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project report on REMOTE SENSING THERMOMETER

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Ever since the invention of thermometer, various techniques have been developed and used to measure temperature of solid, liquid and gaseous matters. But none of these techniques could measure the …

Ever since the invention of thermometer, various techniques have been developed and used to measure temperature of solid, liquid and gaseous matters. But none of these techniques could measure the temperature from a remote place, which sometimes becomes a necessity particularly when the object under testis in a dangerous or inaccessible area. Presented here is a remote sensing thermometer to measure the temperature from a remote place.
The temperature of the object under test is sensed by a temperature sensor convert the sensed voltage into equivalent frequency by using a voltage-to frequency (V-F) converter and send the same to the remote end through a transmitter. At the remote end, a frequency-to-voltage (F-V) converter is used to retrieve the original signal from the received frequency-encoded signal for display or control process.
It can measure from -55°C to 150°C. In a properly calibrated system, meter reading should increase or decrease@ 10mV/°C. Therefore a 0.250V reading on the mV meter indicates 25°C temperature.

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  • 1. 1 A Project Report ON “REMOTE SENSING THERMOMETER” Submitted in partial fulfillment for the award of the Degree of Bachelor of Technology in Department of Electronics & Communication Engineering Submitted to: Submitted by: Ved Prakesh Yadav Vikas Yadav (10ESMEC094) Asst. Prof. EIC Vijay Singh Yadav (10ESMEC093) Sandeep Kumar (10ESMEC074) Department of Electronics and Communication Engineering SMEC Neemrana Rajasthan Technical University, Kota May, 2014
  • 2. 2 Department of Electronics & Communication Engineering St. Margaret Engineering College Neemrana, NH-8, Alwar, Rajasthan CERTIFICATE This is to certify that the Project titled “REMOTE SENSING THERMOMETER” submitted by Mr. VIKAS YADAV, VIJAY SINGH YADAV, SANDEEP KUMAR in partial fulfillment of the course work requirement for B.Tech. Program in the Department of Electronics & Communication Engineering, St. Margaret Engineering College Neemrana have been completed by him under my guidance and supervision. This Project Report has been found quite satisfactory. Head of Department Project Guide Rakesh Chauhan Ved Prakesh Yadav Asst. Prof. Asst. Prof. Department of ECE Department of EIC SMEC, Neemrana SMEC,Neemrana
  • 3. 3 ACKNOWLEDGEMENT The satisfaction and euphoria that accompany the successful completion of any task would be incomplete without the mentioning of the people whose constant guidance and encouragement made it possible. We take pleasure in presenting before you, our project, which is result of studied blend of both research and knowledge. We express our earnest gratitude to our internal guide, Assistant Professor Mr. VED PRAKASH YADAV Department of EIC. Our project guide and project lab assistant Mr. SURENDRA YADAV for his constant support, encouragement and guidance. We are grateful for his cooperation and his valuable suggestions. Vikas Yadav (10ESMEC094) Vijay Singh Yadav (10ESMEC093) Sandeep Kumar(10ESMEC074)
  • 4. 4 ABSTRACT Ever since the invention of thermometer, various techniques have been developed and used to measure temperature of solid, liquid and gaseous matters. But none of these techniques could measure the temperature from a remote place, which sometimes becomes a necessity particularly when the object under testis in a dangerous or inaccessible area. Presented here is a remote sensing thermometer to measure the temperature from a remote place. The temperature of the object under test is sensed by a temperature sensor convert the sensed voltage into equivalent frequency by using a voltage-to frequency (V-F) converter and send the same to the remote end through a transmitter. At the remote end, a frequency-to-voltage (F-V) converter is used to retrieve the original signal from the received frequency-encoded signal for display or control process. It can measure from -55°C to 150°C. In a properly calibrated system, meter reading should increase or decrease@ 10mV/°C. Therefore a 0.250V reading on the mV meter indicates 25°C temperature.
  • 5. 5 INDEX CONTENT……………………………………………………..PAGE NO. CERTIFI CATE ii ACKNOWLEDGEMENT iii ABSTRACT iv CHAPTER 1: INTRODUCTION 8-10 CHAPTER 2: LITERATURE SURVEY 11-12 CHAPTER 3: LM35 TEMPERATURE SENSER 13-15 3.1 Introduction 14 3.2 How does LM35 work’s 14 3.3 Features 15 CHAPTER 4: KA331 IC 16-17 4.1 Introduction 16 4.2: KA331 Internal Structure 16 4.3: Features 17 CHAPTER 5: CA3140 (op-amp IC) 18-22 5.1 Introduction 18 5.2 Internal Structure 19 5.3 Circuit Description 19 5.3.1 Input Stage 20 5.3.2 Second Stage 20
  • 6. 6 5.3.3 Output Stage 20 5.3.4 Bias Circuit 21 5.4 Features 22 CHAPTER 6: MC2TE (OPTO-COUPLER) 23-27 6.1 Introduction 23 6.2 Electric isolation 24 6.3 Types of Opto-Isolators 26 6.4 Application 27 CHAPTER 7: ASK MODULATION 28-32 7.1 Introduction 28 7.2 ASK Transmitter and Receiver Module(433MHz) 29 7.3 Characteristics of ASK Tx/Rx Module 32 7.4 Features 32 CHAPTER 8: VOLTAGE REGULATOR IC 33-36 8.1: Introduction 33 8.1.1 7805 IC 33 8.1.2 7905 IC 34 CHAPTER 9: TRANSISTOR 37-38 9.1 Introduction 37 9.2 BC547 38
  • 7. 7 CHAPTER 10: DIODE 39-43 10.1 Introduction 39 10.2 V-I Characteristics 39 10.3 1N4007 (Rectifier Diode) 42 10.3.1 Features 43 CHAPTER 11: LED (LIGHT EMITTING DIODE) 44-47 11.1 Introduction 44 11.2 Internal Description of LED 44 11.3 Advantages of using LEDs 46 11.4 Disadvantage of using LEDs 47 CHAPTER 12: SWITCH 48-49 12.1 Introduction 48 CHAPTER 13: RESISTOR 50-54 13.1 Introduction 50 13.2 Electronic symbols and notation 51 13.3 Theory of operation 52 13.4 Resistor color coding 53 CHAPTER 14: CAPACITOR 55-59 14.1 Introduction 55 14.2 Theory of operation 57 14.2.1 Energy of electric field 58 14.2.2 Current-voltage relation 58
  • 8. 8 CHAPTER 15: TRANSFORMER 60-62 15.1 Introduction 60 15,2 Working Principle of Transformer 61 15.2.1 Basic Theory of Transformer 61 CHAPTER 16: PROJECT DESCRIPTION 63-72 16.1 Introduction 63 16.2 Component used 63 16.3 Circuit Diagram 65 16.4 Working 66 16.5 Construction 68 16.6 Adjustment for Transmitter Unit 70 16.7 Adjustment for Receiver Unit 71 CONCLUSION 73 REFERENCE 74
  • 9. 9 LIST OF FIGURES SR. NO. NAME OF FIGURE…. …………………………………PAGE NO. 1.1 Block diagram of remote sensing thermometer 10 3.1 LM35 Temperature sensor 13 3.2 Basic Centigrade Temperature Sensor 14 3.3 Full-Range Centigrade Temperature Sensor 14 4.1 IC KA331 IC 16 4.2 Internal diagram of KA331 16 5.1 CA3140 (op-amp IC) 18 5.2 Internal Diagram of CA3140 IC 19 6.1 MC2TE IC 23 6.2 Electric isolation MC2TE IC 24 7.1 ASK Waveform 28 7.2 ASK Mathematical Notation 29 7.3 ASK Transmitter & Receiver Module 30 7.4 ASK Mathematical Notation Diagram 31 8.1 7805 IC 34 8.2 7905 IC 35 9.1 Transistor 37 9.2 BC547 Transistor 38
  • 10. 10 10.1 Diode Symbol 39 10.2 V-I Characteristics of Diode 41 10.3 1N4007 Rectifier Diode 42 11.1 Light Emitting Diode 44 11.2 Internal description of LED 45 11.3 Electronic Symbol of LED 46 12.1 Switches 48 13.1 Resistors 50 13.2 Electronic Symbols 51 13.3 Resistor color coding 53 14.1 Capacitors 55 14.2 Varieties of Capacitors 56 14.3 Theory of operation of capacitor 57 15.1 Transformer 60 15.2 Principle of Transformer 61 16.2 Transmitter Circuit 65 16.3 Receiver Circuit 66 16.4 An actual size, single side PCB for transmitter circuit 68 16.5 An actual size, single side PCB for Receiver circuit 69 16.6 Component layout for the Transmitter circuit 69 16.7 Component layout for Receiver circuit 70
  • 11. 11 LIST OF TABLES SR. NO. NAME OF TABLE…….…………………………………PAGE NO. 6.1 Types of opto isolator 26 13.1 Standard Resistor Color Code 54
  • 12. 12 Chapter 1 INTRODUCTION The temperature of the object under test is sensed by a temperature sensor IC LM 35 and temperature is converted into voltage and convert this sensed voltage into equivalent frequency by using a voltage-to frequency (V-F) converter and send the same to the remote end through a transmitter. At the remote end, a frequency-to-voltage (F-V) converter is used to retrieve the original signal from the received frequency-encoded signal for display the temperature in form of voltage. Temperature is measured by calibrating the voltage. Remote sensing thermometer is based on ASK modulation process, for this purpose ASK transmitter (433MHz) and ASK receiver (433MHz) is used. The transmitter power supply consists of step down transformer 230/9-0-9V(500mA). This transformer step down 230V AC to 9V AC. Now the 9V AC is converted into 9V DC with the help of bridge rectifier. After that 1000/25V capacitor is used to filter the ripples and then it passes through voltage regulator 7805 and 7905 which regulates it to 5V and -5V respectively. LED acts as the power indicator. To derive power supply for the receiver circuit, the 230V AC mains is stepped down by trans- former to deliver a secondary output of 9 V, 500 mA. The transformer output is rectified by a full-wave rectifier filtered by capacitor and regulated by IC 7805.LED acts as the power indicator. Transmitter: The temperature is sensed by a LM35. The resultant voltage developed at the output of the sensor cannot be sent to a remote destination through normal wired path as its magnitude is generally very low and would be highly attenuated during transit. One way to solve this problem is to convert the sensed voltage into equivalent frequency by using a voltage-to frequency (V-F) converter and send the same to the remote end through a transmitter.
  • 13. 13 Receiver: At the remote end, a frequency-to-voltage (F-V) converter is used to retrieve the original signal from the received frequency-encoded signal for display or control process. The circuit of the transmitter unit. It comprises temperature sensor LM35 (IC1), two CA3140 operational amplifiers (IC2 and IC3), voltage-to-frequency converter KA331 (IC4), opto-coupler MC2TE (IC5), 433MHz ASK transmitter, regulators 7805 (IC6) and 7905 (IC7), and a few discrete components. Temperature sensor IC1 develops a voltage at its output pin 2, which is equivalent to the temperature being sensed. It can measure from -55°C to 150°C. LED1 connected to pin 3 of IC1 raises its output by a few hundred millivolts. Thus the voltage obtained at the output is the sum of LED voltage and the sensed voltage. This voltage enhancement is required to transmit the frequency-encoded signal for 0°C and below-0°C temperatures. The output from IC1 is fed to input of the unity-gain inverting amplifier built around operational amplifier IC2. The output signal from pin 6 of IC2 is further fed to V-F converter section comprising an integrator wired around operational amplifier IC3 and V-F converter IC4. Integrator IC3 improves the V-F converter’s linearity in conversion process. The frequency encoded temperature data is then sent to transmitter module TX1 via opto-coupler IC5 and buffer transistor T1. Flickering of LED2 indicates ongoing V-F conversion. Power Supply: To derive power supply for the circuit, the 230V AC mains is stepped down by transformer X1 to deliver a secondary output of 9V-0-9V, 500 mA. The transformer output is rectified by a full- wave rectifier comprising diodes D1 through D4, filtered by capacitors C1 and C2, and regulated by ICs 7805 and 7905 (IC6 and IC7) for +5V and -5V, respectively. Capacitors C3 and C4 bypass ripples present in the regulated supply. Fig. 3 shows the receiver circuit. It comprises NAND gate IC 7400 (IC9), F-V converter KA331 (IC10), regulator 7805 (IC8), 433MHz ASK receiver module (RX1) and a few discrete components. RX1 is used to receive and demodulate the ASK-modulated RF signal transmitted from the transmitter unit. The demodulated output is a train of rectangular pulses as already explained in the transmitter section. Transistor T2 is used to
  • 14. 14 amplify and at the same time limit the amplitude of the pulse between 0 and 5 V. This TTL compatible output is then fed to IC9. The NAND gate helps to get perfectly rectangular wave shaped pulses. LED3 at pin 3 of IC9 flickers to indicate reception of the demodulated signal. The output of IC9 is also fed to F-V converter IC10 through capacitor C8. It generates a voltage equivalent to the frequency of the demodulated signal from receiver module RX1. To get the actual sensed signal voltage developed by sensor LM35, the voltage output at pin 1 of IC10 has to be reduced by a voltage equal to the reference voltage developed by LED1 of the transmitter unit. In order to do this, a stable voltage is first developed across LED4. The required reference voltage is then achieved by adjusting preset VR5. Preset VR5 is pre-adjusted during calibration to generate this reference voltage. To derive power supply for the receiver circuit, the 230V AC mains is stepped down by transformer X2 to deliver a secondary output of 9 V, 500 mA. The transformer output is rectified by a full-wave rectifier comprising diodes D6 through D9, filtered by capacitor C11 and regulated by IC 7805 (IC8). Capacitor C12 bypasses ripples present in the regulated supply. LED5 acts as the power indicator and R24 limits the current through LED5. Fig.1.1 Block diagram of remote sensing thermometer
  • 15. 15 Chapter 2 LITERATURE SURVEY Literature survey 1. Analysis and synthesis of Remote Sensing of Environment Temperature Department of Geography, University of Western Ontario, London, ON, Canada N6A 5C2 Date of Conference: 15 Aug 2003 Author(s): J.A Voogt and T.R Oke Volume: 86, Issue 3 Page(s):370-384 Product Type: Conference Publications Abstract Thermal remote sensing has been used over urban areas to assess the urban heat island, to perform land cover classifications and as input for models of urban surface atmosphere exchange. Here, we review the use of thermal remote sensing in the study of urban climates, focusing primarily on the urban heat island effect and progress made towards answering the methodological questions posed by Roth et al. [International Journal of Remote Sensing 10 (1989) 1699]. The review demonstrates that while some progress has been made, the thermal remote sensing of urban areas has been slow to advance beyond qualitative description of thermal patterns and simple correlations. Advances in the application of thermal remote sensing to natural and agricultural surfaces suggest insight into possible methods to advance techniques and capabilities over urban areas. Improvements in the spatial and spectral resolution of current and next-generation satellite-based sensors, in more detailed surface representations of urban surfaces and in the availability of low cost, high resolution portable thermal scanners are
  • 16. 16 expected to allow progress in the application of urban thermal remote sensing to the study of the climate of urban areas. Literature survey 2. Analysis and synthesis of Remote Sensing Device California Air Resources Board, Haagen-Smit Laboratory 9528 Telstar Avenue El Monte, CA 91734 Date of Conference: 26 Aug 2004 Author(s): Tom Austin, Sierra Research, Andrew D. Burnette, Eastern Research Group, Inc. Rob Klausmeier de la Torre Consulting, Inc. ERG No:187.00.002.001 Product Type: Conference Publications Abstract This report is intended to fulfill one objective (i.e., Task 2) of the Pilot Remote Sensing Study, specifically, to ―provide an organized synthesis and critical assessment of previous and current studies on relevant remote sensing programs. The information obtained from this task would be used to help answer the questions identified in Task 1, define research gaps, establish the need for further studies, and resolve controversies, if any.‖ If possible, research gaps, controversies, etc. would be resolved by performing the rest of the Pilot Remote Sensing Study. Remote sensing measurements can be used to identify some of the vehicles with excessive tailpipe emissions that should receive a Smog Check in the near future. Since whether a vehicle can be classified as a ―high emitter‖ or not depends upon the standards it was designed to meet, a ―high emitter‖ manufactured recently may actually emit much less than an older high emitter. Below certain emission levels, RSD’s ability to distinguish between a ―normal‖ emitter and a ―high‖ emitter is greatly diminished, so newer vehicles may be difficult for RSD to identify as being high emitters.
  • 17. 17 Chapter 3 LM35 TEMPERATURE SENSER 3.1 Introduction The LM35 is an integrated circuit sensor that can be used to measure temperature with an electrical output proportional to the temperature (in o C). The LM35 thus has an advantage over linear temperature sensors calibrated in ˚ Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. Fig.3.1 LM35 Temperature sensor 3.2 How does LM35 work’s It has an output voltage that is proportional to the Celsius temperature. The scale factor is .01 V/degree centigrade.
  • 18. 18 The LM35 does not require any external calibration or trimming and maintain an accuracy of +/- 0.4 degree centigrade. At room temperature. And +/- 0.8 degree centigrade over a range of degree centigrade to +100 degree centigrade. Another important characteristic of the LM35DZ is that it draws only 60 micro amps from its supply and possesses a low self-heating capability. The Sensor Self-Heating causes less than 0.1degree centigrade temperature rise in still air. Fig.3.2 Basic Centigrade Temperature Sensor Fig.3.3 Full-Range Centigrade Temperature Sensor
  • 19. 19 The LM35 datasheet specifies that this ICs are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in ˚ Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. 3.3 Features: It can measure temperature more accurately than a using a thermistor. The sensor circuitry is sealed and not subject to oxidation. The LM35 generates a higher output voltage than thermocouples and may not require that the output voltage be amplified. It has an output voltage that is proportional to the Celsius temperature. The scale factor is .01V/o C.
  • 20. 20 Chapter 4 KA331 IC 4.1 Introduction This voltage to frequency converter provides the output pulse train at a frequency precisely proportional to the applied input voltage. The KA331 can operate at power supplies as low as 4.0V and be changed output frequency from 1Hz to 100KHz. It is ideally suited for use in simple low-cost circuit for analog-to digital conversion, long term integration, linear frequency modulation or demodulation, frequency-to-voltage conversion, and many other functions. Fig.4.1 IC KA331 4.2 KA331 Internal Structure Fig. 4.2 Internal diagram of KA331
  • 21. 21 This IC works in two modes: Voltage to Frequency convertor Frequency to Voltage convertor 4.3 Features Guaranteed linearity: 0.01% max. Low power dissipation: 15mW at 5V Wide range of full scale frequency: 1Hz to 100KHz Pulse output compatible with all logic forms. Wide dynamic range: 100dB min at 10KHz full scale Frequency. Applications: Desktop Pc Mobile Handsets Graphics Card Broadband Modem `
  • 22. 22 Chapter 5 CA3140 (op-amp IC) 5.1 Introduction CA3140 is the 4.5MHz BiMOS Operational Amplifier with MOSFET inputs and bipolar output. This Op Amp combines the advantage of PMOS transistors and high voltage bipolar transistors. The CA3140A and CA3140 are integrated circuit operational amplifiers that combine the advantages of high voltage PMOS transistors with high voltage bipolar transistors on a single monolithic chip. The CA3140A and CA3140 BiMOS operational amplifiers feature gate protected MOSFET (PMOS) transistors in the input circuit to provide very high input impedance, very low input current, and high speed performance. The CA3140A and CA3140 operate at supply voltage from 4V to 36V (either single or dual supply). These operational amplifiers are internally phase compensated to achieve stable operation in unity gain follower operation, and additionally, have access terminal for a supplementary external capacitor if additional frequency roll-off is desired. Terminals are also provided for use in applications requiring input offset voltage nulling. The use of PMOS field effect transistors in the input stage results in common mode input voltage capability down to 0.5V below the negative supply terminal, an important attribute for single supply applications. The output stage uses bipolar transistors and includes built-in protection against damage from load terminal short circuiting to either supply rail or to ground. Fig. 5.1 CA3140 (op-amp IC)
  • 23. 23 5.2 Internal Structure Fig.5.2 Internal Diagram of CA3140 5.3 Circuit Description As shown in the block diagram, the input terminals may be operated down to 0.5V below the negative supply rail. Two class A amplifier stages provide the voltage gain, and a unique class AB amplifier stage provides the current gain necessary to drive low-impedance loads. A biasing circuit provides control of cascoded constant current flow circuits in the first and second stages. The CA3140 includes an on chip phase compensating capacitor that is sufficient for the unity gain voltage follower configuration.
  • 24. 24 5.3.1 Input Stage The schematic diagram consists of a differential input stage using PMOS field-effect transistors (Q9, Q10) working into a mirror pair of bipolar transistors (Q11, Q12) functioning as load resistors together with resistors R2 through R5. The mirror pair transistors also function as a differential-to-single-ended converter to provide base current drive to the second stage bipolar transistor (Q13). Offset nulling, when desired, can be effected with a 10kΩ potentiometer connected across Terminals 1 and 5 and with its slider arm connected to Terminal 4. Cascode- connected bipolar transistors Q2, Q5 are the constant current source for the input stage. The base biasing circuit for the constant current source is described subsequently. The small diodes D3, D4, D5 provide gate oxide protection against high voltage transients, e.g., static electricity. 5.3.2 Second Stage Most of the voltage gain in the CA3140 is provided by the second amplifier stage, consisting of bipolar transistor Q13 and its cascode connected load resistance provided by bipolar transistors Q3, Q4. On-chip phase compensation, sufficient for a majority of the applications is provided by C1. Additional Miller-Effect compensation (roll off) can be accomplished, when desired, by simply connecting a small capacitor between Terminals 1 and 8. Terminal 8 is also used to strobe the output stage into quiescence. When terminal 8 is tied to the negative supply rail (Terminal 4) by mechanical or electrical means, the output Terminal 6 swings low, i.e., approximately to Terminal 4 potential. 5.3.3 Output Stage The CA3140 Series circuits employ a broad band output stage that can sink loads to the negative supply to complement the capability of the PMOS input stage when operating near the negative rail. Quiescent current in the emitter-follower cascade circuit (Q17, Q18) is established by transistors (Q14, Q15) whose base currents are ―mirrored‖ to current flowing through diode D2 in the bias circuit section. When the CA3140 is operating such that output Terminal 6 is sourcing current, transistor Q18 functions as an emitter-follower to source current from the V+ bus (Terminal 7), via D7, R9, and R11. Under these conditions, the collector potential of Q13 is
  • 25. 25 sufficiently high to permit the necessary flow of base current to emitter follower Q17 which, in turn, drives Q18. When the CA3140 is operating such that output Terminal 6 is sinking current to the V- bus, transistor Q16 is the current sinking element. Transistor Q16 is mirror connected to D6, R7, with current fed by way of Q21, R12, and Q20. Transistor Q20, in turn, is biased by current flow through R13, zener D8, and R14. The dynamic current sink is controlled by voltage level sensing. For purposes of explanation, it is assumed that output Terminal 6 is quiescently established at the potential midpoint between the V+ and V- supply rails. When output current sinking mode operation is required, the collector potential of transistor Q13 is driven below its quiescent level, thereby causing Q17, Q18 to decrease the output voltage at Terminal 6. Thus, the gate terminal of PMOS transistor Q21 is displaced toward the V- bus, thereby reducing the channel resistance of Q21. As a consequence, there is an incremental increase in current flow through Q20, R12, Q21, D6, R7, and the base of Q16. As a result, Q16 sinks current from Terminal 6 in direct response to the incremental change in output voltage caused by Q18. This sink current flows regardless of load; any excess current is internally supplied by the emitter- follower Q18. Short circuit protection of the output circuit is provided by Q19, which is driven into conduction by the high voltage drop developed across R11 under output short circuit conditions. Under these conditions, the collector of Q19 diverts current from Q4 so as to reduce the base current drive from Q17, thereby limiting current flow in Q18 to the short circuited load terminal. 5.3.4 Bias Circuit Quiescent current in all stages (except the dynamic current sink) of the CA3140 is dependent upon bias current flow in R1. The function of the bias circuit is to establish and maintain constant current flow through D1, Q6, Q8 and D2. D1 is a diode connected transistor mirror connected in parallel with the base emitter junctions of Q1, Q2, and Q3. D1 may be considered as a current sampling diode that senses the emitter current of Q6 and automatically adjusts the base current of Q6 (via Q1) to maintain a constant current through Q6, Q8, D2. The base currents in Q2, Q3 are also determined by constant current flow D1. Furthermore, current in diode connected transistor Q2 establishes the currents in transistors Q14 and Q15.
  • 26. 26 5.4 Features: Very High Input Impedance (ZIN) -1.5TΩ (Typ) Very Low Input Current (Il) -10pA (Typ) at ±15V Wide Common Mode Input Voltage Range (VlCR) - Can be Swung 0.5V Below Negative Supply Voltage Rail. Output Swing Complements Input Common Mode Range.
  • 27. 27 Chapter 6 MC2TE (Opto-coupler IC) 6.1 Introduction The MCT2XXX series opto isolators consist of a gallium arsenide infrared emitting diode driving a silicon phototransistor in a 6-pin dual in-line package. MCT2 and MCT2E are also available in white package by specifying –M suffix, e.g. MCT2-M. The frequency-encoded temperature data is then sent to transmitter module via opto-coupler IC. Fig. 6.1 MC2TE An opto-isolator, also called an opto coupler, photo coupler, or optical isolator, is a component that transfers electrical signals between two isolated circuits by using light. Opto-isolators prevent high voltages from affecting the system receiving the signal. Commercially available opto-isolators withstand input-to-output voltages up to 10 kV and voltage transients with speeds up to 10 kV/μs.A common type of opto-isolator consists of an LED and a phototransistor in the same opaque package. Other types of source-sensor combinations include LED-photodiode,
  • 28. 28 LED-LASCR, and lamp-photo resistor pairs. Usually opto-isolators transfer digital (on-off) signals, but some techniques allow them to be used with analog signals. 6.2 Electric isolation Fig. 6.2 Electric isolation MC2TE IC Planar (top) and silicone dome (bottom) layouts - cross-section through a standard dual in-line package. Relative sizes of LED (red) and sensor (green) are exaggerated Electronic equipment and signal and power transmission lines can be subjected to voltage surges induced by lightning, electrostatic discharge, radio frequency transmissions, switching pulses (spikes) and perturbations in power supply. Remote lightning strikes can induce surges up to 10 kV, one thousand times more than the voltage limits of many electronic components. A circuit can also incorporate high voltages by design, in which case it needs safe, reliable means of interfacing its high-voltage components with low-voltage ones. The main function of an opto-isolator is to block such high voltages and voltage transients, so that a surge in one part of the system will not disrupt or destroy the other parts. Historically, this function was delegated to isolation transformers, which use inductive coupling between galvanic ally isolated input and output sides. Transformers and opto-isolators are the only two classes of electronic devices that offer reinforced protection they protect both the equipment and the human
  • 29. 29 user operating this equipment. They contain a single physical isolation barrier, but provide protection equivalent to double isolation. An opto-isolator connects input and output sides with a beam of light modulated by input current. It transforms useful input signal into light, sends it across the dielectric channel, captures light on the output side and transforms it back into electric signal. Unlike transformers, which pass energy in both directions with very low losses, opto-isolators are unidirectional (see exceptions) and they cannot transmit power. Typical opto-isolators can only modulate the flow of energy already present on the output side. Both transformers and opto-isolators are effective in breaking ground loops, common in industrial and stage equipment, caused by high or noisy return currents in ground wires. The physical layout of an opto-isolator depends primarily on the desired isolation voltage. Devices rated for less than a few kV have planar (or sandwich) construction. The sensordie is mounted directly on the lead frame of its package (usually, a six-pin or a four-pin dual in-line package). The sensor is covered with a sheet of glass or clear plastic, which is topped with the LED die. The LED beam fires downward. The optical channel is made as thin as possible for a desired breakdown voltage. For example, to be rated for short-term voltages of 3.75 kV and transients of 1 kV/μs, the clear polyimide sheet in the Avago ASSR-300 series is only 0.08 mm thick. Breakdown voltages of planar assemblies depend on the thickness of the transparent sheet and the configuration of bonding wires that connect the dies with external pins. Real in-circuit isolation voltage is further reduced by creepage over the PCB and the surface of the package. Opto-isolators rated for 2.5 to 6 kV employ a different layout called silicone dome. Here, the LED and sensor dies are placed on the opposite sides of the package; the LED fires into the sensor horizontally. The LED, the sensor and the gap between them are encapsulated in a blob, or dome, of transparent silicone. The dome acts as a reflector, retaining all stray light and reflecting it onto the surface of the sensor, minimizing losses in a relatively long optical channel. In double mold designs the space between the silicone blob ("inner mold") and the outer shell ("outer mold") is filled with dark dielectric compound with a matched coefficient of thermal expansion.
  • 30. 30 6.3 Types of opto-isolators Device type Source of light Sensor type Speed Current transfer ratio Resistive opto- isolator (Vactrol) Incandescent light bulb CdS or CdSephotoresistor (LDR) Very low <100%Neon lamp Low GaAs infrared LED Low Diode opto- isolator GaAs infrared LED Silicon photodiode Highest 0.1–0.2%[22] Transistor opto- isolator GaAs infrared LED Bipolar silicon phototransistor Medium 2–120%[22] Darlingtonphototransistor Medium 100–600%[22] Opto-isolated SCR GaAs infrared LED Silicon-controlled rectifier Low to medium >100%[23] Opto-isolated triac GaAs infrared LED TRIAC Low to medium Very high Solid-state relay Stack of GaAs infrared LEDs Stack of photodiodes driving a pair of MOSFETs or an IGBT Low to high[note 7] Practically unlimited Table6.1 Types of opto isolator
  • 31. 31 6.4 Application: Power supply regulators. Digital logic inputs. Microprocessor inputs. Coupling between transmitter and receiver.
  • 32. 32 Chapter 7 ASK MODULATION 7.1 Introduction Amplitude-shift keying (ASK) is a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave. In an ASK system ,binary symbol 1 is represented by transmitting carrier wave of fixed amplitude and fixed frequency for the bit duration T second. Fig. 7.1 ASK Waveform Three parameters specify a sinusoidal carrier wave: amplitude, frequency, and phase. An individual parameter or combination of parameters may be modulated by a message to communicate information. The most basic modulation schemes switch a single parameter between two values to signal a binary 0 or binary 1. In this project, construct and study a transmitter that switches the carrier wave's amplitude between zero and a non-zero value. The term switching is also called keying (as in a telegraph key), and so the transmitter in this project can be said to use binary amplitude shift keying (binary ASK).
  • 33. 33 Bandpass channels possess a non-zero lower cutoff frequency, and therefore cannot transmit a baseband signal. For example, the channel established between two voice-grade telephones begins at 300 Hz and ends at 3,000 Hz. A digital signal (baseband type) must be shifted in frequency so that its significant frequency components all exist within the 300 to 3,000 Hz range. Frequency shifting may be accomplished by impressing the baseband signal onto a sinusoidal carrier wave. A sinusoidal carrier wave c(t)=Ac cos(2πfct+ϕc) possesses three parameters that can be switched (or keyed) by a binary message signal: amplitude, frequency, and phase; the resulting digital continuous wave modulation schemes are called ASK (amplitude shift keying), FSK (frequency shift keying), and PSK (phase shift keying), respectively. Fig. 7.2 ASK Mathematical Notation 7.2 ASK Transmitter and Receiver Module (433MHz) We will be using ASK (Amplitude shifting keying) based Tx/Rx (Transmitter/Receiver) pair operating at 433 mhz. The transmitter module accepts serial data at a maximum of xx baud rate. It can be Directly interfaced with a microcontroller or can be used in remote control applications with the help of encoder/decoder ICs.
  • 34. 34 Fig. 7.3 ASK Transmitter & Receiver Module Any digital modulation scheme uses a finite number of distinct signals to represent digital data. ASK uses a finite number of amplitudes, each assigned a unique pattern of binary digits. Usually, each amplitude encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular amplitude. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the amplitude of the received signal and maps it back to the symbol it represents, thus recovering the original data. Frequency and phase of the carrier are kept constant.
  • 35. 35 Fig. 7.4 ASK Mathematical Notation Diagram The simple circuit consists of a transmitter/receiver pair and functions as an automobile antitheft alert system. The premise for the design is straightforward. You place the transmitter in a vehicle parked outside your home and leave the receiver in your house. When the vehicle leaves the area, this circuit sounds an alarm because the distance between the transmitter and receiver increases and the received power level falls below a predetermined level (threshold). The circuit is, in effect, warning of a potential auto theft. This circuit can also be applied to other applications for security purposes, such as securing USB flash drives or monitoring a child's presence. ASK transmitter system with a carrier frequency of 315MHz. IC1 is the ICM7555, a 555-based timer that provides a bilevel oscillation signal. IC2, the MAX1472 ASK transmitter, has an adjustable output power level of up to +10dBm. The encoder IC takes in parallel data which is to be transmitted, package it into serial format and then transmits it with the help of the RF transmitter module. At the receiver end the decoder IC receives the signal via the RF receiver module, decodes the serial data and reproduce the original data in the parallel format. Now in order to control say a dc motor, we require 2 bits of information (switching on/off) while we need 4 bits of information to control 2 motors. HT12E and HT12D are 4 channel encoder/decoder ICs directly compatible with the specified RF module.
  • 36. 36 7.3 Characteristics of ASK Tx/Rx Module: 7.4 Features: Frequency Range 433MHz Data Rate 8kbps Supply voltage +5V. Power supply and all input/output pins 0-5V. Non operating case temperature -20 to +85. Soldering temperature(10 seconds) 230.
  • 37. 37 Chapter 8 VOLTAGE REGULATOR IC 8.1 Introduction Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable output voltages. They are also rated by the maximum current they can pass. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current ('overload protection') and overheating ('thermal protection'). They include a hole for attaching a heat sink if necessary. 8.1.1 7805 IC: 7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels. The 7805 provides circuit designer with an easy way to regulate DC voltage to 5v. Encapsulated in a single chip/package(IC), the 7805 is a positive voltage DC regulator that has only 3 terminals. They are input voltage, Ground, Output voltage. Although the 7805 is primarily designed for a fixed-voltage output (5v), it is indeed possible to use external components in order to obtain Dc output voltages of : 5V, 6V, 8V, 9V, 10V, 12V, 15, 18V, 20V, 24V. Note :- The input voltage must, of course, be greater that the required output voltage, so it can regulated Downwards.
  • 38. 38 Fig. 8.1 7805 IC Features: Output Current up to 1 A Output Voltages: 5, 6, 8, 9, 10, 12, 15, 18, 24 V Thermal Overload Protection Short-Circuit Protection Output Transistor Safe Operating Area Protection LM78L05 in micro SMD package. Output voltage tolerances of +- 5% over the temp. range. Output current of 100ma. Internal thermal overload protection. Internal short circuit current limit. Available in plastic TO-92 and plastic SO-8 low profile package. No external components. 8.1.2 7905 IC: The LM79XX series of 3-terminal regulators is available with fixed output voltages of b5V, b8V, b12V, and b15V. These devices need only one external component a compensation capacitor at the output. The LM79XX series is packaged in the TO-220 power package and is
  • 39. 39 capable of supplying 1.5A of output current. These regulators employ internal current limiting safe area protection and thermal shutdown for protection against virtually all overload conditions. Low ground pin current of the LM79XX series allows output voltage to be easily boosted above the present value with a resistor divider. The low quiescent current drain of these devices with a specified maximum change with line and load ensures good regulation in the voltage boosted mode. Fig. 8.2 7905 IC The LM7905 three terminal negative voltage regulator IC is available in TO-220 package and with a fixed output voltage of -5 volt, making it useful in a wide range of applications. Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. Features: Thermal, short circuit and safe area protection High ripple rejection 1.5A output current 4% tolerance on preset output voltage Output Current in Excess of 1A
  • 40. 40 Output Voltages of -5V Internal Thermal Overload Protection Short Circuit Protection Output Transistor Safe Operating Area Compensation
  • 41. 41 Chapter 9 TRANSISTOR 9.1 Introduction A transistor is a semiconductor device used to amplify and switch electronic signalsand electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. It is of two type NPN and PNP, which are shown below in fig. Fig. 9.1 Transistor Transistors are commonly used as electronic switches, both for high-power applications such as switched-mode power supplies and for low-power applications such as logic gates. Advantages: Less power consumption. Small size and minimal weight, allowing the development of miniaturized electronic devices. Low operating voltages compatible with batteries of only a few cells.
  • 42. 42 No warm-up period for cathode heaters required after power application. Lower power dissipation and generally greater energy efficiency. Higher reliability and greater physical ruggedness. 9.2 BC547 BC547 is an NPN bi-polar junction transistor. A transistor, stands for transfer of resistance, is commonly used to amplify current. A small current at its base controls a larger current at collector & emitter terminals. Fig. 9.2 BC547 Transistor BC547 is mainly used for amplification and switching purposes. It has a maximum current gain of 800. Its equivalent transistors are BC548 and BC549. The transistor terminals require a fixed DC voltage to operate in the desired region of its characteristic curves. This is known as the biasing. For amplification applications, the transistor is biased such that it is partly on for all input conditions. The input signal at base is amplified and taken at the emitter. BC547 is used in common emitter configuration for amplifiers. The voltage divider is the commonly used biasing mode. For switching applications, transistor is biased so that it remains fully on if there is a signal at its base. In the absence of base signal, it gets completely off.
  • 43. 43 Chapter 10 DIODE 10.1 Introduction A diode is a two-terminal electronic component with asymmetric conductance, it has low (ideally zero) resistance to current flow in one direction, and high (ideally infinite) resistance in the other. The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction). Thus, the diode can be viewed as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, including extraction of modulation from radio signals in radio receivers—these diodes are forms of rectifiers Fig. 10.1 Diode Symbol 10.2 V-I Characteristics A semiconductor diode's behavior in a circuit is given by its current–voltage characteristic, or I– V graph (see graph below). The shape of the curve is determined by the transport of charge carriers through the so-called depletion layer or depletion region that exists at the p–n junction between differing semiconductors. When a p–n junction is first created, conduction- band (mobile) electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (vacant places for electrons) with which the electrons "recombine". When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor (dopant) on the N side and negatively charged acceptor
  • 44. 44 (dopant) on the P side. The region around the p–n junction becomes depleted of charge carriers and thus behaves as an insulator. However, the width of the depletion region (called the depletion width) cannot grow without limit. For each electron–hole pair that recombines, a positively charged dopant ion is left behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-doped region. As recombination proceeds more ions are created, an increasing electric field develops through the depletion zone that acts to slow and then finally stop recombination. At this point, there is a "built-in" potential across the depletion zone. If an external voltage is placed across the diode with the same polarity as the built-in potential, the depletion zone continues to act as an insulator, preventing any significant electric current flow (unless electron–hole pairs are actively being created in the junction by, for instance, light; see photodiode). This is the reverse bias phenomenon. However, if the polarity of the external voltage opposes the built-in potential, recombination can once again proceed, resulting in substantial electric current through the p–n junction (i.e. substantial numbers of electrons and holes recombine at the junction). For silicon diodes, the built-in potential is approximately 0.7 V (0.3 V for Germanium and 0.2 V for Schottky). Thus, if an external current passes through the diode, the voltage across the diode increases logarithmic with the current such that the P-doped region is positive with respect to the N-doped region and the diode is said to be "turned on" as it has a forward bias. The diode is commonly said to have a forward "threshold" voltage, which it conducts above and is cutoff. A diode's I–V characteristic can be approximated by four regions of operation: At very large reverse bias, beyond the peak inverse voltage or PIV, a process called reverse breakdown occurs that causes a large increase in current (i.e., a large number of electrons and holes are created at, and move away from the p–n junction) that usually damages the device permanently. The avalanche diode is deliberately designed for use in the avalanche region. In the Zener diode, the concept of PIV is not applicable. A Zener diode contains a heavily doped p–n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such
  • 45. 45 that the reverse voltage is "clamped" to a known value (called the Zener voltage), and avalanche does not occur. Both devices, however, do have a limit to the maximum current and power in the clamped reverse-voltage region. Also, following the end of forward conduction in any diode, there is reverse current for a short time. The device does not attain its full blocking capability until the reverse bias. Fig. 10.2 V-I Characteristics of Diode At reverse biases more positive than the PIV, has only a very small reverse saturation current. In the reverse bias region for a normal P–N rectifier diode, the current through the device is very low (in the µA range). However, this is temperature dependent, and at sufficiently high temperatures, a substantial amount of reverse current can be observed (mA or more).
  • 46. 46 With a small forward bias, where only a small forward current is conducted, the current– voltage curve is exponential in accordance with the ideal diode equation. There is a definite forward voltage at which the diode starts to conduct significantly. This is called the knee voltage or cut-in voltage and is equal to the barrier potential of the p-n junction. This is a feature of the exponential curve, and is seen more prominently on a current scale more compressed than in the diagram here. At larger forward currents the current-voltage curve starts to be dominated by the ohmic resistance of the bulk semiconductor. The curve is no longer exponential, it is asymptotic to a straight line whose slope is the bulk resistance. This region is particularly important for power diodes. The effect can be modelled as an ideal diode in series with a fixed resistor. 10.3 1N4007 (Rectifier Diode) This is a simple, very common rectifier diode. Often used for reverse voltage protection, the 1N4007 is a staple for many power, DC to DC step up, and breadboard projects. 1N4007 is rated for up to 1A/1000V Fig. 10.3 1N4007 Rectifier Diode
  • 47. 47 10.3.1 Features: Diffused Junction High Current Capability and Low Forward Voltage Drop Surge Overload Rating to 30A Peak Low Reverse Leakage Current
  • 48. 48 Chapter 11 LED (LIGHT EMITTING DIODE) 11.1 Introduction Fig.11.1 Light Emitting Diode A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Appearing as practical electronic components in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. 11.2 Internal Description of LED When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern.
  • 49. 49 Fig. 11.2 Internal description of LED LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output.
  • 50. 50 Fig.11.3 Electronic Symbol of LED Light-emitting diodes are used in applications as diverse as aviation lighting, automotive lighting, advertising, general lighting, and traffic signals. LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in really be advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances. 11.3 Advantages of using LEDs LEDs produce more light per watt. Than do incandescent bulbs; this is useful in battery powered or Energy saving device. LEDs can emit light of an intended color without the use of colour filters that traditional lighting methods require. This is more efficient and can lower initial costs. The solid package of LED can be designed to focus it’s light. Incandescent and florescent sources often require an external reflector to collect light and direct it in a usable manner. When use in application where dimming is require, LED’s do not change their colour tint as the current passing through them is lowered, unlike incandescent lamps, which turn yellow. LEDs are Ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting. LEDs being solid state components, are difficult to damage with external shock. Fluorescent and incandescent bulbs are easily broken if dropped on the ground.
  • 51. 51 LEDs have extremely long life span. One manufacturer has calculated the ETTF (Estimated Time To Failure) for their LEDs to be between 100,000 and 1,000,000 hour’s. Fluorescent tubes typically are rated at about 30,000 hours, and incandescent light bulbs at 1,000- 2,000 hours. 11.4 Disadvantages of using LEDs LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than more conventional lighting technologies. LEDs Performance largely depends on the ambient temperature of the operating environment. Driving an LED hard in high ambient temperature may result in overheating of the LED package. Eventually leading to device failure. Adequate heat- sinking is required to maintain long life. This is especially important when considering automotive, medical, and military applications where the device must operate over a large range of temperature, and are required to have a low failure rate. Voltage sensitivity.
  • 52. 52 Chapter 12 SWITCH 12.1 Introduction In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. Fig.12.1 Switches The momentary push-button switch is a type of biased switch. The most common type is a "push-to-make" (or normally-open or NO) switch, which makes contact when the button is pressed and breaks when the button is released. Each key of a computer keyboard, for example,
  • 53. 53 is a normally-open "push-to-make" switch. A "push-to-break" (or normally-closed or NC) switch, on the other hand, breaks contact when the button is pressed and makes contact when it is released. An example of a push-to-break switch is a button used to release a door held open by an electromagnet. The interior lamp of a household refrigerator is controlled by a switch that is held open when the door is closed. The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts. Each set of contacts can be in one of two states: either 'closed' meaning the contacts are touching and electricity can flow between them, or 'open', meaning the contacts are separated and non-conducting. A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. Automatically-operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another work piece. The common feature of all these usages is they refer to devices that control a binary state: they are either on or off, closed or open, connected or not connected.
  • 54. 54 Chapter 13 RESISTOR 13.1 Introduction A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element Fig.13.1 Resistors The current through a resistor is in direct proportion to the voltage across the resistor's terminals. This relationship is represented by Ohm's law: Where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. The ratio of the voltage applied across a resistor's terminals to the intensity of current in the circuit is called its resistance, and this can be assumed to be a constant (independent of the voltage) for ordinary resistors working within their ratings.
  • 55. 55 Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-chrome). Resistors are also implemented within integrated circuits, particularly analog devices, and can also be integrated into hybrid and printed circuits. The electrical functionality of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than nine orders of magnitude. When specifying that resistance in an electronic design, the required precision of the resistance may require attention to the manufacturing tolerance of the chosen resistor, according to its specific application. The temperature coefficient of the resistance may also be of concern in some precision applications. Practical resistors are also specified as having a maximum power rating which must exceed the anticipated power dissipation of that resistor in a particular circuit: this is mainly of concern in power electronics applications. Resistors with higher power ratings are physically larger and may require heat sinks. In a high-voltage circuit, attention must sometimes be paid to the rated maximum working voltage of the resistor. Practical resistors have a series inductance and a small parallel capacitance; these specifications can be important in high-frequency applications. In a low-noise amplifier or pre-amp, the noise characteristics of a resistor may be an issue. The unwanted inductance, excess noise, and temperature coefficient are mainly dependent on the technology used in manufacturing the resistor. 13.2 Electronic symbols and notation The symbol used for a resistor in a circuit diagram varies from standard to standard and country to country. Two typical symbols are as follows.
  • 56. 56 Fig.13.2 Electronic Symbols 13.3 Theory of operation Ohm's law The behavior of an ideal resistor is dictated by the relationship specified by Ohm's law: Ohm's law states that the voltage (V) across a resistor is proportional to the current (I), where the constant of proportionality is the resistance (R). Equivalently, Ohm's law can be stated:
  • 57. 57 This formulation states that the current (I) is proportional to the voltage (V) and inversely proportional to the resistance (R). Series and parallel resistors In a series configuration, the current through all of the resistors is the same, but the voltage across each resistor will be in proportion to its resistance. The potential difference (voltage) seen across the network is the sum of those voltages, thus the total resistance can be found as the sum of those resistances: Resistors in a parallel configuration are each subject to the same potential difference (voltage), however the currents through them add. The conductance of the resistors then add to determine the conductance of the network. Thus the equivalent resistance (Req) of the network can be computed: 13.4 Resistor color coding Fig.13.3 Resistor color coding
  • 58. 58 To distinguish left from right there is a gap between the C and D bands. Band A is first significant figure of component value (left side) Band B is the second significant figure Band C is the decimal multiplier Band D if present, indicates tolerance of value in percent (no band means 20%) For example, a resistor with bands of yellow, violet, red, and gold will have first digit 4 (yellow in table below), second digit 7 (violet), followed by 2 (red) zeros: 4,700 ohms. Gold signifies that the tolerance is ±5%, so the real resistance could lie anywhere between 4,465 and 4,935 ohms. The Standard Resistor Color Code Table 13.1 Standard Resistor Color Code
  • 59. 59 Chapter 14 CAPACITOR 14.1 Introduction A capacitor (originally known as condenser) is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator); for example, one common construction consists of metal foils separated by a thin layer of insulating film. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Fig.14.1 Capacitors Features: ceramic disc capacitor Linear temperature coefficient of capacitance. High Stability of capacitance. Low loss at wide range of frequency.
  • 60. 60 Specification Operating temp. range -25 to +85 degree centigrade. Rated working voltage DC 50V, 500v. Test Voltage 3 times of the rated voltage. Capacitance within the tolerance and Q-Factor at 1 Mhz, 1+- 0.2 Vrms.25 degree centigrade. Insulation Resistance 10,000 M ohm min. When there is a potential difference (voltage) across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. The capacitance is greatest when there is a narrow separation between large areas of conductor, hence capacitor conductors are often called "plates," referring to an early means of construction. In practice, the dielectric between the plates passes a small amount of leakage current and also has an electric field strength limit, resulting in a breakdown voltage, while the conductors and leads introduce an undesired inductance and resistance. Fig.14.2 Varieties of Capacitors
  • 61. 61 Practical capacitors are available commercially in many different forms. The type of internal dielectric, the structure of the plates and the device packaging all strongly affect the characteristics of the capacitor, and its applications. Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies, in electric power transmission systems for stabilizing voltage and power flow, and for many other purposes. 14.2 Theory of operation A capacitor consists of two conductors separated by a non-conductive region. The non- conductive region is called the dielectric. In simpler terms, the dielectric is just an electrical insulator. Examples of dielectric media are glass, air, paper, vacuum, and even a semiconductor depletion region chemically identical to the conductors. Fig.14.3 Theory of operation of capacitor A capacitor is assumed to be self-contained and isolated, with no net electric charge and no influence from any external electric field. The conductors thus hold equal and opposite charges on their facing surfaces, and the dielectric develops an electric field. In SI units, a capacitance of
  • 62. 62 one farad means that one coulomb of charge on each conductor causes a voltage of one volt across the device. The capacitor is a reasonably general model for electric fields within electric circuits. An ideal capacitor is wholly characterized by a constant capacitance C, defined as the ratio of charge ±Q on each conductor to the voltage V between them. Sometimes charge build-up affects the capacitor mechanically, causing its capacitance to vary. In this case, capacitance is defined in terms of incremental changes: 14.2.1 Energy of electric field Work must be done by an external influence to "move" charge between the conductors in a capacitor. When the external influence is removed the charge separation persists in the electric field and energy is stored to be released when the charge is allowed to return to its equilibrium position. The work done in establishing the electric field, and hence the amount of energy stored, is given by: 14.2.2 Current-voltage relation The current i(t) through any component in an electric circuit is defined as the rate of flow of a charge q(t) passing through it, but actual charges, electrons, cannot pass through the dielectric layer of a capacitor, rather an electron accumulates on the negative plate for each one that leaves the positive plate, resulting in an electron depletion and consequent positive charge on one electrode that is equal and opposite to the accumulated negative charge on the other. Thus the charge on the electrodes is equal to the integral of the current as well as proportional to the voltage as discussed above. As with any anti-derivative, a constant of integration is added to represent the initial voltage v (t0). This is the integral form of the capacitor equation,
  • 63. 63 Taking the derivative of this, and multiplying by C, yields the derivative form The dual of the capacitor is the inductor, which stores energy in a magnetic field rather than an electric field. Its current-voltage relation is obtained by exchanging current and voltage in the capacitor equations and replacing C with the inductance L.
  • 64. 64 Chapter 15 TRANSFORMER 15.1 Introduction A transformer is an electrical equipment that transfers energy by inductive coupling between its winding circuits. A varying current in the primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic flux through the secondary winding. This varying magnetic flux induces a varying voltage in the secondary winding. Transformers can be used to vary the relative voltage of circuits or isolate them, or both. Electrical Power Transformer is a static device which transforms electrical energy from one circuit to another without any direct electrical connection and with the help of mutual induction between two windings. It transforms power from one circuit to another without changing its frequency but may be in different voltage level. This is very short and simple definition of transformer, as we will go through this portion of tutorial related to Electrical Power Transformer, we will understand more clearly and deeply "what is transformer ?" and basic theory of transformer. Fig. 15.1 Transformer
  • 65. 65 15,2 Working Principle of Transformer Fig. 15.2 Principle of Transformer The working principle of transformer is very simple. It depends upon Faraday's law of electromagnetic induction. Actually mutual induction between two or more winding is responsible for transformation action in an electrical transformer. Faraday's Laws of Electromagnetic Induction: "Rate of change of flux linkage with respect to time is directly proportional to the induced EMF in a conductor or coil" 15.2.1 Basic Theory of Transformer Say you have one winding which is supplied by an alternating electrical source. The alternating current through the winding produces a continually changing flux or alternating flux surrounds the winding. If any other winding is brought nearer to the previous one, obviously some portion of this flux will link with the second. As this flux is continually changing in its amplitude and direction, there must be a change in flux linkage in the second winding or coil. According to
  • 66. 66 Faraday's law of electromagnetic induction, there must be an EMF induced in the second. If the circuit of the latter winding is closed, there must be an electric current flows through it. This is the simplest form of electrical power transformer and this is most basic of working principle of transformer.
  • 67. 67 Chapter 16 PROJECT DESCRIPTION 16.1 Introduction The temperature of the object under test is sensed by a temperature sensor IC LM 35 and temperature is converted into voltage, and convert this sensed voltage into equivalent frequency by using a voltage-to frequency (V-F) converter and send the same to the remote end through a transmitter. At the remote end, a frequency-to-voltage (F-V) converter is used to retrieve the original signal from the received frequency-encoded signal for display the temperature in form of voltage. Temperature is measured by calibrating the voltage. Remote sensing thermometer is based on ASK modulation process, for this purpose ASK transmitter (433MHz) and ASK receiver(433MHz) is used. The transmitter power supply consists of step down transformer 230/9-0-9V(500mA). This transformer step down 230V AC to 9V AC. Now the 9V AC is converted into 9V DC with the help of bridge rectifier. After that 1000/25V capacitor is used to filter the ripples and then it passes through voltage regulator 7805 and 7905 which regulates it to 5V and -5V respectively. LED acts as the power indicator. To derive power supply for the receiver circuit, the 230V AC mains is stepped down by trans- former to deliver a secondary output of 9 V, 500 mA. The transformer output is rectified by a full-wave rectifier filtered by capacitor and regulated by IC 7805.LED acts as the power indicator. 16.2 Component used: IC1 - LM35 temperature sensor IC2, IC3 - CA3140 operational amplifier IC4, IC10 - KA331 voltage-to-frequency converter
  • 68. 68 IC5 - MC2TE opto-coupler IC6, IC8 - 7805, 5V regulator IC7 - 7905 -5V regulator IC9 - 7400 NAND gate T1, T2 - BC547 NPN transistor D1-D9 - 1N4007 rectifier diode LED1-LED5 - 5mm LED TX1 - 433MHz ASK transmitter module RX1 - 433MHz ASK receiver module Resistors : R1 - 91-kilo-ohm R2-R4,R17 -100-kilo-ohm R5 - 2.2-kilo-ohm R6, R7, R9, R15, R18, R19, R22, R25, R26 - 10-kilo-ohm R8, R20 - 6.8-kilo-ohm R10, R14 - 1-kilo-ohm R11, R12, R13 - 3.3-kilo-ohm R16, R24 - 470-ohm R21 - 68-kilo-ohm R23 - 4.7-kilo-ohm VR1, VR2,VR4, VR5 - 10-kilo-ohm trim potmeter VR3 - 20-kilo-ohm trim potmeter Capacitors: C1, C2, C11 - 1000μF, 25V electrolytic C3, C4, C12 - 0.1μF ceramic disk C5, C7, C9 - 0.01μF ceramic disk C6, C10 - 1μF, 16V electrolytic C8 - 1nF ceramic disk Transformers: X1 - 230V AC primary to 9V-0-9V,500mA secondary transformer X2 - 230V AC primary to 9V, 500Ma secondary transformer
  • 69. 69 Fig.16.1 Block Diagram of Project 16.3 Circuit Diagram: Fig.16.2 Transmitter Circuit
  • 70. 70 Fig.16.3 Receiver Circuit 16.4 Working: The temperature of the object under test is sensed by a temperature sensor. The resultant voltage developed at the output of the sensor cannot be sent to a remote destination through normal wired path as its magnitude is generally very low and would be highly attenuated during transit. One way to solve this problem is to convert the sensed voltage into equivalent frequency by using a voltage-to frequency (V-F) converter and send the same to the remote end through a transmitter. At the remote end, a frequency-to-voltage (F-V) converter is used to retrieve the original signal from the received frequency-encoded signal for display or control process. Fig. shows the circuit of the transmitter unit. It comprises temperature sensor LM35 (IC1), two CA3140 operational amplifiers (IC2 and IC3), voltage-to-frequency converter KA331 (IC4), opto-coupler MC2TE (IC5), 433MHz ASK transmitter, regulators 7805 (IC6) and 7905 (IC7), and a few discrete components. Temperature sensor IC1 develops a voltage at its output pin 2, which is equivalent to the temperature being sensed. It can measure from -55°C to 150°C. LED1
  • 71. 71 connected to pin 3 of IC1 raises its output by a few hundred millivolts. Thus the voltage obtained at the output is the sum of LED voltage and the sensed voltage. This voltage enhancement is required to transmit the frequency-encoded signal for 0°C and below-0°C temperatures. The output from IC1 is fed to input of the unity-gain inverting amplifier built around operational amplifier IC2. The output signal from pin 6 of IC2 is further fed to V-F converter section comprising an integrator wired around operational amplifier IC3 and V-F converter IC4. Integrator IC3 improves the V-F converter’s linearity in conversion process. The frequency encoded temperature data is then sent to transmitter module TX1 via opto-coupler IC5 and buffer transistor T1. Flickering of LED2 indicates ongoing V-F conversion. To derive power supply for the circuit, the 230V AC mains is stepped down by transformer X1 to deliver a secondary output of 9V-0-9V, 500 mA. The transformer output is rectified by a full- wave rectifier comprising diodes D1 through D4, filtered by capacitors C1 and C2, and regulated by ICs 7805 and 7905 (IC6 and IC7) for +5V and -5V, respectively. Capacitors C3 and C4 bypass ripples present in the regulated supply. Fig. 3 shows the receiver circuit. It comprises NAND gate IC 7400 (IC9), F-V converter KA331 (IC10), regulator 7805 (IC8), 433MHz ASK receiver module (RX1) and a few discrete components. RX1 is used to receive and demodulate the ASK-modulated RF signal transmitted from the transmitter unit. The demodulated output is a train of rectangular pulses as already explained in the transmitter section. Transistor T2 is used to amplify and at the same time limit the amplitude of the pulse between 0 and 5 V. This TTL compatible output is then fed to IC9. The NAND gate helps to get perfectly rectangular wave shaped pulses. LED3 at pin 3 of IC9 flickers to indicate reception of the demodulated signal. The output of IC9 is also fed to F-V converter IC10 through capacitor C8. It generates a voltage equivalent to the frequency of the demodulated signal from receiver module RX1. To get the actual sensed signal voltage developed by sensor LM35, the voltage output at pin 1 of IC10 has to be reduced by a voltage equal to the reference voltage developed by LED1 of the transmitter unit. In order to do this, a stable voltage is first developed across LED4. The required reference voltage is then achieved by adjusting preset VR5. Preset VR5 is pre-adjusted during calibration to generate this reference
  • 72. 72 voltage. To derive power supply for the receiver circuit, the 230V AC mains is stepped down by transformer X2 to deliver a secondary output of 9 V, 500 mA. The transformer output is rectified by a full-wave rectifier comprising diodes D6 through D9, filtered by capacitor C11 and regulated by IC 7805 (IC8). Capacitor C12 bypasses ripples present in the regulated supply. LED5 acts as the power indicator and R24 limits the current through LED5. 16.5 Construction An actual-size, single-side PCB for the transmitter circuit is shown in Fig.16.4 and its component layout in Fig.16.6. PCB for the receiver circuit is shown in Fig.16.5 and its component layout in Fig.16.7. Assemble the circuits on PCBs to minimize time and assembly errors. Carefully assemble the components and double-check for any overlooked error. Use IC base and, before inserting the IC, check the supply voltage. Refer test points given in the table to check the circuit for proper functioning. For proper operation of the remote sensing thermometer, pre-adjustment of some components is necessary. Fig. 16.4 An actual size, single side PCB for transmitter circuit
  • 73. 73 Fig.16.5 An actual size, single side PCB for Receiver circuit Fig.16.6 Component layout for the Transmitter circuit
  • 74. 74 Fig.16.7 Component layout for Receiver circuit 16.6 Adjustment for Transmitter Unit Offset adjustment: Measure the voltage at TP3 with respect to ground by using a digital voltmeter. Disconnect R1 and short the inverting input to ground. Switch on the ±5V supply. Adjust preset VR2 to get 0V reading on the voltmeter. Gain adjustment: Operational amplifier IC2 acts as a unity-gain amplifier. Reconnect resistor R1. Connect pin 3 of IC1 directly to ground by shorting LED1. Keep sensor IC1 at a fixed temperature. If room temperature is constant, keep the sensor free to sense the room temperature. Measure output voltage of the sensor with a digital mV meter. Connect another digital mV meter to read the output voltage at TP3. Adjust preset VR1 to get the same voltage reading on TP3 but with negative polarity. If required, change the value of R1. V-F gain adjustment: The V-F converter should generate frequency in hertz exactly equal to the voltage input in millivolts. To get this, the gain of the V-F converter is to be adjusted. For this, connect a frequency counter between test point TP5 and ground, and a digital mV meter between
  • 75. 75 TP3 and ground. Adjust VR3 to get a frequency in Hz that is equal to the meter reading in mV. Sensor IC1 must be kept at a fixed temperature. 16.7 Adjustment for Receiver Unit F-V gain adjustment: The F-V converter should generate output voltage in millivolts exactly equal to the input frequency in Hz. To get this, the gain of the F-V converter is adjusted. To do this, connect a frequency counter to pin 3 of IC9 and a digital millivolt meter at pin 1 of F-V converter IC10. Switch on the transmitter and the receiver units. The frequency counter should display the frequency transmitted from the transmitter unit. LED3 connected to output pin 3 of the NAND gate indicates the incoming frequency signal. Adjust preset VR4 to get a mV reading on the voltmeter that equals the frequency in Hz displayed on the frequency counter. Adjustment of reference voltage: As already stated in the transmitter unit description, pin 3 of temperature sensor IC1 is raised above the ground potential by the reference voltage developed across LED1. At the receiver end, this voltage is to be subtracted to get the actual temperature- sense voltage developed by sensor IC1. To do this, connect the positive lead of the millivolt meter to pin 1 of F-V converter IC10 and negative lead of the meter to the rotary arm of preset VR5. Now adjust preset VR5 to get actual temperature on the meter’s screen. In a properly calibrated system, meter reading should increase or decrease @ 10mV/°C. Therefore a 0.250V reading on the mV meter indicates 25°C temperature. Final Project PCB To make the final project PCB firstly at the transmitter side we take wooden board then we place a transformer and transmitter PCB circuit on it. At the Receiver side we take a wooden board then we place transformer and Receiver PCB circuit on it. These Tx/Rx transmit and receive signal by ASK modulation, which have range up to 50ft. Working of project as described above section.
  • 76. 76 Fig.16.8 Actual PCB of Transmitter Unit Fig.16.9 Actual PCB of Receiver Unit
  • 77. 77 CONCLUSION Ever since the invention of thermometer, various techniques have been developed and used to measure temperature of solid, liquid and gaseous matters. But none of these techniques could measure the temperature from a remote place, which sometimes becomes a necessity, particularly when the object under test is in a dangerous or inaccessible area. Presented here is a remote sensing thermometer to measure the temperature from a remote place. The main scope of this project is to measure the temperature in industries where human can not reach. This project will monitor the temperature from remote area and show the temperature at receiver side in the form of voltage, with the help of calibration between temperature and voltage. We measure the temperature of the machine in industries at critical area where temperature of machine is not measured directly.
  • 78. 78 REFERENCE http://www.ehow.com/about_4697090_what-do-optocouplers-do.html#ixzz30M7ZnkHm http://www.efymag.com/previousissue.asp?month=June&year=2013&tot=1&id=12 “Analysis and synthesis of Remote Sensing of Environment Temperature” Department of Geography, University of Western Ontario, London, ON, Canada N6A 5C2,Author(s) : J.A Voogt and T.R Oke Volume: 86, Issue 3,Page(s):370-384 Product Type: Conference Publications http://www12.fairchildsemi.com/ds/KA/KA331.pdf http://multyremotes.com/DOWNLOAD/MCT2E.PDF http://www.intersil.com/content/dam/Intersil/documents/ca31/ca3140a.pdf “Analysis and synthesis of Remote Sensing Device” California Air Resources Board, Haagen-Smit Laboratory 9528 Telstar Avenue El Monte, CA 91734 Author(s) : Tom Austin, Sierra Research, Andrew D. Burnette, Eastern Research Group, Inc. Rob Klausmeier de la Torre Consulting, Inc. ERGNo.:187.00.002.001 Product Type: Conference Publications http://en.wikipedia.org/wiki/Voltage_regulator http://www.technologystudent.com/elec1/transis1.html http://en.wikipedia.org/wiki/Transformer http://letstalkaboutscience.wordpress.com/2012/05/28/how-resistors-and-capacitors- work/ http://www.allaboutcircuits.com/vol_4/chpt_4/1.html

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