Summer Internship 2016Indian Institute of Technology,Delhi

MDIT Lab, Instrument Design Development Centre

Rajat Dwivedi UE144061

BE(Electrical & Electronics Engineering)University Institute of Engineering & Technology,

Panjab University,Chandigarh

undergone at

The Indian Institute of Technology Delhi (abbreviated IIT Delhi or IITD) is a public research university located in Delhi, India. It was declared to be Institute of National Importance by Government of India under Institutes of Technology Act. IIT Delhi is one of the two educational institutes in India which have been listed in Quacquarelli Symonds’ (QS) list of top 200 universities globally in 2015.

The Instrument Design Development Centre (IDD Centre) was set up in 1970. The Centre, interdisciplinary in nature, is engaged in design and development of instruments and other industrial and consumer products. It runs a postgraduate programme in Instrument Technology and is also actively involved in the teaching of an interdisciplinary M.Des. programme in Industrial Design. The Centre has expert faculty and specialised facilities in the disciplines of Electronics, Industrial Design, Mechanical and Optical instrumentation. The Centre also supports many doctoral students working in these areas of competence.

IDDC- IIT Delhi

I take this opportunity to express my sincere thanks and deep gratitude to all those people who extended their whole hearted co-operation and have helped me in completing this project successfully. I’d like to express my sincere gratitude towards Prof. D.T.Shahani for allowing me to work in MDIT Lab as a Summer Trainee. Special thanks to my training mentor Masood Sir for all the help and guidance extended to me by him in every stage during my training. Their inspiring suggestions and timely guidance enabled me to perceive the various aspects of the project in a new light. I would also like to thank all senior members, students and workers of MDIT Lab for guiding and encouraging me throughout the duration of the project. I am highly grateful to Professor Renu Vig, Director, UIET, Panjab University, Chandigarh , for providing me this opportunity to carry out four weeks of vocational training at Indian Institute of Technology, Delhi. I take immense pleasure in thanking our Head of Department Mr. Y.P. Verma and all the teachers in Electrical and Electronics Engineering Department for providing me with a wonderful platform to improve my technical skills.

Rajat DwivediUIET Panjab University,Chandigarh

Acknowledgement

Works done on:REGULATED POWER SUPPLIES: 1. Op Amp based Regulated power supply 2. Three Terminal Regulators 3. Regulator IC Chips

555 TIMER: 1. 555 Timer descriptions:a) Monostable b) Astable

555 based Projects 1. Police light circuit 2. Voltage doubler circuit 3. Traffic light control using timer circuit 4. Dummy alarm 5. PWM LED Dimmer using 555 timer

I. Regulated Power Supplies

1. Op Amp based Regulated power supply 2. Three Terminal Regulators 3. Regulator IC Chips

1. Op Amp based Regulated power supply:

Rectifier diodes D1 and D2 along with capacitor C1 provide the main unregulated supply. D3, C2, R8 and zener diode provide a negative voltage supply for the 741. The non-inverting input terminal of 741 is given a stable voltage by R3 which is the control to set the output. A fraction of the regulated output is fed back via R4 and R5 to the inverting input terminal. The operational amplifier adjusts its output voltage so as to keep the voltage at the input terminals equal. Thus the output gets regulated. The output of 741 is amplified by a compound emitter follower T1 and T2. All the current flows through R6. If the load current exceeds 1A, the voltage drop across R6 exceeds 0.6 volts and T3 starts conducting. This bypasses the supply to T1 and T2 and the regulating action stops. The output voltage therefore starts falling when the load current exceeds 1A. Any of the output terminals can be grounded to get a positive or a negative voltage with respect to the ground.

Circuit Diagram for Op-Amp based regulated power supply

2. Three Terminal Regulators :

Voltage regulation is the process of holding a voltage steady under conditions of changing applied voltage and changing load current. Many electronic systems require a stable power supply voltage and use voltage regulators to accomplish that. The purpose of a voltage regulator is to maintain a constant voltage across a load regardless of variations in the applied input voltage and variations in the load current. A voltage regulator is designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feed-forward" design or may include negative feedback control loops. There are two types of voltage regulators, shunt and series. The name comes from where the control element (typically a transistor) is placed. Except for the special case of a Zener diode shunt regulator which is open-loop, virtually all voltage regulators are closed loop high-gain proportional control systems.

3. Regulator IC Chips :

An IC regulator provides very precise regulation of output voltage for both line and load variations. This unit contains the circuitry for reference source, error amplifier, control device and overload protection all in a single IC chip. The internal construction is somewhat different from discrete voltage regulator circuits, but the external operation is quite same. The IC voltage regulators are divided into the following three types. 1. Three terminal fixed voltage regulator. 2. Adjustable output voltage regulator. 3. Precision voltage regulators IC regulators are versatile, relatively inexpensive and are available with features such as programmable output, current, voltage boosting and floating operation for high voltage applications.

IC 723 Voltage Regulator Circuit

•The regulated output voltage (Volt) represents minimum and maximum amounts in continuous mode (DC). Output voltage can be fixed, or adjustable. •The output current (IOUT) is measured under specified conditions. •Measured in amperes (A) during the idling state, the quiescent current never makes it to the load. Instead, it flows from the battery to power the regulator itself. •Dropout voltage (VD) is the minimum voltage drop across the regulator that maintains output voltage regulation. IC voltage regulators that operate with small dropout voltages dissipate less internal power, but have relatively high efficiencies. •The operating temperature is a full-required range.

Performance Specifications of IC Voltage Regulators:

A fault is introduced in the given regulated power supply circuit and then the circuit is troubleshooted. The troubleshooting is done by giving supply to the circuit and measuring different circuit parameters using Multimeter. All the values are then compared with those observed for correct working. The inferences made through troubleshooting for fault detection are :•Driver transistor TR2 have its emitter and base terminals short-circuited.•Pin 2 and 3 of the error amplifier OP-Amp were shorted.•Transistor for Current limit,i.e.TR5 was shorted.

Troubleshooting for Fault Analysis:(OP-Amp based Regulated Power Supply)

II. 555 Timer

1. 555 Timer Description2. Monostable mode of operation 3. Astable mode of operation

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. Depending on the manufacturer, the standard 555 package includes 25 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8). The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555 part number designated the military temperature range, −55 °C to +125 °C. These were available in both high-reliability metal can (T package) and inexpensive epoxy plastic (V package) packages. Thus the full part numbers were NE555V, NE555T, SE555V, and SE555T. It has been hypothesized that the 555 got its name from the three 5 kΩ resistors used within, but Hans Camenzind has stated that the number was arbitrary. •Pins:- The connection of the pins for a DIP package is as follows:- 1 GND:- Ground reference voltage, low level (0 V) 2 TRIG:- The OUT pin goes high and a timing interval starts when this input falls below 1/2 of CTRL voltage (which is typically 1/3VCC, CTRL being 2/3 VCC by default if CTRL is left open). 3 OUT:- This output is driven to approximately 1.7 V below +VCC, or to GND. 4 RESET:- A timing interval may be reset by driving this input to GND, but the timing does not begin again until RESET rises above approximately 0.7 volts. Overrides TRIG which overrides THR. 5 CTRL :-Provides "control" access to the internal voltage divider (by default, 2/3 VCC). 6 THR:- The timing (OUT high) interval ends when the voltage at THR ("threshold") is greater than that at CTRL (2/3 VCC if CTRL is open). 7 DIS:- Open collector output which may discharge a capacitor between intervals. In phase with output. 8 VCC:- Positive supply voltage, which is usually between 3 and 15 V depending on the variation. Pin 5 is also sometimes called the CONTROL VOLTAGE pin. By applying a voltage to the CONTROL VOLTAGE input one can alter the timing characteristics of the device. In most applications, the CONTROL VOLTAGE input is not used. It is usual to connect a 10 nF capacitor between pin 5 and 0 V to prevent interference. The CONTROL VOLTAGE input can be used to build an astable multivibrator with a frequency modulated output.

555 Timer Description

Monostable: - The output pulse ends when the voltage on the capacitor equals 2/3 of the supply voltage. The output pulse width can be lengthened or shortened to the need of the specific application by adjusting the values of R and C. The output pulse width of time t, which is the time it takes to charge C to 2/3 of the supply voltage, is given by

Where t is in seconds, R is in ohms (resistance) and C is in farads (capacitance).While using the timer IC in monostable mode, the main disadvantage is that the time span between any two triggering pulses must be greater than the RC time constant.

Monostable mode of operation

Astable mode of operation Astable: •In astable mode, the 555 timer puts out a continuous stream of rectangular pulses having a specified frequency. Resistor R1 is connected between VCC and the discharge pin (pin 7) and another resistor (R2) is connected between the discharge pin (pin 7), and the trigger (pin 2) and threshold (pin 6) pins that share a common node. Hence the capacitor is charged through R1 and R2, and discharged only through R2, since pin 7 has low impedance to ground during output low intervals of the cycle, therefore discharging the capacitor. • In the astable mode, the frequency of the pulse stream depends on the values of R1, R2 and C:

•The high time from each pulse is given by:

and the low time from each pulse is given by:

Astable mode (contd…)where R1 and R2 are the values of the resistors in ohms and C is the value of the capacitor in farads.•Particularly with bipolar 555s, low values of R1 must be avoided so that the output stays saturated near zero volts during discharge, as assumed by the above equation. Otherwise the output low time will be greater than calculated above. The first cycle will take appreciably longer than the calculated time, as the capacitor must charge from 0V to 2/3 of VCC from power-up, but only from 1/3 of VCC to 2/3 of VCC on subsequent cycles. •To achieve a duty cycle of less than 50% a small diode (that is fast enough for the application) can be placed in parallel with R2, with the cathode on the capacitor side. This bypasses R2 during the high part of the cycle so that the high interval depends approximately only on R1 and C. The presence of the diode is a voltage drop that slows charging on the capacitor so that the high time is longer than the expected and often-cited ln(2)*R1C = 0.693 R1C. The low time will be the same as without the diode as shown above. With a diode, the high time is

where V is when the diode has a current of 1/2 of Vcc/R1 which can be determined from its datasheet or by testing. As an extreme example, when Vcc= 5 and V= 0.7, high time = 1.00 R1C which is 45% longer than the "expected" 0.693 R1C. At the other extreme, when Vcc= 15 and V= 0.3, the high time = 0.725 R1C which is closer to the expected 0.693 R1C. The equation reduces to the expected 0.693 R1C if V= 0. •The operation of RESET in this mode is not well defined, some manufacturers' parts will hold the output state to what it was when RESET is taken low, others will send the output either high or low.

III. 555 Timer based Projects

1. Police light circuit 2. Voltage doubler circuit 3. Traffic light control using timer circuit 4. Dummy alarm 5. PWM LED Dimmer using 555 timer

•WORKING PRINCIPLE:- 1. Here 555 IC work in a astable mode. 2. We can adjust the pulse width by varying R&C values. 3. Firstly two leds blinks for specific interval of time,here for 45sec (according to practical). 4. Then this two leds off and other two leds blink for a specific interval of time and make it work as a police light.

•COMPONENTS USED:- 1. Two 555 ICs 2. 12v battery 3. LED-4 (2 green, 2 red) 4. 2 Transistor (BC 547, BC 557) 5. 2 Diodes ( 1N4148) 6. 2 Capacitor ( 100µf, 2.2µf) 7. 10 Resistors ( 8-470Ω, 1-33kΩ 2-22kΩ )

A. Police Lights

B. Voltage Doubler Circuit•WORKING :-The voltage doubler circuit is fed with 12V regulated D.C. Supply and voltage are measured across the two 22F capacitors. The voltage of the capacitor directly connected to the ground is found to be almost double of that across the other capacitor.

•COMPONENTS USED:- 1. One 555 IC2. 12v battery 3. 2 Diodes (1N4004) 4. 1 Diode ( 1N4148) 5. 4 Capacitors (1nF,100nF,two 22µF); 1 Resistor (33kΩ)

C. Traffic Lights Control using 555 Timer

Traffic signals are used to control the flow of vehicles. In the recent year, the need of transportation has gain immense importance for logistics as well as for common human. This has given rise to the number of vehicles on the road. Due to this reason, traffic jams and road accidents are a common sight in any busy city. Traffic signals provide an easy, cheap, automatic and justified solution to the road points where the vehicle may turn to other direction. That’s why we make automatic traffic control using 555 timer IC.

•WORKING PRINCIPLE:- In this the red LED has an equal on-off period and when it is off, the first 555 delivers power to the second 555. This illuminates the green LED and then the second 555 changes state to turn off the green LED and turn on the orange LED for a short period of time before the first 555 changes state to turn off the second 555 and turn on the red LED. A supply voltage of 9v to 12v is needed because the second 555 receives a supply of about 2v less than rail. This circuit also shows how to connect LEDs high and low to a 555 and also turn off the 555 by controlling the supply to pin 8. Connecting the LEDs high and low to pin 3 will not work and since pin 7 is in phase with pin 3, it can be used to advantage in the design.

•COMPONENTS USED:- 1. Two 555 ICs 2. 12v battery 3. LED-3 (1 green,1 orange,1 red) 4. 2 Capacitors ( 100µf) 5. 5 Resistors ( two 220Ω, 470Ω, 100kΩ, 47kΩ )

D. Dummy Alarm•WORKING PRINCIPLE:- In Dummy alarm circuit , 555 timer works in monostable configuration. Pin 1 is grounded and other pins are connected as shown in the figure below. On fed by 12V battery , the capacitor connected is charged and the LED glows.

•COMPONENTS USED:- 1. One 555 IC 2. 12v battery 3. LED-14. 1 Capacitors ( 100µf) 5. 3 Resistors

E. PWM LED Dimmer using 555 Timer

The Pulse Width Modulation (PWM) plays an important role in controlling the circuits. If you want to control the speed of the motor PWM plays a key role. The width of pulse will give the command to the machine to work either slow or fast. If we can control the pulse width we can easily control the machine. In this project we will use this PWM to dim the intensity of light of the LED.

The DC source is given to the NE555 timer. NE555 timer is used to generate the PWM signal. The width of the PWM signal always depends on the duty cycle, so we can vary the duty cycle through NE555, if we can vary duty cycle we can generate the pulse with various width. so we use timer to generate the PWM to dimmer the LED or increase brightness of the LED.NE555:NE555 is developed by Texas instruments (T1).the ne555 has 8 pins the VCC pin is used to give the main supply voltage to the IC the operating voltage may vary from 3v to 15V.the threshold and voltage control pins are used to vary the voltage to generate the PWM in various duty cycles. Reset pin is used to reset the complete IC if there is any error. The IC output can be taken from the out pin. The NE555 timer can work in monostable or astable operations.it had features like timing for micro second through hours, adjustable duty cycles and ability work in various voltages etc.it had wide range of applications like lamp dimmers, motor control, joysticks etc.

•WORKING PRINCIPLE:- •The 12V DC supply is given to the VCC for operating voltage of 555 timer. The reset pin also directly connected to the 12V as shown in the circuit diagram for resetting the IC if there is any error while circuit is working. The pin5 or voltage control pin is not used in this application so we grounded pin5 with the capacitor C1. The trigger pin (pin2) and threshold pin (pin 6) are connected the VCC through the resistance R12, R2, potentiometer R4 and capacitor C2 for varying the voltage to generate the PWM in various duty cycles. The out pin is connected to the LED panel through a transistor.Pin7 is connected to a transistor internally which will act as a switch and generate the pulse according the duty cycles or frequency generated by the pin2 and pin6.•Here in this project the NE555 should operate in the astable multivibrator. The resistors R12, R2, potentiometer R4 and capacitor C2 will play the important role. Pins 2 and 6 have upper comparator and lower comparator respectively. The upper comparator has the value 2/3 of the vcc and lower comparator has 1/3 of the vcc.•If the astable multivibrator is high at starting and capacitor C2 is started to charge through R12, R2 and pot R4. When the capacitor reaches the voltage of 2/3 its vcc then upper comparator makes the astable multivibrator to goes low. Then the voltage in the capacitor starts to discharge when it reaches the voltage of 1/3 its vcc then lower comparator flips and make the astable multivibrator to go high .Here diode D1 plays the key role diode will allow the voltage when the capacitor is discharging and it will not allow reverse current when the multivibrator is at high or capacitor is charging. The high and low of the multivibrator we generate a pulse. According to resistance generated by the potentiometer we can generate the width of the pulse.•The output of the NE555 is taken form pin 3 and connected to the led panel through the transistor Q1 and resistor R1. The resistor R1 is used to limit the base current of the transistor and transistor is used as an amplifier to limit or enhance the current which is given to the LED panel.

•COMPONENTS USED:- 1. One 555 IC 2. 12v battery 3. LED-6(3 blue, 3 yellow) 4. 1 Transistor (Q12N2222) 5. 1 Diode ( 1N4001) 6. 2 Capacitors ( 0.01µf) 7. 10 Resistors ( Nine 1kΩ,One POT )