CRO AIM:- To study the use of Cathode Ray Oscilloscope (CRO).

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1 1. 1 To study CRO. CRO AIM:- To study the use of Cathode Ray Oscilloscope (CRO). Apparatus: - C.R.O, Connecting probe (BNC cable). Theory:An CRO is easily the most useful instrument available for testing circuits at different points. The best way to investigate any electronic circuit is to monitor or check signal at input and output of each block, if they are correctly linked or not to next stage. The function of CRO is to draws graph of voltage against time (V/t), in that voltage is on vertical or Y-axis and time is on horizontal or X-axis. There are 8 squares or division on the X-axis and 10 squares on the Y-axis. The squares are of 1cm in each direction. FIGURE :-

2 1. To study CRO. Panel Control :Switch No. Switch Use 1 Power On/Off Push button switch to supplying power to instrument. X 10 MAG When pushed, gives 10 times magnification of the X signal. 3 XY 4 CH-1 / CH- Select between channel 1 (when out) and channel (when pressed) 5 Mono/Dual Selects Mono or Dual trace option. 6 ALT/CHOP/ADD 7 EXT. 8 Line 9 ALT 10 +/- 11 AT/NORM 1 Level Controls the trigger level from peak to peak amplitude of signal. 13 Component tester When pressed starts component testing operation. 14 Pilot Lamp When glow indicates power ON position. 15 X-POS Controls horizontal position of the trace. 16 TB-VAR Controls time speed between two steps of Time/Div switch, for calibration put it fully anticlockwise. 17 Trace Sep Separate traces X1 & X10 in 4 trace operation. 18 HOLD Off 19 TRIG. INP Selects alternate or chopped in dual mode and enable for addition or subtraction of channel in mono mode i.e CH-1± CH-. When pressed allows external triggering signal to be fed. When pressed displayed signal is synchronized with mains line frequency. Selects alternate trigger mode from Ch1 and Ch. In this mode both the signals are synchronized. Selects the slope of triggering whether it is positive going or negative going. Controls Hold Off time between sweeps used for stable triggering. To feed external trigger signal in EXT(external) Trigger mode.

3 1. 3 To study CRO. 0 Intens Controls the brightness of trace. 1 TR Controls alignment of the trace with graticule. Focus Controls sharpness of trace. 3 DC/AC/GD Input coupling switch for each channel. 4 CH1(Y) & CH(X) BNC connector serve as input connection for CH1 and CH. 5 Illume For switching ON/Off graticule illumination. 6 CALOUT Socket provided for square wave output 00mv 7 CT To test any component in CT mode, put one test probe in this socket and another to ground. 8 INV CH When pressed invert polarity of CH. 9 Digital Readout LCD window displays Volt/Div and Time/Div. 30 Y Pos I & II Controls Vertical Position of signal. 31 Volts/Div Selects Volt/Div step for CH1. 3 Volts/Div Selects Volt/Div step for CH. 33 NOR/ALT Switch selects Normal or Alternately expanded simulation position. 34 Time/Div Selects Time/Div step for CH1 and CH. Application :1) ) 3) 4) 5) 6) 7) Measurement of magnitude of signal. View different type of signal. Measurement of voltage, time period, frequency of any waveform. To test component. Compare two signal. Measurement of phase difference. To test electronic circuit. PROCEDURE :1) For measurement of Voltage :a) Calculate the number of division covered by the entire height of the waveform.

4 1. 4 To study CRO. b) Check the volt/div setting. c) Now multiply two quantities: number of division covered by signal and reading of Volt/Div. Amplitude = Number of Division X Voil/Div. ) For measurement of Currents :A CRO is basically a voltage indicating device. For measuring current, it is passed through a suitable known resistor. Then the potential development across this resistor is measured and put that value in below equation and the current can be find. I=V/R Where, I= current V= Voltage / potential difference R= Resistance 3) For measurement of frequency :a) b) c) Calculate the number of division in horizontal direction that are covered by the 1 complete cycle of waveform. Observe the reading of Time/Div on the CRO front panel. Multiply both, thus Time period = No. of division X Time/Div Frequency = 1 / Time period 4) For measurement of Phase Difference :a) b) c) d) Put the CRO in dual mode. Apply two signals to CH-1 and CH- respectively and adjust the waveform. Measure the time for one complete cycle of the signal, call it T sec. Measure the time difference between the starting points or any same points of the two signals. Call it t sec. e) Now the phase difference between two signal is, Phase Difference = (360 X t) / T. CONCLUSION :

1 To study FUNCTION GENERATOR Function Generator: Apparatus :- C.R.O, Function Generator, BNC cable. Theory:The Function generator is a device which is used to generate different kind of waveforms.

5 1 To study FUNCTION GENERATOR Function Generator: Apparatus :- C.R.O, Function Generator, BNC cable. Theory:The Function generator is a device which is used to generate different kind of waveforms. These waveforms are used to test different electronic circuit. the function generator is having frequency range from Hz to MHz. It can generate different type of waveforms like Sine wave, Square wave, Saw tooth Wave, Triangle Wave, Pulse Train etc. Figure: Panel Control :Switch No. Switch Use 1 Power On/Off Push button switch to switch ON device. Display 7 Segment LED display to see value of Frequency. 3 Duty Cycle To adjust On/OFF time period of square wave.

6 To study FUNCTION GENERATOR 4 Freq. Vari. Adjust to Vary frequency. 5 Amp. Vari Adjust to vary amplitude of signal. 6 DC offset To remove DC component form AC waveform. 7 Attenuation (40 db/0 db) To attenuate amplitude of signal. 8 FM ext ( max Vp-p ) To apply FM external input. 9 Frequency range 10 Output (50Ω,0Vpp,O.C.) Band selection to generate frequency from Hz to MHz. 11 FM Connect output probe to this knob. Press it to take external FM input. Application :1) ) 3) 4) To generate different frequencies. For modulation of any signal. To provide different waveforms. To test any electronic circuit. PROCEDURE :1) ) 3) 4) 5) 6) 7) Switch ON the power supply. Now select the range of frequency between Hz to 00MHz. To change types of waveform select the type. To change frequency preciously just vary frequency variation probe. To change amplitude of waveform vary amplitude variation button. Also can change the duty cycle of waveform. To change DC level of waveform vary DC offset.

7 3 To study FUNCTION GENERATOR WAVEFORM :- CONCLUSION :-

8 03 1 To test half wave rectifier AIM:- To test half wave rectifier. Apparatus :- Trainer kit, Variable Voltage DC regulated power supply, Digital Multimeter, Connecting probes, CRO. Theory:Rectification means conversion of AC into DC. Diode has characteristics such that it allows current to flow in one direction i.e. only in forward biased condition. AC is a sinusoidal waveform as shown in Figure. Using positive half cycle current increases from zero to peak value and returns to zero according to sine wave properly. During negative half cycle current goes to peak and returns to zero. Half wave rectifier circuit using diode is shown in Figure. During positive half cycle of AC diode is forward biased, so it conducts heavily and current flows through the load resistance. During negative half cycle of AC diode is reverse biased so no current flows through the diode as well as through load resistance. Only a very small leakage current flows through the circuit. Thus output voltage appears only during positive half cycles and waveform of voltage across load resistance is as shown in Figure 3. Peak inverse voltage (PIV) is the maximum voltage across diode reverse bias. PIV is the same as the peak amplitude of the input voltage as shown in Figure 4. PROCEDURE :1) ) 3) 4) Connect the circuit as shown in figure-1. Connect the resistance of known value Measure the voltage and observe waveform with the help of CRO. Draw the waveform across diode, supply voltage and output. CIRCUIT DIAGRAM :-

9 To test half wave rectifier 03 Waveform :- OBSERVATION TABLE :- SR No. V(p-p) Vout (p) PIV = Vm CONCLUSION :-

10 04 1 To test full wave rectifier AIM:- To test full wave rectifier. Apparatus :- Trainer kit, Digital Multimeter, Connecting probes, CRO. Theory:In Full wave rectifier circuit, Center tapped transformer is used and two diodes are connected as shown in Figure 1. During positive half cycle diode D1 conducts and current flows through the load resistance. In this half cycle diode D is reverse biased and the maximum reverse voltage D is the twice of the input peak voltage rating of the diode. During negative half cycle diode D conducts and current flows through the load resistance in the same direction. In this half cycle diode D1 remains reverse biased. Output from rectifier is pulsating DC. Most of the applications require smooth DC. This output contains an AC portion, which is called ripple. Filters are used at output of rectifier to give smooth DC without ripple. A circuit in which capacitive filter is used as shown in Figure 1. During first quarter cycle in which output is increasing, capacitor is charged to peak voltage. Then in second quarter cycle output of rectifier decreases during that time capacitor discharges through the load resistance. But before capacitor voltage discharges to zero, a next half cycle starts which again charges the capacitor. In this way capacitive filter keeps the output voltage almost near to peak voltage by not allowing it to fall to zero value. Thus ripples in rectifier output are filtered out by capacitance filter. Load resistance provides path for capacitor discharge so it is also called bleeding resistance. In capacitor filter circuit diodes do not conduct continuously. When output voltage from transformer becomes larger than capacitor voltage, diode conducts. But most of the times diodes are subjected to reverse voltage. Diodes must handle high peak current during recharging of capacitor for a short period and this current increases with the value of capacitance. As the value of capacitor or bleeding resistance increases ripple is reduced i.e. ripple factor is reduced. It means that load resistance affects the ripple factor. Ripple factor is defined as the ratio of RMS value of AC component present at output to DC voltage level at output. PROCEDURE :1) ) 3) 4) 5) 6) Connect the circuit as shown in figure-1. Connect voltmeter across load resistance. Connect the C for capacitor load. Turn ON the power supply Measure voltage from voltmeter that is VDL and observe the output waveform.. Keep CRO in AC mode, measure the peak to peak voltage.

11 04 To test full wave rectifier CIRCUIT DIAGRAM :- WAVEFORM :-

12 3 To test full wave rectifier 04 OBSERVATION TABLE :SR No. VDL Vp-p CONCLUSION :-

13 05 1 To test full wave rectifier bridge rectifier. AIM:- To test full wave bridge rectifier. Apparatus :- Trainer kit, Digital Multimeter, Connecting probes, CRO. Theory:In Full wave rectifier circuit, Center tapped transformer is used and two diodes are connected as shown in Figure 1. During positive half cycle diode D1 conducts and current flows through the load resistance. In this half cycle diode D is reverse biased and the maximum reverse voltage D is the twice of the input peak voltage rating of the diode. During negative half cycle diode D conducts and current flows through the load resistance in the same direction. In this half cycle diode D1 remains reverse biased. Output from rectifier is pulsating DC. Most of the applications require smooth DC.This output contains an AC portion, which is called ripple. Filters are used at output of rectifier to give smooth DC without ripple. A circuit in which capacitive filter is used as shown in Figure 1. During first quarter cycle in which output is increasing, capacitor is charged to peak voltage. Then in second quarter cycle output of rectifier decreases during that time capacitor discharges through the load resistance. But before capacitor voltage discharges to zero, a next half cycle starts which again charges the capacitor. In this way capacitive filter keeps the output voltage almost near to peak voltage by not allowing it to fall to zero value. Thus ripples in rectifier output are filtered out by capacitance filter. Load resistance provides path for capacitor discharge so it is also called bleeding resistance. In capacitor filter circuit diodes do not conduct continuously. When output voltage from transformer becomes larger than capacitor voltage, diode conducts. But most of the times diodes are subjected to reverse voltage. Diodes must handle high peak current during recharging of capacitor for a short period and this current increases with the value of capacitance. As the value of capacitor or bleeding resistance increases ripple is reduced i.e. ripple factor is reduced. It means that load resistance affects the ripple factor. Ripple factor is defined as the ratio of RMS value of AC component present at output to DC voltage level at output. PROCEDURE :1) ) 3) 4) 5) 6) Connect the circuit as shown in figure-1. Connect voltmeter across load resistance. Connect the C for capacitor load. Turn ON the power supply Measure voltage from voltmeter that is VDL and observe the output waveform.. Keep CRO in AC mode, measure the peak to peak voltage.

14 05 To test full wave rectifier bridge rectifier. CIRCUIT DIAGRAM :- OBSERVATION TABLE :SR No. VDL Vp-p

15 05 3 To test full wave rectifier bridge rectifier. WAVEFORM:- CONCLUSION :-

16 6 1 TO STUDY P-N JUNCTION IN FORWARD BIAS AIM: TO STUDY P-N JUNCTION IN FORWARD BIAS. APPARATUS: Trainer kit, Variable voltage DC regulated power supply, Voltmeter, Milli ammeter, Micro ammeter, connecting probes. THEORY: When diode is connected in such a way that its P terminal is connected with positive terminal of battery and N terminal is connect to negative terminal of battery. Diode is forward bias is shown in fig. in forward bias. Diode allows large current to flow in the circuit and voltage is developed across resistance R1. As supply voltage is increased. Voltage across resistance increases because once diode is turned on. The voltage across diode does not change appreciably. In forward bias the voltage across diode is about 0.3V for germanium diode and 0.7V for a silicon diode. The reminder of the applied voltage appears the resistor connected in series of the diode. Circuit Diagram: PROCEDURE: 1. Note down maximum forward current and peak inverse voltage of the diode given by manufacturer.. Connect the circuit as shown in fig. 3. Increase the supply voltage in small steps and measure the current passing through the circuit as well as voltage across diode. Note down the readings in table. 4. Plot forward current Vs forward voltage.

17 6 TO STUDY P-N JUNCTION IN FORWARD BIAS OBSERVATION TABLE: Sr. No. Forward current Forward voltage Reverse current Reverse voltage V-I characteristic: CONCLUSION:

18 1 Obtain the V-I characteristic of zener diode. 07 AIM: - Obtain the V-I characteristic of zener diode. Apparatus: - Trainer kit, Variable Voltage DC regulated power supply, Digital Multimeter, Connecting probes. Theory:Normal P-N junction diode, in reverse bias carries large amount of current,so large amount of power dissipation occurs that damage the P-N junction diode, so does not used in reverse bias. While Zener diode is highly doped compare to P-N junction diode so it can be used in reverse bias region. Symbol of Zener diode is shown in Figure-1. Characteristic of voltage V/S current of zener diode is shown in figure-. In forward bias zener diode is same as forward characteristic of normal P-N junction diode. When the diode is reverse-biased, a small reverse current is remains relatively constant despite an increase in reverse bias, until the Zener breakdown region, in the vicinity of the Zener voltage Vz, is reached. In this vicinity reverse current starts rising rapidly because of avalanche effect. Finally Zener breakdown occurs when the Zener voltage Vz is reached. Zener breakdown need not result in the destruction of the diode. CIRCUIT DIAGRAM :- If (ma) Vz (v) Vf (v) Iz (ma) Figure. Characteristic of Zener Diode

19 07 Obtain the V-I characteristic of zener diode. PROCEDURE :1) Connect the circuit as shown in figure-3. ) Connect regulated DC power supply of 0-18v. 3) Turn ON the power supply and increase slowly supply voltage and measure and note down zener voltage Vz and zener current Iz. 4) Plot characteristic graph of zener voltage versus zener current. OBSERVATION TABLE :Sr. No Forward Bias Diode Voltage Forward Current 0.1v 0.v 0.3v 0.4v 0.5v 0.6v 0.7v 0.8v 0.9v Reverse Bias Diode Reverse current Voltage 0.5v 1v 1.5v v 3v 4v 5v 6v 7v CONCLUSION :-

20 8 1 To Study Filter AIM: To Study Filter. Apparatus : Trainer kit, CRO, Connecting probes Theory : 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 center-tapped full wave rectifier also. Circuit Diagram: 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. Advantages: No center tap is required in the transformer secondary hence transformer design is simple. If stepping up and stepping down not required than transformer can be eliminated. (In SMPS used in TV and computer, 30V is directly applied to the input of bridge rectifier). The PIV of the diode is half than in center tap full wave rectifier Transformer utilization factor is higher than in center tapped full wave rectifier Smaller size transformer required for given capacity because transformer is utilized effectively during both AC cycles. Disadvantages: Requires Four diodes (But package is low cost) Forward voltage drop across two diodes. This will reduce efficiency particularly when low voltage (less than 5V ) is required. Load resistance and supply source have no common point which may be earthed.

21 8 To Study Filter Waveform: Conclusion:

22 09. 1 TO BUILD AND TEST COLPITTS OSCILLATOR. AIM: TO BUILD AND TEST COLPITTS OSCILLATOR. Apparatus : Oscilloscope, +1V DC Adapter, Patch Cords. Circuit Diagram : Procedure : 1. Connect +1V DC Supply (adapter) to the trainer. Now connect +1V terminal to TP and Gnd to Gnd as shown in figure. 3. Connect terminals 1 and and similarly 4 and Gnd together. 4. Switch On the mains supply. 5. Connect oscilloscope between Vout and Gnd. 6. Measure the value of output frequency on oscilloscope. 7. Calculate the resonance frequency (theoretical) using equation Compare measured frequency with the theoretically calculated value. 9. Switch Off the supply.

23 09. TO BUILD AND TEST COLPITTS OSCILLATOR. Observation Table: SR. NO. Capacitors Ceq. (Equivalent Capacitance) Output frequency (Measured) Output frequency (Theoretical) CONCLUSION:

24 10. 1 TO BUILD AND TEST HARTELY OSCILLATOR. AIM: TO BUILD AND TEST HARTELY OSCILLATOR. APPARATUS: Power Supply. Trainer kit, Connecting probe, CRO. THEORY: Any circuit generates an alternating voltage is called an oscillator. To generate AC voltage, the circuit. is supplied energy from a DC source. Main application of positive feedback is oscillator. If output signal varies sinusoidally, the circuit is referred to as a sinusoidal oscillator. If output voltage rises quickly to one voltage level and later drops quickly to another voltage level, the circuit. is generally referred to as a pulse or square wave oscillator. Consider the feedback circuit, which is shown in the fig. When the switch at the amplifier input is open, no oscillation occurs. Consider that we have a input (Vi). This results in an output voltage Vo = AVi after the amplifier stage and in a voltage Vf = B (AVi) after the feed back stage. Thus, we have a feedback voltage Vf = BAVi where BA is referred to as the loop gain if the circuit of the base amplifier and feedback network provide BA of correct magnitude and phase, Vf can be made equal to Vi. Then when the switch is closed and voltage Vi is removed, the circuit will continue operating since the feedback voltage is sufficient to drive the amplifier and feedback circuit resulting in a proper input voltage to sustain the loop operation. The output waveform will still exist after the switch is closed. We derive the expression for the over all voltage gain of the amp. can be written as Af=A/1-A. It can now be seen that if AB =1, so Af=. The gain becoming infinity means that there is a output without any input. In other words, the amp. Becomes an oscillator. The condition, AB=1 is known as barkhausen critetion of oscillation. As shown in the fig. of Hartley oscillator, two inductors L1 &L are placed across a capacitor C. Frequency is determine by L1,L and C (tank circuit). When the circuit is turned ON, the capacitor is charged. When this capacitor is fully charged it discharges through coils L1 and L.The output voltage of the ampere appears across L1 and feedback voltage across L. The voltage across L is 180 out of phase with the voltage developed across L1. It is easy to see that voltage feedback to the transistor provides positive feedback. A phase shift of 180 is produced by the transistor and the L1-L voltage divider produces further phase shift of 180, in this way feedback is continuous un-damped oscillation. PROCEDURE: 1. Assemble the circuit as shown in the fig.. Connect the CRO at the output terminals and observed the sine wave output. 3. Measure the output frequency on CRO. OBSERVATION TABLE: No. Inductor (L) Capacitor (C1) Capacitor (C) Observed frequency Theoretical frequency

25 10. TO BUILD AND TEST HARTELY OSCILLATOR. Circuit diagram: CONCLUSION:

26 11 1 To understand working of transistor as a switch. AIM: To understand working of transistor as a switch. Introduction: Transistor can be operated in three region: cut-off region, active region and saturation region. While using transistor in amplifier circuit, we are using active region. If transistor operated in cut-off and saturation region in amplifier, clipping of waveforms will occur. When we use transistor as a switch, only two regions cut-off and saturation are used. In saturation region transistor acts as ON switch. In cutoff region, transistor acts as OFF switch. We are using only two points of DC load line while using transistor as a switch. Circuit diagram: Experiment Procedure to obtain input characteristics: Connect circuit as shown in the circuit diagram for input characteristics Adjust collector supply Vcc = +1V and base supply VBB=+5V You may use base voltage supply switch instead of switch shown in the circuit diagram. Measure base current when switch is OFF (It will be zero). Measure collector current and voltage between collector and emitter. LED is off because transistor is in cut-off region, Now apply base voltage +5V, LED will be ON. Measure collector current and collector-emitter voltage. Transistor is in saturation region.

27 11 To understand working of transistor as a switch. Observations: [1] Switch off (VBB=0): Ib = VCE = Ic = [] Switch ON (VBB=+5V): Ib = VCE = Ic = Conclusion:

Dev Bhoomi Institute Of Technology Department of Electronics and Communication Engineering PRACTICAL INSTRUCTION SHEET

Dev Bhoomi Institute Of Technology Department of Electronics and Communication Engineering PRACTICAL INSTRUCTION SHEET LABORATORY MANUAL EXPERIMENT NO. ISSUE NO. : ISSUE DATE: REV. NO. : REV. DATE : PAGE: