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1 EC010 307 PREPERAED BY DEEPAK P. APPROVED BY HOD 2 INDEX Sl No 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Contents INTRODUCTION INSTRUCTION TO STUDENTS LAB CYCLES FAMILIARIZATION OF EQUIPMENTS DIODES CHARACTERISTICS ZENER DIODES CHARACTERISTICS HALF WAVE RECTIFIERS FULL WAVE RECTIFIERS BDIDGE RECTIFIERS CLIPPERS CLAMPING RC CIRCUITS CHARACTERISTICS OF CE CONFIGURATION CHARACTERISTICS OF CB CONFIGURATION RC COUPLED CE AMPLIFIER ZENER VOLTAGE REGULATOR TRANSISTOR VOLTAGE REGULATOR APPENDIX I (SYMBOLS, VARIABLES) APPENDIX II(RATING OF TRANSISTOR) APPENDIX III(COMPONENT VALUE IDENTIFICATION) Page No 3 4 5 6 12 19 24 29 34 40 53 59 71 77 82 90 94 97 99 101 3 INTRODUCTION “A practical approach is probably the best approach to mastering a subject and gaining a clear insight.” Analog Circuits Practical session covers those practical oriented electronic circuits that are very essential for the students to solidify their theoretical concepts. This workbook provides a communication bridge between the theory and practical world of the electronic circuits. The knowledge of these practical are very essential for the engineering students. All of these practical are arranged on the modern electronic trainer boards. This practical session comprises of two sections. The first section consists of Diode circuits. Some of the very useful diode based circuits are discussed in this section. The second section describes the Bipolar Junction Transistor based circuits. Different configurations of BJT amplifier are discussed in this part of the book. Each and every practical provides a great in depth practical concepts of BJT. 4 INSTRUCTIONS TO THE STUDENTS 1. Write Experiment number , Experiment name, Experiment date in the rough record 2. Keep your rough record/ Fare record neat and clean. 3. Draw circuit diagram neatly with HB pencil in the rough record as per circuit given in the lab manual/available in your laboratory. 4. Wire the circuit using electronic components available in the lab. 5. Write the readings in the observation table in the given format in the lab manual. 6. Draw waveforms in the given space. 7. Prepare for vive based on the experiment that you are going to do in a day. 8. The viva questions are included in the semester hand book as well as lab manual 9. Use text book, reference book or internet to find out answers of the questions. 10. Every student must complete your rough record get sign from the faculty on the same day of your lab or the very next day itself. 11. Fare record must be completed and submitted in the next lab. 12. Keep the work place neat and clean. 5 EC010 307 ANALOG CIRCUITS LAB LAB CYCLES Cycle 1 1. Familiarization of Equipments 2. Characteristics of Ordinary Diodes. 3. Characteristics of Zener diodes. 4. Half wave, Full wave and Bridge Rectifiers. 5. Clipping circuits. 6. Clamping circuits. 7. Frequency responses of RC circuits (RC Low pass and high pass filters, RC Integrating and Differentiating circuits.) Cycle 2 8. Zener Voltage Regulator 9. Characteristics of Transistors (CE & CB). 10. RC Coupled CE amplifier – frequency response characteristics. 11. Transistor Voltage regulator. . 6 EXPERIMENT NO. 1 FAMILIARIZATION OF EQUIPMENTS AIM: To observe sine wave, square wave, triangular wave and ramp waveforms on the C.R.O. and to measure amplitude and frequency of the waveforms. Introduction: a) D.S.O Specification Instek GDS-1052-U 50 MHz Digital Storage Oscilloscope Brand: Instek Model No: GDS-1052-U Our Model No: GDS1052U b) FUNCTION GENERATOR This instrument is basically the frequency generator that can generate signals of different frequency, amplitude and shape. It is known as variable frequency source. 7 1.LED DISPLAY. Displays internal or external frequency. 2. INTERNAUEXTERNAL SWITCH. PUSH IN : External Frequency Counter. PUSH OUT: Internal Frequency Counter. 3. RANGE SWITCHES. Frequency range Selector. 4. FUNCTION SWITCHES. Select Sine wave, Triangle wave or Square wave output. 5. ATTENUATOR. Selects Output Level by -20 dB. 6. GATE TIME INDICATOR. Gate Time Is selected automatically by input signal. 7. FREQUENCY DIAL. Controls Output frequency in selected range. 8. MHz, KHz, Hz, mHz INDICATOR. Indicates unit of frequency. 9. EXTERNAL COUNTER INPUT BNC. Used as an External Frequency Counter. 10. SWEEP RATE CONTROL. On/Off Switch for Internal Sweep Generator, adjusts Sweep rate of Internal Sweep Generator. 11. SWEEP WIDTH CONTROL. Pull out and adjusts Magnitude of Sweep. 12. VCF INPUT BNC. Voltage controlled Frequency Input permits External Sweep. Frequency control sweep rate control should be off when applying External Voltage at this BNC. 13 SYMMETRY CONTROL. Adjust Symmetry of Output Waveform 1:1to 10:1 with Push/Pull Switch On. 14. TTL/CMOS CONTROL. Selects TTL or CMOS mode 15. TTL/CMOS OUTPUT BNC. TTL/CMOS Level Output. 16. DC OFFSET CONTROLS. Adds Positive or Negative DC Component to Output Signal. 17. MAIN OUTPUT BNC. Impedance 50 Ohm. 18. AMPLITUDE CONTROL. Adjusts Output Level from 0 to 20 dB. 19. TILT STAND. Pull Out to adjust tilt. 8 20. POWER SWITCH. Push type switch. turning on the power when pressed. 21. FUSE HOLDER. Replacing fuse with unscrewing 22. AC INLET. For connection of the supplied AC power. Procedure: 1. Connect function generator output at the input of C.R.O. at channel 1 or at channel 2 2. Select proper channel i.e. if signal is connected to channel 1 select CH1 and if signal is connected to channel 2 select CH2 3. Adjust Time /Div knob to get sufficient time period displacement of the wave on the CRO screen. 4. With fine tuning of time/Div make the waveform steady on screen. 5. Use triggering controls if waveform is not stable 6. Keep volt/div knob such that waveform is visible on the screen without clipping 7. Measure P-P reading along y-axis. This reading multiplied with volt/div gives peak to peak amplitude of the ac i/p wave. 8. Measure horizontal division of one complete cycle. This division multiplied by time/div gives time period of the i/p wave. 9. Calculate frequency using formula f = 1/T. 10. Note down your readings in the observation table 11. Draw waveforms of sine, square, ramp and triangular in the given space. 9 Usually these are the shapes of the signal that can be generated using Function Generator. WORKSHEET Observation Table Draw observed waveforms: Sine wave: (Amplitude : ________ Frequency: _____________ ) 10 Square wave: (Amplitude : ________ Frequency: _____________ ) Triangular wave: (Amplitude : ________ Frequency: _____________ ) Ramp: ((Amplitude : ________ Frequency: _____________ ) 11 Conclusion: Result The DSO, Function Generator familiarization was done and the wave forms are noted. 12 EXPERIMENT NO. 2 DIODE CHARACTERISTICS. AIM: To obtain V-I characteristics of PN junction diode. Introduction: The semiconductor diode is formed by doping P-type impurity in one side and N-type of impurity in another side of the semiconductor crystal forming a p-n junction as shown in the following figure. At the junction initially free charge carriers from both side recombine forming negatively charged ions in P side of junction(an atom in P-side accept electron and becomes negatively charged ion) and positively charged ion on n side(an atom in n-side accepts hole i.e. donates electron and becomes positively charged ion)region. This region deplete of any type of free charge carrier is called as depletion region. Further recombination of free carrier on both side is prevented because of the depletion voltage generated due to charge carriers kept at distance by depletion (acts as a sort of insulation) layer as shown dotted in the above figure. 13 Working principle: When voltage is not applied across the diode, depletion region forms as shown in the above figure. When the voltage is applied between the two terminals of the diode (anode and cathode) two possibilities arises depending on polarity of DC supply. [1] Forward-Bias Condition: When the +Ve terminal of the battery is connected to P-type material & -Ve terminal to N-type terminal as shown in the circuit diagram, the diode is said to be forward biased. The application of forward bias voltage will force electrons in N-type and holes in P-type material to recombine with the ions near boundary and to flow crossing junction. This reduces width of depletion region. This further will result in increase in majority carriers flow across the junction. If forward bias is further increased in magnitude the depletion region width will continue to decrease, resulting in exponential rise in current as shown in ideal diode characteristic curve. [2]Reverse-biased: If the negative terminal of battery (DC power supply) is connected with Ptype terminal of diode and +Ve terminal of battery connected to N type then diode is said to be reverse biased. In this condition the free charge carriers (i.e. electrons in N-type and holes in Ptype) will move away from junction widening depletion region width. The minority carriers (i.e. –ve electrons in p-type and +ve holes in n-type) can cross the depletion region resulting in minority carrier current flow called as reverse saturation current(Is). As no of minority carrier is very small so the magnitude of Is is few microamperes. Ideally current in reverse bias is zero. In short, current flows through diode in forward bias and does not flow through diode in reverse bias. Diode can pass current only in one direction. 14 Diode Characteristics Expressed as a Resistance Experiment Procedure: 1. Connect the power supply, voltmeter, current meter with the diode as shown in the figure for forward bias diode. You can use two multi meter (one to measure current through diode and other to measure voltage across diode) 2. Increase voltage from the power supply from 0V to 20V in step as shown in the observation table 3. Measure voltage across diode and current through diode. Note down readings in the observation table. 4. Reverse DC power supply polarity for reverse bias 5. Repeat the above procedure for the different values of supply voltage for reverse bias 6. Draw VI characteristics for forward bias and reverse bias in one graph 15 Circuit diagram (forward bias) Circuit diagram (reverse bias) 16 WORKSHEET Observation table: (Forward bias) Observation table: (Reverse bias) 17 Draw V-I characteristics of PN junction diode: Forward bias Reverse bias Conclusion: Current through Silicon based diode starts increasingly exponentially when potential across diode is approximately milli volts (Cut-in Voltage). 18 A germanium diode requires a lower voltage due to its higher atomic number, which makes it more unstable. Silicon is used far more extensively than germanium in solid state devices because of its stability. Important Viva Questions 1. List important specifications of the diode 2. What is breakdown voltage? What is the breakdown voltage of diode 1N4001 and 1N4007? 3. What is the highest forward current in the diode 1N4007? 4. List different types of the diode 5. List applications of the diode? 6. How to check diode with help of multimeter? 7. What is the reason for reverse saturation current ? 8. What is the forward voltage drop of silicon diode and germanium diode? Result: The diode characteristics were done and the wave forms are noted. The characteristics curves are plotted. 19 EXPERIMENT NO. 3 CHARACTERISTICS OF ZENER DIODES. AIM: To obtain V-I characteristics of Zener diode. Introduction: The Zener diode is designed to operate in reverse breakdown region. Zener diode is used for voltage regulation purpose. Zener diodes are designed for specific reverse breakdown voltage called Zener breakdown voltage (VZ). The value of VZ depends on amount of doping. Breakdown current is limited by power dissipation capacity of the zener diode. If power capacity of the Zener is 1 W and Zener voltage is 10V, highest reverse current is 0.1A or 100 mA. If current increases more than this limit, diode will be damaged. Forward characteristics of the Zener diode is similar to normal PN junction diode. Experiment Procedure: 1. Connect the power supply, voltmeter, current meter with the diode as shown in the figure for reverse bias. You can use two multimeter (one to measure current through diode and other to measure voltage across diode) 2. Increase voltage from the power supply from 0V to 20V in step as shown in the observation table 3. Measure voltage across diode and current through diode. Note down readings in the observation table. 4. Reverse DC power supply polarity for forward bias 5. Repeat the above procedure for the different values of supply voltage for reverse bias 6. Draw VI characteristics for reverse bias and forward bias in one graph 20 Circuit diagram (reverse bias) Circuit diagram (forward bias): Model Graph 21 WORKSHEET Observation table: (Reverse bias) Observation table: (Forward bias) 22 Draw V-I characteristics of Zener diode: Conclusion: Important Viva Questions 1. What is the breakdown voltage of Zener diode used in your practical? What is the power capacity. What is the maximum current that you can pass through it? 2. Can we operate normal PN junction diode in breakdown region for longer duration? Give reason 3. What is the specialty of Zener diode so as we can operate it in breakdown region for longer duration 4. What is the difference between Zener breakdown and Avalanche breakdown? 5. Draw Zener regulator circuit to obtain regulated DC voltage 6.8 V. Considering input DC voltage in the range from 10V to 30V. Consider load resistance of 10KΩ. 6. Determine maximum and minimum value of Zener current if value of series resistance is 1 K, load resistance is 2K and input varies from 10V to 30V. Zener voltage is 5 V. 23 7. Draw output waveform in the circuit of question 5, if we apply AC wave of 10V at the input. Result The Zener diode characteristics were done and the wave forms are noted. The characteristics curves are plotted. 24 EXPERIMENT NO. 4 I. HALF WAVE RECTIFIER AIM: To observe waveform at the output of half wave rectifier with and without filter capacitor and to measure DC voltage, DC current, ripple factor with and without filter capacitor Introduction: One of the very important applications of diode is in DC power supply as a rectifier to convert AC into DC. DC Power supply is the important element of any electronic equipment. This is because it provides power to energize all electronic circuits like oscillators, amplifiers and so on. In electronic equipments, D.C. power supply is must. For example, we can’t think of television, computer, radio, telephone, mobile as well as measuring instruments like CRO, multi-meter etc. without DC power supply. The reliability and performance of the electronic system proper design of power supply is necessary. The first block of DC power supply is rectifier. Rectifier may be defined as an electronic device used to convert ac voltage or current into unidirectional voltage or current. Essentially rectifier needs unidirectional device. Diode has unidirectional property hence suitable for rectifier. Rectifier broadly divided into two categories: Half wave rectifier and full wave rectifier. In this experiment, you will construct half wave rectifier. Working principle of half wave rectifier: In half wave rectifier only half cycle of applied AC voltage is used. Another half cycle of AC voltage (negative cycle) is not used. Only one diode is used which conducts during positive cycle. The circuit diagram of half wave rectifier without capacitor is shown in the following figure. During positive half cycle of the input voltage anode of the diode is positive compared with the cathode. Diode is in forward bias and current passes through the diode and positive cycle develops across the load resistance RL. During negative half cycle of input voltage, anode is negative with respected to cathode and diode is in reverse bias. No current passes through the diode hence output voltage is zero. 25 Half wave rectifier without filter capacitor convert AC voltage into pulsating DC voltage. Filter capacitor is used to obtain smooth DC voltage. Construct following circuit to perform this practical. Practical Circuit diagram: List of components: 1. Transformer Input : 230V AC, output : 12V AC, 500 mA 2. Diode 1N4007 3. Resistor 10K 4. Capacitor 1000μF 5. Toggle Switch Experiment Procedure: 1. Construct circuit on the bread board. 2. Keep toggle switch OFF to perform practical of half wave rectifier without filter capacitor and ON to connect filter capacitor. 26 WORKSHEET Waveforms: Without filter capacitor: Input Waveform at secondary of transformer Output waveform: 27 With filter capacitor: Input Waveform at secondary of transformer: Output waveform: 28 Observations: Without filter capacitor 1. AC Input voltage (rms) Vrms= ___________ 2. DC output voltage VDC = ___________ 3. DC current: IDC =______________ 4. AC output voltage (Ripple voltage) Vr: __________ 5. Ripple factor: (Vr/VDC) = ______________ With filter capacitor 1. AC Input voltage (rms) Vrms= ___________ 2. DC output voltage VDC = ___________ 3. DC current: IDC =______________ 4. AC output voltage (Ripple voltage) Vr: __________ 5. Ripple factor: (Vr/VDC) = ______________ Conclusion: Important Viva Questions 1. Define ripple factor 2. What is the effect of load resistance on ripple voltage in presence of filter capacitor? 3. What is the effect of value of filter capacitor on ripple voltage? 4. What is the PIV necessary for the diode if transformer of 24V is used ? 5. What is the mathematical relationship between rms input AC voltage and DC output voltage in half wave rectifier with and without filter capacitor? Result The Half wave rectifier circuit was done and the wave forms with and without filter capacitor are noted. The DC voltage, DC current, ripple factor with and without filter capacitor is noted. 29 EXPERIMENT NO. 5 II. FULL WAVE RECTIFIER AIM: To observe waveform at the output of full wave rectifier with and without filter capacitor. To measure DC voltage, DC current, ripple factor with and without filter capacitor. Introduction: Full wave rectifier utilizes both the cycle of input AC voltage. Two or four diodes are used in full wave rectifier. If full wave rectifier is designed using four diodes it is known as full wave bridge rectifier. Full wave rectifier using two diodes without capacitor is shown in the following figure. Center tapped transformer is used in this full wave rectifier. During the positive cycle diode D1 conducts and it is available at the output. During negative cycle diode D1 remains OFF but diode D2 is in forward bias hence it conducts and negative cycle is available as a positive cycle at the output as shown in the following figure. Note that direction of current in the load resistance is same during both the cycles hence output is only positive cycles. 30 Advantages of full wave rectifier over half wave rectifier: 1. The rectification efficiency is double than half wave rectifier 2. Ripple factor is less and ripple frequency is double hence easy to filter out. 3. DC output voltage and current is higher hence output power is higher. 4. Better transformer utilization factor 5. There is no DC saturation of core in transformer because the DC currents in two halves of secondary flow in opposite directions. Disadvantages: 1. Requires center tap transformer 2. Requires two diodes compared to one diode in half wave rectifier. Practical Circuit diagram: List of components: 1. Transformer (center tapped) 12-0-12 V AC, 500 mA 2. Diode 1N4007 ---- 2 No. 3. Resistor 10K 4. Capacitor 1000μF 5. Toggle Switch 31 Experiment Procedure: 1. Construct circuit on the general board. 2. Keep toggle switch OFF to perform practical of full wave rectifier without filter capacitor and ON to connect filter capacitor. WORKSHEET Waveforms: Without filter capacitor: Input Waveform at secondary of transformer: Output waveform: 32 With filter capacitor: Input Waveform at secondary of transformer: Output waveform: 33 Observations: Without filter capacitor 1. AC Input voltage (rms) Vrms= ___________ 2. DC output voltage VDC = ___________ 3. DC current: IDC =______________ 4. AC output voltage (Ripple voltage) Vr: __________ 5. Ripple factor: (Vr/VDC) = ______________ With filter capacitor 1. AC Input voltage (rms) Vrms= ___________ 2. DC output voltage VDC = ___________ 3. DC current: IDC =______________ 4. AC output voltage (Ripple voltage) Vr: __________ 5. Ripple factor: (Vr/VDC) = ______________ Conclusion: Important Viva Questions 1. What is the frequency of AC component at the output of full wave rectifier? Give reason. 2. What is the difference in DC output voltage in half wave and full wave rectifier for the same AC input? 3. What is the PIV necessary for the diode if transformer of 24-0-24 V is used ? 4. What is the mathematical relationship between rms input AC voltage and DC output voltage in half wave rectifier with and without filter capacitor? Result The Full wave rectifier circuit was done and the wave forms with and without filter capacitor are noted. The DC voltage, DC current, ripple factor with and without filter capacitor is noted. 34 EXPERIMENT NO. 6 III. BRIDGE RECTIFIER AIM: To observe waveform at the output of bridge rectifier with and without filter capacitor. To measure DC voltage, DC current, ripple factor with and without filter capacitor. Introduction: The Bridge rectifier is a circuit, which converts an ac voltage to dc voltage using both half cycles of the input ac voltage. The Bridge rectifier circuit is shown in the following figure. 35 The circuit has four diodes connected to form a bridge. The ac input voltage is applied to the diagonally opposite ends of the bridge. The load resistance is connected between the other two ends of the bridge. For the positive half cycle of the input ac voltage, diodes D1 and D2 conduct, whereas diodes D3 and D4 remain in the OFF state. The conducting diodes will be in series with the load resistance RL and hence the load current flows through RL. For the negative half cycle of the input ac voltage, diodes D3 and D4 conduct whereas, D1 and D2 remain OFF. The conducting diodes D3 and D4 will be in series with the load resistance RL and hence the current flows through RL in the same direction as in the previous half cycle. Thus a bi-directional wave is converted into a unidirectional wave. The circuit diagram of the bridge rectifier with filter capacitor is shown in the following figure. When capacitor charges during the first cycle, surge current flows because initially capacitor acts like a short circuit. Thus, surge current is very large. If surge current exceeds rated current capacity of the diode it can damage the diode. To limit surge current surge resistance is used in series as shown in the figure. Similar surge resistance can be used in half wave as well as centertapped full wave rectifier also. Bridge rectifier package (combination of four diodes in form of bridge) is easily available in the market for various current capacities ranging from 500 mA to 30A. For laboratory purpose you can use 1A package. 36 Advantages of bridge rectifier: 1. No center tap is required in the transformer secondary hence transformer design is simple. 2. If stepping up and stepping down not required than transformer can be eliminated. (In SMPS used in TV and computer, 230V is directly applied to the input of bridge rectifier). 3. The PIV of the diode is half than in center tap full wave rectifier 4. Transformer utilization factor is higher than in center tapped full wave rectifier 5. Smaller size transformer required for given capacity because transformer is utilized effectively during both AC cycles. Disadvantages of bridge rectifier: 1. Requires Four diodes (But package is low cost) 2. Forward voltage drop across two diodes. This will reduce efficiency particularly when low voltage (less than 5V) is required. 3. Load resistance and supply source have no common point which may be earthed. Practical circuit diagram: List of components: 1. Transformer 12 V AC, 500 mA 2. Diode 1N4007 ---- 4 No. or 1 A bridge rectifier package 3. Resistor 10K [4] Capacitor 1000μF [5] Toggle Switch 37 Experiment Procedure: 1. Construct circuit on the bread board. 2. Keep toggle switch OFF to perform practical of full wave rectifier without filter capacitor and ON to connect filter capacitor. WORKSHEET Waveforms: Without filter capacitor: Input Waveform at secondary of transformer: Output waveform: 38 With filter capacitor: Input Waveform at secondary of transformer: Output waveform: Observations: Without filter capacitor 1. AC Input voltage (rms) Vrms= ___________ 2. DC output voltage VDC = ___________ 3. DC current: IDC =______________ 4. AC output voltage (Ripple voltage) Vr: __________ 5. Ripple factor: (Vr/VDC) = ______________ 39 With filter capacitor 1. AC Input voltage (rms) Vrms= ___________ 2. DC output voltage VDC = ___________ 3. DC current: IDC =______________ 4. AC output voltage (Ripple voltage) Vr: __________ 5. Ripple factor: (Vr/VDC) = ______________ Conclusion: Important Viva Questions 1. What is the mathematical expression for ripple factor. What is the ripple factor of bridge rectifier without filter capacitor? 2. What is the mathematical relationship between rms AC input and DC output from the bridge rectifier with and without filter capacitor? If transformer of 24V is used, what is the DC output voltage with and without filter capacitor? 3. What is the PIV necessary for the diode if transformer of 12-0-12 V is used ? 4. What is the efficiency of full wave bridge rectifier? Result The Bridge rectifier circuit was done and the wave forms with and without filter capacitor are noted. The DC voltage, DC current, ripple factor with and without filter capacitor is noted. 40 EXPERIMENT NO. 7 CLIPPERS AIM: To observe waveforms at the output of various clipper circuits. Introduction: Clipping circuit is used to select for transmission that part of an arbitrary waveform which lies above or below some reference level. Clipping circuit “clips” some portion of the waveform. Clipping circuit is also referred to as voltage limiters. Clamping circuit preserves shape of the waveform while clipping circuit does not preserve shape of waveform. Clipping circuit uses some reference level. Waveform above or below this reference level is clipped. Clipping circuits are also known as voltage limiter or amplitude limiter or slicers. Some clipper circuits are explained here. Positive cycle clipper circuits: Positive cycle clipper circuits are shown in the figure with series and shunt diode. Transfer characteristics and output waveform for sinusoidal input is shown. Circuit Diagram For series 41 For series diode: 1. When vi(t)<0, Diode D is in ON condition, input waveform is available at the output. 2. When vi(t)>0, Diode D is in OFF condition, input waveform is not available at the output and output remains zero. For shunt diode: 1. When vi(t)<0, Diode D is in ON condition which bypass the signal to the ground and hence input waveform is not available at the output. 2. When vi(t)>0, Diode D is in OFF condition and acts like a OFF switch, input waveform is available at the output. For negative cycle clipper, polarity of diode is reverse. Series diode positive clipping with positive reference: In the circuit shown in the following figure, DC reference voltage is used. This is useful of we do not want to clip entire positive cycle but some portion of positive half cycle. When vi(t)<VR, Diode D is in ON condition, input waveform is available at the output. When vi(t)> VR, Diode D is in OFF condition, input waveform is not available at the output and output remains zero. Thus portion of output cycle clips as shown in the waveform. Series diode positive clipping with negative reference: If want to clip entire positive half cycle along with some portion of the negative cycle then negative DC reference can be used as shown in the following figure. In this case only some portion of negative cycle passes to the output. 42 1. When vi(t)<-VR, Diode D is in ON condition, input waveform is available at the output. 2. When vi(t)> -VR, Diode D is in OFF condition, input waveform is not available at the output and output remains constant equal to VR. Thus entire positive cycle and some portion of negative cycle below –VR clips. Series diode negative clipping with reference: Negative clipping can be achieved by changing polarity of the diode. Negative clipper with negative reference voltage is shown in the following figure. This will clip some portion of negative cycle. 1. When vi(t)>-VR, Diode D is in ON condition, input waveform is available at the output. 2. When vi(t)< -VR, Diode D is in OFF condition, input waveform is not available at the output and output voltage remains constant which is equal to –VR. Shunt diode positive clipping with negative reference voltage: Shunt diode positive clipping with negative reference voltage is as shown in the following circuit. This will clip entire positive cycle and some portion of negative cycle as shown in the waveform. 43 1. When vi(t)<-VR, Diode D is in OFF condition (open circuit) and input waveform is available at the output. 2. When vi(t)> -VR, Diode D is in ON condition, input waveform is not available at the output and negative voltage –VR is extended to the output. Output voltage remains constant equal to VR. Thus entire positive cycle and some portion of negative cycle below –VR clips. Shunt diode negative clipping with negative reference: Negative clipping with negative reference voltage can be achieved by reversing polarity of the diode. Some portion of negative cycle clips. 1. When vi(t)>-VR, Diode D is in OFF condition (open circuit) and input waveform is available at the output. 2. When vi(t) < -VR, Diode D is in ON condition, input waveform is not available at the output and negative voltage –VR is extended to the output. Output voltage remains 44 constant equal to VR. Thus entire positive cycle and some portion of negative cycle below –VR clips. List of components: Experiment Procedure: 1. Connect function generator with CRO. Set sine wave with 6V peak to peak. Ensure that offset voltage is 0. 2. Connect the function generator at the input of the clipping circuit 3. Observe output waveforms on the CRO for different clipping circuits and draw output waveforms. WORKSHEET Circuit 1: 45 46 Circuit 2: 47 Circuit 3: 48 Circuit 4: Waveforms: Input Waveform: Output waveform for circuit 1: 49 Output waveform for circuit 2: 50 Output waveform for circuit 3: Output waveform for circuit 4: 51 Conclusion: Important Viva Questions 1. What are the other names for the clippers? 2. Draw output waveform for the following circuits if sinusoidal signal of 6V peak-to-peak with zero offset is applied at the input. Consider reference voltage VR = +2V Consider Zener voltage 2.5V 52 VR = -3V Result The performance of different clipper circuit is observed and their transfer characteristics are obtained. 53 EXPERIMENT NO. 8 CLAMPING AIM: To observe waveforms at the output of clamper circuits Introduction: Diodes are widely used in clipping and clamping circuits. Clamping circuits are used to change DC level (average level) of the signal which adds or subtracts DC value with the signal. In clamping, shape of waveform remains same only offset value (DC level) will change. Positive clamping adds positive DC level in the signal while negative clamping adds negative DC level in the signal. Capacitor is widely used in the clamping circuit. Typical clamping waveforms for the sinusoidal signal is shown below for positive clamping and negative clamping. 54 Clamping circuit is used in video amplifier of television receiver to restore DC level of video signal to preserve overall brightness of the scene. Clamping circuit is also used in offset control of function generator. Zero offset means no DC value is added in the AC signal. Circuit operation: Typical circuit operation of the positive clamping and negative clamping is given below. Positive clamping: Consider that 4V peak to peak signal with zero offset is applied at the input of the clamping circuit. On the first negative half cycle of the input signal, diode D turns ON because anode voltage is greater than cathode voltage. Capacitor charges to the negative peak voltage let us say -2V in our example. The value of R should be high so that it will not discharge the capacitance. After completion of negative cycle, positive cycle starts and diode turns OFF. Capacitance voltage is in series with the input voltage. As per the Kirchoff’s law output voltage will be addition of input voltage and capacitance voltage. Input signal is positive swing of +2V and capacitor voltage is +2V. Thus during the positive peak of the input voltage total output voltage will be +4V. We can consider that during the positive cycle capacitor acts like a battery and adds +2V in the input. Waveforms are drawn here considering ideal diode, no leakage in the capacitance under ideal situations which will be different in practical situations. 55 Negative clamping: In a negative clamping circuit polarity of diode is reverse than in positive clamping. In our signal input swings from -2V to +2V (peak to peak 4V). Diode turns ON during the positive cycle and charge is stored in the capacitor. Capacitor will charge up to +2 V in our example. During the negative cycle this voltage will be in series with the input voltage and gives total output -4V during negative peak of the input signal. List of components: Experiment Procedure: 1. Connect function generator with CRO. Set sine wave with 4V peak to peak. Ensure that offset voltage is 0. 2. Connect the function generator at the input of the clamping circuit 3. Observe output waveforms on the CRO for different clamping circuits and draw output waveforms. 56 WORKSHEET Draw circuit diagrams (as per circuit available in the laboratory or circuit connected on breadboard): Waveforms: Input Waveform: Output waveform for circuit 1: 57 Output waveform for circuit 2: Conclusion: Important Viva Questions 58 Draw output waveform for the following circuits if input of 4V peak-to-peak with zero offset is applied. Result The performance of different clamper circuit is observed and their transfer characteristics are obtained. 59 EXPERIMENT NO. 9 RC CIRCUITS AIM: To obtain the characteristics of RC circuits. THEORY: Electrical devices are controlled by switches which are closed to connect supply to the device, or opened in order to disconnect the supply to the device. The switching operation will change the current and voltage in the device. The purely resistive devices will allow instantaneous change in current and voltage. An inductive device will not allow sudden change in current and capacitance device will not allow sudden change in voltage. Hence when switching operation is performed in inductive and capacitive devices, the current & voltage in device will take a certain time to change from pre switching value to steady state value after switching. This phenomenon is known as transient. The study of switching condition in the circuit is called transient analysis. The state of the circuit from instant of switching to attainment of steady state is called transient state. The time duration from the instant of switching till the steady state is called transient period. The current & voltage of circuit elements during transient period is called transient response. FORMULA: Time constant of RC circuit = RC APPARATUS REQUIRED: 60 PROCEDURE: 1. Connections are made as per the circuit diagram. 2. Before switching ON the power supply the switch S should be in off position 3. Now switch ON the power supply and change the switch to ON position. 4. The voltage is gradually increased and note down the reading of ammeter and voltmeter for each time duration in RC.In RL circuit measure the Ammeter reading. 5. Tabulate the readings and draw the graph of Vc(t)Vs t CIRCUIT DIAGRAM: MODEL GRAPH: Charging 61 Discharging Observation Table Charging: Discharging: 62 The process whereby the form of a non sinusoidal signal is altered by transmission through a linear network is called “linear wave shaping”. An ideal low pass circuit is one that allows all the input frequencies below a frequency called cutoff frequency fc and attenuates all those above this frequency. For practical low pass circuit (Fig.) cutoff is set to occur at a frequency where the gain of the circuit falls by 3 dB from its maximum at very high frequencies the capacitive reactance is very small, so the output is almost equal to the input and hence the gain is equal to 1. Since circuit attenuates low frequency signals and allows high frequency signals with little or no attenuation, it is called a high pass circuit. 63 64 65 66 Sample Readings LPF 67 HPF 68 69 Conclusion: 70 Important Viva Questions Result RC low pass and high pass circuits are designed, frequency response and response at different time constants is observed. 71 EXPERIMENT NO. 10 CHARACTERISTICS OF CE CONFIGURATION AIM: To obtain common emitter characteristics of NPN transistor Introduction: Transistor is three terminal active device having terminals collector, base and emitter. Transistor is widely used in amplifier, oscillator, electronic switch and so many other electronics circuits for variety of applications. To understand operation of the transistor, we use three configurations common emitter, common base and common collector. In this practical, we will understand common emitter configuration. As the name suggest, emitter is common between input and output. Input is applied to base and output is taken from collector. We will obtain input characteristics and output characteristics of common emitter (CE) configuration. We will connect variable DC power supply at VBB and VCC to obtain characteristics. Input voltage in CE configuration is base-emitter voltage Vbe and input current is base current Ib. Output voltage in CE configuration is collector to emitter voltage VCE and output current is collector current Ic. We will use multi-meter to measure these voltages and currents for different characteristics. Collector to emitter junction is reverse biased and base to emitter junction is forward biased. The CE configuration is widely used in amplifier circuits because it provides voltage gain as well as current gain. In CB configuration current gain is less than unity. In CC configuration voltage gain is less than unity. Input resistance of CE 72 configuration is less than CC configuration and more than CB configuration. Output resistance of CE configuration is more than CC configuration and less than CB configuration. WORKSHEET Circuit setup for input characteristics Experiment Procedure: 1. Connect circuit as shown in the circuit diagram for input characteristics 2. Connect variable power supply 0-30V at base circuit and collector circuit. 3. Keep Vcc fix at 0V (Or do not connect Vcc) 4. Increase VBB from 0V to 20V, note down readings of base current Ib and base to emitter voltage Vbe in the observation table. 5. Repeat above procedure for Vcc = +5V and Vcc = +10V 6. Draw input characteristics curve. Plot Vbe on X axis and Ib on Y axis. 73 Observation table Transistor: __________ Input Characteristics 74 Circuit setup for output characteristics Experiment Procedure: 1. Connect circuit as shown in the circuit diagram for output characteristics 2. Connect variable power supply 0-30V at base circuit and collector circuit. 3. Keep base current fix (Initially 0) 4. Increase VCC from 0V to 30V, note down readings of collector current Ic and collector to emitter voltage Vce in the observation table. 5. Repeat above procedure for base currents Ib = 5μA, 50 μA, 100 μA. Increase base current by increasing VBB. 6. Draw output characteristics curve. Plot Vce on X axis and Ic on Y axis. 75 Observation table: Transistor: __________ Output Characteristics 76 Conclusion Important Viva Questions 1. How to check transistor with help of multimeter? 2. How to check type of transistor (NPN or PNP) with help of multimeter? 3. Define current gain of the transistor in CE configuration. What is the DC current gain you obtain in this practical? Result CE Transistor configuration was set up, I/P and O/P characteristics were plotted. 77 EXPERIMENT NO. 11 CHARACTERISTICS OF CB CONFIGURATION AIM: To obtain common base characteristics of NPN transistor Introduction: In a common base configuration, base terminal is common between input and output. The output is taken from collector and the input voltage is applied between emitter and base. The base is grounded because it is common. To obtain output characteristics, we wil l measure collector current for different value of collector to base voltage (VCB). Input current is emitter current Ie and input voltage is Veb. To plot input characteristics we wi ll plot Veb versus Ie . Current gain for CB configuration is less than unity. CB configuration is used in common base amplifier to obtain voltage gain. Output impedance of common base configuration is very high. CB amplifier is used in multi-stage amplifier where impedance matching is required between different stages. Circuit diagram to obtain input characteristics: 78 Circuit diagram to obtain output characteristics WORKSHEET Experiment Procedure to obtain input characteristics: 1. Connect circuit as shown in the circuit diagram for input characteristics 2. Connect variable power supply 0-30V (VEE) at emitter base circuit and another power supply 0-30V at collector base circuit (Vcc). 3. Keep Vcc fix at 0V (Or do not connect Vcc) 4. Increase VEE from 0V to 20V, note down readings of emitter current Ie and emitter to base voltage Veb in the observation table. 5. Repeat above procedure for Vcc = +5V and Vcc = +10V 6. Draw input characteristics curve. Plot Veb on X axis and Ie on Y axis. Experiment Procedure to obtain output characteristics: 1. Connect circuit as shown in the circuit diagram for output characteristics 2. Connect variable power supply 0-30V at emitter circuit and collector circuit. 3. Keep emitter current fix (Initially 0) 79 4. Increase VCC from 0V to 30V, note down readings of collector current Ic and collector to base voltage Vcb in the observation table. 5. Repeat above procedure for base currents Ie = 1mA, 5 mA and 10mA. Increase emitter current by increasing VEE. 6. Draw output characteristics curve. Plot Vcb on X axis and Ic on Y axis. Observation table for input characteristics: Transistor: __________ Input Characteristics 80 Observation table for output characteristics: Transistor: __________ Output Characteristics 81 Conclusion Important Viva Questions 1. What is early effect? Have you observed early effect in your experiment? 2. Compare common base and common emitter configuration 3. Justify the statement: Common base amplifier is used as buffer 4. What is the value of phase shift between input and output signal in common base and common emitter amplifier? Result CB Transistor configuration was set up, I/P and O/P characteristics were plotted. 82 EXPERIMENT NO. 12 RC COUPLED CE AMPLIFIER AIM: To observe input-output waveforms of common emitter (CE) amplifier. To measure gain of amplifier at different frequencies and plot frequency response Introduction: Common emitter amplifier is used to amplify weak signal. It utilizes energy from DC power supply to amplify input AC signal. Biasing of transistor is done to tie Q point at the middle of the load line. In the circuit shown, voltage divider bias is formed using resistors 10K and 2.2K. During positive cycle, forward bias of base-emitter junction increases and base current increases. Q point moves in upward direction on load line and collector current increases β times than base current. (β is current gain). Collector resistor drop Ic*Rc increases due to increase in collector current Ic. This will reduce collector voltage. Thus during positive input cycle, we get negative output cycle. When input is negative cycle, forward bias of base-emitter junction and base current will reduce. Collector current reduces (Q point moves downside). Due to decrease in collector current, collector resistance voltage drop IcRc reduces and collector voltage increases. Change in collector voltage is much higher than applied base voltage because less base current variation causes large collector current variation due to current gain B. This large collector current further multiplied by collector resistance Rc which provides large voltage output. Thus CE amplifier provides voltage gain and amplifies the input signal. Without emitter resistance gain of amplifier is highest but it is not stable. Emitter resistance is used to provide stability. To compensate effect of emitter resistance emitter bypass capacitor is used which provides AC ground to the emitter. This will increase gain of amplifier. CE amplifier does not provide constant voltage gain at all frequencies. Due to emitter bypass and coupling capacitors reduces gain of amplifier at low frequency. Reactance of capacitor is high at low frequency, hence emitter bypass capacitor does not provide perfect AC ground (Emitter impedance is high). There is voltage drop across coupling capacitor at low frequency because of high reactance at low frequencies. Gain of CE amplifier also reduces at very high frequency because of stray capacitances. Audio frequency transistors like AC127, AC128 works for audio frequency range. It does not provide large voltage gain for frequency greater than 20 KHz. 83 Medium frequency transistors are BC147/BC148/BC547/BC548 provides voltage gain up to 500 KHz. High frequency transistors like BF194/BF594/BF200 provides gain at radio frequencies in the MHz range. If we apply large signal at the input of CE amplifier, transistor driven into saturation region during positive peak and cut-off region during negative peak (Q point reaches to saturation and cut-off points). Due to this clipping occurs in amplified signal. So we have to apply small signal at the input and ensure that transistor operates in active region. Circuit diagram 84 Experimental procedure: 1. Connect function generator at the input of the amplifier circuit. 2. Set input voltage 10 mV and frequency 100 Hz. 3. Connect CRO at the output of the amplifier circuit. 4. Observe amplified signal and measure output voltage 5. Increase frequency from the function generator and repeat above step 6. Note down readings of output voltage in the observation table for frequency range from 100 Hz to 10 MHz 7. Calculate voltage gain for different frequencies and gain in dB. Plot frequency response. 85 MODEL GRAPH Observation table Input voltage: Vi = 10 Mv 86 87 Conclusion 1. Design and set up an ampli_er for the speci_cations: gain = -50, output voltage = 10 VPP ; fL = 50 Hz and calculate Zi. 2. Set up an RC coupled ampli_er and measure its input and output impedances Measurement of input resistance Method 1: Connect a known resistor (say 1 k) in series between the signal generator and the input of the circuit. Calculate the current though the resistor from the potential di_erence across it. Since this current also ows into the circuit, input resistance can be measured taking the ratio of the voltage at the right side of the resistor to the current. Method 2: Connect a pot in series between the signal source and the input of the circuit. Adjust the pot until the input voltage to the circuit is 50% of the signal generator voltage. Remove the pot from the circuit and measure its resistance using a multimeter. Measurement of output resistance Method 1: Measure the open circuit output voltage. This is the Thevenin voltage. Output resistance of the circuit is actually the Thevenin resistance in series with the Thevenin voltage. Connect a known value resistor, say 1 k and measure the voltage across it. A reduction in the output voltage can be observed. Calculate the current through the resistor. Since this current also ows trough the Thevenin resistance, output resistance is the ratio of the di_erence in the output voltage to the current. 88 Method 2: Connect a pot at the output of the circuit. Adjust the pot until the voltage across it is 50% of the open circuit voltage. Remove the pot from the circuit and measure its resistance using a multimeter. 3. Differentiate between ac and dc load lines? 4. Explain their importance in ampli_er analysis. 5. Why is the center point of the active region chosen for dc biasing? 6. What happens if extreme portions of the active region are chosen for dc biasing? 7. Draw the output characteristics of the ampli_er and mark the load-line on it. Also mark 8. the three regions of operation on the output characteristics. 9. Which are the di_erent forms of coupling used in multi-stage ampli_ers? Important Viva Questions 1. What will be emitter current in the given circuit diagram in absence of input AC signal? 2. Draw DC load line of CE amplifier circuit. Show Q point on it. 3. Draw output waveform when inverted sine wave is applied at the CE amplifier circuit 4. What is bandwidth? What is the approximate bandwidth of CE amplifier that you have used during your practical. 5. What is the effect on gain of amplifier if value of Rc increases? 6. What are the different biasing methods? 7. What happens if emitter bypass capacitor is removed from the circuit? 89 Result With CE: 1. Mid-band gain of the amplifier =: : : : : : 2. Bandwidth of the amplifier =: : : : : : Hz Without CE: 1. Mid-band gain of the amplifier = : : : : : : 2. Bandwidth of the amplifier = : : : : : :Hz 90 EXPERIMENT NO. 12 ZENER VOLTAGE REGULATOR AIM 1. To study zener diode as voltage regulator 2. To calculate % line regulation 3. To calculate % load regulation APPARATUS Zener diode, Resistors, Power supply, Multi meter CIRCUIT DIAGRAM 91 THEORY Zener diode is a PN junction diode specially designed to operate in the reverse biased mode. It is acting as normal diode while forward biasing. It has a particular voltage known as break down voltage, at which the diode break downs while reverse biased. In the case of normal diodes the diode damages at the break down voltage. But Zener diode is specially designed to operate in the reverse breakdown region. The basic principle of Zener diode is the Zener breakdown. When a diode is heavily doped, it’s depletion region will be narrow. When a high reverse voltage is applied across the junction, there will be very strong electric field at the junction. And the electron hole pair generation takes place. Thus heavy current flows. This is known as Zener break down. So a Zener diode, in a forward biased condition acts as a normal diode. In reverse biased mode, after the break down of junction current through diode increases sharply. But the voltage across it remains constant. This principle is used in voltage regulator using Zener diodes The figure shows the zener voltage regulator, it consists of a current limiting resistor RS connected in series with the input voltage Vs and zener diode is connected in parallel with the load RL in reverse biased condition. The output voltage is always selected with a breakdown voltage Vz of the diode REGULATION WITH A VARYING INPUT VOLTAGE (LINE REGULATION): It is defined as the change in regulated voltage with respect to variation in line voltage. It is denoted by ‘LR’. In this, input voltage varies but load resistance remains constant hence, the load current remains constant. As the input voltage increases, form equation (3) Is also varies accordingly. Therefore, zener current Iz will increase. The extra voltage is dropped across the Rs. 92 Since, increased Iz will still have a constant Vz and Vz is equal to Vout. The output voltage will remain constant. If there is decrease in Vin, Iz decreases as load current remains constant and voltage drop across Rs is reduced. But eve n though Iz may change, Vz remains constant hence, output voltage remains constant. REGULATION WITH THE VARYING LOAD (LOAD REGULATION) It is defined as change in load voltage with respect to variations in load current. To calculate this regulation, input voltage is constant and output voltage varies due to change in the load resistance value. Consider output voltage is increased due to increasing in the load current. The left side of the equation (4) is constant as input voltage Vin, IS and Rs is constant. Then as load current changes, the zener current Iz will also change but in opposite way such that the sum of Iz and IL will remain constant. Thus, the load current increases, the zener current decreases and sum remain constant. Form reverse bias characteristics even Iz changes, Vz remains same hence, and output voltage remains fairly constant. PROCEDURE A) Line Regulation: 1. Make the connections as shown in figure below. 2. Keep load resistance fixed value; vary DC input voltage from 5V to 15V. 3. Note down output voltage as a load voltage with high line voltage ‘VHL’ and as a load voltage with low line voltage ‘VLL’. 4. Using formula, % Line Regulation = (VHL-VLL)/ VNOM x100, where VNOM = the nominal load voltage under the typical operating conditions. For ex. VNOM = 9.5 ± 4.5 V B) Load Regulation: 1. For finding load regulation, make connections as shown in figure below. 93 2. Keep input voltage constant say 10V, vary load resistance value 3. Note down no load voltage ‘VNL’ for maximum load resistance value and full load voltage ‘VFL’ for minimum load resistance value. 4. Calculate load regulation using, % load regulation = (VNL-VFL)/ VFL x100 OBSERVATION TABLE Calculations % Line Regulation = (VHL-VLL) / VNOM x100 = ------------% %voltage regulation = (VNL-VFL)/VFLx100 =----------% Result Line regulation: 1. % of regulation =: : : : : : Load regulation: 1. % of regulation =: : : : : : 94 EXPERIMENT NO. 13 TRANSISTOT VOLTAGE REGULATOR Aim: To study the performance of zener diode regulator with emitter follower output and to plot line regulation and load regulation characteristics. Components and Equipments required: Transistor, zener diode, resistor, rheostat, dc source, voltmeter, ammeter and bread board. Theory The limitations of an ordinary zener diode regulator are, the changes in current owing through the zener diode cause changes in output voltage, the maximum load current that can be supplied is limited and large amount of power is wasted in zener diode and series resistance. These defects are recti_ed in a zener regulator with emitter follower output. It is a circuit that combines a zener regulator and an emitter follower. The dc output voltage of the emitter follower is V0 = VZ + VBE. When input voltage changes, zener voltage remains the same and so does the output voltage. In an ordinary zener regulator, if the load current IL required is in the order of amperes, zener diode should also have the same current handling capacity. But in zener regulator with emitter follower output, current owing through the zener is IL/β. Another advantage of this circuit is low output impedance. The expression for the output voltage can also be expressed as V_ = Vi�VCE. This means that when the input voltage increases, output remains constant by dropping excess voltage across the transistor. The limitation of this circuit is that the output voltage directly depends on the zener voltage. This is rectified in the series voltage regulator with feedback using error amplifier. Procedure 1. Set up the circuit on the bread board after identifying the component leads. 2. Verify the circuit using a multimeter. 3. Note down output voltage by varying the input voltage from 0 V to 30 V in steps of 1 V. 4. Plot line regulation characteristics with Vi along x-axis and V0 along y-axis. 5. Calculate percentage line regulation using the expression ΔV0/ΔVi. 95 6. Keep the input voltage at 15 V and note down output voltage by varying load current from 0 to 500 mA in equal steps using a rheostat. Plot load regulation characteristics with IL along x-axis and V0along y-axis. 7. Measure the full load voltage VFL by adjusting the rheostat until ammeter reads 500 mA. 8. Remove the rheostat and measure the output voltage to get no-load voltage VNL. 9. Mark VNL and VFL on the load regulation characteristics and calculate load regulation as per the equation, VR = (VNL – VFL/VNL)*100%. Circuit Diagram Design Output requirements V0= 8:5 V, IL = 500 mA when input is in the range 15 ±5 V. Selection of transistor Select the power transistor 2N3055. Details of 2N3055: type: Si-NPN. Application: AF Power, Maximum ratings: VCB = 100 V, VCE = 60 V, VEB = 7 V, IC max = 15 A, P = 115 W, Nominal ratings: VCE=4V,IC=4A,hFE=20to70. 96 Selection of Zener diode We know that, VZ = V0+ VBE. Since the required output voltage V0 = 8.5 V, VZ = V0 + 0.6 V = 9.1 V. Select SZ9.1 zener diode. Result The performance of transistor regulator circuit is observed. 97 APPENDIX – I SYMBOLS 98 VARIABLES 99 APPENDIX – II MAXIMUM RATINGS OF COMMONLY USED TRANSISTORS BC107 Specifications: 1. Type : Si – NPN 2. operating point temp : 65o to 200oC 3. IC(max) : 100mA 4. hfe (min) = 110 : 100 5. hfe (max) : 450 6. VCE (max) : 45V 7. Ptot(max) : 300mW 8. Category(typical use) : Audio, low power 9. Possible substitutes :BC182, BC547 100 DIODE 101 APPENDIX – III COMPONENT VALUE IDENTIFICATION RESISTOR VALUE IDENTIFICATION 102 103 STANDARD CAPACITOR VALUES