 I D.R S / V GS (off)) 2 CS = 33 F Choose CS = 47 F I D = I DSS.(1 + I 2 2 D.R S / 16 - I D.R S /2) Choose CC1 = CC2 = 0.1 F I D = 12 x 10-3 x (1 + I 2 D.330 2 / 16 - I D.330 /2) 81.675I 2 D - 2.98I D +12 x 10-3 = 0 I D = 4.6 ma or I D = 31.9 ma Since I D cannot be greater than I DSS, Choose I D = 4.6 ma Assume V DS = 50 % V DD V DS = 5V Dept. of EEE, CIT, Gubbi, Tumkur 572 216 32

Procedure: 1. Components / Equipment are tested for their good working condition. 2. Connections are made as shown in the circuit diagram. 3. By keeping the voltage knobs in minimum position and current knob in maximum position switch on the power supply. 4. By disconnecting the AC source measure the quiescent point (VDS and ID = VRD / RD) 5. Connect the AC source. Keeping the frequency of the AC source in mid band region (say 10 khz) adjust the amplitude to get the distortion less output. Note down the amplitude of the input signal. 6. Keeping the input amplitude constant, Vary the frequency in suitable steps and note down the corresponding output amplitude. 7. Calculate AV and gain in decibels. Plot a graph of frequency Vs gain in db. From the graph calculate f L, f H and band width. 8. Calculate figure of merit. To find the input impedance ( Zi ) : 1. Connections are made as shown in the diagram. 2. Keeping the DRB in its minimum position, apply input signal at mid band frequency (say 10 khz) and adjust the amplitude of the input signal to get distortion less output. Note down the output amplitude. 3. Vary the DRB until the output amplitude becomes half of its previous value. The corresponding DRB value gives the input impedance. To find the output impedance ( Zo ) : 1. Connections are made as shown in the diagram. 2. Keeping the DRB in its maximum position, apply input signal at mid band frequency (say 10 khz) and adjust the amplitude of the input signal to get distortion less output. Note down the output amplitude. 3. Vary the DRB until the output amplitude becomes half of its previous value. The corresponding DRB value gives the output impedance. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 33

Circuit to find input impedance ( Zi ) : Circuit to find output impedance ( Zo ) : Ideal Graph : Gain db 3dB Band width f in Hz f L f H f L = Lower cutoff frequency f H = Higher cutoff frequency Tabular Column: Vi = V Gain in db = 20*log F in Hz Vo in Volt AV = Vo / Vi AV Dept. of EEE, CIT, Gubbi, Tumkur 572 216 34

Result: 1. Quiescent point : VDS = V, ID = ma, VGS = V 2. Voltage Gain ( AV ) = ( in mid band region ) 3. Bandwidth (BW) = Hz 4. figure of merit ( FM = AV * BW ) = Hz 5. Input impedance (Zi) =, Output Impedance (Zo) = Dept. of EEE, CIT, Gubbi, Tumkur 572 216 35

1. 4-BIT BINARY ADDER Example: 7+2=11 (1001) 7 is realized at A3 A2 A1 A0 = 0111 2 is realized at B3 B2 B1 B0 = 0010 Sum = 1001 Procedure: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply augend and addend bits on A and B and cin=0. 5. Verify the results and observe the output of ADDER CIRCUIT Circuit : 2. 4-Bit Binary Subtractor. (i) 4 bit subtraction operation using 7483 for A>B and Cin=1 Example: 8 3 = 5 (0101) 8 is realized at A3 A2 A1 A0 = 1000 3 is realized at B3 B2 B1 B0 through X-OR gates = 0011 Output of X-OR gate is 1 s complement = 1100 2 s Complement can be obtained by adding Cin = 1 Therefore Cin =1 A3 A2 A1 A0 = 1 0 0 0 B3 B2 B1 B0 = 1 1 0 0 S3 S2 S1 S0 = 0 1 0 1 Cout = 1 (Ignored) Dept. of EEE, CIT, Gubbi, Tumkur 572 216 36

Experiment No. : 6 Date: / / Realization of parallel adder/subtractors using 7483 chip- BCD to Excess-3 code conversion & Vice Versa, Binary to Gray code conversion and viceversa 6 a) parallel adder/subtractors using 7483 Aim: To design and set up the following circuit using IC 7483. i) A 4-bit binary parallel adder. ii) A 4-bit binary parallel subtractor. Components Required: IC 7483, IC 7486, Trainer kit, etc Theory: The Full adder can add single-digit binary numbers and carries. The largest sum that can be obtained using a full adder is 112. Parallel adders can add multiple-digit numbers. If full adders are placed in parallel, we can add two- or four-digit numbers or any other size desired. Figure below uses STANDARD SYMBOLS to show a parallel adder capable of adding two, two-digit binary numbers The addend would be on A inputs, and the augend on the B inputs. To add four bits need four full adders arranged in parallel. IC 7483 is a 4- bit parallel adder is used. MSB LSB INPUTS Cin A3 A2 A1 A0 B3 B2 B1 B0 OUTPUT Cout S3 S2 S1 S0 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 37

ii) 4 bit subtraction operation using 7483 for A<B and Cin=1 Example: 14 15 = -1 (1111) 14 is realized at A3 A2 A1 A0 = 1110 15 is realized at B3 B2 B1 B0 through X-OR gates = 1111 Output of X-OR gate is 1 s complement of 15 = 0000 2 s Complement can be obtained by adding Cin = 1 Therefore Cin = 1 A3 A2 A1 A0 = 1 1 1 0 B3 B2 B1 B0 = 0 0 0 0 S3 S2 S1 S0 = 1 1 1 1 since the most significant bit of the result is 1, this is a negative number, so form the two's complement of (1111)=0001(-1) Procedure: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply Minuend and subtrahend bits on A and B and cin=1. 5. Verify the results and observe the outputs. Circuit: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 38

Experiment 6(b): CODE CONVERTERS. Aim: To design and realize the following using IC 7483. (i) Excess-3 to BCD Code conversion and vice-versa (ii) Realization of Binary to Gray code conversion and vice versa Components Required: IC 7483, IC 7486, Patch Cords & IC Trainer Kit. Theory: Code converter is a combinational circuit that translates the input code word into a new corresponding word. The excess-3 code digit is obtained by adding three to the corresponding BCD digit. To Construct a BCD-to-excess-3- code converter with a 4-bit adder feed BCD code to the 4-bit adder as the first operand and then feed constant 3 as the second operand. The output is the corresponding excess-3 code. To make it work as a excess-3 to BCD converter, we feed excess-3 code as the first operand and then feed 2's complement of 3 as the second operand. The output is the BCD code. Excess-3-code to BCD: Truth Table: Excess-3 inputs BCD outputs E3 E2 E1 E0 S3 S2 S1 S0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 1 0 1 0 0 1 0 0 1 1 0 0 0 1 1 0 1 1 1 0 1 0 0 1 0 0 0 0 1 0 1 1 0 0 1 0 1 1 0 1 0 1 0 0 1 1 1 1 0 1 1 1 0 0 0 1 1 0 0 1 0 0 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 39

Procedure: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply Excess-3-code code as first operand (A) and binary 3 as second operand(b) and Cin=1 for realizing Excess-3-code to BCD. Circuit: BCD to Excess-3-code: Truth Table: BCD inputs Excess-3 outputs A3 A2 A1 A0 S3 S2 S1 S0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 1 0 0 1 0 1 0 0 1 1 0 1 1 0 0 1 0 0 0 1 1 1 0 1 0 1 1 0 0 0 0 1 1 0 1 0 0 1 0 1 1 1 1 0 1 0 1 0 0 0 1 0 1 1 1 0 0 1 1 1 0 0 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 40

Procedure: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4 Apply BCD code as first operand(a) and binary 3 as second operand(b) and cin=0 for Realizing BCD-to-Excess-3-code: Circuit : RESULT: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 41

Binary to Gray code Realization using Nand Gates Dept. of EEE, CIT, Gubbi, Tumkur 572 216 42

(ii)binary to Gray code conversion and vice versa Components Required: IC 7486, IC 7400and IC 7408. Theory: Binary to gray code conversion is a very simple process. There are several steps to do this types of conversions. Steps given below elaborate on the idea on this type of conversion. (1) The M.S.B. of the gray code will be exactly equal to the first bit of the given binary number. (2) Now the second bit of the code will be exclusive-or of the first and second bit of the given binary number, i.e if both the bits are same the result will be 0 and if they are different the result will be 1. (3)The third bit of gray code will be equal to the exclusive -or of the second and third bit of the given binary number. Thus the Binary to gray code conversion goes on. One example given below can make your idea clear on this type of conversion. Gray code to binary conversion is again very simple and easy process. Following steps can make your idea clear on this type of conversions. (1) The M.S.B of the binary number will be equal to the M.S.B of the given gray code. (2) Now if the second gray bit is 0 the second binary bit will be same as the previous or the first bit. If the gray bit is 1 the second binary bit will alter. If it was 1 it will be 0 and if it was 0 it will be 1. (3) This step is continued for all the bits to do Gray code to binary conversion. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 43

Karaungh maps: (i)realization using Basic Gates: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 44

Procedure: 1. Verify that the gates are working. 2. Write the proper truth table for the given Binary to Gray /Gray to binary converter 3. Draw Karnaugh maps for each bit of output. Simplify the Karnaugh maps to get simplified Boolean Expressions. 4. Make connections on the trainer kit as shown in the circuit diagram for the Binary to Gray /Gray to Binary converter. 5. Check the outputs for the corresponding inputs. BINARY TO GRAY CONVERSION: Truth Table: Binary inputs Gray outputs B3 B2 B1 B0 G3 G2 G1 G0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 1 0 0 0 1 1 0 0 1 1 0 0 1 0 0 1 0 0 0 1 1 0 0 1 0 1 0 1 1 1 0 1 1 0 0 1 0 1 0 1 1 1 0 1 0 0 1 0 0 0 1 1 0 0 1 0 0 1 1 1 0 1 1 0 1 0 1 1 1 1 1 0 1 1 1 1 1 0 1 1 0 0 1 0 1 0 1 1 0 1 1 0 1 1 1 1 1 0 1 0 0 1 1 1 1 1 1 0 0 0 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 45

GRAY TO BINARY CONVERSION : Truth Table: Gray inputs Binary outputs G3 G2 G1 G0 B3 B2 B1 B0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 1 1 0 0 1 0 0 0 1 0 0 0 1 1 0 1 1 0 0 1 0 0 0 1 1 1 0 1 0 1 0 1 0 1 0 1 1 0 0 1 0 0 0 1 1 1 1 1 0 0 1 0 0 0 1 1 0 1 1 0 0 1 1 1 1 1 1 0 1 0 1 1 1 0 1 0 1 1 1 0 1 0 1 1 0 0 1 0 1 1 1 1 0 1 1 0 0 1 1 1 1 0 1 0 0 0 1 1 1 1 Karnaugh maps: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 46

(i)realization using Basic Gates: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 47

d) Realization using Nand Gates: RESULT: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 48

Experiment No. : 7 Date: / / RC Phase Shift Oscillator Aim: To design and test an RC phase shift oscillator for the given frequency of oscillations. Apparatus Required: Theory: Sl. No. Particulars Range Quantity 1. Transistor SL 100-01 2. Resistors & Capacitors As per design - 3. CRO Probes - 3 Set 4. Multi meter - 01 5. DRB - 01 6. Spring board and connecting wires - - An oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. RC-phase shift oscillator is used generally at low frequencies (Audio frequency). It consists of a CE amplifier as basic amplifier circuit and three identical RC networks for feed back, each section of RC network introduces a phase shift of 60 and the total phase shift by feedback network is 180. The CE amplifier introduces 180 phase shift hence the overall phase shift is 360. The feed back factor for an RC phase shift oscillator is 1/29, hence the gain of amplifier (A) should be 29 to satisfy Barkhausen criteria. The Barkhausen criteria states that in a positive feedback amplifier to obtain sustained oscillations, the overall loop gain must be unity ( 1 ) and the overall phase shift must be 0 or 360. When the power supply is switched on, due to random motion of electrons in passive components like resistor, capacitor a noise voltage of different frequencies will be developed at the collector terminal of transistor, out of these the designed frequency signal is fed back to the amplifier by the feed back network and the process repeats to give suitable oscillation at output terminal Dept. of EEE, CIT, Gubbi, Tumkur 572 216 49

Circuit Diagram : C B 0.1 F 0.1 F E SL100 or CL100 R3 = R-Ri Vo t Design : Given, VCE = 5 V, IC = 2 ma and (Assume = 100) T VCC = 2VCE = 2 X 5 = 10 V Let VRE = 10% VCC = 1 V RE = VRE / ( IC + IB ) IB = IC / = 2mA / 100 = 20 A RE = 1 / ( 2m + 20 ) = 495 Choose RE = 470 fo = 1 / T Hz Apply KVL to collector loop VCC IC RC VCE VE = 0 RC = ( VCC VCE VE ) / IC = ( 10 5 1 ) / 2 m RC = 2 K Choose RC = 1.8 K Let IR1 = 10 IB = 10 X 20 A = 200 A VR2 = VBE + VE = 0.6 + 1 = 1.6 V ( Since transistor is silicon make VBE = 0.6 V ) R2 = VR1 / ( IR1 IB ) = 1.6 / ( 200 A - 20 A ) R2 = 8.8 K Choose R2 = 8.2 K R1 = ( VCC VR2 ) / IR1 = ( 10 1.6 ) / 200 A R1 = 42 K Choose R1 = 47 K Dept. of EEE, CIT, Gubbi, Tumkur 572 216 50

XCE < < RE XCE = RE / 10 1 / ( 2 f CE ) = 470 / 10 Let f = 100 Hz CE = 33 F Choose CE = 47 F Choose CC1 = CC2 = 0.1 F Tank Circuit : Assume fo = 1 khz f o = 1/[(2 x x R x C (6+4k) 0.5 ] where k = R c / R, and R i = R 1 R 2 h ie 4k+23+29/k h fe Assume h fe = β = 100 Therefore 4k+23+29/k = 100 4k 2 +23k+29 = 100 4k 2 77k + 29 = 0 k = 18.865 or 0.385 if k = 18.865, R c / R = 18.865 R is very small. Therefore proper oscillations are not obtained Choosing k = 0.385 R c = 1.8 k R = 4.675 k Choose R = 4.7 k C =1/[2 x x f o x R (6+4 x 0.385) 0.5 ] C = 0.012 µf Choose C = 0.01 µf R i = 8.2K 47K 1.1K R i = 0.9 k R 3 = R R i R 3 = 3.8 k Procedure : 1. Components / equipment are tested for their good working condition. 2. Connections are made as shown in the diagram 3. The quiescent point of the amplifier is verified for the designed value. 4. Observe the output wave form on CRO and measure the frequency. 5. Verify the frequency with the designed value. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 51

Result: Q Point: VCE = V, Ic = ma fo Theoretical = Hz fo Practical = Hz Dept. of EEE, CIT, Gubbi, Tumkur 572 216 52

Experiment No. : 8 Design and testing Ring counter/johnson counter. Date: / / Aim: To design and study the operation of a ring counter and a Johnson Counter. Components required: IC 7495, IC 7404, Patch Cards & IC Trainer Kit. Theory: A ring counter is a circular shift register which is initiated such that only one of its flip-flops is the state one while others are in their zero states. A ring counter is a Shift Register with the output of the last one connected to the input of the first, that is, in a ring. Typically, a pattern consisting of a single bit is circulated so the state repeats every n clock cycles if n flip-flops are used. It can be used as a cycle counter of n states. A Johnson counter (or switchtail ring counter, twisted-ring counter, walking-ring counter, or Moebius counter) is a modified ring counter, where the output from the last stage is inverted and fed back as input to the first stage. The register cycles through a sequence of bit-patterns, whose length is equal to twice the length of the shift register, continuing indefinitely. These counters find specialist applications, including those similar to the decade counter, digital-to-analog conversion, etc. They can be implemented easily using D- or JK-type flip-flops. Procedure: 1. Make the connections as shown in the respective circuit diagram. 2. Apply an initial input (1000) at the A, B, C, D pins respectively. 3. Keep Select Mode = HIGH (1) and apply one clock pulse. 4. Next, Select Mode = LOW (0) to switch to serial mode and apply clock pulses. 5. Observe the output after each clock pulse, record the observations and verify that they match the expected outputs from the truth table. 6. Repeat the same procedure as above for the Johnson Counter circuit and verify its operation Dept. of EEE, CIT, Gubbi, Tumkur 572 216 53

1.Ring Counter: Circuit Truth Table Dept. of EEE, CIT, Gubbi, Tumkur 572 216 54

2.JHONSON COUNTER Truth Table: Circuit: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 55

Experiment No. : 9 Aim : To design and test a crystal oscillator. Crystal Oscillator Date: / / Apparatus Required : Sl. No. Particulars Range Quantity 1. Transistor SL 100, Crystal - 1 each 2. Resistors & Capacitors As per design - 3. CRO Probes - 3 Set 4. Multi meter - 01 5. DCB - 02 6. Spring board and connecting wires - - Theory : An oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them were called "crystal oscillators". Procedure : 1. Components / equipment are tested for their good working condition. 2. Connections are made as shown in the diagram 3. The quiescent point of the amplifier is verified for the designed value. 4. Observe the output wave form on CRO and measure the frequency. 5. Verify the frequency with the crystal frequency. Result: Q Point: VCE = V, Ic = ma fo Crystal = Hz fo Practical = Hz Dept. of EEE, CIT, Gubbi, Tumkur 572 216 56

Design : Given, VCE = 5 V and IC = 2 ma Assume = 100 VCC = 2VCE = 2 X 5 = 10 V Let VRE = 10% VCC = 1 V RE = VRE / ( IC + IB ) IB = IC / = 2mA / 100 = 20 A RE = 1 / ( 2m + 20 ) = 495, Choose RE = 470 Apply KVL to collector loop VCC IC RC VCE VE = 0 RC = ( VCC VCE VE ) / IC = ( 10 5 1 ) / 2 m RC = 2 K Choose RC = 1.8 K Let IR1 = 10 IB = 10 X 20 A = 200 A VR2 = VBE + VE = 0.6 + 1 = 1.6 V ( Since transistor is silicon make VBE = 0.6 V ) R2 = VR1 / ( IR1 IB ) = 1.6 / ( 200 A - 20 A ) = 8.8 K Choose R2 = 8.2 K R1 = ( VCC VR2 ) / IR1 = ( 10 1.6 ) / 200 A = 42 K Choose R1 = 47 K XCE < < RE, XCE = RE / 10 1 / ( 2 f CE ) = 470 / 10 Let f = 100 Hz CE = 33 F Choose CE = 47 F Choose CC1 = CC2 = 0.1 F Dept. of EEE, CIT, Gubbi, Tumkur 572 216 57

Vo C B T t E SL100 or CL100 f o = 1 / T Hz Dept. of EEE, CIT, Gubbi, Tumkur 572 216 58

Experiment No. : 10 Date: / / Design and testing of Sequence generator. Aim: To design and study the operation of a Sequence Generator. Components required: IC 7495, IC 7486, Patch Cards & IC Trainer Kit. Procedure: 1. Truth table is constructed for the given sequence, and Karnaugh maps are drawn in order to obtain a simplified Boolean expression for the circuit. 2. Connections are made as shown in the circuit diagram. 3. Mode M is set to LOW (0), and clock pulses are fed through Clk 1 (pin 9). 4. Clock pulses are applied at CLK 1 and the output values are noted, and checked against the expected values from the truth table. 5.The functioning of the circuit as a sequence generator is verified. Karnaugh Map: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 59

Circuit Truth Table Result: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 60

Experiment No. : 11 Date: / / Class B Push Pull Power Amplifier Aim: To determine the efficiency of class B push pull amplifier and to find the optimum load. Apparatus Required: Sl. No. Particulars Range Quantity 1. Transistor AD149 and 2N3055-1 each 2. Resistors as per design - - 3. Mili ammeter 0-20 ma 01 4. Multimeter - 01 5. CRO Probes - 3 Set 6. Spring Board and Connecting wires - - Theory: To improve the full power efficiency of the Class A type amplifier it is possible to design the amplifier circuit with two transistors in its output stage producing a "push-pull" type amplifier configuration. Push-pull operation uses two "complementary" transistors, one an NPN-type and the other a PNP-type with both power transistors receiving the same input signal together that is equal in magnitude, but in opposite phase to each other. This results in one transistor only amplifying one half or 180 0 of the input waveform while the other transistor amplifies the other half or remaining 180 0 of the waveform with the resulting "two-halves" being put back together at the output terminal. This pushing and pulling of the alternating half cycles by the transistors gives this type of circuit its name but they are more commonly known as Class B Amplifiers The transistor base inputs are in "anti-phase" to each other as shown in circuit diagram, thus if TR1 base goes positive driving the transistor into heavy conduction, its collector current will increase but at the same time the base current of TR2 will go negative further into cut-off and the collector current of this transistor decreases by an equal amount and vice versa. Hence negative halves are amplified by one transistor and positive halves by the other transistor giving this push-pull effect. Unlike the DC condition, these AC currents are ADDITIVE resulting in the two output half-cycles being combined to reform the sine-wave which then appears across the load. Class B Amplifiers have the advantage over Class A amplifier so that no current flows through the transistors when they are in their quiescent state (ie, with no input signal), therefore no power is dissipated in the output transistors when there is no signal present Unlike Class A amplifier stages that require significant base bias thereby dissipating lots of heat - even with no input signal. So the overall conversion efficiency ( η ) of the amplifier is greater than Dept. of EEE, CIT, Gubbi, Tumkur 572 216 61

that of the equivalent Class A with efficiencies reaching as high as 75% possible resulting in nearly all modern types of push-pull amplifiers operated in this Class B mode. While Class B amplifiers have a much high gain than the Class A types, one of the main disadvantages of class B type push-pull amplifiers is that they suffer from an effect known commonly as Crossover Distortion. This occurs during the transition when the transistors are switching over from one to the other as each transistor does not stop or start conducting exactly at the zero crossover point even if they are specially matched pairs. This is because the output transistors require a baseemitter voltage greater than 0.7v for the bipolar transistor to start conducting which results in both transistors being "OFF" at the same time. One way to eliminate this crossover distortion effect would be to bias both the transistors at a point slightly above their cut-off point. This then would give us what is commonly called an Class AB Amplifier circuit. Ideal Graph: % max Optimum load RL in Procedure : 1. Connections are made as shown in circuit diagram 2. Keep RL = 1K, and adjust the amplitude of input signal for distortion less output waveform. 3. RL is varied in convenient steps and corresponding Vo and IC are recorded. 4. Calculate PDC and Pac and calculate efficiency 5. Plot a graph of % versus RL and obtain the optimum load. Result : Maximum efficiency = %, Optimum load, RL opt = Dept. of EEE, CIT, Gubbi, Tumkur 572 216 62

Circuit Diagram : C TR1 0.1 F 1000 F TR2 OC26 E B C 2N3055 / OC26 Vo t Cross over distortion Tabular Column: Vi = V : VCC = V Sl. No. RL in Ic in ma Vo in Volt Pdc = VCC. IC Pac=Vo 2 / 8RL % =Pac / PDC Dept. of EEE, CIT, Gubbi, Tumkur 572 216 63

Experiment No. : 12 Date: / / Realization of 3 bit counters as a sequential circuit and MOD N counter design using 7476,7490, 74192, 74193. Experiment 12(a): ASYNCHRONOUS COUNTERS Aim: To design and test 3-bit binary asynchronous up/down counter using flip-fop IC 7476 for the given sequence. Components required: IC 7476,patch cards,trainer kit etc. Theory: An asynchronous (ripple) counter is a single JK-type flip-flop, with its J (data) input fed from its own inverted output. This circuit can store one bit, and hence can count from zero to one before it overflows (starts over from 0). Notice that this creates a new clock with a 50% duty cycle at exactly half the frequency of the input clock. If this output is then used as the clock signal for a similarly arranged D flip-flop (remembering to invert the output to the input), one will get another 1 bit counter that counts half as fast. Putting them together yields a two-bit counter: We can continue to add additional flip-flops, always inverting the output to its own input, and using the output from the previous flip-flop as the clock signal. The result is called a ripple counter, which can count to 2 n 1 where n is the number of bits (flip-flop stages) in the counter PROCEDURE: 1. Check all the components for their working. 2. Make connections as shown in the circuit diagram. 3. Clock pulses are applied one by one at the clock input and output is observed at QA,QB and QC. 4. Verify the Truth Table and observe the outputs. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 64

1. 3 Bit Asynchronous Up Counter Truth Table: Circuit: Clock QC QB QA 0 0 0 0 1 0 0 1 2 0 1 0 3 0 1 1 4 1 0 0 5 1 0 1 6 1 1 0 7 1 1 1 8 0 0 0 9 0 0 1 Wave Forms: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 65

2. 3 Bit Asynchronous Down Counter Truth Table: Circuit: Clock QC QB QA 0 1 1 1 1 1 1 0 2 1 0 1 3 1 0 0 4 0 1 1 5 0 1 0 6 0 0 1 7 0 0 0 8 1 1 1 9 1 1 0 Wave Forms: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 66

3. Mod 5 Up Counter: Truth Table Waveforms: Clock QC QB QA 0 0 0 0 1 0 0 1 2 0 1 0 3 0 1 1 4 1 0 0 5 0 0 0 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 67

4. Mod 4 Down Counter: Truth Table: Clock QC QB QA Wave forms 0 1 1 1 1 1 1 0 2 1 0 1 3 1 0 0 4 1 1 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 68

Circuit: Waveforms: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 69

Experiment 12(b): SYNCHRONOUS COUNTERS Aim: To design and test a 3 bit synchronous counter using 7476 Components required: IC7476,7408,Patch cards,trainer kit,etc. Theory: In synchronous counters, the clock inputs of all the flip-flops are connected together and are triggered by the input pulses. Thus, all the flipflops change state simultaneously (in parallel). A synchronous binary counter counts from 0 to 2 N -1, where N is the number of bits/flip-flops in the counter. Each flip-flop is used to represent one bit. The flip-flop in the lowest-order position is complemented with every clock pulse and a flip-flop in any other position is complemented on the next clock pulse provided all the bits in the lower-order positions are equal to 1. Procedure: 1. Check all the components for their working. 2. Make connections as shown in the circuit diagram. 3. Clock pulses are applied one by one at the clock input and output is observed at QA,QB and QC. 4. Verify the Truth Table and observe the outputs. Truth Table: Clock QC QB QA 0 0 0 0 1 0 0 1 2 0 1 0 3 0 1 1 4 1 0 0 5 1 0 1 6 1 1 0 7 1 1 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 70

1. MOD 10 Counter: Truth Table: Circuit: Clock QD QC QB QA 0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1 10 0 0 0 0 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 71

Experiment 12(c): DECADE COUNTERS Aim: To rig up Mod N counter using IC 7490. Components required: IC7490,Patch-cords,trainer kit,etc. Procedure: 1. Check all the components for their working. 2. Make connections as shown in the circuit diagram. 3. Clock pulses are applied one by one at the clock input and output is observed at QA,QB,QC and QD 4. Verify the Truth Table and observe the outputs. Vcc QA QB QC QD 5 12 9 8 11 I/p A Clk 14 Mod 2 Mod5 10 1 2 3 6 7 I/p B R1 R2 S1 S2 Wave forms Dept. of EEE, CIT, Gubbi, Tumkur 572 216 72

2. MOD 8 Counter: Truth Table: Circuit: Clock QD QC QB QA 0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 0 0 0 0 Waveforms: RESULT: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 73

Experiment 12(d): PROGRAMMABLE 4 BIT SYNCHRONOUS UP/DOWN COUNTERS Aim: To rig up Mod N Synchronous up/down counter using IC 74193& 74192 Components required: IC74193,7400,7432,74192,Patch cards,trainer kit,etc. Procedure: 1. Check all the components for their working. 2. Make connections as shown in the circuit diagram. 3. The preset value is made available at the data inputs C,B and A. 4. The load pin is made low so that the preset value appear at QA,QB,QC andqd. 5. Connect the output of the gate to the load input. 6. Clock pulses are applied and truth table are verified. 1.Count from 3 to 8: Truth table: Circuit Clk QD QC QB QA 0 0 0 1 1 1 0 1 0 0 2 0 1 0 1 3 0 1 1 0 4 0 1 1 1 5 1 0 0 0 6 0 0 1 1 Dept. of EEE, CIT, Gubbi, Tumkur 572 216 74

2.Count from 12 to 5 Truth table: Clk QD QC QB QA Preset value=12, N=8 Circuit 0 1 1 0 0 1 1 0 1 1 2 1 0 1 0 3 1 0 0 1 4 1 0 0 0 5 0 1 1 1 6 0 1 1 0 7 0 1 0 1 8 1 1 0 0 Result: Dept. of EEE, CIT, Gubbi, Tumkur 572 216 75

References 1. Functional Electronics by K. V. Ramanan, Tata McGraw Hill Publications. 2. Electronic Devices and Circuits by David A. Bell, PHI India Publications, New Delhi 4 th edition 2004. 3. Electronic Devices and Circuit Theory by Robert L. Boylestad and Louis Nashelsky, PHI India Publications, New Delhi 8 th edition 2009. 4. Integrated Electronics by Jacob Millman and Christos C. Halkias, Tata McGraw Hill Publications, 1991 edition. 5. Network Analysis by M. E. Van Valkenburg, PHI India Publications, 3 rd Edition, 1974. 6. Network Analysis by G. K. Mithal, Kanna Publication, 14 th Edition. 7. Modern Physics by Kenneth S. Krane, John Wiley and Sons Publications, 2 nd Edition 1998. 8. Digital Logic Applications and Design, John Yarbrough, Thomson Learning, 2001. 9. Digital Principles and Design, Donald D Givone, Tata McGraw Hill Edition, 2002. 10. Fundamentals of logic design, Charles H Roth, Jr; Thomson Learning, 2004. 11. Logic and computer design Fundamentals, Mono and Kim, Pearson, Second edition, 2001. 12. Logic Design, Sudhakar Samuel, Pearson/Saguine, 2007. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 76

Viva Questions 1. Define rectifier. 2. Compare different type of rectifiers. 3. What are the different types of filters. 4. What are conductors, insulators, and semi-conductors? Give examples. 5..Define gain of the amplifier 6. What are the functions of the three resistances R 1, R 2, R e? 7..What are the functions of the capacitances C E and C C? 8. Which configuration of a transistor is preferred when a transistor is used as a switch and why? 9. What is quiescent point? 10..What is load line? 11. Compare FET with BJT. 12. 1.Explain the function of the tank circuit. 13. What is Barkhausen s criterion and how is it satisfied? 14..How can the frequency of oscillations be altered 15. What are Analog Systems? Give Examples 16. What are Digital Systems? Give Examples 17. State Demorgans Law? 18. Define MINTERM, MAX TERM 19. Which are the basic gates, universal gates 20. Define combinational network with example 21. Define Sequential Network with example 22. Explain the significance of a Don t care function 23. What is a minimal Sum, Minimal product? 24. Define Comparator 25. Define Decoder 26. Define Encoder 27. Define setting and clearing in terms of flip-flop 28. Explain SR Latch 29. Give an application of SR Latch 30. Explain Timing Diagram 31. Explain Propagation Delay in gates Dept. of EEE, CIT, Gubbi, Tumkur 572 216 77

MODEL QUESTIONS 1. a) Design a RC coupled single stage BJT amplifier and determine the Gain-frequency response, input and output impedances. b) Realize and verify the truth table of a full adder and half adder using basic gates and NAND gates only 2. a) Design a RC coupled single stage FET amplifier and determine the Gain-frequency response, input and output impedances. b) Realize and verify the truth table of full and half subtractor using basic gates and NAND gates only 3. a) Design the clipping circuit, which has the following transfer characteristics. b) Conduct a suitable experiment on 7483 IC to realize the following Operation on the given 4 bit data i) Addition ii) 2 s Complement Subtraction 4. a) Design and test the performance of BJT-RC phase shift oscillator for fo = 1kHz. b) Simplify and realize the given Boolean Expression using Basic Logic gates/universal gates and verify the truth table 5. a) Rig up and test Center tap full wave rectifier circuit with and without C filter and determine ripple factor, efficiency and regulation. b) Realize a 3-bit binary asynchronous up counter/down counter using IC 7476 (N<=7) and verify its truth table 6. a) Design the clipping circuits to obtain the following output waveform. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 78

b) Realize using XOR/ NAND gates and verify the truth table of (i) Binary to gray converter (ii) Gray to Binary Converter 7. a) Design and test the performance of a BJT Crystal oscillator. b) Conduct an experiment to convert the given BCD data to excess-3 code/excess-3 to BCD Using minimum number of basic gates 8. a) Design and test clamping circuits to clamp positive peak\ negative peak to reference level b) Design and realize a Ring counter/johnson counter. 9. a) Design and test clipping (series) circuits to pass positive peak above Reference level b) Design and realize a sequence generator for the sequence. 10. a) Rig up and test Bridge rectifier circuit with and without C filter and determine ripple factor, efficiency and regulation b) Realize a Mod N binary synchronous counter using 7476 and verify the truth table 11. a) Rig up and test a class B push pull amplifier and determine its conversion efficiency. b) Realize and verify the truth table of full and half subtractor using basic gates and NAND gates only 12. a) Design and test clipping (shunt) circuit to remove positive peak above Reference level b) Realize a Modulo N counter using 74192/ 74193 with a given preset value and verify its truth table. Dept. of EEE, CIT, Gubbi, Tumkur 572 216 79

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 80

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 81

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 82

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 83

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 84

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 85

Dept. of EEE, CIT, Gubbi, Tumkur 572 216 86