Department of Electronics & Telecommunication.

Transcription

1 BASIC ELECTRONICS ENGINEERING 1 Department of Electronics & Telecommunication. Experiment No. : 01 Date of Performance: Name of the student: Division: Roll No. : Passive Components AIM: Study of Passive components Resistors, Capacitors, Inductors, Relays, Switches, Transformers, Connectors. PREREQUISITE: Knowledge of active components. Knowledge of passive components. Difference between active and passive components. OBJECTIVE: Types and subtypes of passive components. Applications of passive components. COMPONENTS: 1) Resistors, 2) Capacitors, 3) Inductors, 4) Relays, 5) Switches, 6) Transformers, 7) Connectors THEORY: Resistor A resistor is a two terminal electronic component that produces a voltage across its terminals that is proportional to the electric current through it in accordance with Ohm s law. V = I.R Where, V = Voltage across resistor I = Current flowing through resistor R = Resistance of the resistor Resistor having the physical material which resists the flow of electric current to some extent is called as resistor. Resistors are circuit element having function of offering electrical resistance in circuit. The resistance of a material with length l and area A is given by, R= ( * l) / A Where is the resistivity Classification of Resistor: A) Fixed Resistor: Fixed resistor are classified into 4 types based on various factors like manufacturing style, resistance range, power rating etc.

2 BASIC ELECTRONICS ENGINEERING 2 1) Carbon composition 2) Carbon film 3) Metal film (Thick and Thin film type) 4) Wire-wound (Power and Precision style type) Symbol of Fixed Resistor B) Variable Resistor: Variable type resistor are used in electronic circuits to adjust the value of voltages and currents. For example it used in Television as volume control, brightness control etc. There are three types of variable resistor. 1) Potentiometer 2) Rheostat 3) Trimmer Symbol of Variable resistor Types of Fixed resistor: 1) Carbon composition resistors: It is the most common type as they are cheap general purpose resistor. Their resistive element is manufactured from a mixture of finely ground carbon dust or graphite (similar to pencil lead) and non-conducting ceramic (clay) powder to bind it all together. Carbon composition resistors are low to medium power resistors with low inductance which makes them ideal for high frequency application but they can also suffer form noise and stability when heat is dissipated in temperature. 2) Carbon film and Metal film resistors: They are generally made by depositing pure metals, such as nickel or an oxide film, tin-oxide onto an insulating ceramic rod or substrate.

3 BASIC ELECTRONICS ENGINEERING 3 The resistive value of the resistor is controlled by increasing the desired thickness of the film and then by laser cutting a spiral helix groove type pattern into this film. It has much better temperature stability, low noise and is generally better for high frequency or radio frequency applications. 3) Wire wound resistors:- Wire wound resistor is made by winding a thin metal alloy wire (Nichrome) or similar wire onto on insulating ceramic former in the form of a spiral helix similar to the film resistors. These types of resistors are generally only available in very low ohmic high precision values (from 0.01 to 100Kohm) due to gauge of the wire and number of turns possible on the former making them ideal for use in measuring circuits and Wheatstone bridge type applications. Types of Variable resistor: 1) Potentiometer: A potentiometer (colloquially known as pot ) is a three terminal resistor with sliding contact that forms an adjustable voltage divider. Where, A and B fixed terminals W is the variable terminal 2) Rheostat: The most common way to vary the resistance in a circuit is to use a variable resistor or a rheostat. A rheostat is two terminal variable resistors. Symbol of Rheostat Actual picture of Rheostat They are designed to handle much higher voltage and current. Typically these are constructed as a resistive wire wrapped to form a toroid coil with the moving over the upper surface of toroid, sliding from one turn of the wire to next.

4 BASIC ELECTRONICS ENGINEERING 4 3) Trimmer: A trimmer is a miniature adjustable electrical component. It is called trimmer potentiometer or trimpots. Actual pictures of the trimmers. How to calculate the value of fixed resistor using colour code? There are four color bands which are painted on resistors. First band indicates first digit, second band indicate second digit and third band indicates the decimal multiplier. 1 st color band First digit 2 nd color band Second digit 3 rd color band Decimal multiplier 4 th color band Tolerance By using following table we can calculate the fixed resistors values. Capacitor An electric circuit element which is used to store charge temporarily, consisting in general of two metallic plates (conductors) separated and insulated from each other by a dielectric. Also called condenser. Symbol of Capacitor

5 BASIC ELECTRONICS ENGINEERING 5 When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. An ideal capacitor is characterized by a single constant value, capacitance, which is measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. Capacitors are widely used in electronic circuits to block the flow of direct current while allowing alternating current to pass, to filter out interference, to smooth the output of power supplies, and for many other purposes. They are used in resonant circuits in radio frequency equipment to select particular frequencies from a signal with many frequencies. Types of Capacitors: A) Fixed Capacitors: Types of fixed capacitors are: 1) Electrolytic capacitors: Aluminum Electrolytic Capacitors are polarized, and can be used in DC circuits. Typical values range form 0.1uF to 68000uF. Ideal for use in filtering and smoothing applications in power supplies. Also used for coupling and bypassing in audio circuits and as a timing element in non-critical circuits. They have a high reliability and low leakage. 2) Paper capacitor: In these paper is used as dielectric. They are used for high voltage and high current applications. Sometimes on surface of paper vapors deposition of Zn or Al metal is made to avoid separate winding of metal foil and paper. 3) Mica Capacitor: Natural mica has significant advantages. It is inert. It will not change physically or chemically with age and hence good temperature ability. a) Small mica capacitor b) Transmitting mica capacitors 4) Glass Capacitor: It is stable, durable and practically immune to temperature aging, voltage, moisture vibrations. Aluminum foil is used.glass is drawn to 1mm thick flexible layers of foil are interleaved and then leads are attached. Then assembly is fused at high temperature.

6 BASIC ELECTRONICS ENGINEERING 6 5) Ceramic Capacitors: These are manufactured in many shapes and sizes depending on applications. Dielectric material for this capacitor is high temperature sintered inorganic compound. Types of Ceramic capacitors are: 1] Disc ceramic capacitors 2] Tubular ceramic capacitors 3] Monolithic Ceramic Capacitors. 4] Button, Cart wheel, door knob ceramic capacitors. 6) Aluminum Electronic Capacitors: These are electro chemical devices. Two aluminum foils separated by insulting papers are wound into cylinder. The roll is impregnated with liquid electrolyte, stabilized. Other types of electrolytic capacitors are: 1] Tantalum electrolytic capacitors. 2] Tantalum foils electrolytic capacitors. 3] Wet slug Tantalum capacitors. 4] Solid electrolyte Tantalum capacitors. B) Variable Capacitors: Variable capacitors are mostly used in radio tuning circuits and they are sometimes called 'tuning capacitors', having very small capacitance values, typically between 100pF and 500pF (100pF = µF). Actual pictures of variable capacitor and trimmer with its symbols respectively.

7 BASIC ELECTRONICS ENGINEERING 7 How to calculate the value of Capacitor using number coding and colour coding? Most capacitors have numbers printed on their bodies to indicate their electrical characteristics. Some are indicated with XYZ J/K/M VOLTS V where XYZ represents the capacitance (calculated as XY x 10 Z ), the letters J, K or M indicate the tolerance (±5%, ±10% and ±20% respectively) and VOLTS V represents the working voltage. Example: A capacitor with the following text on its body: 105 K 330 V has a capacitance of 10 x 10 5 pf = 1µF (±10%) with a working voltage of 330 V. A capacitor with the following text: 473 M 100 V has a capacitance of 47 x 10 3 pf = 47 nf (±20%) with a working voltage of 100 V. A number code is often used on small capacitors where printing is difficult: The 1st number is the 1st digit, The 2nd number is the 2nd digit, The 3rd number is the number of zeros to give the capacitance in pf. Ignore any letters - they just indicate tolerance and voltage rating. For example: 102 means 1000pF = 1nF (not 102pF) For example: 472J means 4700pF = 4.7nF (J means 5% tolerance). It can be difficult to find the values of these small capacitors because there are many types of them and several different labeling systems. Many small value capacitors have their value printed but without a multiplier, so you need to use experience to work out what the multiplier should be! For example 0.1 means 0.1µF = 100nF. Sometimes the multiplier is used in place of the decimal point: For example: 4n7 means 4.7nF.

8 BASIC ELECTRONICS ENGINEERING 8 Color coding Sr. No. Color Significant digits Multipliers Capacitance tolerance Characte r-eristic DC working voltage Operating temperature 1 Black 0 1 ±20% 55 C to +70 C 2 Brown 1 10 ±1% B Red ±2% C 55 C to +85 C 4 Orange 3 1,000 D Yellow 4 10,000 E 55 C to +125 C 6 Green 5 ±5% F Blue 6 55 C to +150 C 8 Violet 7 9 Grey 8 10 White 9 11 Gold ±0.5%* Silver ±10% *Or ±0.5 pf, whichever is greater. A color code was used on polyester capacitors for many years. The colors should be read like the resistor code, the top three color bands giving the value in pf. Ignore the 4th band (tolerance) and 5th band (voltage rating).

9 BASIC ELECTRONICS ENGINEERING 9 For example: Brown, black, orange means 10000pF = 10nF = 0.01µF. For example: Wide red, yellow means 220nF = 0.22µF. (Note that there are no gaps between the color bands, so 2 identical bands actually appear as a wide band).inductor An inductor or a reactor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries. Typically an inductor is a conducting wire shaped as a coil, the loops helping to create a strong magnetic field inside the coil due to Faraday's Law of Induction. Inductors are one of the basic electronic components used in electronics where current and voltage change with time, due to the ability of inductors to delay and reshape alternating currents. Symbol of fixed inductor Types of Inductor: 1) Iron core Inductor: This classification includes chokes and transformers, both of which have laminated iron cores. A choke is a single winding and a transformer has two or more windings. Typical values of inductance for chokes range from 0.1 of a Henry to 50 henries. Lamination decreases eddy current losses. b) Air core Inductor: It consists of number of turns of wire wound on a former made of cardboard. Since air is inside the former, the inductor is called as air core inductor. The only adjustment available with air core inductors is by tapping all or part of a turn, or by varying the spacing between turns.

10 BASIC ELECTRONICS ENGINEERING 10 c) Ferrite core Inductor: By inserting a ferrite or iron dust core in a coil it is possible to double its inductance. If the core is threaded, its position within the coil can be varied to alter the inductance. This type of coil is used throughout the HF range, and into the VHF, for low-level signal circuits. Losses in the cores make them unsuitable for use in power circuits. Values range from a few micro henries to about a milli Henry. How to calculate the value of Inductor using color code? Some Radio Frequency chokes have their values indicated by a color code similar to that of resistors: Applications Filter chokes are used in smoothing pulsating current in rectifier. Audio frequency chokes are used to provide high impedance to audio frequencies. Radio frequency chokes are used to block the radio frequencies in communication systems. Switches The term "switch" typically refers to electrical power or electronic telecommunication circuits. In applications where multiple switching options are required (e.g., a telephone service), mechanical switches have long been replaced by electronic variants which can be intelligently controlled and automated.

11 BASIC ELECTRONICS ENGINEERING 11 In the simplest case, a switch has two pieces of metal called contacts that touch to make a circuit, and separate to break the circuit. There are different types of standard switches used in electronics. Type of Switch Circuit Symbol Example 1) ON-OFF Single Pole, Single Throw = SPST - A simple on-off switch. Such switches can be used to switch the power supply to a circuit. (ON)-OFF Push-to-make = SPST Momentary - A push-to-make switch returns to its normally open (off) position when you release the button, this is shown by the brackets around ON. This is the standard doorbell switch. ON-(OFF) Push-to-break = SPST Momentary- A push-to-break switch returns to its normally closed (on) position when you release the button. 2) ON-ON Single Pole, Double Throw = SPDT - This switch can be on in both positions, switching on a separate device in each case. It is often called a changeover switch. A SPDT toggle switch may be used as a simple on-off switch by connecting to COM and one of the A or B terminals shown in the diagram. ON-OFF-ON SPDT Centre Off- A special version of the standard SPDT switch. It has a third switching position in the centre which is off. Momentary (ON)- OFF-(ON) versions are also available where the switch returns to the central off SPST toggle switch Push-to-make switch Push-to-break switch SPDT toggle switch SPDT slide switch (PCB mounting) SPDT rocker switch

12 BASIC ELECTRONICS ENGINEERING 12 position when released. 3) Dual ON-OFF Double Pole, Single Throw = DPST- A pair of on-off switches which operate together, DPST switch is often used to switch mains electricity because it can isolate both the live and neutral connections. Dual ON-ON Double Pole, Double Throw = DPDT- A pair of on-on switches which operate together (shown by the dotted line in the circuit symbol). A DPDT switch can be wired up as a reversing switch for a motor as shown in the diagram. DPST rocker switch DPDT slide switch ON-OFF-ON DPDT Centre Off - A special version of the standard SPDT switch. It has a third switching position in the centre which is off. This can be very useful for motor control because you have forward, off and reverse positions. Momentary (ON)-OFF-(ON) versions are also available where the switch returns to the central off position when released. Wiring for Reversing Switch Special Switches Type of Switch Example 1) Push-Push Switch (e.g. SPST = ON-OFF) - This looks like a momentary action push switch but it is a standard on-off switch: push once to switch on, push again to switch off. This is called a latching action. 2) Micro switch (usually SPDT = ON-ON)-Micro switches are designed to switch fully open or closed in response to small

13 BASIC ELECTRONICS ENGINEERING 13 movements. They are available with levers and rollers attached. 3) Key switch - A key operated switch. The example shown is SPST. 4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid and when tilted this bridges the contacts inside, closing the switch. They can be used as a sensor to detect the position of an object. 5) Reed Switch (usually SPST) - The contacts of a reed switch are closed by bringing a small magnet near the switch. They are used in security circuits, for example to check that doors are closed. Standard reed switches are SPST (simple on-off) but SPDT (changeover) versions are also available. 6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of miniature SPST on-off switches; the example shown has 8 switches. The package is the same size as a standard DIL (Dual In-Line) integrated circuit. This type of switch is used to set up circuits, e.g. setting the code of a remote control. 7) Multi-pole Switch - The picture shows a 6-pole double throw switch, also known as a 6-pole changeover switch. It can be set to have momentary or latching action. Latching action means it behaves as a push-push switch, push once for the first position, push again for the second position etc. 8) Multi-way (Rotary) Switch - Multi-way switches have 3 or more conducting positions. (Several poles, contact sets). A popular type has a rotary action and it is available with a range of contact arrangements from 1-pole 12-way to 4-pole 3 way. Multi-way rotary switch 1-pole 4-way switch symbol

14 BASIC ELECTRONICS ENGINEERING 14 9) Tactile Switch These switches used in instruments keyboards. Connectors An electrical connector is a conductive device for joining electrical circuits together. The connection may be temporary, as for portable equipment, or may require a tool for assembly and removal, or may be a permanent electrical joint between two wires or devices. Connectors may join two lengths of flexible wire or cable, or may connect a wire or cable to an electrical terminal. There are hundreds of types of electrical connectors. Out of that some of the connecters given below: 1) Battery clips and holders The standard battery and battery holders such as the 6 AA cell holder shown. Battery holders are also available with wires attached, with pins for PCB mounting, or as a complete box with lid, switch and wires. 2) Terminal blocks and PCB terminals Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with a sharp knife, large wire cutters or a junior hacksaw. They are sometimes called 'chocolate blocks' because of the way they can be easily cut to size. PCB mounting terminal blocks provide an easy way of making semi-permanent connections to PCBs. PCB terminal block Terminal block

15 BASIC ELECTRONICS ENGINEERING 15 3) Crocodile clips The 'standard' crocodile clip has no cover and a screw contact. However, miniature insulated crocodile clips are more suitable for many purposes including test leads. Crocodile clips 4) 4mm plugs, sockets and terminals These are the standard single pole connectors used on meters and other electronic equipment. They are capable of passing high currents (typically 10A) and most designs are very robust. Plugs Plugs may have a screw or solder terminal to hold the cable. Sockets these are usually described as 'panel mounting' because they are designed to be fitted to a case. Terminals In addition to a socket these have provision for attaching a wire by threading it through a hole (or wrapping it around the post) and tightening the top nut by hand. 4mm terminal and solder tag 5) DC power plugs and sockets These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally reversed. The standard sizes are 2.1 and 2.5mm plug diameter. Standard plugs have a 10mm shaft, 'long' plugs have a 14mm shaft. 6) Jack plugs and sockets

16 BASIC ELECTRONICS ENGINEERING 16 These are intended for audio signals so mono and stereo versions are available. The sizes are determined by the plug diameter: ¼" (6.3mm), 3.5mm and 2.5mm. The 2.5mm size is only available for mono. ¼" (6.3mm) jack plug and socket 3.5mm jack plug and socket 3.5mm jack line socket (for fitting to a cable) 3.5mm jack plug and socket connections (the R connection is not present on mono plugs) L = left channel signal, R = right channel signal, COM = common (0V, screen) (Do not use jack plugs for power supply connections because the contacts may be briefly shorted as the plug is inserted. Use DC power connectors for this). 7) Phono plugs and sockets These are used for screened cables carrying audio and video signals. Stereo connections are made using a pair of phono plugs and sockets. 8) Coax plugs and sockets These are similar to the phono plugs and sockets described above but they are designed for use with screened cables carrying much higher frequency signals, such as TV aerial leads. They provide better screening because at high frequencies this is essential to reduce electrical noise.

17 BASIC ELECTRONICS ENGINEERING 17 Construction of a screened cable 9) BNC (Bayonet Neill-Concelman) plugs and sockets These are designed for screened cables carrying high frequency signals where an undistorted and noise free signal is essential, for example oscilloscope leads. BNC plugs are connected with a push and twist action, to disconnect you need to twist and pull. Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the cable's impedance. 11) D connectors These are multi-pole connectors with provision for screw fittings to make semi-permanent connections, for example on computer equipment. The D shape prevents incorrect connection. Standard D-connectors have 2 rows of contacts (top picture); 9, 15 and 25-way versions are the most popular. 12) IDC communication connectors These multi-pole insulation displacement connectors are used for computer and telecommunications equipment. They automatically cut through the insulation on wires when installed and special tools are required to fit them. They are available as 4, 6 and 8-way versions. They are called BT (British Telecom) connectors.

18 BASIC ELECTRONICS ENGINEERING 18 13) USB Connector The Universal Serial Bus is a serial bus standard to interface devices, founded in Relays A relay is an electrically operated switch. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and they are double throw (changeover) switches. Relays allow one circuit to switch a second circuit which can be completely separate from the first. For example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit. There is no electrical connection inside the relay between the two circuits, the link is magnetic and mechanical. Following figure shows a working of relay with its coil and switch contacts. You can see a lever on the left being attracted by magnetism when the coil is switched on. This lever moves the switch contacts. There is one set of contacts (SPDT) in the foreground and another behind them, making the relay DPDT. Circuit symbol for a relay Picture of a relay The relay's switch connections are usually labeled COM, NC and NO:

19 BASIC ELECTRONICS ENGINEERING 19 COM = Common, always connect to this; it is the moving part of the switch. NC = Normally Closed, COM is connected to this when the relay coil is off. NO = Normally Open, COM is connected to this when the relay coil is on. Connect to COM and NO if you want the switched circuit to be on when the relay coil is on. Connect to COM and NC if you want the switched circuit to be on when the relay coil is off. Advantages of relays: Relays can switch AC and DC, transistors can only switch DC. Relays can switch high voltages, transistors cannot. Relays are a better choice for switching large currents (> 5A). Relays can switch many contacts at once. Disadvantages of relays: Relays are bulkier than transistors for switching small currents. Relays cannot switch rapidly (except reed relays), transistors can switch many times per second. Relays use more power due to the current flowing through their coil. Relays require more current than many ICs can provide, so a low power transistor may be needed to switch the current for the relay's coil. Transformer A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core, and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is called mutual induction.

20 BASIC ELECTRONICS ENGINEERING 20 Symbol of transformer If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (V S ) is in proportion to the primary voltage (V P ), and is given by the ratio of the number of turns in the secondary (N S ) to the number of turns in the primary (N P ) as follows: By appropriate selection of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be "stepped up" by making N S greater than N P, or "stepped down" by making N S less than N P. Actual pictures of transformer Types of Transformer: 1) Step-up Transformer 2) Step-down Transformer

21 BASIC ELECTRONICS ENGINEERING 21 CONCLUSION: ***

22 BASIC ELECTRONICS ENGINEERING 22

23 BASIC ELECTRONICS ENGINEERING 23 Department of Electronics & Telecommunication. Experiment No. : 02 Date of Performance: Name of the student: Division: Roll No. : To Study Different Electronics Measuring Components AIM: a) Study of settings of DMM and Measurement of parameters like AC, DC voltage, current. b) Study of controls of CRO. Measurement of frequency, Phase, AC and DC Voltages using CRO. c) Study of controls of Function Generator a) Study of settings of DMM and Measurement of parameters like AC, DC voltages, currents. PREREQUISITE: Knowledge of different measuring instruments. Difference between AC, DC voltages and currents. Basic concept of diode and transistors. Internal construction of CRO and how it works. Use of function generator and power supply. Basic knowledge of different types of waveforms. OBJECTIVE: Use of DMM for measuring various types of components and parameters. Use of each and every control on front panel of CRO. Use of front panel control of function generator and power supply. EQUIPMENTS & COMPONENTS: 1) Digital Multimeter. 2) Connecting Probes. 3) Cathode Ray Oscilloscope. 4) Function Generator. 5) Power Supply. 6) Multimeter.

24 BASIC ELECTRONICS ENGINEERING 24 THEORY: Digital multimeters are usually referred to as "digital-multi-meters", abbreviated DMM. A multimeter can be a handheld device useful for basic fault finding and field service work or a bench instrument which can measure to a very high degree of accuracy. Such an instrument will commonly be found in a calibration lab and can be used to characterize resistance and voltage standards or adjust and verify the performance of multi-function calibrators. By using mentioned DMM we can measure resistance, AC, DC voltage and current and diode and transistor testing. Control Panels: 1) LCD Display: A 3 ½ digit display (maximum reading 1999) indicates measured values, and features symbols indicating ranges, low Battery. 2) Function Selector: To select ACV, DCV, ACA, DCA, RESISTANCE, Diode, Continuity &Transistor test. 3) Input Jacks: Test leads are inserted into these jacks for voltage, resistance, current measurements continuity and diode checks. 4) Input socket for transistor test: NPN or PNP transistors are inserted in the sockets provided to measure their ratings. PROCEDURE 1) Measuring voltage and current with DMM:- 1. Select a range with a maximum greater than you expect the reading to be. 2. Connect the meter, making sure the leads are the correct way round. Digital meters can be safely connected in reverse, but an analog meter may be damaged 3. If the reading goes off the scale: immediately disconnect and select a higher range 2) Testing diode with a DMM:- Digital multimeters have a special setting for testing a diode, usually labeled with the diode symbol.

25 BASIC ELECTRONICS ENGINEERING 25 Connect the red (+) lead to the anode and the black (-) to the cathode. The diode should conduct and the meter will display a value (usually the voltage across the diode in mv, 1000mV = 1V). Reverse the connections. The diode should NOT conduct this way so the meter will display "off the scale" (usually blank except for a 1 on the left). a=anode k=cathode Diodes 3) Testing a transistor with DMM:- Set a digital multimeter to diode test and an analog multimeter to a low resistance range such as 10, as described above for testing a diode. The base-emitter (BE) junction should behave like a diode and conduct one way only. The base-collector (BC) junction should behave like a diode and conduct one way only. The collector-emitter (CE) should not conduct either way. The diagram shows how the junctions behave in an NPN transistor. The diodes are reversed in a PNP transistor but the same test procedure can be used

26 BASIC ELECTRONICS ENGINEERING 26 FRONT PANEL CONTROLS: Measurements: 1. Resistance: 2. AC Voltage: 3. DC Voltage: 4. AC Current: 5. DC Current:

27 BASIC ELECTRONICS ENGINEERING 27 b) Study of controls of CRO. Measurement of frequency, Phase, AC and DC voltages using CRO. THEORY: The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides accurate time and amplitude measurements of voltage signals over a wide range of frequencies. Its reliability, stability, and ease of operation make it suitable as a general purpose laboratory instrument. The heart of the CRO is a cathode-ray tube shown schematically in Fig.1. The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode) and accelerated toward the fluorescent screen. The assembly of the cathode, intensity grid, focus grid, and accelerating anode (positive electrode) is called an electron gun. Its purpose is to generate the electron beam and control its intensity and focus. Between the electron gun and the fluorescent screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam and one pair oriented to give vertical deflection to the beam. These plates are thus referred to as the horizontal and vertical deflection plates. The combination of these two deflections allows the beam to reach any portion of the fluorescent screen. Wherever the electron beam hits the screen, the phosphor is excited and light is emitted from that point. This conversion of electron energy into light allows us to write with points or lines of light on an otherwise darkened screen.

28 BASIC ELECTRONICS ENGINEERING 28 FRONT PANEL DIAGRAM: FRONT PANEL CONTROLS: 1) Power ON / OFF: Push button switches for supplying power to instrument. 2) X & Y-POS: Controls horizontal & vertical position of the trace. 3) Time Base -VAR: controls the time speed in between two steps of TIME/DIV switch. For calibration put this fully anticlockwise. 4) X10 MAG: Switch when pushed gives 10 times magnification of the signal X. 5) XY: Switch when pressed cuts off the time base (XY Display) & allows access the ext. horizontal signal to be feed through CH2 6) CH-1/CH-2: Selects channel from Channel 1 and channel 2. 7) MONO/DUAL: Switch selects mono or dual trace operation. 8) ALT/CHOP/ADD: Switch selects alternate or chopped in DUAL mode. If mono is selected then this switch enable addition or subtraction of channel i.e. CH1 +/-CH2. 9) EXT.: Switch when pressed allows external triggering signal to be feed from the socket marked TRIG.INP. 10) LINE: switch when pressed display signal synchronized with mains line frequency. 11) ALT: Selects alternate trigger mode from CH1 & CH2. In this mode both the signal are synchronized. 12) LEVEL: Controls the trigger level from peak to peak amplitude of signal. 13) COMPONENT TESTER: Switch when pressed starts Component testing operation. 14) INTENS: Controls the brightness of the trace. 15) TR: Controls the alignment of the trace with latitude. 16) FOCUS: Controls the sharpness of the trace.

29 BASIC ELECTRONICS ENGINEERING 29 17) DC/AC/GD: Input coupling switch for each channel. In AC the signal is coupled through 0.1MFD capacitor. 18) CH1 & CH 2: BNC connectors serve as input connection for CH 1 and Ch 2. Channel 2 input connections also serve as Horizontal External Signal. 19) INV CH2: Switch when pressed invert polarity of CH2. 20) DIGITAL READOUT: LCD window for displaying digital readout for V/Div & Time/Div Settings. 21) VOLTS/DIV: Switch selects V/Div for channel 1 & 2. PROCEDURE: 1. DC Voltage Measurements: i) Adjust beam to reference level. ii) Keep AC/DC selector switch on DC position. iii) Apply test voltage to CRO input probe. iv) Measure the shift of beam from reference level. v) Calculate the DC voltage DC Voltage = No. of Divisions on Y-Axis * Volts/Div. 2. AC Voltage Measurements: i) Adjust beam to reference level. ii) Keep AC/DC selector switch on AC position. iii) Apply test voltage to CRO input probe. iv) Measure the peak to peak voltage. v) Calculate the AC voltage AC Voltage = No. of Divisions on Y-Axis * Volts/Div. 3. Frequency Measurements: i) Adjust beam to reference level. ii) Apply test voltage to CRO input probe. iii) Measure the time period required to complete one cycle. iv) Calculate the frequency Frequency = 1/ (No. of Divisions on X-axis *Time/Div.) 4. Phase Measurements: i) Adjust beam to reference level. ii) Apply test voltages to both CRO input channels. iii) Measure the difference between the two waves on X-axis (i. e. Δt). iv) Measure the time period required to complete one cycle of channel 1 (i.e. t1).

30 BASIC ELECTRONICS ENGINEERING 30 v) Calculate the Phase: Phase (Φ) = (Δt *180) / (t1) (Channel 2 is having the phase shift of Φ with channel - 1) Observation Table: Sr. No. Parameter Actual Value Observed Value 1 DC Voltage 2 AC Voltage 3 Frequency 4 Phase

31 BASIC ELECTRONICS ENGINEERING 31 c) Study of controls of Function Generator THEORY: A function generator is a device that can produce various patterns of voltage at a variety of frequencies and amplitudes. The electrical leads from the device are attached to the ground and signal input terminals of the device under test. FRONT PANEL CONTROLS: Front panel controls: Waveform key: Selects the waveform: sine, square and triangle. TTL activation: Activates TTL output. Numerical keys: Specifies frequency. Frequency unit selection: Specifies the frequency unit: MHz, khz or Hz Cursor selection: Moves the cursor (frequency editing point)left or right -40db attenuation: Attenuates amplitude by-40db. Frequency/Voltage display selection: Switches the display between frequency and voltage Shift key: Selects the 2 nd function associated to the entry keys. The LED lights when Shift is activated. Output On/Off key: Turns the output On/Off. The LED lights when the output is on. Frequency Editing knob: Increases (right turn) or decreases (left turn) the frequency. Main output Outputs sine, square and triangle waveform BNC 50 output impedance TTL output: Outputs TTL waveform.

32 BASIC ELECTRONICS ENGINEERING 32 Amplitude control: Sets the sine/square/triangle waveform amplitude Turn left (decreases)or right (increase). DC offset control: When pulled out, sets the DC offset level for sine/square/triangle waveform. Turn left (decrease) or right (increase).the range is-5v +5v, in 50 load. Duty cycle control: When pulled out, sets the square or TTL wave duty cycle Turn left (decrease)or right (increase). Power switch: Turns the main power On/Off. PROCEDURE: 1) Connect sine/square/triangular waveform from function generator to the C.R.O. 2) Take down the various observations by varying the various controls of function generator on C.R.O screen. 3) Plot the changes in waveform on graph paper CONCLUSION: ***

33 BASIC ELECTRONICS ENGINEERING 33 Department of Electronics & Telecommunication. Experiment No. : 03 Date of Performance: Name of the student: Division: Roll No. : Regulated Power Supply using Bridge Rectifier, Capacitor Filter And Three Terminal Regulator AIM: a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification. b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data sheet specifications. c) To measure voltages and observe waveforms at transformer secondary output of bridge rectifier output regulator. a) Identify pins of rectifier diode(such as 1N4001)and study of its data sheet specification. PREREQUISITE: Basics of diode, rectifier diode. Basics of voltage regulator Basics of transformer, Bridge rectifier. OBJECTIVE: To study working principle of rectifier diode. To study working of voltage regulators. To study & measure voltages & observe waveforms of transformer secondary output of bridge rectifier output regulator. EQUIPMENTS & COMPONENTS: 1) 1N ) Multimeter. 3) Trainer kit. 4) C.R.O. 5) C.R.O probes, connecting wires.

34 BASIC ELECTRONICS ENGINEERING 34 THEORY: 1N4001-1N4007 Figure a. Typical Diode. A diode is a two-terminal electronic component with asymmetric transfer characteristic, with low (ideally zero) resistance to current in one direction, and high (ideally infinite) resistance in the other. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p-n junction connected to two electrical terminals. Features Diffused Junction High Current Capability and Low Forward Voltage Drop Surge Overload Rating to 30A Peak Low Reverse Leakage Current Lead Free Finish

35 BASIC ELECTRONICS ENGINEERING 35 Figure b: Max.ratings of Electrical characteristics of 1N4001 Diode.

36 BASIC ELECTRONICS ENGINEERING 36 b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data sheet specifications. LM 78LXX: The LM78LXX series of three terminal positive regulators is available with several fixed output voltages making them useful in a wide range of applications. When used as a zener diode/resistor combination replacement, the LM78LXX usually results in an effective output impedance improvement of two orders of magnitude, and lower quiescent current. These regulators can provide local on card regulation, eliminating the distribution problems associated with single point regulation. The voltages available allow the LM78LXX to be used in logic systems, instrumentation, HiFi, and other solid state electronic equipment. The LM78LXX is available in the plastic TO-92 (Z) package, LM 78L05: Features LM78L05 in micro SMD package Output voltage tolerances of ±5% over the temperature range Output current of 100 ma. Internal thermal overload protection Output transistor safe area protection Internal short circuit current limit Available in plastic TO-92 and plastic SO-8 low profile packages No external components Output voltages of 5.0V, 6.2V, 8.2V, 9.0V, 12V, 15V

37 BASIC ELECTRONICS ENGINEERING 37 LM78L09: Figure c: Max.ratings of Electrical characteristics of LM78L05 Features: 3-Terminal Regulators Output Current Up to 100 ma. No External Components Required Internal Thermal-Overload Protection Internal Short-Circuit Current Limiting Direct Replacement for Motorola MC79L00

38 BASIC ELECTRONICS ENGINEERING 38 Theory: This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a wide range of applications. These include on-card regulation for elimination of noise and distribution problems associated with single-point regulation. In addition, they can be used to control series pass elements to make high-current voltage-regulator circuits. One of these regulators can deliver up to 100 ma of output current. The internal current-limiting and thermal-shutdown features make them essentially immune to overload. When used as a replacement for a zener-diode and resistor combination, these devices can provide emf current. Figure c: Max.ratings of Electrical characteristics of LM79L05

39 BASIC ELECTRONICS ENGINEERING 39 c) To measure voltages and observe waveforms at transformer secondary output of bridge rectifier output regulator. CIRCUIT DIAGRAM: THEORY: For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct current.during this time diodes D3 and D4 are reverse biased. For negative half cycle of the input voltage diodes D3 and D4 forward biased and conduct current.during this time diodes D1and D2 are reverse biased. Capacitor C1 and C2 are used as filter capacitor. IC 7805 is positive voltage regulator and Ic 7905 is negative voltage regulator. Capacitors C3 and C4 are required if the regulator is located at an appreciable distance from the power supply filter and capacitors C5 and C6 are used to improve the transient response of the regulator. PROCEDURE 1. Make the connections as shown in the circuit diagram. 2. Vary the load resistance and measure the corresponding load voltage and ripple voltage values. 3. Observe and study the output waveforms on CRO.

40 BASIC ELECTRONICS ENGINEERING 40 OBSERVATION TABLE: Without Filter With Filter Load Load Vm Load Load Vrpp Current Voltage (V) current Voltage (V) I L,(mA) V L,(V) I l, (ma) V l, (ma) CALCULATIONS:

41 BASIC ELECTRONICS ENGINEERING 41 CONCLUSIONS: ***

42 BASIC ELECTRONICS ENGINEERING 42

43 BASIC ELECTRONICS ENGINEERING 43 Department of Electronics & Telecommunication. Experiment No. : 04 Date of Performance: Name of the student: Division: Roll No. : Bipolar Junction Transistor (BJT) AIM: Single stage BJT Common Emitter amplifier: a. To identify pins of a BJT (BC547) and study of its data sheet & specifications. b. To measure voltages and observe waveforms at input and output terminals of single stage BJT Common Emitter amplifier circuit. c. Calculate voltage gain of the amplifier. PREREQUISITE: Basics of Bipolar Junction Transistor (BJT) & its biasing methods. Basics of gain of amplifier. OBJECTIVE: To study Characteristics and parameters of BJT. Equipments & COMPONENTS: 1) Transistor, 2) Bread Board, 3) Function Generator, 4) CRO, 5) CRO Probes, 6) Connecting Probes. a. Identify pins of a BJT (BC547) and study of its data sheet specifications. THEORY: Transistor is a three terminal active device made from different semiconductor materials that can act as either an insulator or a conductor by the application of a small signal voltage. The transistor's ability to change between these two states enables it to have two basic functions: Switching & amplification (analog electronics). There are two types of BJT

44 BASIC ELECTRONICS ENGINEERING 44 PNP transistor NPN transistor The Bipolar Junction Transistor s basic construction consists of two PN-junctions producing three connecting terminals with each terminal being given a name to identify it from the other two. These three terminals are known and labeled as the Emitter (E), the Base (B) and the Collector (C) respectively. The principle of operation of the two transistor types PNP and NPN, is exactly the same only difference is in their biasing and the polarity of the power supply for each type. The BJT construction is shown in figure1. (a) NPN Transistor Figure1.BJT Construction (b) PNP Transistor The middle region of each type is called the base of the transistor. This region is very thin and lightly doped. The process by which the impurities are added in a pure semiconductor is called doping. The remaining two regions are called emitter and collector. The emitter and collector are heavily doped. But the doping level in emitter is slightly greater than that of collector and the collector region area is slightly more than that of emitter. Relative doping levels in the base, emitter and collector junctions must be satisfied to work that device as a transistor. Two normal pn-junction diodes cannot satisfy this requirement. In figure1 the symbol of NPN and PNP transistors are shown. Arrow head on a transistor symbol indicate the conventional current which is opposite to the direction of electron current in emitter. The transistor has two pn-junctions. One junction is between the emitter and the base is called emitter-base junction or simply the emitter junction. The other junction is between the base and the collector and is called collector-base junction or simply collector junction.

45 BASIC ELECTRONICS ENGINEERING 45 Bipolar Transistors are current regulating devices that control the amount of current flowing through them in proportion to the amount of biasing voltage applied to their base terminal acting like a current-controlled switch. b. To measure voltages and observe waveforms at input and output terminals of single stage BJT Common Emitter amplifier circuit. THEORY: In CE-configuration input is applied between base and emitter, and output is taken from collector and emitter. Here, emitter of the transistor is common to both, input and output circuits, and hence the name common emitter configuration. CE-configuration for both NPN and PNP transistor are shown in figure2. Configurations: (a) NPN Transistor (b) PNP Transistor Figure2.CE-Configuration Circuit Diagram: As shown in figure 3.below the bias voltage V BB forward biases the base-emitter junction and V CC is used to reverse bias the collector-base junction. The input voltage in the CE-configuration is the base-emitter voltage and the output voltage is the collector-emitter voltage. The input current is I B and the output current is I C

46 BASIC ELECTRONICS ENGINEERING 46 Figure3.Transistor currents and voltages in CE-Configuration Characteristics of transistor in CE-Configuration: a. Input Characteristics It is the curve between input current I B (base current) and input voltage V BB (base-emitter voltage) at constant collector-emitter voltage, V CE. The base current is taken along Y-axis and V BB is taken along X-axis as shown in figure4. Figure4.Input Characteristics of the transistor in CE-Configuration From this characteristic we observe the following important points: 1. As the input to a transistor in the CE configuration is between the base-to- emitter junction, the CE input characteristics resembles a family of forward biased diode curves. A typical set of CE input characteristics for an npn transistor is shown in figure4. 2. For a fixed value of V BE, I B decreases as V CE is increased. A large value of V CE results in a large reverse bias at collector-base pn-junction. This increases the depletion region and reduces the effective width of the base. Hence there are fewer recombinations in the base region, reducing the base current I B. b. Output Characteristics 1. This characteristic shows the relationship between the collector current I C and collector

47 BASIC ELECTRONICS ENGINEERING 47 voltage V CE, for various fixed values of I B. This characteristic is often called collector characteristics as shown in figure5. Figure.5 Output characteristics of the transistor in CE configuration 2. The value of β dc of the transistor can be found at any point on the characteristics by taking the ratio I C to I B at that point. β dc = I C / I B 3. The output characteristics of CE configuration consists of three regions: a. Active Region - the transistor operates as an amplifier and I C = β dc.i B b. Saturation - the transistor is "fully-on" operating as a switch and Ic=I(saturation) c. Cut-off - the transistor is "fully-off" operating as a switch and Ic=0. PROCEDURE: a. Input Characteristics Give 10v from power supply 1 to the input side & 50mv from power supply 2 to the output side. Vary base current from 0 to 30µA in steps of 5µA by using the input pot & take corresponding V BE reading. Repeat the above step for V CE =100mv and V CE =150mv. Plot the graphs corresponding to these set of readings on the graph paper. b. Output Characteristics Apply 10v from power supply 1 to the input side & adjust I B using input pot to 0µA. Vary the output of power supply 2 i.e V CE in steps of 1v from 0 to 15v. Take corresponding I C reading. Repeat the above step for I B =5µA, 10µA &15µA.

48 BASIC ELECTRONICS ENGINEERING 48 Plot the graphs corresponding to these set of readings on the graph paper. OBSERVATION TABLE: a. Input Characteristics V CE I B µa V BE 50mv mv b. Output Characteristics I B V CE Ic µa 5 µa µa

49 BASIC ELECTRONICS ENGINEERING 49 c. Calculate voltage gain of the amplifier. THEORY: In electronics, gain is a measure of the ability of a circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output. It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. It may also be defined on a logarithmic scale, in tens of the decimal logarithm of the same ratio ("db gain"). A gain greater than one (zero db), that is, amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one. PROCEDURE: Voltage Gain Measurement: Apply V CC =9v. Adjust the AC input frequency to 10 KHz, and connect the source to the circuit. Observe the amplifier output on CRO. Adjust the AC input voltage so as to get maximum undistorted output. Calculate voltage gain A V = V O / V in. Draw the waveform for input and output on graph paper. OBSERVATION TABLE: i/p Voltage o/p Voltage A V = V O / V in db=20log 10 A V CONCLUSION:

50 BASIC ELECTRONICS ENGINEERING 50 ***

51 BASIC ELECTRONICS ENGINEERING 51 Department of Electronics & Telecommunication Experiment No. : 05 Date of Performance: Name of the student: Division: Roll No. : Operational Amplifier AIM: Op-amp based Summing amplifier and difference amplifier. a) Identify pins of an op-amp (such as LM 741) b) Implement given voltage equation for two inputs with Op-amp based Summing and Difference amplifier (such as V 0 = 2V 1 + 3V 2 ) and V 0 = 4V 1 V 2 ) PREREQUISITE: Knowledge of different parameters of op-amp. Brief description of Summing and Difference amplifier. OBJECTIVE: Pin Diagram of LM 741 Application of Summing and Difference amplifier. EQUIPMENTS & COMPONENTS: 1) IC 741 2) Bread board 3) Resistor (As Specified) 4) Connecting wires 5) D.C. Power supply (+12V) 6) C.R.O.

52 BASIC ELECTRONICS ENGINEERING 52 a) Identify Pins of an Op-amp LM 741. THEORY: The LM 741 is a high performance operational amplifier. The high gain and wide range of operating voltage provides superior performance in many applications. Pin No. Pin Pin description Abbreviation 1 OFFSET NULL (-) Offset voltage is the differential dc voltage required between the inputs to force the output to zero volts. Offset voltage is nulled by application of a voltage of opposite polarity to the offset. 2 INVERTED All input signals at this pin will be inverted at output pin 6. INPUT 3 NON- INVERTED All input signals at this pin will be processed normally without inversion. INPUT 4 V EE It is the negative supply voltage terminal. Desired operating range is -5V to -15V. 5 OFFSET Same as pin 1 except opposite polarity. NULL (+) 6 OUTPUT Output voltage polarity will be opposite to that of input terminal if the input signal is applied at op-amp s inverting point. 7 V CC It is the positive supply voltage terminal. It specified operation voltage range is +5V to +15 V. 8 N/C It stands for NO CONNECTION. Nothing is connected to this pin. It is just there to make it standard 8-pin package. \

53 BASIC ELECTRONICS ENGINEERING 53 CIRCUIT DIAGRAM: Fig 5.1 Symbol of Op-amp 741. Fig 5.2 Pin Diagram of Op-amp 741.

54 BASIC ELECTRONICS ENGINEERING 54 b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and difference amplifier THEORY: I: Summing Amplifier It has two or more inputs, and its output voltage is proportional to the negative of the algebraic sum of its input voltages. It is also called as summing inverter or Voltage adder. The amplifier is connected with feedback to produce a closed loop operation. CIRCUIT DIAGRAM: Fig. 5.3 Circuit diagram of Summing Amplifier Fig. 5.4 Circuit diagram of Summing Amplifier with N inputs.

55 BASIC ELECTRONICS ENGINEERING 55 Summing Amplifier Equation: Applying Kirchhoff s current equation at node A (which is virtual ground) I F = I 1 + I 2 Since V out = -I F R F V out = - (I 1 + I 2 ) R F V out = - ( ) If all the three resistors are equal (R 1 = R 2 = R F = R), then V out = - ( ) Vout = - (V in1 + V in2 ) General expression for unity gain summing amplifier with N inputs, General expression for gain greater than unity with N inputs, Vout = - ( ) PROCEDURE: Vout = ( ) 1. Make the connection for summing amplifier on breadboard as shown in the circuit diagram. 2. Apply 12 V dual supply to the summing amplifier. 3. Apply input voltages as V in1 = 2 mv and V in2 = 5 mv. 4. Measure the value of output voltage using DMM. OBSERVATION TABLE: PARAMETER THEORITICAL PRACTICAL Output voltage

56 BASIC ELECTRONICS ENGINEERING 56 CALCULATIONS: 1. Implement following equation using difference amplifier V out = - (10V 1 + 5V 2 ). 2. Given the value of R F = 10KΩ, Therefore V out = - ( ) 3. Calculate R 1 and R 2 using the equation: 4. From the equation of the output voltage, we obtain R 1 and R Implement the values obtained through calculation on the circuit and calculate theoretical as well as practical values of output voltage. II: Difference Amplifier For the subtraction of two input voltages or to amplify the difference between two voltages subtractor or Difference amplifier is employed. The output voltage is proportional to the difference between the two input voltages.

57 BASIC ELECTRONICS ENGINEERING 57 CIRCUIT DIAGRAM: Fig. 5.5 Circuit diagram of Difference amplifier. Difference Amplifier Equation: Applying Kirchhoff s current equation at node A (which is virtual ground) I F = I 1 + I 2 I 1 = I 2 = I F = ( ) V B = ( ) Summing point V A = V B If V B =0 then, V out(a) = -V 1 ( )

58 BASIC ELECTRONICS ENGINEERING 58 If V A = 0 then, V out (B) = -V 2 ( ) ( ) V out = V out(a) + V out(b) When Resistors R 1 = R 2, then Vout = -V 1 ( ) + V 2 ( ) ( ) Vout = ( ) PROCEDURE: 1. Make the connection for summing amplifier on breadboard as shown in the Fig Apply 12 V dual supply to the summing amplifier. 3. Apply input voltages as V in1 = 2mV and V in2 = 5 mv. 4. Measure the value of output voltage using DMM. OBSERVATION TABLE: PARAMETER THEORITICAL PRACTICAL Output voltage CALCULATIONS: 1. Implement following equation using summer amplifier V out = 4(V 1 - V 2 ). 2. Given the value R 1 = 1KΩ, R F = 4KΩ. Therefore Vout = ( )

59 BASIC ELECTRONICS ENGINEERING With the help of step 2 and step 3, we will implement the values obtained through calculation on the circuit and calculate theoretical as well as practical values of output voltage. CONCLUSION: ***

60 BASIC ELECTRONICS ENGINEERING 60

61 BASIC ELECTRONICS ENGINEERING 61 Department of Electronics & Telecommunication Experiment No. : 06 Date of Performance: Name of the student: Division: Roll No. : Timer IC 555 AIM: Study of Timer IC 555 circuit. a) Identify pins of Timer IC 555 b) Observe output waveform and measure frequency of output wave for Timer IC 555 used in Astable mode. PREREQUISITE: Knowledge of Timer IC 555. Knowledge of Astable Multivibrator along with derivation of duty cycle. OBJECTIVE: Pin Diagram of Timer IC 555 Working of Astable multivibrator. EQUIPMENTS & COMPONENTS: 1) Timer IC 555 2) Bread board 3) Resistor (As Specified) 4) Capacitor (As Specified) 5) Connecting wires 6) D.C.Power supply 7) C.R.O.

62 BASIC ELECTRONICS ENGINEERING 62 a) Identify Pins of TIMER IC 555. THEORY: The connection of the pins for a DIP package as follows: Pin Pin Pin description No. Abbreviation 1 GND Ground: All voltages are measured with respect to this terminal. 2 TRIG Trigger: it depends upon the amplitude of the external trigger pulse applied to this pin. If the voltage at this pin is greater than 2/3 V CC, output is LOW and if greater than 1/3 V CC then output is HIGH. 3 OUT Output: Load can be connected between pin 3 and pin 1(ground) or between pin 3 and pin 8 (Supply voltage) depending upon the nature of output whether high or low. 4 RESET Reset: Timer IC 555 can be reset (disabled) by applying negative pulse to this pin. If reset not in use, it should be connected to +V CC. 5 CTRL Control voltage: An external voltage applied to this pin changes the threshold as well as the trigger voltage. 6 THR Threshold: It is non inverting input terminal of comparator, which monitors the voltage across the external capacitor. 7 DIS Discharge: It is connected internally to the collector of transistor. 8 +V CC Supply Voltage: The positive supply voltage between +5V to +18V with respect to ground.

63 BASIC ELECTRONICS ENGINEERING 63 CIRCUIT DIAGRAM: Fig 6.1 Pin Diagram of TIMER IC 555. Fig 6.2 Internal diagram of TIMER 555 IC.

64 BASIC ELECTRONICS ENGINEERING 64 b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in Astable Mode. THEORY: Timer IC 555 is a timing circuit that can produce an accurate and highly stable time delays or oscillations. Its timing varies from microseconds to hours. It operates on +5V to + 18V supply voltage. The timer basically operates in one of the two modes either as Astable (Free Running) Multivibrator or as Monostable (one shot) Multivibrator. An Astable Multivibrator is a rectangular wave generating circuit. It does not require an external triggering pulse to change the state of the output. Hence the name Astable Multivibrator. The time during which output remains high is determined by external resistors R A and R B and capacitor C. Initially when output is high, the capacitor C starts charging towards +V CC through R A and R B. However as soon as voltage across capacitor reaches 2/3 V CC, upper comparator triggers the Flip-Flop and Output Switches low. Now Comparator C starts discharges through R B and internal discharge transistor. When voltage across capacitor reaches 1/3 V CC, Lower comparator triggers the Flip-Flip and output switches High. CIRCUIT DIAGRAM: Fig. 6.3 Circuit diagram of Astable multivibrator PROCEDURE: 1. Make the connection for Astable multivibrator on breadboard as shown in the circuit diagram with R A = 1K ohm, R B = 2Kohm and C= 0.1µF.

65 BASIC ELECTRONICS ENGINEERING Connect D.C. power supply of 5V.Connect CRO at the output terminals of 555 IC and measure the value of output frequency. 3. Sketch the waveforms on graph paper. Measure ON and OFF time periods of waveform on C.R.O. 4. Calculate the Frequency of Oscillations (f O ) practically and verify with theoretical frequency. OBSERVATION TABLE: PARAMETER THEORITICAL PRACTICAL t ON (µsec) t OFF (µsec) T (µsec) F O (KHz) CALCULATIONS: 1. The timing during which capacitor C starts charges from 1/3 Vcc to 2/3 Vcc (t C ), is equal the time when output is HIGH (t ON ). The t ON : Charge ON time. It is calculated as: t ON = t C = 0.69 (R A +R B ) C 2. The timing during which capacitor discharges from 2/3 Vcc to 1/3 Vcc(t d ) is equal to the time when output is HIGH (t OFF ). The t OFF : Discharge OFF time. It is calculated as: t OFF = t d = 0.69 (R B ) C 3. The total time period (T) of the output waveform is given by T = t ON + t OFF T= t C + t d = 0.69 (R A + 2R B ) C 4. The output frequency (f O ) of the output waveform is given as: f O = 1/T

66 BASIC ELECTRONICS ENGINEERING Duty cycle for the Astable multivibrator is the ratio of the ON time divided by the Total time (t ON + t OFF ). It can be calculated as: Duty cycle = t ON / (t ON + t OFF ) = R A + R B % R A + 2R B CONCLUSION: ***

67 BASIC ELECTRONICS ENGINEERING 67 Department of Electronics & Telecommunication Experiment No. : 07 Date of Performance: Name of the student: Division: Roll No. : Digital Circuits AIM: a) Identify pins of Digital Logic Gates ICs such as AND, OR, NOT, XOR, NAND. b) Implement Half & Full adder circuits with basic logic gate ICs. PREREQUISITE: Basic knowledge regarding digital circuits. Knowledge of various binary operations. OBJECTIVE: Identify pins of Digital Logic Gates. Practically building & testing half adder and full adder circuits. Verification of their respective truth tables. EQUIPMENTS & COMPONENTS: 1) ICs7408 (AND), 7432(OR), 7404(NOT), 7486(EX-OR), 7400(NAND), 7402(NOR) 2) Power Supply 3) Digital trainer Kit. 4) Connecting wires, etc

68 BASIC ELECTRONICS ENGINEERING 68 a) Identify pins of Digital Logic Gates ICs such as AND,OR,NOT,EX-OR,NAND. PIN DIAGRAMS: NOT GATE: Truth table:y=a Input Output A Y OR GATE: Truth table:y=a+b Inputs Output A B Y AND GATE: Truth table:y=a.b Inputs Output A B Y

69 BASIC ELECTRONICS ENGINEERING 69 NOR GATE: Truth table: Y=A+B Inputs Output A B Y NAND GATE: Truth table: Y=A.B Inputs Output A B Y EX-OR GATE: Truth table:a.b+a.b Inputs Output A B Y

70 BASIC ELECTRONICS ENGINEERING 70 b) Implement Half & Full adder circuits with basic logic gate ICs. THEORY: Binary Addition: In the binary number system we have only two digits 0 and 1. During the addition of two binary digits total four cases are involved. Let us have binary addition of these four cases as: 1) Sum 2) Sum 3) Sum 4) Carry 1 0 Sum Observe carefully these cases. What is your observation? We see here that Sum=0, When both inputs are equal (same) and Sum = 1 when inputs are unequal (not same). In digital electronics we come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal inputs. It is the exclusive-or (X-OR) gate. It means that X-OR gate has output equal to the sum of its inputs. But this addition is incomplete, because it does not produce proper carry as appeared in the last case. The careful observation for producing carry 1 is nothing but AND ing both inputs. Therefore the Boolean expression for sum and carry will be: Sum = A B Carry = A.B The Half Adder: Half adder is an electronic circuit which can add two binary digits and producing its sum with proper carry. From the above discussion it is clear that an X-OR gate and an AND gate is required for its construction. The fig. 1 shows half adder constructed from one X-OR and single AND gate. The half adder adds two binary digits, but it has a disadvantage that it is not useful during the addition two binary numbers having more than one binary digit. This is because if there is any carry produced during the addition of LSB, there is no provision for such carry in the addition of next LSB. So this circuit can add two single bit binary numbers only.

71 BASIC ELECTRONICS ENGINEERING 71 Circuit diagram for Half adder TRUTH TABLE FOR HALF ADDER: A B Sum Carry FULL ADDER: The full adder is a circuit which can add three binary bits. This circuit becomes essential during the addition of two binary numbers containing more than one bit. This is because the third input is useful carry generated in the addition of previous binary digits. Now look at the sum of three binary digits given below. There are total eight different possible combinations of inputs, but we will consider five of them which are quite illustrative = 0 where sum is 0 and carry is = 1 where sum is 1 and carry is = 10 where sum is 0 and carry is = 10 where sum is 0 and carry = 11 where sum is 1 and carry is 1. Basically we have a circuit to add the two binary digits called half adder. To add three bits, we will add the third bit in the addition of sum of the first two binary digits. Let us observe now what happens to this addition if we proceed in this manner.

72 BASIC ELECTRONICS ENGINEERING 72 The first case: No first carry No second carry 0 Therefore Final sum=0; but final carry = 0 The second case: No first carry : 1 Sum + 0 Sum Final Sum No second carry 1 Final Sum Therefore final Sum = 1; but final carry = 0 The third case: First carry 1: 0 Sum + 0 No second carry 0 final Sum Therefore final sum = 0; but final carry = 1 The fourth case: No first carry: Sum Second carry 1: 0 final Sum Therefore final sum = 0; but final carry = 1

73 BASIC ELECTRONICS ENGINEERING 73 The fifth case: First carry 1: Sum Second carry 1: 1 final Sum Therefore final Sum = 1; but final carry = 1 It is observed from these five different sum that, final sum is obtained by adding third bit in the sum of two bits and final carry is obtained by ORing the carries produced at two stages. Therefore the circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in following Figure. Circuit diagram for Full adder Sum = A B C Carry = A.B+AC+BC INPUT OUT PUT A B C Sum Carry

74 BASIC ELECTRONICS ENGINEERING 74 PROCEDURE Half Adder: 1) Select one EX-OR gate from IC 7486 and one AND gate from IC ) Connect A and B inputs to the inputs of two gates as shown in figure. 3) Connect output of both gates to logic indicators. 4) Connect supply wires to appropriate pins of each IC. 5) Connect both inputs A and B to ground switch on the power supply. 6) Note output from X-OR gate as sum of inputs A and B while output from AND gate as carry. 7) By changing inputs A and B complete the truth table from and observed output states for all possible combinations of inputs. Full Adder: 1) Select two EX-OR gate from IC 7486,two AND gate from IC 7408 one OR gate from IC ) Connect A and B inputs to the inputs of two gates as shown in figure. 3) Connect output of both gates to logic indicators. 4) Connect supply wires to appropriate pins of each IC. 5) Connect both inputs A and B to ground switch on the power supply. 6) Note output from X-OR gate as sum of inputs A and B while output from OR gate as carry. 7) By changing inputs A and B complete the truth table from and observed output states for all possible combinations of inputs. CONCLUSION:

75 BASIC ELECTRONICS ENGINEERING 75 Department of Electronics & Telecommunication Experiment No. : 08 Date of Performance: Name of the student: Division: Roll No. : Soldering Techniques AIM: Build and test an application circuit of IC such as Timer IC 555. Prepare a report on it. PREREQUISITE: Find an importance of soldering in any electronic application. Knowledge of good and bad soldering. OBJECTIVE: To study different soldering techniques. Procedure and precautions to be considered while soldering. EQUIPMENTS & COMPONENTS: 1) Soldering Iron, 2) Soldering Metal, 3) Flux, 4) Timer IC 555 4) DMM 5) C.R.O. THEORY: Theory for Soldering: What is solder? Solder is an alloy (mixture) of tin and lead, typically 60% tin and 40% lead. It melts at a temperature of about 200 C. Coating a surface with solder is called 'tinning' because of the tin content of solder. Lead is poisonous and you should always wash your hands after using solder. Solder for electronic components contains tiny cores of flux, like the wires inside a mains flux. The flux is corrosive, like an acid, and it cleans the metal surfaces as the solder melts. This is why you must melt the solder actually on the joint, not on the iron tip. Without flux most joints would fail because metals quickly oxidize and the solder itself will not flow properly into dirty, oxidized, metal surface. The best size of solder for electronics is 22swg (swg = standard wire gauge).

76 BASIC ELECTRONICS ENGINEERING 76 Reels of solder Flux: Flux reacts with or removes oxide and other contamination on the surface to be soldered. Dissolve the metal salts formed during the reaction with the metal oxides. Protect the surface from reoxidation before soldering occurs. Provide a thermal blanket to spread the heat evenly during soldering. Reduce the interfacial surface tension between the solder and the substrate in order to enhance wetting Flux provides several benefits: Cleans the base metal (copper trace) Protects the solder and base metal from oxidizing during the soldering process. Promotes wetting action of the melted solder Flux represents some trade offs: Can become entrained in the joint Is corrosive and so must be removed Soldering Techniques: To achieve a soldered joint, the solder and the base metal must be heated above the melting point of the solder used. The method, by which the necessary heat is applied, depends among other things on nature and type of the joint, melting temperature of the solder and flux.generally applied soldering methods are iron soldering, torch soldering, mass soldering, electrical soldering (high frequency soldering, resistance soldering), furnace soldering, and other methods. Here, we shall have a closer look at the iron soldering and the mass soldering. 1) Iron soldering 2) Mass soldering a. Dip soldering b. Wave soldering c. Drag soldering

77 BASIC ELECTRONICS ENGINEERING 77 PROCEDURE: Preparing the soldering iron: Place the soldering iron in its stand and plug in. The iron will take a few minutes to reach its operating temperature of about 400 C. Dampen the sponge in the stand. The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet. Wait a few minutes for the soldering iron to warm up. You can check if it is ready by trying to melt a little solder on the tip. Wipe the tip of the iron on the damp sponge. This will clean the tip. Melt a little solder on the tip of the iron. This is called 'tinning' and it will help the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron, and occasionally while soldering if you need to wipe the tip clean on the sponge. You are now ready to start soldering: Hold the soldering iron like a pen, near the base of the handle. Imagine you are going to write your name!. Remember to never touch the hot element or tip. Touch the soldering iron onto the joint to be made. Make sure it touches both the component lead and the track. Hold the tip there for a few seconds and... Feed a little solder onto the joint. It should flow smoothly onto the lead and track to form a volcano shape as shown in the diagram. Apply the solder to the joint, not the iron. Remove the solder, then the iron, while keeping the joint still. Allow the joint a few seconds to cool before you move the circuit board. Inspect the joint closely. It should look shiny and have a 'volcano' shape. If not, you will need to reheat it and feed in a little more solder. This time ensure that both the lead and track are heated fully before applying solder.

78 BASIC ELECTRONICS ENGINEERING 78 Good Soldering Bad Soldering Using a heat sink Some components, such as transistors, can be damaged by heat when soldering so if you are not an expert it is wise to use a heat sink clipped to the lead between the joint and the component body. You can buy a special tool, but a standard crocodile clip works just as well and is cheaper. Crocodile clip How to solder Actual components on board? Soldering Advice for Components It is tempting to start soldering components onto the circuit board straight away, but please take time to identify all the parts first. You are much less likely to make a mistake if you do this! 1. Stick all the components onto a sheet of paper using sticky tape. 2. Identify each component and write its name or value beside it. 3. Add the code (R1, R2, C1 etc.) if necessary. Many projects from books and magazines label the components with codes (R1, R2, C1, D1 etc.) and you should use the project's parts list to find these codes if they are given.

79 BASIC ELECTRONICS ENGINEERING Resistor values can be found using the resistor colour code which is explained on our Resistors page. You can print out and make your own Resistor Colour Code Calculator to help you. 5. Capacitor values can be difficult to find because there are many types with different labelling systems! The various systems are explained on our Capacitors page. For most projects it is best to put the components onto the board in the order given below: Components Pictures Reminders and Warnings 1 IC Holders (DIL sockets) Connect the correct way round by making sure the notch is at the correct end. Do NOT put the ICs (chips) in yet. 2 Resistors No special precautions are needed with resistors. 3 4 Small value capacitors (usually less than 1µF) Electrolytic capacitors (1µF and greater) These may be connected either way round. Take care with polystyrene capacitors because they are easily damaged by heat. Connect the correct way round. They will be marked with a + or - near one lead. 5 Diodes 6 LEDs 7 Transistors Connect the correct way round. Take care with germanium diodes (e.g. OA91) because they are easily damaged by heat. Connect the correct way round. The diagram may be labelled a or + for anode and k or - for cathode; yes, it really is k, not c, for cathode! The cathode is the short lead and there may be a slight flat on the body of round LEDs. Connect the correct way round. Transistors have 3 'legs' (leads) so extra care is needed to ensure the connections are correct. Easily damaged by heat.

80 BASIC ELECTRONICS ENGINEERING 80 Use single core wire, this is one solid wire 8 Wire Links between points on the circuit board. single core wire which is plastic-coated. If there is no danger of touching other parts you can use tinned copper wire, this has no plastic coating and looks just like solder but it is stiffer. Wires to parts off the circuit board, You should use stranded wire which is 9 including switches, relays, variable resistors stranded wire flexible and plastic-coated. Do not use single core wire because this will break when it is repeatedly flexed. and loudspeakers. De-soldering: At some stage you will probably need to desolder a joint to remove or re-position a wire or component. There are two ways to remove the solder: Using a desoldering pump (solder sucker) 1. With a desoldering pump (solder sucker) Set the pump by pushing the spring-loaded plunger down until it locks. Apply both the pump nozzle and the tip of your soldering iron to the joint. Wait a second or two for the solder to melt. Then press the button on the pump to release the plunger and suck the molten solder into the tool. Repeat if necessary to remove as much solder as possible. The pump will need emptying occasionally by unscrewing the nozzle.

81 BASIC ELECTRONICS ENGINEERING 81 With solder remover wick (copper braid) Solder remover wick Apply both the end of the wick and the tip of your soldering iron to the joint. As the solder melts most of it will flow onto the wick, away from the joint. Remove the wick first, then the soldering iron. Cut off and discard the end of the wick coated with solder. After removing most of the solder from the joint(s) you may be able to remove the wire or component lead straight away (allow a few seconds for it to cool). If the joint will not come apart easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling the joint apart, taking care to avoid burning yourself. Precautions: First a few safety precautions: Never touch the element or tip of the soldering iron. They are very hot (about 400 C) and will give you a nasty burn. Take great care to avoid touching the mains flux with the tip of the iron. The iron should have a heatproof flex for extra protection. An ordinary plastic flux will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock. Always return the soldering iron to its stand when not in use. Never put it down on your workbench, even for a moment! Work in a well-ventilated area. The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.