Electronics as a Branch of Electrical Engineering - Essay Example

ELECTRONICS Electronics in general conversation is used with little idea of the meaning of the term or of its importance. Electronics is that branchof electrical engineering in which the circuit includes electronic devices, circuit's systems are only important because of the functions they provide and even then, the importance of a particular item depends on the relative cost, size, efficiency and reliability. It is possible that a new non-electronic technology might be discovered and makes the electronic stereo hafiz-system as dead and archaic as is the Edwardian today. In the ever developing technology of today, electronics is essential in many areas such as communications, automatic control, automation, computing and instrumentation. The function of the electronic parts in these systems is to receive input information, to process this information and then to produce an output. For example, in a computer, the input information is provided by pressing the buttons on a keyboard, the processing may involve arithmetic or comparison with previous information in a memory and the output will be a print out or a display on a video display unit. In another example, both input and output of a communications system may be sound such as words or music. In other areas such as instrumentation and control, these are many non-electronic systems widely used. Both power steering and servo assisted brakes in automobiles are usually non-electronic and mechanical clocks and watches still have a share of the market. Electronic systems are required to process or react to information. The information may have many forms, including physical quantities such as temperatures, velocity or mass, simple on/off information resulting from a switch being operated, or the highly concentrated and detailed information in speech, music and pictures. All these different forms of information have one common factor i.e. both amplitude and frequency may vary with time. This means that they can be illustrated by means of graphs and in many cases they can be defined as functions of time with mathematical expressions. Electronic circuit's can only react to information in the form of time-varying voltages and currents. We can conveniently refer to these forms of information as signals. There must therefore be some form of interface or converter between the real world and the electronic world. The interface may simply be a transducer for example; a microphone converts sound energy containing information into electrical energy in the form of a signal which contains the same information. An electronic system will have input signals from transducers and output signals which are reconverted by other transducers to produce energy in various required forms. Between these two processes, within the system there will be other signal forms. Lets quickly look at the function of electronic circuit any systems. And the function is to process signal, many different processes are possible and useful but, before considering a wide range of processes, it will be helpful to examine some simple system and to consider what type of processes may be required. A radio communication system: requires transmitting speech and music from a concert Hall to a place 100 miles away while other similar transmission is occurring in the same area. While the problems are: Alternating signals (A.C.) can result in radiated electromagnetic waves (radio signals) but signals at audio frequencies do not radiate efficiently. Also, as there would be similar transmissions in the same area, there would be interference as all the radiated signals would be received more or less equality. The solution use higher frequencies which can be radiated readily, in order to carry the signal information on these higher frequencies, use different high frequency carriers for each separate transmission to avoid interferences. The process required is: The minimum needed for a simple radio communication system can be represented in the block system. Let's look at am automatic washing machine. The requirement for this electronic is to fill a washing chamber with water and detergent, to raise and maintain the temperature of the water to a pre-selected level to agitate the water for a pre-selected time to remove the hot soiled water, to refill with cold water, agitate and replace several times to rotate the chamber at high speed for a pre-selected time and finally, to prevent opening of the chamber unless it is stationary and with no water in it. The solution is to operate the machine in a series of logically controlled states e.g. water ON, heater OFF, motor ON (agitating); water OFF, heater OFF, motor OFF, pump ON; etc. The sequence of states is to be predetermined by the chosen program. The duration of each state will be determined by sensor signals for temperature or water level and by a pre-selected timer. The process required is a major part of the system outlined consists of electrical and electromechanical components such as motors and heaters. These will be controlled by electromechanical or electronic relays which in turn will be operated by signals from an electronic controller. Other signals will be fed to the controller from temperature level sensors (transducers) and from manually selected inputs. The electronic controller must have a memory to know which state it is which state it must change to have a memory to know which state it is in which state it must change to (as a result of program signals) and when it is to change (as a result of sensor signals or a tuner). As the controller changes state, it must generate and direct control signals to the relays operating motors and heaters. Let's also look at a cathode rag oscilloscope. The requirement is to provide an automatic graphical display of time varying voltage signals to that their form may be inspected or measured. The solution is that a cathode ray to be (CRT) is a device having a screen, one point of which fluorescence (emits light) when it is struck by an electron beam from the rear. The point of impact of the electron beam can be moved either horizontally or vertically by suitable signals. The position of the point depends on the actual voltages applied a rapidly changing voltage results in a rapidly moving point of light. The result is a line of light, the shape of which is dependent on the voltage signals. Thus the required system will consist of a cathode ray tube with any associated circuits necessary for its operation together with circuits to process the signals that are to be measures or inspected. Let's quickly study about components and devices in electronics: Nearly all electronic circuits consist of interconnected passive components and electronic devices. The passive components are resistors, capacitors and inductors; these may be residual effects such as capacitance between conductors, inductance of wires or the resistance of a poor insulator. Passive components can be described by simple mathematical relationships, which are usually independent of signals associated with them. Electronic devices (e.g. diodes, transistors, thermion valves) can have many forms of which the most widely used are constructed from the semi conductor element silicon. Other devices use other semiconductors, insulators, magnetic materials and electrons passing between conductors mounted in a vacuum or in an inert gas. One common factor in their behaviour is that they cannot be described by simple mathematical relationships. Another factor in many devices is that the useful or required behaviour depends on the correct current levels in the device and on the correct voltage between the device terminals. These currents and voltages are known as the bias conditions. Additional properties: An electron circuit does not function in isolation; it requires signals to process and other circuits or transducers to which the processed signals can be applied. Additional circuit properties, the input and output impedances, may modify the input signal of limit the form of following circuits or transducers. The input impedance which appears between the pair of input terminals to which a signal is connected. This impedance may be a simple resistance at normal operating frequencies or it may be a simple resistance at normal operating frequencies or it may be complex and vary with signal frequency. It may also be very small, nearly a short circuit, very large or somewhere in between. The relative importance of this depends on the form of signal to be processed (voltage or current) and upon the internal impedance of the transducer or other circuit providing the signal if a voltage signal is being used, an input impendence. In some cases, maximum power transfer from source to circuit is describable; in such cases the input resistance should be the same as the source resistance. A similar situation arises when the signal is supplied by a transmission line, which has a property known as its characteristics impedance. It will then be essential to that the input impedance has the same value as this characteristics impedance, as otherwise the mismatch can cause signals to be reflected back along the transmission line, which may interfere with the correct operation of the other parts of the system. The output impedance of an electronic circuit is the effective interval impedance that is in series with the processed output signal. The relationship between this interval impedance and a following lead is the same as the relationship between the source impedance and input impedance described above. The whole combination is illustrated and is summarized below: If zing is large compared with Zs, the voltage signal will be maximum If zing is small compared with Zs, the current signal will be maximum If zing = Zs, the power supplied to the circuit will be maximum If Z1 is large compared with Z out, the voltage signal output will be maximum If Z1 is small compared with Z out the current signal output will be maximum If Z1 = Z out the signal power supplied to Z1 will be maximum. Let's look at signal limitation: The correct performance of an electronic circuit also depends upon the amplitude, frequency and waveform of the input signal for example, an amplifier might perform correctly, i.e. amplify or increase the signal amplitude by a factor of 200 for sinusoidal signals between 0.1mv and 20mv in amplitude. The resulting output waveform would be sinusoidal. An input signal of 40mv however, might produce an object of 6v (amplified by 150) and the wave form may be changed or distorted. With further increase in signal amplitude, the output saturated at perhaps 8v and appears to be square wave. At the other extreme, when the input is very small, the output shows electrical noise. This is random mixture of all frequencies (white noise) and has as average amplitude in the example pf perhaps 1mv at the output. An input signal of less than 5uv should produce an output of less than 1mv; since such an output cannot be separated from the noise, the amplifier does not perform correctly, at very small signals. The signal frequency and waveform are also important and only those in the correct range will be properly processed. Environmental limitations: The environment of an electronic circuit must include the electrical environment provided by the energy sources or power supplies mentioned above. With some circuits, the voltage or current levels of these power supplies is very critical. Other circuits are more tolerant and perform correctly with a wide range of power supply conditions. Other environmental factors include temperature, humidity, vibration and radiation. Most circuits will operate correctly within a comparatively wide range of these factors, but if this range is exceeded the resulting breakdown may well be catastrophic. Having elaborated on this few components in electricity will now move on to look at integrated circuits in electronics a broad perspective. The integrated circuit was introduced in 1958. It has been called the most significant technological development pf the twentieth century. Integrated circuits have allowed electronics to expand at an amazing rate. Most of the growth has been in the area of digital electronics. Developments in linear integrated circuits lagged behind those of digital 1cs for the first 10yrs or so. Lately, linear 1cs have received more attention and a broad variety of these types of devices is now available and more analogy functions are now achieved using digital technology. Electronics is growing rapidly for several reasons. One major reason is that electronics continues to advance in performance while the cost remains stable and decreases from time to time. Another reason for the growth in electronics is that circuits and systems have become increasingly reliable over the years. Integrated circuits have had much to do with these gains. Discrete circuits use individual resistors, capacitors, diodes, transistors and other devices to achieve the circuit function. These individual or discrete parts must be interconnected. The usual approach is to use a circuit board, assembly, soldering and testing all make up a p [art of the cost. Integrated circuit does not eliminate the need for circuit boards, soldering and testing. Make up a part of the cost. Integrated circuits do not eliminate the need for circuit boards, assembly, soldering and testing. However, with 1cs the number of discrete parts can be reduced. This means that the circuit boards can be smaller, often use less power, and that they will cost less to produce, it may also be possible to reduce the overall size of the equipment by using integrated circuits, which can reduce costs in the chassis and cabinet. Integrated circuits may lead to circuits that require fewer alignment steps at the factory. This is especially true with digital devices. Alignment is expensive and fewer steps mean lower costs. Also, variable components, and if some components can be eliminated, savings are realized. Integrated circuits may also increase performance. Certain 1cs work better than equipment discrete circuits. A good example is a modern integrated voltage regulator. A typical unit may offer 0.03 percent regulations excellent ripple and noise suppression, automatic current limiting and thermal shut down. An equivalent discrete regulator may contain dozens of parts cost six times as much and still not work as well. Reliability is related indirectly to the number of parts goes up, the reliability comes down. Integrated circuits make it possible to reduce the number of discrete parts in a piece of equipment. Thus, electronic equipment can be made more reliable by the use of more 1cs and fewer discrete components. Integrated circuits are available in variety pf package styles. Some of them are designed for surface-mount technology. The plastic quad flat package and the flat-pack, the pin grid array package and the leadless package can be used with sockets. The dual in-line package (DIP), it may have 14 or 16 pins. The mini-DIP is a shorter version of the dual in-line package. It has 8 pins. The To-5 package is available with 8, 10, or 12 pins. The To-3 and To-220 packages are mainly for voltage regulator 1cs. Their appearance can be identical to that of packages used for power transistor. This is a good example of how valuable services literate and part numbers are when a technician trouble shoots equipment for its first time. Positive component identification cannot be based on a visual check alone. Schematics seldom show any of the internal features for integrated circuits. A technician usually does not need to know circuit details for the inside of a 1c. It is more important to know what 1c is suppose to do and how it functions as a part of the overall circuit. The voltage regulator function is simple and straight forward. The voltage specifications are all that a technician would normally have to check to verify proper operation of the 1c. Finally, for the purpose of this project we would step here, however, electronics is a very wide and broad topic, you can't cover all in one day but this study is characterized by the basic things in electronics and what it is made up of. Let's quickly discuss and compare digital and analogue devices as there are very important subjects as we study electronics. And a very good classification is done here to understand what digital or analogue devices are this will prompt a better understanding about the distinct value between both of them. It is vitally important to understand what there are distinctly made and that will clarify everybody about the differences between both of them and also to understand the components that are in them this would help us understand how there function. And in conclusion and below is a classification made between a digital and an analogue device. 99. Digital & analogue voltmeters Digital Analogue Easier to read - greater accuracy due to greater amount of decimal places. Less accuracy. Needs batteries. Requires no batteries. Samples voltage about twice a second. Easier to read a changing voltage due to the continuous reading. Higher resistance (20M) Lower resistance (160K) Analogue means any value is possible. Digital means only 2 values are possible. These are normally referred to as 0 / 1, or on/off. Analogue devices Digital devices Light dependent resistor Car warning lights Thermometer Traffic lights Microphone Thermostat Loudspeaker Computer memory Television CD player 10. Logic - Digital electronics In digital electronics, there are only 2 levels: on or off. These are normally represented as a 0 for off & a 1 for on. It is also sometimes represented by true / false conditions. The actual values can be anything, such as 5V or 0V. We use logic in gates. We display the results in a truth table. REFERENCES Hamilton, D. J., Howard, W. G., Basic Integrated circuit. Engineering, McGraw Hill, N. J. 1976. Mill man, J., microelectronics: Digital and Analog circuits and systems, McGraw Hill, N. J., 1970. Shalimova K.V., physics of semi conductors. 2nd edition, Moscow, Energiya, 1976 (in Russia) Handbook of semi conductor Electron, CS, Edited by Hunter L. P., 3rd edition, McGraw Hill, 1970 Streetman B. G., solid state Electronic Devices, 2nd edition prentice Hall, 1980 Stepaneniko, I. P., Basic Theory of Transistors and Transistor circuits, 4th edition, Moscow, Energiya 1977 (in Russia) David, Tor; Understanding electronics Matus publishing house (1981) Shimannaiga, P., Basic Electronics (1979) Peter, Strongman; Electronics in a broad spectrum, 2nd edition (1986) Industrial Electronics, Frank D. Petroizella. Mathematics for Electronic: Principles and Applications, fifth Edition, Roger L. Tokheim How electronics works, 2nd edition (1989) David brunnel Communication Electronics, second Edition, Louis E. Frenzelo Enter training Electronics, fourth edition (1983) Muken publishing house. Read More