st. martin’s engineering college - smec edc...2 electronic devices and circuits lab part a: (only...

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St. MARTIN’S ENGINEERING COLLEGE

DEPT. OF ELECTRONICS &COMMUNICATION ENGINEERING

ELECTRONIC DEVICES AND CIRCUITS LAB

LAB INCHARGE: RAJESHWAR GOUD HOD

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ELECTRONIC DEVICES AND CIRCUITS LAB

PART A: (Only for Viva-voce Examination)

Electronic Workshop Practice (In 3 Lab Sessions):

1. Identification, Specifications, Testing of R, L, C Components (Color Codes), Potentiometers, Switches (SPDT, DPDT, and DIP), Coils, Gang Condensers, Relays, Bread Boards, PCB’s

2. Identification, Specifications and Testing of Active Devices, Diodes, BJT’s, Low power JFET’s, MOSFET’s, Power Transistors, LED’s, LCD’s, SCR, UJT.

3. Study and operation ofi) Multi-meters (Analog and Digital)ii) Function Generatoriii) Regulated Power Suppliesiv) CRO.

PART B: (For Laboratory Examination – Minimum of 10 experiments)

1. Forward & Reverse Bias Characteristics of PN Junction Diode.2. Zener diode characteristics and Zener as voltage Regulator.3. Input & Output Characteristics of Transistor in CB Configuration and h-

parameter calculations.4. Input & Output Characteristics of Transistor in CE Configuration and h-

parameter calculations.5. Half Wave Rectifier with & without filters.6. Full Wave Rectifier with & without filters.7. FET characteristics.8. Design of Self-bias circuit.9. Frequency Response of CC Amplifier.10.Frequency Response of CE Amplifier.11.Frequency Response of Common Source FET amplifier .12.SCR characteristics.13.UJT Characteristics14.Switching Characteristics of Transistor15. UJT as Relaxation Oscillator

PART C: Equipment required for Laboratories:

1. Regulated Power supplies (RPS) - 0-30 V2. CRO’s - 0-20 MHz.3. Function Generators - 0-1 MHz.4. Multimeters5. Decade Resistance Boxes/Rheostats6. Decade Capacitance Boxes7. Ammeters (Analog or Digital) - 0-20 μA, 0-50μA, 0-100μA, 0-

200μA, 0-10 mA.8. Voltmeters (Analog or Digital) - 0-50V, 0-100V, 0-250V9. Electronic Components -Resistors, Capacitors, BJTs, LCDs, SCRs, UJTs, FETs,

LEDs, MOSFETs, Diodes- Ge& Si type, Transistors – NPN, PNP type)

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1. BASIC ELECTRONIC COMPONENTS

1.1. RESISTOR

A Resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. The current through a resistor is in direct proportion to the voltage across the resistor's terminals. This relationship is represented by Ohm's law:

V = RI

Where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms.

The ratio of the voltage applied across a resistor's terminals to the intensity of current in the circuit is called its resistance, and this can be assumed to be a constant (independent of the voltage) for ordinary resistors working within their ratings.

1.2. COLOR CODING OF RESISTOR

Color Codes are used to identify the value of resistor. The numbers to the Colors are identified in the following sequence which is remembered as BBROY GREAT BRITAN VERY GOOD WIFE (BBROYGBVGW) and their assignment is listed in following table.

Black Brown Red Orange Yellow Green Blue Violet Grey White

0 1 2 3 4 5 6 7 8 9

Table 1: Color codes of resistor

Figure 1: Procedure to find the value of Resistor using Colour codesResistor Color Codes: Resistors are devices that limit current flow and provide a

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voltage drop in electrical circuits. Because carbon resistors are physically small, they are color- coded to identify their resistance value in Ohms. The use of color bands on the body of a resistor is the most common system for indicating the value of a resistor. Color-coding is standardized by the Electronic Industries Association (EIA).

Use the Resistor Color Code Chart (above) to understand how to use the color code system. When looking at the chart, note the illustration of three round resistors with numerous color code bands. The first resistor in the chart (with 4 bands) tells you the minimum information you can learn from a resistor. The next (a 5-band code) provides a little more information about the resistor. The third resistor (a 6-band) provides even more information. Each color band is associated with a numerical value.

How to read a typical 4-band, 5-band and 6-band resistor: 4-Band: Reading the resistor from left to right, the first two color bands represent significant digits , the third band represents the decimal multiplier, and the fourth band represents the tolerance. 5- Band: The first three color bands represent significant digits, the fourth band represents the decimal multiplier, and the fifth band represents the tolerance. 6-Band: The first three color bands represent significant digits, the fourth band represents the decimal multiplier, the fifth band represents the tolerance, and the sixth band represents the temperature coefficient.

Definitions of color bands: The color of the multiplier band represents multiples of 10, or the placement of the decimal point. For example: ORANGE (3) represents 10 to the third power or 1,000. The tolerance indicates, in a percentage, how much a resistor can vary above or below its value. A gold band stands for +/- 5%, a silver band stands for +/- 10%, and if there is no fourth band it is assumed to be +/- 20%. For example: A 100-Ohm 5% resistor can vary from 95 to 105 Ohms and still be considered within the manufactured tolerance. The temperature coefficient band specifies the maximum change in resistance with change in temperature, measured in parts per million per degree Centigrade (ppm/°C).

Example (from chart): Lets look at the first resistor on the chart. In this case, the first color band is BROWN. Following the line down the chart you can see that BROWN represents the number 1. This becomes our first significant digit. Next, look at the second band and you will see it is BLACK. Once again, follow the line down to the bar scale; it holds a value of 0, our second significant digit. Next, look at the third band, the multiplier, and you will see it is ORANGE. Once again, follow the line down to the bar scale; it holds a value of 3. This represents 3 multiples of 10 or 1000. With this information, the resistance is determined by taking the first two digits, 1 and 0 (10) and multiplying by 1,000. Example: 10 X 1000 = 10,000 or 10,000 Ohms. Using the chart, the fourth band (GOLD), indicates that this resistor has a tolerance of +/- 5%. Thus, the permissible range is: 10,000 X .05 = +/- 500 Ohms, or 9,500 to 10,500 Ohms.

1.3. TYPES OF RESISTORS

1. Carbon Resistors

2. Wire wound Resistors

Carbon Resistors

There are many types of resistors, both fixed and variable. The most common type

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for electronics use is the carbon resistor. They are made in different physical sizes with power dissipation limits commonly from 1 watt down to 1/8 watt. The resistance value and tolerance can be determined from the standard resistor color code.

A variation on the color code is used for precision resistors which may have five colored bands. In that case the first three bands indicate the first three digits of the resistance value and the fourth band indicates the number of zeros. In the five band code the fifth band is gold for 1% resistors and silver for 2%.

Figure 2: Images of Carbon Resistors

Wire Wound Resistors

Wire wound resistors are commonly made by winding a metal wire, usually nichrome, around a ceramic, plastic, or fiberglass core. The ends of the wire are soldered or welded to two caps or rings, attached to the ends of the core. The assembly is protected with a layer of paint, molded plastic, or an enamel coating baked at high temperature. Because of the very high surface temperature these resistors can withstand temperatures of up to +450 °C.[6] Wire leads in low power wire wound resistors are usually between 0.6 and 0.8 mm in diameter and tinned for ease of soldering. For higher power wire wound resistors, either a ceramic outer case or an aluminum outer case on top of an insulating layer is used. The aluminum-cased types are designed to be attached to a heat sink to dissipate the heat; the rated power is dependent on being used with a suitable heat sink, e.g., a 50 W power rated resistor will overheat at a fraction of the power dissipation if not used with a heat sink. Large wire wound resistors may be rated for 1,000 watts or more.Because wire wound resistors are coils they have more undesirable inductance than other types of resistor, although winding the wire in sections with alternately reversed direction can minimize inductance. Other techniques employ bifilar winding, or a flat thin former (to reduce cross-section area of the coil). For the most demanding circuits, resistors with Ayrton-Perry winding are used.

Applications of wire wound resistors are similar to those of composition resistors with the exception of the high frequency. The high frequency response of wire wound resistors is substantially worse than that of a composition resistor.

Figure 3: Images of Carbon Resistors

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1.4. CAPACITOR

A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electro statically in an electric field. By contrast, batteries store energy via chemical reactions. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator); for example, one common construction consists of metal foils separated by a thin layer of insulating film. Capacitors are widely used as parts of electrical circuits in many common electrical devices.

When there is a potential difference (voltage) across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value, capacitance. This is the ratio of the electric charge on each conductor to the potential difference between them. The SI unit ofcapacitance is the farad, which is equal to one coulomb per volt.

Figure 4: Electrolytic capacitors of different voltages and capacitance

Figure 5: Solid-body, resin-dipped 10 μF 35 V Tantalum capacitors.

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Table 2: Common capacitor specifications and trade offs

1.5. COLOUR CODING OF CAPACITORS

In general, a capacitor consists of two metal plates insulated from each other by a dielectric. The capacitance of a capacitor depends primarily upon its shape and size and upon the relative permittivity εr of the medium between the plates. In vacuum, in air, and in most gases, εr ranges from one to several hundred.

One classification of capacitors comes from the physical state of their dielectrics, which may be gas (or vacuum), liquid, solid, or a combination of these. Each of these classifications may be subdivided according to the specific dielectric used. Capacitors may be further classified by their ability to be used in alternating-current (ac) or direct- current (dc) circuits with various current levels.

Capacitor Identification Codes: There are no international agreements in place to standardize capacitor identification. Most plastic film types (Figure1) have printed values and are normally in microfarads or if the symbol is n, nanofarads. Working voltage is easily identified. Tolerances are upper case letters: M = 20%, K = 10%, J = 5%, H = 2.5% and F = ± 1pF.

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Figure 6: Plastic Film Types

A more difficult scheme is shown in Figure 2 where K is used for indicating Picofarads. The unit is picofarads and the third number is a multiplier. A capacitor coded 474K63 means 47 × 10000 pF which is equivalent to 470000 pF or 0.47 microfarads. K indicates 10% tolerance. 50, 63 and 100 are working volts.

Figure 7: Pico Farads Representation

Ceramic disk capacitors have many marking schemes. Capacitance, tolerance, working voltage and temperature coefficient may be found. Capacitance values are given as number without any identification as to units. (uF, nF, pF) Whole numbers usually indicate pF and decimal numbers such as 0.1 or 0.47 are microfarads. Odd looking numbers such as 473 is the previously explained system and means 47 nF.

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Figure 8: Ceramic Disk capacitor

Figure 9: Miscellaneous Capacitors

Electrolytic capacitor properties:

There are a number of parameters of importance beyond the basic capacitance and capacitive reactance when using electrolytic capacitors. When designing circuits using electrolytic capacitors it is necessary to take these additional parameters into consideration for some designs, and to be aware of them when using electrolyticcapacitors.

ESR Equivalent series resistance:

Electrolytic capacitors are often used in circuits where current levels are relatively high. Also under some circumstances and current sourced from them needs to have low source impedance, for example when the capacitor is being used in a power supply circuit as a reservoir capacitor. Under these conditions it is necessary to consult the manufacturers‟ datasheets to discover whether the electrolytic capacitor chosen will meet the requirements for the circuit. If the ESR is high, then it will not be able to deliver the required amount of current in the circuit, without a voltage drop resulting from the ESR which will be seen as a source resistance.

Frequency response:

One of the problems with electrolytic capacitors is that they have a limited frequency response. It is found that their ESR rises with frequency and this

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generally limits their use to frequencies below about 100 kHz. This is particularly true for large capacitors, and even the smaller electrolytic capacitors should not be relied upon at high frequencies. To gain exact details it is necessary to consult the manufacturer’s data for a given part.

Leakage:

Although electrolytic capacitors have much higher levels of capacitance for a given volume than most other capacitor technologies, they can also have a higher level of leakage. This is not a problem for most applications, such as when they are used in power supplies. However under some circumstances they are not suitable. For example they should not be used around the input circuitry of an operational amplifier. Here even a small amount of leakage can cause problems because of the high input impedance levels of the op-amp. It is also worth noting that the levels of leakage are considerably higher in the reverse direction.

Ripple current:

When using electrolytic capacitors in high current applications such as the reservoir capacitor of a power supply, it is necessary to consider the ripple current it is likely to experience. Capacitors have a maximum ripple current they can supply. Above this they can become too hot which will reduce their life. In extreme cases it can cause the capacitor to fail. Accordingly it is necessary to calculate the expected ripple current and check that it is within the manufacturer’s maximum ratings.

Tolerance:

Electrolytic capacitors have a very wide tolerance. Typically this may be -50% + 100%. This is not normally a problem in applications such as decoupling or power supply smoothing, etc. However they should not be used in circuits where the exact value is of importance.

Polarization:

Unlike many other types of capacitor, electrolytic capacitors are polarized and must be connected within a circuit so that they only see a voltage across them in a particular way.

The physical appearance of electrolytic capacitor is as shown in Figure 5.The capacitors themselves are marked so that polarity can easily be seen. In addition to this it is common for the can of the capacitor to be connected to the negative terminal.

Electrolytic Capacitor

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It is absolutely necessary to ensure that any electrolytic capacitors are connected within a circuit with the correct polarity. A reverse bias voltage will cause the centre oxide layer forming the dielectric to be destroyed as a result of electrochemical reduction. If this occurs a short circuit will appear and excessive current can cause the capacitor to become very hot. If this occurs the component may leak the electrolyte, but under some circumstances they can explode. As this is not uncommon, it is very wise to take precautions and ensure the capacitor is fitted correctly, especially in applications where high current capability exists.

1.6. COLOUR CODING OF INDUCTORS

Inductor is just coil wound which provides more reactance for high frequencies and low reactance for low frequencies. Molded inductors follow the same scheme except the units are usually micro henries. A brown-black-red inductor is most likely a 1000 uH. Sometimes a silver or gold band is used as a decimal point. So a red-gold-violet inductor would be a 2.7 uH. Also expect to see a wide silver or gold band before the first value band and a thin tolerance band at the end. The typical Colour codes and their values are shown in Figure 6.

1000uH (1millihenry), 2% 6.8 uH, 5%

Figure 11: Typical inductors Color coding and their values.

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CIRCUIT DIAGRAM:

RESISTORS:

-fixed resistor

-variable resistor

CAPACITORS:

fixed capacitor

variable capacitor

INDUCTORS:

-Fixed inductor

Variable inductorTRANSFORMERS:

Primary secondary

SWITCHES:

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SEMICONDUCTORS:

P-N Junction diode

Zener diode

BREAD BOARD

An experimental version of a circuit generally lay out on a flat board and

assembled with temporary connections so that circuit elements may be easily

substituted or changed. The name originates from the fact that early electrical

circuits were actually wired on wood bread boards.

SOLDERING PRACTICE- SIMPLE CIRCUITS USING ACTIVE AND PASSIVE COMPONENTS

Soldering is a process for joining metal parts with the aid of molten metal, where

the melting temperature is situated below that of material joined and where by the

surface of part are coated without turn in becoming molten.

A soldering connection ensures metal continuity on the other hand, when two metals

are joined , behave like a single solid metal by joining disconnected. (or) physically

attaching to each other, the connection could be

Types of soldering:

1. Iron soldering

2.Mass soldering

3.Dip soldering

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4.Wave soldering

Solder alloys:

Tin lead, Tin antimony, Tin lead antimony, Tn silver, Tin Zinc.

Soldering is an alloying process between two metals with which it divides some of

the metal, with which it comes into contact. A flux is used to remove this oxide from

the area to be soldered.

Soldering of solder alloy:

Even though the alloy Sb 60/pb 60 is cheaper and still finds a good market, it is

advisable to prefer Sn63/pb 37 for high quality inter connection because

It has a5c higher melting point which means soldering range is 5c higher. The

tensile strength as well as shoal strength of Sn60/pb 37

Is higher in comparison to Sn 60/pb 40.

Only tin trans the inter molecular bond with copper of CU3Sn andCU6SN. The specific

gravity of Sn63/ pb 37 is also lesser than that of Sn60/ pb 40.

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STUDY AND OPERATION OF MULTIMETERS, FUNCTION GENERATOR, REGULATED POWER SUPPLIES

AIM: To study and operation of multi-meters, function generator, and regulated power supply.

APPARATUS: Multi-meter

Function generator

Regulated power supply.

THEORY:

REGULATED POWER SUPPLY

Power supplies provided by a regulated DC voltage facilities fine and

coarse adjustments and monitoring facilities for voltage and current. They will work

in constant voltage and current mode depending on current limit and output load.

The current limit has good stability, load and line regulations. Outputs are

protected against overload and short circuit damages. They are available in single

and dual channel models with different voltage and current capacities. Overload

protection circuit of constant self restoring type is provided to prevent the unit as

well as the circuit under use.

The power supplies are specially designed and developed for well regulated DC

output.

These are useful for high regulation laboratory power supplies, particularly

suitable for experimental setup and circuit development in R&D.

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FUNCTION GENERATOR

Wave form : Sine, squares, triangles, TTL square waves

Amplitude : 0-20V for all the functions.

Sine distortion : Less than 1% from 0.1 HZ to 100 HZ harmonics

Modulation showed down fundamental for 100K

HZ to 1MHG.

Offset : Continuously variable 10V

Frequency range : 0.1 HZ to 1Μhz in ranges.

Output impedance : 600 ohms, 5%.

Square wave duty cycle : 49% to 51%.

Differential linearity : 0.5%

Range selectors: Decode frequency by multiplying the range selected with the

frequency indicated by dial gives the output frequency, which applies for all

functions.

Function selectors: Selected desired output wave form which appears at 600T output.

VCO input: An external input will vary the output frequency. The change in

frequency is directly proportional to input voltage.

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TTL output: A TTL square wave is available at this jack. The frequency is determined

by the range selected and the setting of frequency dial. This output is independent of

amplitude and D.C OFFSET controls.

Amplitude control: Control he amplitude of the output signal, which appears at

600ohms. OFFSET control: Control the DC offset of the output. It is continuously

variable for ±5V, ±100V.

Fine frequency dial: Multiplying the setting of this dial to the frequency range

selected gives the output frequency of the wave forms at the 600ohms.

MULTIMETER:

DIGITAL MULTIMETER

A multi-meter is a versatile instrument and is also called Volt-Ohm-Milli

ammeter (VOM). It is used to measure the d.c and a.c voltages and resistance

values.

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A digital multi-meter essentially consists of an analog to digital converters. It

converts analog values in the input to an equivalent binary forms. These values

are processed by digital circuits to be shown on the visual display with decimal

values. The liquid crystal display system is generally employed. Actually all the

functions in DMM depend on the voltage measurements by the converter and

comparator circuits

Result: The operation of multi-meters, function generator, and Regulated Power

Supply are studied

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STUDY OF CRO

An oscilloscope is a test instrument which allows us to look at the 'shape' of electrical signals by displaying a graph of voltage against time on its screen. It is like a voltmeter with the valuable extra function of showing how the voltage varies with time. A graticule with a 1cm grid enables us to take measurements of voltage and time from the screen.

The graph, usually called the trace, is drawn by a beam of electrons striking the phosphor coating of the screen making it emit light, usually green or blue. This is similar to the way a television picture is produced.

Oscilloscopes contain a vacuum tube with a cathode (negative electrode) at one end to emit electrons and an anode (positive electrode) to accelerate them so they move rapidly down the tube to the screen. This arrangement is called an electron gun. The tube also contains electrodes to deflect the electron beam up/down and left/right.

The electrons are called cathode rays because they are emitted by the cathode and this gives the oscilloscope its full name of cathode ray oscilloscope or CRO.

A dual trace oscilloscope can display two traces on the screen, allowing us to easily compare the input and output of an amplifier for example. It is well worth paying the modest extra cost to have this facility.

Figure 1: Front Panel of CRO

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BASIC OPERATION:

Setting up an oscilloscope:

Oscilloscopes are complex instruments with many controls and they require some care to set up and use successfully. It is quite easy to 'lose' the trace off the screen if controls are set wrongly.

There is some variation in the arrangement and labeling of the many controls. So, the following instructions may be adapted for this instrument.

1. Switch on the oscilloscope to warm up (it takes a minute or two).2. Do not connect the input lead at this stage.3. Set the AC/GND/DC switch (by the Y INPUT) to DC.4. Set the SWP/X-Y switch to SWP (sweep).5. Set Trigger Level to AUTO.6. Set Trigger Source to INT (internal, the y input).7. Set the Y AMPLIFIER to 5V/cm (a moderate value).8. Set the TIMEBASE to 10ms/cm (a moderate speed).9. Turn the time base VARIABLE control to 1 or CAL.10. Adjust Y SHIFT (up/down) and X SHIFT (left/right) to give a trace across the middle of the screen, like the picture.11. Adjust INTENSITY (brightness) and FOCUS to give a bright, sharp trace.

The following type of trace is observed on CRO after setting up, when there is no input signal connected.

Figure 3: Absence of input signal

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Connecting an oscilloscope:

The Y INPUT lead to an oscilloscope should be a co-axial lead and the figure 4 shows its construction. The central wire carries the signal and the screen is connected to earth (0V) to shield the signal from electrical interference (usually called noise).

Most oscilloscopes have a BNC socket for the y input and the lead is connected with a push and twist action, to disconnect we need to twist and pull. Professionals use a specially designed lead and probes kit for best results with high frequency signals and when testing high resistance circuits, but this is not essential for simpler work at audio frequencies (up to 20 kHz).

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Figure 5: Oscilloscope lead and probes kit

Obtaining a clear and stable trace:

Once if we connect the oscilloscope to the circuit, it is necessary to adjust the controls to obtain a clear and stable trace on the screen in order to test it.

The Y AMPLIFIER (VOLTS/CM) control determines the height of the trace. Choose a setting so the trace occupies at least half the screen height, but does not disappear off the screen. The TIMEBASE (TIME/CM) control determines the rate at which the dot sweeps across the screen. Choose a setting so the trace shows at least one cycle of the signal across the screen. Note that a steady DC input signal gives a horizontal line trace for which the time base setting is not critical. The TRIGGER control is usually best left set to AUTO.

The trace of an AC signal with the oscilloscope controls correctly set is as shown in Figure 6.

Figure 6: Stable waveform

Measuring voltage and time period

The trace on an oscilloscope screen is a graph of voltage against time. The shape of this graph is determined by the nature of the input signal. In addition to the properties labeled on the graph, there is frequency which is the number of cycles per second. The diagram shows a sine wave but these properties apply to any signal with a constant shape

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Figure 7: Properties of Trace

Amplitude is the maximum voltage reached by the signal. It is measured in volts.

Peak voltage is another name for amplitude. Peak-peak voltage is twice the peak voltage (amplitude). When reading an

oscilloscope trace it is usual to measure peak-peak voltage. Time period is the time taken for the signal to complete one cycle. It is

measured in seconds (s), but time periods tend to be short so milliseconds (ms) and microseconds (µs) are often used. 1ms = 0.001s and 1µs = 0.000001s.

Frequency is the number of cycles per second. It is measured in hertz (Hz), but frequencies tend to be high so kilohertz (kHz) and megahertz (MHz) are often used. 1kHz = 1000Hz and 1MHz = 1000000Hz.

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EXPERIMENT –1: FORWARD AND REVERSE BIAS CHARACTERISTICS OF PN JUNCTION DIODE

1.1 OBJECTIVE:- To observe and draw the Forward and Reverse bias V-I Characteristics of a P-N Junction diode.

1.2 RESOURCES:-

P-N Diode IN4007.

Regulated Power supply (0-30v)

Resistor 1KΩ

Ammeters (0-200 mA)(0-200uA)

Voltmeter (0-20 V)

Bread board

Connecting wires

1.3 THEORY:-

A p-n junction diode conducts only in one direction. The V-I

characteristics of the diode are curve between voltage across the diode and

current through the diode. When external voltage is zero, circuit is open and the

potential barrier does not allow the current to flow. Therefore, the circuit current

is zero. When P-type (Anode is connected to +ve terminal and n- type (cathode)

is connected to –ve terminal of the supply voltage, is known as forward bias. The

potential barrier is reduced when diode is in the forward biased condition. At

some forward voltage, the potential barrier altogether eliminated and current

starts flowing through the diode and also in the circuit. The diode is said to be in

ON state. The current increases with increasing forward voltage.

When N-type (cathode) is connected to +ve terminal and P-type (Anode) is

connected to –ve terminal of the supply voltage is known as reverse bias and the

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potential barrier across the junction increases. Therefore, the junction resistance

becomes very high and a very small current (reverse saturation current) flows in

the circuit. The diode is said to be in OFF state. The reverse bias current due to

minority charge carriers.

1.4 CIRCUIT DIAGRAM:-

FORWARD BIAS:-

REVERSE BIAS:-

1KΩ

1KΩ

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1.5 MODEL WAVEFORM:-

1.6 PROCEDURE:-

1.6.1 FORWARD BIAS:-

1. Connections are made as per the circuit diagram.

2. For forward bias, the RPS +ve is connected to the anode of the diode and

RPS –ve is connected to the cathode of the diode,

3. Switch on the power supply and increases the input voltage (supply voltage) in Steps.

4. Note down the corresponding current flowing through the diode and voltage across the diode for each and every step of the input voltage.

5. The reading of voltage and current are tabulated.

6. Graph is plotted between voltage and current.

1.6.2 OBSERVATION:-

S.NO APPLIED VOLTAGE (V) VOLTAGE ACROSS CURRENT

DIODE(V) THROUGH

DIODE(mA)

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1.6.3 REVERSE IAS:-

1. Connections are made as per the circuit diagram

2. For reverse bias, the RPS +ve is connected to the cathode of the diode and RPS –ve is connected to the anode of the diode.

3. Switch on the power supply and increase the input voltage (supply voltage) in Steps

4. Note down the corresponding current flowing through the diode voltage across the diode for each and every step of the input voltage.

5. The readings of voltage and current are tabulated

6. Graph is plotted between voltage and current.

1.6.4 OBSEVATION:-

S.NO APPLIEDVOLTAGE VOLTAGE CURRENT

ACROSSDIODE(V) ACROSS THROUGH

DIODE(V) DIODE(mA)

1.7 PRECAUTIONS:-

1. All the connections should be correct.

2. Parallax error should be avoided while taking the readings from the Analog meters.

1.8 RESULT:- Forward and Reverse Bias characteristics for a p-n diode is

Observed

1.9 PRE EXPERIMENT QUESTIONS:-

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1. Define depletion region of a diode?

2. What is meant by transition & space charge capacitance of a diode?

3. Is the V-I relationship of a diode Linear or Exponential?

4. Define cut-in voltage of a diode and specify the values for Si and Ge diodes?

5. What are the applications of a p-n diode?

1.10 ASSIGNMENT QUESTIONS:-

1. Find the cut-in voltage for Ge diode? 2. Obtain V-I characteristics of BY127 diode?

1.11 POST EXPERIMENT QUESTIONS:

1. Draw the ideal characteristics of P-N junction diode?

2. What is the diode equation?

3. What is PIV?

4. What is the break down voltage?

5. What is the effect of temperature on PN junction diodes?

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EXPERIMENT –2: ZENER DIODE CHARACTERISTICS AND ZENER DIODE AS A VOLTAGE REGULATOR

2.1 OBJECTIVE :- a) To observe and draw the static characteristics of a zener diodeb) To find the voltage regulation of a given zener diode

2.2 RESOURCES:-

Zener diode.-FZ5V1 DIODE

Regulated Power Supply (0-30v).

Voltmeter (0-20v)

Ammeter (0-100mA)

Resistor (1KOhm)

Bread Board

Connecting wires


STATIC CHARACTERISTICS:-

REGULATION CHARACTERISTICS:-

1KΩ

1KΩ

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2.4 Theory:-A zener diode is heavily doped p-n junction diode, specially made to

operate in the break down region. A p-n junction diode normally does not conduct when

reverse biased. But if the reverse bias is increased, at a particular voltage it starts

conducting heavily. This voltage is called Break down Voltage. High current through the

diode can permanently damage the device

To avoid high current, we connect a resistor in series with zener diode.

Once the diode starts conducting it maintains almost constant voltage across the

terminals what ever may be the current through it, i.e., it has very low dynamic

resistance. It is used in voltage regulators.

2.5PROCEDURE:-

Static characteristics:-


2. The Regulated power supply voltage is increased in steps.

3. The zener current (lz), and the zener voltage (Vz.) are observed and then noted in the tabular form.

4. A graph is plotted between zener current (Iz) and zener voltage (Vz).

Regulation characteristics:-

1. Connection are made as per the circuit diagram

2. The load is placed in full load condition and the zener voltage (Vz), Zener current (lz), load current (IL) are measured.

3. The above step is repeated by decreasing the value of the load in steps.

4. All the readings are tabulated.

5. The percentage regulation is calculated using the above formula

31

2.6 OBSERVATIONS:-

Static characteristics:-ZENER ZENER

S.NO VOLTAGE(VZ) CURRENT(IZ)

Regulation characteristics:-

Load Regulations: VS = Constant

S.No RL(KΩ) VZ(V) IZ(mA) IL(mA)

Line Regulations: RL = Constant

S.No VS(V) VZ(V) IZ(mA) IL(mA)

32

2.7 MODEL WAVEFORMS:-

LINE REGULATIONS:

LOAD REGULATION:

33

2.8 PRECAUTIONS:-

1. The terminals of the zener diode should be properly identified

2. While determined the load regulation, load should not be immediately shorted.

3. Should be ensured that the applied voltages & currents do not exceed the ratings of the diode.

2.9 RESULT:-

a) Static characteristics of zener diode are obtained and drawn.

b) Percentage regulation of zener diode is calculated.


1. What type of temp? Coefficient does the zener diode have?

2. If the impurity concentration is increased, how the depletion width effected?

3. Does the dynamic impendence of a zener diode vary?

4. Explain briefly about avalanche and zener breakdowns?

5. Draw the zener equivalent circuit?

2.11 ASSIGNMENT QUESTIONS:

1. Find the breakdown voltage for 3.9v Zener diode?

2. Obtain 3.9v Zener diode acts as Voltage Regulator?


1. Differentiate between line regulation & load regulation?

2. In which region zener diode can be used as a regulator?

3. How the breakdown voltage of a particular diode can be controlled?

4. What type of temperature coefficient does the Avalanche breakdown has?

5. By what type of charge carriers the current flows in zener and avalanche breakdown diodes?

34

EXPERIMENT –3: INPUT & OUTPUT CHARACTERISTICS OF TRANSISTOR IN CB CONGIGURATION AND H-PARAMETER CALCULATION

3.1 OBJECTIVE:- 1. To observe and draw the input and output characteristics of a transistor

connected in common base configuration.

2. To find α of the given transistor.

3.2 RESOURCES:-Transistor, BC 107

Regulated power supply (0-30V)

Voltmeter (0-20V)

Ammeters (0-100mA)

Resistor, 1kΩ, 1kΩ

Bread board

Connecting wires

3.3 THEORY:

A transistor is a three terminal active device. T he terminals are emitter, base, collector. In CB configuration, the base is common to both input (emitter) and output (collector). For normal operation, the E-B junction is forward biased and C-B junction is reverse biased.

In CB configuration, IE is +ve, IC is –ve and IB is –ve.

So,VEB=f1 (VCB,IE) and

IC=f2 (VCB,IB)

With an increasing the reverse collector voltage, the space-charge width at the

output junction increases and the effective base width ‘W’ decreases. This

phenomenon is known as “Early effect”. Then, there will be less chance for

recombination within the base region. With increase of charge gradient with in the

base region, the current of minority carriers injected across the emitter junction

increases. The current amplification factor of CB configuration is given by,

α= ∆IC/ ∆IE

35

3.4 CIRCUIT DIAGRAM

3.5 PROCEDURE:

INPUT CHARACTERISTICS:


2. For plotting the input characteristics, the output voltage VCE is kept constant at 0V and for different values of VEB note down the values of IE.

3. Repeat the above step keeping VCB at 2V, 4V, and 6V.All the readings are tabulated.

4. A graph is drawn between VEB and IE for constant VCB.

OUTPUT CHARACTERISTICS:

1. Connections are made as per the circuit diagram. 2. For plotting the output characteristics, the input IE iskept constant at 10m A and

for different values of VCB, note down the values of IC.

3. Repeat the above step for the values of IE at 20 mA, 40 mA, and 60 mA, all the readings are tabulated.

4. A graph is drawn between VCB and Ic for constant IE

1KΩ 1KΩ

36

3.6 OBSERVATIONS:


S.No VCB=0V VCB=5V VCB=10V

VEB(V) IE(mA) VEB(V) IE(mA) VEB(V) IE(mA)

OUTPUT CHARACTERISTICS:

IE=2mAIE=5mA IE=10m

A

S.No

VCB(V) IC(mA) VCB(V) IC(mA) VCB(V) IC(mA)

37

3.7 MODEL GRAPHS:

INPUT CHARACTERISTICS

OUTPUT CHARACTERISTICS

38

H -PARAMETERS:-

1. Input Impedance hib = ΔVbe / ΔIe at Vcb constant2. Output admittence hob = ΔIc / ΔVcb at Ie constant3. Reverse Transfer Voltage Gain hre = ΔVbe / ΔVcb at Ie constant 4. Forward Transfer Current Gain hfb = ΔIc / ΔIe at constant Vcb

3.8 PRECAUTIONS:

1. The supply voltages should not exceed the rating of the transistor.

2. Meters should be connected properly according to their polarities.

3.9 RESULT:

1. The input and output characteristics of the transistor are drawn.2. The α of the given transistor is calculated.


1. What is the range of α for the transistor?

2. Draw the input and output characteristics of the transistor in CB configuration?

3. Identify various regions in output characteristics?

4. What is the relation between α and β?

5. What are the applications of CB configuration?


1. Find the input & output characteristics of 2N2222 NPN Transistor?2. Find the input & output characteristics of BC640 PNP Transistor?


1. What are the input and output impedances of CB configuration?

2. Define α(alpha)?

3. What is EARLY effect?

4. Draw diagram of CB configuration for PNP transistor?

5. What is the power gain of CB configuration?

39

EXPERIMENT –4: INPUT & OUTPUT CHARACTERISTICS OF TRANSISTOR IN CE CONGIGURATION AND H-PARAMETER

CALCULATION

4.1 OBJECTIVE:-

1. To draw the input and output characteristics of transistor connected inCE configuration.

2. To find β of the given transistor.

4.2 RESOURCES:-

Transistor (BC 107)

R.P.S (O-30V) 2Nos

Voltmeters (0-20V) 2Nos

Ammeters (0-200µA)

(0-500mA)

Resistors 1K, 47k

Bread board

4.3 THEORY:A transistor is a three terminal device. The terminals are emitter, base,

collector. In common emitter configuration, input voltage is applied between base and

emitter terminals and output is taken across the collector and emitter terminals.

Therefore the emitter terminal is common to both input and output.

The input characteristics resemble that of a forward biased diode curve.

This is expected since the Base-Emitter junction of the transistor is forward biased. As

compared to CB arrangement IB increases less rapidly with VBE . Therefore input

resistance of CE circuit is higher than that of CB circuit

The output characteristics are drawn between Ic and VCE at constant IB. the

collector current varies with VCE unto few volts only. After this the collector current

becomes almost constant, and independent of VCE. The value of VCE up to which the

collector current changes with V CE is known as Knee voltage. The transistor always

operated in the region above Knee voltage, IC is always constant and is approximately

equal to IB.

The current amplification factor of CE configuration is given by Β = IC/IB

40

4.4CIRCUIT DIAGRAM:

4.5 PROCEDURE:

INPUT CHARECTERSTICS:

1. Connect the circuit as per the circuit diagram. 2. For plotting the input characteristics the output voltage VCE is kept constant at 1V

and for different values of VBE . Note down the values of IC

3. Repeat the above step by keeping VCE at 2V and 4V.

4. Tabulate all the readings. 5. plot the graph between VBE and IB for constant VCE

OUTPUT CHARACTERSTICS:

1. Connect the circuit as per the circuit diagram

2.for plotting the output characteristics the input current IB is kept constant

at 10µA and for different values of VCE note down the values of IC

3. repeat the above step by keeping IB at 75 µA 100 µA

4. tabulate the all the readings 5. plot the graph between VCE and IC for constant IB

41

4.6 OBSERVATIONS:


VCE = 1V VCE = 2V VCE = 4VS.NO

VBE(V) IB(µA) VBE(V) IB(µA) VBE(V) IB(µA)

OUT PUT CHAREACTARISTICS:

IB = 50 µA

IB = 75 µA

IB = 100 µA

S.NOVCE(V) IC(mA) VCE(V) ICmA) VCE(V) IC(mA)

H -PARAMETERS:-

1. Input Impedance hie = ΔVBE / ΔIB at VCE constant2. Output impedance hoe = ΔVCE / ΔIC at IB constant

3. Reverse Transfer Voltage Gain hre = ΔVBE / ΔVCE at IB constant

4. Forward Transfer Current Gain hfe = ΔIC / ΔIB at constant VCE

42

4.7 MODEL GRAPHS:

INPUT CHARACTERSTICS:

OUTPUT CHARECTERSTICS:

4.8 PRECAUTIONS:

1. The supply voltage should not exceed the rating of the transistor

2. Meters should be connected properly according to their polarities

4.9 RESULT:

1. The input and output characteristics of a transistor in CE configuration are Drawn2. The β of a given transistor is?

43


1. What is the range of α for the transistor?

2. What are the input and output impedances of CE configuration?

3. Identify various regions in the output characteristics?

4. what is the relation between α and β

5. Define current gain in CE configuration?


1. Find the input & output characteristics of 2N2222 NPN Transistor?2. Find the input & output characteristics of BC640 PNP Transistor?


1. Why CE configuration is preferred for amplification?

2. What is the phase relation between input and output?

3. Draw the diagram of CE configuration for PNP transistor?

4. What is the power gain of CE configuration?

5. What are the applications of CE configuration?

44

EXPERIMENT –5: HALF WAVE RECTIFIER WITH & WITHOUT FILTERS

5.1 OBJECTIVE: -

To obtain the load regulation and ripple factor of a half-rectifier1. with Filter2. without Filter

5.2 RESOURCES:-

1. Experimental Board

2. Multimeters –2No’s.

3. Transformer (9-0-9).

4. Diode, 1N 4007

5. Capacitor 47µf.

6. Resistance Box. Connecting wires

5.3 THEORY: -

During positive half-cycle of the input voltage, the diode D1 is in forward bias and

conducts through the load resistor R1. Hence the current produces an output voltage

across the load resistor R1, which has the same shape as the +ve half cycle of the input

voltage.

During the negative half-cycle of the input voltage, the diode is reverse biased and

there is no current through the circuit. i.e, the voltage across R1 is zero. The net result

is that only the +ve half cycle of the input voltage appears across the load. The average

value of the half wave rectified o/p voltage is the value measured on dc voltmeter.

For practical circuits, transformer coupling is usually provided for two reasons.

1. The voltage can be stepped-up or stepped-down, as needed.2. The ac source is electrically isolated from the rectifier. Thus preventing shock

hazards in the secondary circuit.

45


WITH AND WITHOUT FILTER:

5.5 PROCEDURE:-

1. Connections are made as per the circuit diagram. 2. Connect the primary side of the transformer to ac mains and the secondary side

46

to the rectifier input. 3. By the multi-meter, measure the ac input voltage of the rectifier and, ac and dc

voltage at the output of the rectifier. 4. Find the theoretical of dc voltage by using the formula,

Vdc=Vm/ПWhere, Vm=2Vrms, (Vrms=output ac voltage.) The Ripple factor is calculated by using the formula

= ac output voltage/dc output voltage.

5. The voltage regulation of any device is usually expressed as percentage regulation

6. The percentage regulation is given by the formula 1. ((VNL-VFL)/VFL)X1002. VNL=Voltage across the diode, when no load is connected.

VFL=Voltage across the diode, when load is connected.

REGULATION CHARACTERSTICS:-


2. By increasing the value of the rheostat, the voltage across the load and current flowing through the load are measured.

3. The reading is tabulated. 4. Draw a graph between load voltage (VL and load current ( IL ) taking VL on X-

axis and IL on y-axis

5. From the value of no-load voltages, the %regulation is calculated using the formula,

Theoretical calculations for Ripple factor:-

Without Filter:-

Vrms=Vm/2

Vm=2Vrms

Vdc=Vm/П

Ripple factor r=√ (Vrms/ Vdc )2 -1 =1.21With Filter:-

Ripple factor, r=1/ (2√3 f C R)

Where f =50Hz

C =100µFRL=1KΩ

47

PRACTICAL CALCULATIONS:-

Vac=Vdc=Ripple factor without Filter =Ripple factor with Filter =

5.6 OBSERVATIONS:-

WITHOUTFILTER:-Vdc=Vm/П, Vrms=Vm/2, Vac=√ ( Vrms2- Vdc 2)

S.No RL(KΩ) VAC (V)= (Vm/2)

VDC (V) Ripple Factor = Vac/VDC

% Regulation = ((VNL-VFL)/VFL)X100

WITHFILTER

S.No RL(KΩ) VAC (V)= (Vm/2)



5.7 PRECAUTIONS:

1. The primary and secondary sides of the transformer should be carefully identified.

2. The polarities of the diode should be carefully identified.

3. While determining the % regulation, first Full load should be applied and then it should be decremented in steps.

48

5.8 RESULT:-1. The Ripple factor for the Half-Wave Rectifier with and without filters is measured.

2. The % regulation of the Half-Wave rectifier is calculated.


1.What is the PIV of Half wave rectifier?

2.What is the efficiency of half wave rectifier?

3.What is the rectifier?

4. What is the difference between the half wave rectifier and full wave Rectifier?

5. What is the o/p frequency of Bridge Rectifier?


1. Find the Ripple factor for Half-Wave rectifier using Inductor filter?2. Find out %of regulation for Half-Wave rectifier using π filter?


1. What are the ripples?

2. What is the function of the filters?

3. What is TUF?

4. What is the average value of o/p voltage for HWR? 10. What is the peak factor?

49

EXPERIMENT –6: FULL WAVE RECTIFIER WITH & WITHOUT FILTERS

6.1 OBJECTIVE:-

To find the Ripple factor and regulation of a Full-wave Rectifier with and without filter.

6.2 RESOURCES:-

1. Experimental Board

2. Transformer (9-0-9v).

3. P-n Diodes, (lN4007) ---2 No’s

4. Multimeters–2No’s

5. Filter Capacitor -47UF Connecting Wires

6. Resistance Box

6.3 THEORY:-

The circuit of a center-tapped full wave rectifier uses two diodes D1&D2. During positive half cycle of secondary voltage (input voltage), the diode D1 is forward biased and D2is reverse biased.The diode D1 conducts and current flows through load resistor RL. During negative half

cycle, diode

D2 becomes forward biased and D1 reverse biased. Now, D2 conducts and current flows through the load resistor RL in the same direction. There is a continuous current flow through the load resistor RL, during both the half cycles and will get unidirectional current as show in the model graph. The difference between full wave and half wave rectification is that a full wave rectifier allows unidirectional (one way) current to the load during the entire 360 degrees of the input signal and half-wave rectifier allows this only during one half cycle (180 degree).

50


WITH AND WITHOUT FILTER:

6.5 PROCEDURE:


3. Connect the ac mains to the primary side of the transformer and the secondary

51

side to the rectifier.

4. Measure the ac voltage at the input side of the rectifier.

5. Measure both ac and dc voltages at the output side the rectifier.

6. Find the theoretical value of the dc voltage by using the formula Vdc=2Vm/П

7. Connect the filter capacitor across the load resistor and measure the values of Vac and Vdc at the output.

8. The theoretical values of Ripple factors with and without capacitor are calculated.

9. From the values of Vac and Vdc practical values of Ripple factors are calculated. The practical values are compared with theoretical values.

10.The percentage regulation is given by the formula ((VNL-VFL)/VFL)X100

VNL=Voltage across the diode, when no load is connected. VFL=Voltage across the diode, when load is connected

6.6 THEORITICAL CALCULATIONS:-

Vrms = Vm/ √2

Vm =Vrms √2

Vdc=2Vm/ПWithout filter:

Ripple factor, r = √ ( Vrms/ Vdc )2 -1 = 0.482With filter:

Ripple factor, r = 1/ (4√3 f C RL) where f =50HzC = 100µF

R = 1KΩ

52

PRACTICAL CALCULATIONS:

Without Filter:

Vrms = Vm/ √2 , Vdc=2Vm/П , Ripple Factor = √( Vrms2- Vdc 2)-1

S.No RL(KΩ) VAC (V)= (Vm/√2)

VDC (V) Ripple Factor = √( Vrms2- Vdc 2)-1


With Filter

S.No RL(KΩ) VAC (V)= (Vm/√2)



6.7 PRECAUTIONS:

1. The primary and secondary side of the transformer should be carefully identified

2. The polarities of all the diodes should be carefully identified.

6.8 RESULT:-

The ripple factor of the Full-wave rectifier (with filter and without filter) is calculated.


1. Define regulation of the full wave rectifier?

2. Define peak inverse voltage (PIV)? And write its value for Full-wave rectifier?

3. If one of the diode is changed in its polarities what wave form would you get?

4. Does the process of rectification alter the frequency of the waveform?

5. What is ripple factor of the Full-wave rectifier?

53


1. Find the Ripple factor for Full-Wave rectifier using Inductor filter?2. Find out %of regulation for Full-Wave rectifier using π filter?


1. What is the necessity of the transformer in the rectifier circuit?

2. What are the applications of a rectifier?

3. What is ment by ripple and define Ripple factor?

4. Explain how capacitor helps to improve the ripple factor?

5. Can a rectifier made in INDIA (V=230v, f=50Hz) be used in USA (V=110v, f=60Hz)?

54

EXPERIMENT –7: FET CHARACTERISTICS

7.1 OBJECTIVE:

1. To draw the drain and transfer characteristics of a given FET.

2. To find the drain resistance (rd) amplification factor (µ) and Tran conductance

(gm) of the given FET.

7.2 RESOURCES:-

1. FET (BFW-11)

2. Regulated power supply

3. Voltmeter (0-20V)

4. Ammeter (0-100mA)

5. Bread board

6. Connecting wires

7. Resistors 1KΩ - 2

7.3 THEORY:

A FET is a three terminal device, having the characteristics of high input impedance and less noise, the Gate to Source junction of the FET s always reverse biased. In response to small applied voltage from drain to source, the n-type bar acts as sample resistor, and the drain current increases linearly with VDS. With increase in ID the ohmic voltage drop between the source and the channel region reverse biases the junction and the conducting position of the channel begins to remain constant. The VDS at this instant is called “pinch of voltage”.If the gate to source voltage (VGS) is applied in the direction to provide additional

reverse bias, the pinch off voltage ill is decreased.

In amplifier application, the FET is always used in the region beyond the pinch-off.

𝐼𝐷 = 𝐼𝐷𝑆𝑆(1 -𝑉𝐺𝑆

𝑉𝑃 )2

55

7.4 CIRCUIT DIAGRAM

7.5 PROCEDURE:

1. All the connections are made as per the circuit diagram. 2. To plot the drain characteristics, keep VGS constant at 0V. 3. Vary the VDD and observe the values of VDS and ID. 4. Repeat the above steps 2, 3 for different values of VGS at 0.1V and 0.2V.

5. All the readings are tabulated. 6. To plot the transfer characteristics, keep VDS constant at 1V. 7. Vary VGG and observe the values of VGS and ID. 8. Repeat steps 6 and 7 for different values of VDS at 1.5 V and 2V.

9. The readings are tabulated. 10.From drain characteristics, calculate the values of dynamic resistance (rd) by 11.using the formula

i. rd =∆VDS/∆ID

12.From transfer characteristics, calculate the value of transconductace (gm) 13.By using the formula

1. Gm=∆ID/∆VDS

14.Amplification factor (µ) = dynamic resistance. Tran conductance

(0-20V)

(0-20V)

(0-20mA)

BFW11

56

a. = ∆VDS/∆VGS7.6 OBSERVATIONS:

DRAIN CHARACTERISTICS:

S.NO VGS=0V VGS=-1V VGS=-2V

VDS(V) D(mA) VDS(V) ID(mA) VDS(V) ID(mA)

TRANSFER CHARACTERISTICS:

S.NO VDS = 6V Constant

VGS (V) ID(mA)

57

7.7 MODEL GRAPH:

TRANSFER CHARACTERISTICS

DRAIN CHARACTERISTICS

58

7.8 PRECAUTIONS:

1. The three terminals of the FET must be carefully identified

2. Practically FET contains four terminals, which are called source, drain, Gate, substrate.

3. Source and case should be short circuited.

4. Voltages exceeding the ratings of the FET should not be applied.

7.9 RESULT:

1. The drain and transfer characteristics of a given FET are drawn 2. The dynamic resistance (rd), amplification factor (µ) and Tran conductance (gm)

of the given FET are calculated.

7.10 PRE EXPERIMENT QUESTIONS:-1. What are the advantages of FET?

2. Different between FET and BJT?

3. Explain different regions of V-I characteristics of FET? 4. What are the applications of FET?

7.11 ASSIGNMENT QUESTIONS:-1. How a FET can be used as a voltage variable Resistance (VVR)?2. Explain the construction & operation of a P-channel MOSFET in enhancement and

depletion modes with the help of static drain characteristics and transfer characteristics?

3. Explain the operation of FET with its characteristics and explain the different regions in transfer characteristics?

4. Define pinch-off voltage and trans-conductance in field effect transistors?5. With the help of neat sketches and characteristic curves explain the construction

& operation of a JFET and mark the regions of operation on the characteristics?6. Explain how a FET can be made to act as a switch?


1. What are the types of FET?

2. Draw the symbol of FET.

3. What are the disadvantages of FET?

59

4. What are the parameters of FET? EXPERIMENT –8: FREQUENCY RESPONSE OF CE AMPLIFIER

8.1 OBJECTIVE:

1. To Measure the voltage gain of a CE amplifier2. To draw the frequency response curve of the CE amplifier

8.2 RESOURCES:-

1. Transistor BC-1072. Regulated power Supply (0-30V, 1A)3. Function Generator4. CRO5. Resistors [100KΩ, 1KΩ, 10KΩ, 4.7KΩ]6. Capacitors- 10µF - 2No

i. 47µF7. Bread Board8. Connecting Wires

8.3 THEORY:

The CE amplifier provides high gain &wide frequency response. The

emitter lead is common to both input & output circuits and is grounded. The emitter-

base circuit is forward biased. The collector current is controlled by the base current

rather than emitter current. The input signal is applied to base terminal of the

transistor and amplifier output is taken across collector terminal. A very small change

in base current produces a much larger change in collector current. When +VE half-

cycle is fed to the input circuit, it opposes the forward bias of the circuit which causes

the collector current to decrease, it decreases the voltage more –VE. Thus when input

cycle varies through a -VE half-cycle, increases the forward bias of the circuit, which

causes the collector current to increases thus the output signal is common emitter

amplifier is in out of phase with the input signal.

60

8.4 CIRCUIT DIAGRAM:

8.5 PROCEDURE:

1. Connect the circuit as shown in circuit diagram

2. Apply the input of 20mV peak-to-peak and 1 KHz frequency using Function Generator

3. Measure the Output Voltage Vo (p-p) for various load resistors

4. Tabulate the readings in the tabular form. 5. The voltage gain can be calculated by using the expression Av= (V0/Vi)6. For plotting the frequency response the input voltage is kept Constant at 20mV

peak-to-peak and the frequency is varied from 100Hz to 1MHz Using function

generator

7. Note down the value of output voltage for each frequency. 8. All the readings are tabulated and voltage gain in dB is calculated by Using The

expression Av=20 log10 (V0/Vi) 9. A graph is drawn by taking frequency on x-axis and gain in dB on y-axis on

Semi-log graph.

The band width of the amplifier is calculated from the graph Using the expression,Bandwidth, BW=f2-f1

Where f1 lower cut-off frequency of CE amplifier, and Where f2 upper cut-off frequency of CE amplifier

The bandwidth product of the amplifier is calculated using the Expression

61

Gain Bandwidth product=3-dBmidband gain X Bandwidth8.6 OBSERVATIONS:

FREQUENCY RESPONSE: Input voltage Vi= 40mV Constant

OUTPUT GAIN GAIN IN dB

FREQUENCY(Hz) VOLTAGE (V0) AV=(V0/Vi) Av=20log10

(V0/Vi)

62

8.7 MODELWAVE FORMS:

INPUT WAVE FORM:

OUTPUT WAVE FORM

FREQUENCY RESPONSE

63

8.8 RESULT:

The voltage gain and frequency response of the CE amplifier are obtained. Also gain bandwidth product of the amplifier is calculated.


1. What is phase difference between input and output waveforms of CE amplifier? 2. What type of biasing is used in the given circuit? 3. If the given transistor is replaced by a p-n-p, can we get output or not? 4. What is effect of emitter-bypass capacitor on frequency response?

What is the effect of coupling capacitor?


1. Find the frequency response of CE Amplifier using 2N2222 NPN Transistor?

2. Find the frequency response of CE Amplifier using BC640 PNP Transistor?


1. What is region of the transistor so that it is operated as an amplifier?

2. How does transistor acts as an amplifier?

3. Draw the h-parameter model of CE amplifier?

4. What type of transistor configuration is used in intermediate stages of a multistage amplifier?

5. What is early effect?

64

EXPERIMENT –9: FREQUENCY RESPONSE OF CC AMPLIFIER

9.1 OBJECTIVE:

1. To measure the voltage gain of a CC amplifier2. To draw the frequency response of the CC amplifier

9.2 RESOURCES:-

1. Transistor BC 1072. Regulated Power Supply (0-30V)3. Function Generator4. CRO5. Resistors 100KΩ,10KΩ, 1KΩ6. Capacitors 10µF -2Nos7. Breadboard8. Connecting wires

9.3 THEORY:

In common-collector amplifier the input is given at the base and the output is taken at

the emitter. In this amplifier, there is no phase inversion between input and output.

The input impedance of the CC amplifier is very high and output impedance is low.

The voltage gain is less than unity. Here the collector is at ac ground and the

capacitors used must have a negligible reactance at the frequency of operation.

This amplifier is used for impedance matching and as a buffer amplifier. This circuit is also known as emitter follower.


65

9.5 PROCEDURE:

1. Connections are made as per the circuit diagram. 2. For calculating the voltage gain the input voltage of 20mV peak-to-peak and 1

KHz frequency is applied and output voltage is taken for various load resistors. 3. The readings are tabulated. 4. The voltage gain calculated by using the expression, Av=V0/Vi5. For plotting the frequency response the input voltage is kept constant a

20mV peak-to- peak and the frequency is varied from 100Hzto 1MHz.

6. Note down the values of output voltage for each frequency. 7. All the readings are tabulated the voltage gain in dB is calculated by using the

expression, Av=20log 10(V0/Vi) 8. A graph is drawn by taking frequency on X-axis and gain in dB on y-axis on

Semi-log graph sheet.9. The Bandwidth of the amplifier is calculated from the graph using the Expression,

Bandwidth BW=f2-f1Where f1 is lower cut-off frequency of CE amplifier

f2 is upper cut-off frequency of CE amplifier10.The gain Bandwidth product of the amplifier is calculated using the

Expression,

Gain -Bandwidth product=3-dB midband gain X Bandwidth

9.6 OBSERVATIONS:

FREQUENCY RESPONSE: Vi = 100mV Constant


FREQUENCY(Hz) VOLTAGE( V0) Av=V0/Vi

Av=20log 10(V0/Vi)

66

9.7 WAVEFORM:

9.8 PRECAUTIONS:

1. The input voltage must be kept constant while taking frequency response.

2. Proper biasing voltages should be applied.

9.9 RESULT:

The voltage gain and frequency response of the CC amplifier are obtained. Also gain Bandwidth product is calculated.


1. What are the applications of CC amplifier? 2. What is the voltage gain of CC amplifier? 3. What are the values of input and output impedances of the CC amplifier? 4. To which ground the collector terminal is connected in the circuit? 5. Identify the type of biasing used in the circuit?

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1. Find the frequency response of CC Amplifier using 2N2222 NPN Transistor?

2. Find the frequency response of CC Amplifier using BC640 PNP Transistor?


1. Give the relation between α, β and γ.

2. Write the other name of CC amplifier?

3. What are the differences between CE,CB and CC?

4. When compared to CE, CC is not used for amplification. Justify your answer?

5. What is the phase relationship between input and output in CC?

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EXPERIMENT –10: FREQUENCY RESPONSE OF COMMON SOURCE FET AMPLIFIER

10.1 OBJECTIVE:

1. To obtain the frequency response of the common source FET Amplifier

2. To find the Bandwidth

10.1 RESOURCES:-

1. N-channel FET (BFW11) 2. Resistors (3.3KΩ, 1MΩ, 10KΩ) 3. Capacitors (10µF, 47µF) 4. Regulated power Supply (0-30V) 5. Function generator6. CRO7. CRO probes Bread board Connecting wires


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10.3 THEORY:

A field-effect transistor (FET) is a type of transistor commonly used for

weak-signal amplification (for example, for amplifying wireless (signals). The device can

amplify analog or digital signals. It can also switch DC or function as an oscillator. In

the FET, current flows along a semiconductor path called the channel. At one end of the

channel, there is an electrode called the source. At the other end of the channel, there

is an electrode called the drain. The physical diameter of the channel is fixed, but its

effective electrical diameter can be varied by the application of a voltage to a control

electrode called the gate. Field-effect transistors exist in two major classifications.

These are known as the junction FET (JFET) and the metal-oxide- semiconductor FET

(MOSFET). The junction FET has a channel consisting of N-type semiconductor (N-

channel) or P-type semiconductor (P-channel) material; the gate is made of the

opposite semiconductor type. In P-type material, electric charges are carried mainly in

the form of electron deficiencies called holes. In N-type material, the charge carriers

are primarily electrons. In a JFET, the junction is the boundary between the channel

and the gate. Normally, this P-N junction is reverse-biased (a DC voltage is applied to

it) so that no current flows between the channel and the gate. However, under some

conditions there is a small current through the junction during part of the input signal

cycle. The FET has some advantages and some disadvantages relative to the bipolar

transistor. Field-effect transistors are preferred for weak-signal work, for example in

wireless, communications and broadcast receivers. They are also preferred in circuits

and systems requiring high impedance. The FET is not, in general, used for high-power

amplification, such as is required in large wireless communications and broadcast

transmitters.

Field-effect transistors are fabricated onto silicon integrated circuit (IC) chips. A single

IC can contain many thousands of FETs, along with other components such as resistors,

capacitors, and diodes.

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10.4 PROCEDURE:

1. Connections are made as per the circuit diagram. 2. A signal of 1 KHz frequency and 50mV peak-to-peak is applied at the Input of

amplifier. 3. Output is taken at drain and gain is calculated by using the expression,

Av=V0/Vi4. Voltage gain in dB is calculated by using the expression, Av=20log 10(V0/Vi)5. Repeat the above steps for various input voltages. 6. Plot Av vs. Frequency 7. The Bandwidth of the amplifier is calculated from the graph using the

8. Expression, Bandwidth BW=f2-f1

9. Where f1 is lower 3 dB frequency f2 is upper 3 dB frequency

10.5 OBSERVATIONS:

FREQUENCY RESPONSE: Vi = 100mV Constant


FREQUENCY(Hz) VOLTAGE( V0) Av=V0/Vi

Av=20log 10(V0/Vi)

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10.6 MODEL GRAPH:

10.7 PRECAUTIONS:

1. All the connections should be tight.

2. Transistor terminals must be identified properly

10.8 RESULT:

The frequency response of the common source FET Amplifier and Bandwidth is obtained.


1. What is the difference between FET and BJT? 2. FET is uni-polar or bipolar? 3. Draw the symbol of FET? 4. What are the applications of FET? 5. FET is voltage controlled or current controlled?


1. Find the frequency response of FET Amplifier using BFW10 transisor.2. What are the FET applications?

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1. Draw the equivalent circuit of common source FET amplifier?

2. What is the voltage gain of the FET amplifier?

3. What is the input impedance of FET amplifier?

4. What is the output impedance of FET amplifier?

5. What are the FET parameters?

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EXPERIMENT –11: SCR CHARACTERISTICS11.1 OBJECTIVE:

To draw the V-I Characteristics of SCR

11.2 RESOURCES:-

1. SCR (TYN612)2. Regulated Power Supply (0-30V)3. Resistors 1kΩ, 1kΩ4. Ammeter (0-50) µA5. Voltmeter (0-10V)6. Breadboard7. Connecting Wires.


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11.4 THEORY:

It is a four layer semiconductor device being alternate of P-type and N-type silicon. It consists os 3 junctions J1, J2, J3 the J1 and J3 operate in forward direction and J2 operates in reverse direction and three terminals called anode A, cathode K , and a gate G. The operation of SCR can be studied when the gate is open and when the gate is positive with respect to cathode.

When gate is open, no voltage is applied at the gate due to reverse bias of the junction J2 no current flows through R2 and hence SCR is at cut off. When anode voltage is increased J2 tends to breakdown.

When the gate positive, with respect to cathode J3junction is forward biased and J2 is reverse biased .Electrons from N-type material move across junction J3 towards gate while holes from P-type material moves across junction J3 towards cathode. So gate current starts flowing, anode current increase is in extremely small current junction J2 break down and SCR conducts heavily.

When gate is open thee break over voltage is determined on the minimum

forward voltage at which SCR conducts heavily. Now most of the supply voltage

appears across the load resistance. The holding current is the maximum anode current

gate being open, when break over occurs.

11.5 PROCEDURE:

1. Connections are made as per circuit diagram.

2. Keep the gate supply voltage at some constant value

3. Vary the anode to cathode supply voltage and note down the readings of voltmeter and ammeter.Keep the gate voltage at standard value.

4. A graph is drawn between VAK and IAK .

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11.6 OBSERVATION

IG = Constant

VAK(V) IAK ( mA)

11.7 MODEL WAVEFORM:

11.8 RESULT:

SCR Characteristics are observed.

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1. What the symbol of SCR?

2. IN which state SCR turns of conducting state to blocking state?

3. What are the applications of SCR?

4. What is holding current?

5. What are the important type’s thyristors?


1. Explain the significance of Threshold voltage.

2. List out the applications of SCR.


1. How many numbers of junctions are involved in SCR?

2. What is the function of gate in SCR?

3. When gate is open, what happens when anode voltage is increased?

4. What is the value of forward resistance offered by SCR?

5. What is the condition for making from conducting state to non conducting state?

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EXPERIMENT –12: UJT CHARACTERISTICS

12.1 OBJECTIVE:

To observe the characteristics of UJT and to calculate the Intrinsic Stand-Off Ratio (η).

12.2 RESOURCES:-

Regulated Power Supply (0-30V, 1A) - 2Nos

UJT 2N2646

Resistors 1k,1k

Voltmeters 2nosAmmeter 1noResistors 1k-2nos

Breadboard

Connecting Wires

12.3 CIRCUIT DIAGRAM

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12.4 THEORY:

A Unijunction Transistor (UJT) is an electronic semiconductor device that has

only one junction. The UJT Unijunction Transistor (UJT) has three terminals an emitter

(E) and two bases (B1 and B2). The base is formed by lightly doped n-type bar of

silicon. Two ohmic contacts B1 and B2 are attached at its ends. The emitter is of p-type

and it is heavily doped. The resistance between B1 and B2, when the emitter is open-

circuit is called inter base resistance. The original uni junction transistor, or UJT, is a

simple device that is essentially a bar of N type semiconductor material into which P

type material has been diffused somewhere along its length. The 2N2646 is the most

commonly used version of the UJT.

Circuit symbol

The UJT is biased with a positive voltage between the two bases. This causes a

potential drop along the length of the device. When the emitter voltage is driven

approximately one diode voltage above the voltage at the point where the P diffusion

(emitter) is, current will begin to flow from the emitter into the base region. Because

the base region is very lightly doped, the additional current (actually charges in the

base region) causes (conductivity modulation) which reduces the resistance of the

portion of the base between the emitter junction and the B2 terminal. This reduction in

resistance means that the emitter junction is more forward biased, and so even more

current is injected. Overall, the effect is a negative resistance at the emitter terminal.

This is what makes the UJT useful, especially in simple oscillator circuits. When the

emitter voltage reaches

Vp, the current starts to increase and the emitter voltage starts to decrease. This is

represented by negative slope of the characteristics which is referred to as the negative

resistance region, beyond the valley point ,RB1 reaches minimum value and this region,

VEB proportional to IE.

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12.5 PROCEDURE:

1. Connection is made as per circuit diagram.

2. Output voltage is fixed at a constant level and by varying input voltage corresponding emitter current values are noted down.

3. This procedure is repeated for different values of output voltages.

4. All the readings are tabulated and Intrinsic Stand-Off ratio is calculated using η = (Vp-VD) / VBB

5. A graph is plotted between VEE and IE for different values of VBE.

12.6 MODEL GRAPH:

12.7 OBSEVATIONS:

VBB=1V VBB=2V VBB=3V

VEB(V) IE(mA) VEB(V) IE(mA) VEB(V) IE(mA)

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12.8 CALCULATIONS:

VP = ηVBB + VD

η = (VP-VD) / VBB

𝜼 = 𝑹𝑩𝟏

𝑹𝑩𝟏 + 𝑹𝑩𝟐

12.9 RESULT:

The characteristics of UJT are observed and the values of Intrinsic Stand-Off Ratio is calculated


1. What is the symbol of UJT?

2. Draw the equivalent circuit of UJT?

3. What are the applications of UJT?

4. Formula for the intrinsic standoff ratio?

5. What does it indicates the direction of arrow in the UJT?


1. Find the characteristics of 2N4871 UJT?2. Find the Hysteresis for 2N2646 UJT?


1. What is the difference between FET and UJT?

2. Is UJT is used an oscillator? Why? 3. What is the Resistance between B1 and B2 is called as? 4. What is its value of resistance between B1 and B2?

5. Draw the characteristics of UJT?

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EXP NO:13 DESIGN OF SELF BIAS CIRCUIT

Objective: To design and verify a Self Bias circuit for a given operating point.

Components:

S.No. Name Quantity

1 Transistor BC107 1(One) No.

2 Resistors According to values calculated

3 Bread board 1(One) No.

Equipment:

S.No. Name Quantity

1 Dual DC Regulated Power supply (0 – 30 V) 1(One) No.

2 Digital Ammeters ( 0 – 200 mA) 1(One) No.

3 Digital Voltmeter (0-20V) 1(One) No.

4 Connecting wires (Single Strand)

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Circuit Diagram:

Operation:

A self bias circuit stabilizes the bias point more appropriately than a fixed bias circuit. In this experiment CE configuration is used and a self bias circuit is designed and verified.

Calculations:

Given VCC = 10V, RE = 220 ohm IC = 4mA VCE = 6V, VBE = 0.6V hfe = 200

Note: VE value should be 1/4th or 1/10th of VCC.

IB = IC/

RE = VE/IE = VE/IC

RC = (VCC - VCE - VE)/IC

10R2 <= RE

VBB=IB*RB+VBE +(IB+IC)RE

R1=(VCC/VBB)*RB

R2=RB/(1-VBB/VCC)

VB = [R2/(R1 + R2) ]VCC

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Procedure:

1. Calculate the values of R1, R2, RC, RE, according to the given specifications and design equations.

2. Connect the circuit as shown in the circuit diagram with the designed values.3. Apply voltage VCC, measure the values of IC, IB, VCE,VBE.

Observations:

Parameter Theoritical Practical

VCE

VBE

IC

IB

Precautions:

1. The supply voltage should not exceed the rating of the transistor2. Loose connections should be avoided.

Result:

The self bias circuit is designed and verified.

Outcomes:

Students are able to design self bias circuit and test its performance for a given operating point.

Viva Questions:

1. What are the advantages of self bias?2. What are the various other techniques available for biasing?3. What is the best biasing technique among all biasing technique?4. Why biasing circuit is needed for amplifier?5. What is the effect of input dc signal on Q-point?6. What is Pc max?7. What is thermal runaway?8. What is the reason for thermal runaway?9. Can DC signal be amplified by CE or CB amplifier?10.What type of feedback is provided by RE in self biasing technique of CE

configuration?

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EXP NO: 14 SWITCHING CHARACTERISTICS OF A TRANSISTOR

14.1 OBJECTIVE: To design and observe the performance of a transistor as a switch.

14.2 RESOURCES:

1. Transistor (BC 107).2. Breadboard.3. CRO.(0-20/30/50MHZ)4. Resistors (1K, 470).5. DC power supply.(0-30MHZ)6. Function Generator.(0-3MHZ)7. Connecting patch cards.

14.3 CIRCIUT DIAGRAM:

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14.4 EXPECTED WAVEFORMS:

14.5 THEORY:

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The transistor Q can be used as a switch to connect and disconnect the load RL from the source VCC. When a transistor is saturated, it is like a closed switch from the collector to the emitter. When a transistor is cut-off, it is like an open switch

IC= (VCC-VCE)/RL

Cut-off and Saturation: The point at which the load line intersects the IB = 0

curve is known as cut-off. At this point, base current is zero and collector current is

negligible small i.e. only leakage current ICEO exists. At cut-off, the emitter diode

comes out of forward bias and normal transistor action is lost.

VCE(sat) = VCC

The intersection of the load line and the IB = IB(sat) is called saturation. At this point base current is IB(sat) and the collector current is maximum. At saturation, the collector diode comes out of reverse bias, and normal transistor action is again lost.

Ice(sat)=Vcc/RL

In figure:3 IB(sat) represents the amount of base current that just produces saturation. If base current is less than IB(sat), the transistor operates in the active region somewhere between saturation and cut-off. If base current is greater than IB(sat), the collector currentapproximately equals VCC/RC. The transistor appears like a closed

switch VBB=VBE+IBRB

If base current (IB) is zero, the transistor operates at the lower end of the load line and the transistor appears like an open switch.

14.6 PROCEDURE :

6.Connect the circuit as shown in the figure 1.

7.Connect 12V power supply to VCC and 0V to the input terminals.

8.Measure the voltage (1) across collector – to – emitter terminals, (2) across collector – to – base terminals and (3) Base – to – emitter terminals.

9.Connect 5V to the input terminals.

10. Measure the voltage (1) across collector – to – emitter terminals, (2) across collector – to – base terminals and (3) Base – to – emitter terminals.

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11. Observe that the LED glows when the input terminals are supplied with 0 volts. The LED will NOT glow when the input voltage is 5V.

12. Remove the load (1kΩand LED) and DC power supply (connected between RB and Gnd.). Now connect a function generator to the input terminals.

13. Apply Square wave of 1 KHz, V (p-p) is 10V

14. Observe the waveforms at the input terminals and across collector and ground.

15.Plot the waveform on a graph sheet. Note the inversion of the signal from input to output.

14.7 RESULT:

The waveforms are plotted as shown and the practical T is verified to the theoretical value

14.8 PRE LAB:

1. Study the operation and working principle of transistor switch circuit.

2. Identify all the formulae you will need in this Lab.

3. Study the procedure of performing switching characteristics of a transistor

14.9 ASSIGNMENT QUESTIONS:

1. Design transistor switch circuit using different transistors like BC547 and 2N2222A.

2. Design a PCB layout for the transistor switch circuit.

14.10 POST LAB QUESTIONS:

1. What are the different switching times of a transistor? 2. Define ON time of a transistor? 3. Define OFF time of a transistor? 4. Explain how transistor acts as a switch? 5. Define delay time (td), raise time (tr), saturation time (ts) and fall time

(tf) of a transistor?

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EXP NO:15 UJT RELAXATION OSCILLATOR

15.1 OBJECTIVE:

To study the operation of UJT Relaxation Oscillator

15.2 RESOURCES:

1.Resistors (470ohm, 220ohm, 100K Potentiometer)

2.Capacitors (.01F,0.1F, 1F)

3.Cathode Ray Oscilloscope

4.Bread board

5.UJT(2N2646)


figure 1: UJT relaxation oscillator.

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15.4 THEORY:

The UJT exhibits a negative resistance characteristics, it can be used to provide time delayed trigger pulses for activating other devices like SCR. The basic trigger circuit is shown in the figure.

The external resistances RB1 and RB2 are of the UJT base. The emitter potential Ve is varied depending on the charging rate of capacitor C. The Charging resistance Rc should be such that the load line intersects the device characteristics only , in the negative resistance region AB. If the Rc load line intersects the device characteristics either in region PR or in BQ ,the resulting operating point will be stable and the circuit will not oscillate. This sets the max and minimum limits on the permissible values of Rc.

As the Capacitor charges, when the emitter voltage goes to the peak point voltage (Vb +VD ) , regeneration will start and the capacitor will discharges through resistor RB1. The rise time of the output pulse will depend on the switching speed of the UJT, and the duration will be proportional to the time constant RB1C of the discharge circuit. The emitter –base -1 diode will again be reverse biased until the capacitor is charged to (Vb +VD ) . The output pulses are shown in figure and the duration and their period T is given by T = RC ln (1/1-)

15.5 PROCEDURE:

1. Connect the circuit as shown in figure. Apply 15V DC power supply to the circuit.

2. Observe the output pulses on the CRO at B1, B2 and Ve (Vc).3. Vary the time constant (RC) by varying capacitance value and

potentiometer value (R), observe the variations in the out pulses on the CRO at B1, B2 and Ve (Vc).

4. Plot the graphs as shown in the expected waveforms.

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15.6 EXPECTED WAVEFORMS:

The UJT relaxation oscillator output wave forms are as shown in the figure.

15.7 RESULT:

The waveforms are plotted as shown and the practical T is verified to the theoretical value.

15.8 PRE LAB:

1. Study the operation and working principle of UJT circuit.

2. Identify all the formulae you will need in this Lab.

3. Study the procedure of performing UJT relaxation oscillator.

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15.9 ASSIGNMENT QUESTIONS:1. Design UJT using different transistors like BC107,2N2222A etc.

2. Design a PCB layout for the UJT.

15.10 POST LAB QUESTIONS:

1. What is a relaxation oscillator?2. Specifications of UJT?3. What is the importance of UJT?4. When will be UJT is switched?

st. martin’s engineering college - smec edc...2 electronic devices and circuits lab part a: (only...

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