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LAB MANUAL for zener diode. help ful for ug and pg student
Typology: Lab Reports
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S.NO. NAME OF THE EXPERIMENT Page No.
3(a).
3(b). 3(c).
To study and draw the characteristics of half wave and full wave rectifiers. To study and draw the characteristics of rectifier filter circuit. Study of Clipping & Clamping circuit.
6(a).
6(b).
6(c)
To Study the characteristics of transistor in Common Base configuration. To plot and study the input and output characteristics of BJT in common-emitter configuration. Graphical determination of small signal hybrid parameter of BJT.
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Important note: The most common mistake when using a multimeter is not switching the test leads when switching between current sensing and any other type of sensing (voltage, resistance). It is critical that the test leads be in the proper jacks for the measurement you are making. Safety Information Be sure the test leads and rotary switch are in the correct position for the desired measurement. Never use the meter if the meter or the test leads look damaged. Never measure resistance in a circuit when power is applied. Never touch the probes to a voltage source when a test lead is plugged into the 10 A or 300 mA input jack. To avoid damage or injury, never use the meter on circuits that exceed 4800 watts. Never apply more than the rated voltage between any input jack and earth ground (600 V for the Fluke 73). Be careful when working with voltages above 60 V DC or 30 V AC rms. Such voltages pose a shock hazard. Keep your fingers behind the finger guards on the test probes when making measurements. To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator appears.
A function generator is a device that can produce various patterns of voltage at a variety of frequencies and amplitudes. It is used to test the response of circuits to common input signals. The electrical leads from the device are attached to the ground and signal input terminals of the device under test.
Features and controls Most function generators allow the user to choose the shape of the output from a small number of options.
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A component may be classified as passive or active. The strict physics definition treats passive components as ones that cannot supply energy themselves, whereas a battery would be seen as an active component since it truly acts as a source of energy. Passive components are ones which cannot introduce net energy into the circuit they are connected to. They also cannot rely on a source of power except for what is available from the (AC) circuit they are connected to. As a consequence they are unable to amplify (increase the power of a signal), although they may well increase a voltage or current such as is done by a transformer or resonant circuit. Among passive components are familiar two-terminal components such as resistors, capacitors, inductors, and transformers. Active components rely on a source of energy (usually from the DC circuit, which we have chosen to ignore) and are usually able to inject power into a circuit although this is not part of the definition[1]. This includes amplifying components such as transistors, triode vacuum tubes(valves), and tunnel diodes. Passive components can be further divided into lossless and lossy components: Lossless components do not have a net power flow into or out of the component. This would include ideal capacitors, inductors, transformers, and the (theoretical) gyrator. Lossy or dissipative components do not have that property and generally absorb power from the external circuit over time. The prototypical example is the resistor. In practice all non-ideal passive components are at least a little lossy, but these are typically modeled in circuit analysis as consisting of an ideal lossless component with an attached resistor to account for the loss. Most passive components with more than two terminals can be described in terms of two-port parameters satisfying the principle of reciprocity, although there are some rare exceptions[2]. In contrast, active components (which have more than two terminals) generally lack that property. Note that these distinctions only apply to components listed below which would be modeled as elements within circuit analysis. Practical items which act as transducers or have other connections to the outside world such as switches, cannot be subject to this form of classification since they defy the view of the electronic circuit as a closed system.
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A breadboard is used to build and test circuits quickly before finalizing any circuit design. The breadboard has many holes into which circuit components like ICs and resistors can be inserted. A typical breadboard is shown below:
The bread board has strips of metal which run underneath the board and connect the holes on the top of the board. The metal strips are laid out as shown below. Note that the top and bottom rows of holes are connected horizontally while the remaining holes are connected vertically.
To use the bread board, the legs of components are placed in the holes. Each set of holes connected by a metal strip underneath forms a node. A node is a point in a circuit where two components are connected. Connections between different components are formed by putting their legs in a common node. The long top and bottom row of holes are usually used for power supply connections. The rest of the circuit is built by placing components and connecting them together with jumper wires. ICs are placed in the middle of the board so that half of the legs are on one side of the middle line and half on the other. A completed circuit might look like the following.
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Q: How the frequency of a function generator is controlled? A: By varying the magnitude of current that drives the integrator Q: What is a regulated power supply? A: An electronic circuit which provide constant DC voltage of predetermined value across load terminals, which is independent of variations in load current. Q: What are the basic components of a regulated power supply? A: A transformer, rectifier circuit, filter, voltage regulator Q: What is the need of voltage regulators? A: To keep output voltage constant against variations in load current & in AC mains voltage. Q. what is breadboard? A. A breadboard is used to build and test circuits quickly before finalizing any circuit design. The breadboard has many holes into which circuit components like ICs and resistors can be inserted. Q. What is the difference between active and passive components? A. Passive elements don't require power from the supply to produce its effect on a signal. They derive the power of the input signal to perform its action. for example, a resistor doesn't require a separate supply to provide its action of resistance in a circuit. Where as in active elements there should be a power source for its working. They require a supply for there working. For instance, transistors - Only after biasing the transistor in required region of operation, its characteristics are applied on the signal. i.e, for amplification, transistor requires a source from where it can work in.
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EXPERIMENT NO. 2
Ammeter (0-20mA), Voltmeter (0-20V), Connecting Leads.
diode. It is the combination of P-type & N-type Semiconductor. This offers nearly zero resistance to current on forward biasing & nearly infinite Resistance to the flow of current when in reverse biased.
Forward biasing: When P-type semiconductor is connected to the +ve terminal and N-type to –ve terminal of voltage source. Nearly zero resistance is offered to the flow of current.
Reverse biasing: When P-type semiconductor is connected to the –ve terminal and N-type to +ve terminal. Nearly zero current flow in this condition.
(1) When diode is forward biased (2) When diode is reverse biased
(1) Connect the circuit as shown in fig. (2) Switch on the power supply. (3) Vary the value of input dc supply in steps. (4) Note down the ammeter & voltmeter readings for each step. (5) Plot the graph of Voltage Vs Current. (6) Connect the circuit as shown in fig.
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2
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Q.4 what do you mean by reverse biased? A. When +ve terminal of battery is connected to N side & -ve terminal to P side of diode. Q.5 Define Knee voltage? A. The forward voltage at which current through the junction starts increasing rapidly. Q.6 Define breakdown voltage? A. Reverse voltage at which PN junction breaks down with sudden rise in reverse current. Q.7 Define max. Forward current? A. It is highest instantaneous forward current that a PN junction can conduct without damage to Junction. Q.8 Define max. Power rating? A. Max. Power that can be dissipated at junction without damage to it. Q.9. What is ideal diode? A. Diode have been ideal if it acted as perfect conductor (resistance zero) when forward biased and as a perfect insulator (resistance infinite) when reverse biased. Q10.What are the application of pn diodes? Ans. As rectifiers in dc power supplies, in demodulation or detector circuits.
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EXPERIMENT NO. 3(a)
half-wave rectifier, only one diode is used. During +ve half cycle the diode is forward biased & it conducts current through the load resistor R .During –ve half cycle diode is reverse biased Hence, no current flow through the circuit. Only +ve half cycle appears across the load, whereas, the –ve half cycle is suppressed.
Full Wave Rectifier: In full-wave rectifier, when a.c supplied at the input, both the half cycle current flows through the load in the same direction. The following two circuits are commonly employed. Centre-tap full-wave Rectifier: In this rectifier, two diode & a center-tap transformer is used. During +ve half cycle the diode D1 is forward biased & D2 is reverse biased. Output will be obtained across load resistor R .During –ve half cycle diode D1 is reverse biased &D2 is forward biased. Output will be obtained cross load resistor R & the direction of output is same i.e., DC output is obtained. Bridge Rectifier: The circuit Contains four diodes connected to form a bridge. In this an ordinary transformer is used. During +ve half cycle of secondary voltage, diodes D1 & D3 are forward Biased & diodes D2& D4 are reverse biased & vice versa.
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Q.No. QUESTION ANSWERS
1 Define Full wave rectifier? In both the half cycles current flows through the load in the same direction. 2 Which are different types of Full Wave rectifier?
Different types of full wave rectifier are Centre-Tap full wave rectifier & Bridge rectifier 3 How many no. of diodes are used in full wave rectifier?
4 No. of diodes are used for Bridge rectifier.
4 Give disadvantage of centre-Tap full wave rectifier?
Necessity of transformer with secondary winding.
5 Write ripple factor for FW rectifier? The ripple factor for Full wave rectifier is 0.48.
6 What is the efficiency of FW rectifier?
Efficiency of full wave rectifier is 81.2%
7 Write advantages of bridge rectifier? Suitable for high-voltage applications.
8 Write one feature of Full wave rectifier?
The current drawn in both the primary & secondary of the supply transformer is Sinusoidal.
9 Define Transformer Utilization Factor?
Transformer Utilization Factor (TUF) is the ratio of d.c power to be delivered to the load to the a.c rating of the Transformer secondary.
10 Write value for DC current? DC current is Idc= Im /.
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EXPERIMENT NO. 3(b)
ac components, called ripples along it. It is important to reduce ripples from the pulsating dc supply available from rectifier circuits to the minimum. This is achieved by using a filter circuit which removes the ac components and allows only dc components to reach the load. A filter circuit is a device that converts pulsating output into a steady dc level. A filter circuit is generally a combination of inductors & capacitors. The filtering action of L & C depends upon the facts that an inductor allows dc only & capacitor allows ac only to pass.
(a) Connect the circuit as per the circuit diagram (b) First introduce capacitor filter and note down the waveforms on CRO (c) Then introduce inductor filter and note down the waveforms on CRO
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To CRO
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1
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No
1 What is filter? The device that converts the pulsating output of a rectifier into a steady dc level is known as filter
2 Give commonly used filters? Commonly used filters are Series inductor filter Shunt capacitor filter LC filter filter
3 Define ripple factor? Ripple factor is defined as the ratio of rms value of the ac component to the dc value of the wave.
4 What is dc output voltage given by?
The dc output voltage is given by Vdc =Idc RL
5 When we can use inductor small?
We can use inductor filter when RL is consistently small.
6 What happens when the filter capacitor value larger?
When the filter capacitor value larger, larger will be the peak current in the rectifying diode.
7 What is the value of ripple factor for bridge rectifier?
The value of ripple factor for bridge rectifier is 1.21.
8 What is the ripple factor of power supply measured off?
The ripple factor of a power supply is a measure of purity of power output.
9 What happens when form factor of filter is higher?
Greater the form factor of a filter, higher its ripple factor.
10 What is the value of ripple factor for half wave rectifier?
The value of ripple factor for half wave rectifier is 0.48.
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EXPERIMENT NO. 3(C)
Connecting leads, CRO.
Clipping: The clippers have the ability to remove signal voltages above or below a specified level & hence change the wave shape of the I/P signal. Most of the clippers employ diodes & are known as diode clippers. Different type of clippers are-
Positive & Negative clipper: A circuit that removes +ve half-cycle of the signal is called +ve clipper. Some times, it is required to remove the –ve half cycle of the I/P signal, the only thing to be done is to reverse the polarity of the diode connected across load, such a clipper is known as a –ve clipper. Biased clipper: A clipper used to remove a small portion of +ve or –ve half cycle of the signal Voltage is called a biased clipper. A diode is employed in series with a battery of different volts depending upon the requirement. Combination clipper: In this circuit small portion of +ve as well as small portion of
- ve half- Cycle of the signal voltage is removed.
Clamper: A clamping circuit adds d.c component to the signal in such away that it pushes the signal either on the +ve side or on the –ve side. When the circuit pushes the signal on the +ve side then –ve peak of the signal falls on the zero level, this circuit is called a +ve clamper. When the circuit pushes the signal on the –ve side, this is –ve clamper.
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