Solar Seeker (major Project)

MAJOR PROJECT Solar Seeker Cell At

Mechanical Engineering Department Lovely Institute of Technology Jalandhar-Ludhiana G.T Road, Phagwara., Punjab-144402

PROJECT BY: Abhishek Dogra (5081110781) Sukhdeep Singh (5081110835) Ekanshu Sharma (5081110798) Amit Dhadwal (608114369) BTECH (ME) FINAL YEAR L.I.T.

PROJECT GUIDE: Mr. Ranjeet Singh Mechanical Department L.I.T.

ACKNOWLEDGEMENT We take this opportunity to express our sincere gratitude to honorable Mr. Ashok Mittle, President, Lovely Institutes, Phagwara for giving us the privilege to undertake this project in LIT. We would like to thank our project guide Mr. Rajneet Singh (Lecturer, Mechanical Department, LIT) for providing us the valuable guidance and assistance throughout our project work. We also express our gratitude of thanks to Mr. Vishal Bhalla (Class Incharge) for his timely assistance and co-operation with us. We are also indebted to Mr. Ajay Sood, Mr. Gurveen Singh ( Faculty, Mechanical Department) for their golden ideas and heartiest cooperation throughout the project work. Last but not least we are grateful to one and all that had been associated with our project work. PROJECT MEMBER Abhishek Dogra Sukhdeep Singh Ekanshu Sharma Amit Dhadwal

CERTIFICATE This is to be certify that this major project entitled “Solar Seeker Cell” in Mechanical Engineering Department, Lovely Institute of Technology, Jalandhar-Ludhiana G.T Road, Phagwara., Punjab-144402 is submitted by Abhishek Dogra, Sukhdeep Singh, Ekanshu Sharma & Amit Dhadwal student of B.TECH (Mechanical Engineering) at Lovely Institute of Technology, Phagwara (Punjab). I further certify that this work is a original work done by them. This work has been completed under my supervision and guidance. I wish them all success in life. Date: 2009-05-08

Mr. Ranjeet Singh

Place: LIT, Phagwara

Faculty LIT, Phagwara

PROJECT DIRECTIVE

Title: Solar Seeking Cell Team: Abhishek Dogra (5081110781) Amit Dhadwal (608114369) Sukhdeep Singh (5081110835) Ekanshu Sharma (5081110798)

Objective/ Aim: To make a solar seeking cell. The device will have sunlight sensors which will sense the sun and hence move the solar cell towards the sun.

Technical details: A solar cell converts solar energy into electricity by the photovoltaic effect.  Photons in sunlight hit the solar panel and are absorbed by semi conducting materials, such as silicon.  Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction. The complementary positive charges that are also created (like bubbles) are called holes and flow in the direction opposite of the electrons in a silicon solar panel.  An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity. Innovativeness & Usefulness: 1) Most commercially available solar cells are capable of producing electricity for at least twenty years without a significant decrease in efficiency. 2) The seeker will increase the production rate of solar cell. 3) This device will be highly useful for the automobiles because of their movements in various directions.

INTRODUCTION In this project we show that how we design a solar seeking device. In this project we use one rotating platform which is mounted on the dc motor. When motor rotate then platform is also rotate and change its direction with the help of two proximity sensors on each side. One photo sensor is mounting on the platform. When light fall on the platform then photodiode sense the light and instant stop the dc motor . Now platform is also stopped automatically. When platform stop under the maximum intensity of light then solar seeking device capture maximum energy. We use this technique with solar seeking device to capture maximum sun light.

COMPONENTS USED IN THIS PROJECT:  MICROCONTROLLER 89C2051  H BRIDGE  DC MOTOR  REED SENSOR  PHOTO-SENSOR  OPTOCOUPLER

MICROCONTROLLER In this project we use micro controller to control the direction of motor with proximity switches and at the same time sense the light from photo sensor. Here in this project we use IC 89c2051 controller to sense all the logic. 89c2051 is a 20 pin member of the main 40 pin controller. We use 89c2051 because here in this project we use only 2 outputs for motor and control signal is only three. Out of three two sensor change the direction and one sensor sense the sun light from the sun. 89c2051 is a small microcontroller with 128 byte of ram and 2 k byte of flash memory. How to program a microcontroller: For programming purpose we wrote a program in the assembly language and we use any 8051 assembler to assemble the software.

We use 8051 IDE software to assemble the assembly code.

Instructions are written in the assembly code under the instruction set of the 8051 controller. After assemble the software, assembler shows a 0 error and at the same time assembler convert this code into hex code. This hex code is now transferring into blank IC with the help of serial port programmer. We use serial port programmer kit to transfer the data from the computer to the blank IC. Lot of kits are available in the market, here we use FRONTLINE KIT.

With the help of this kit we program the IC. We use this IC for the project purpose. When platform rotate then, platform changes its direction with the help of the magnetic proximity sensor. Here we use reed switch to monitor the platform. Reed switch is a special switch, sense the magnetic field. One magnet is mounting on the base of the platform. When platform rotate then magnet influence the reed switch. When sensor influenced by the magnet then sensor plated join together and at the same time sensor is activate and sensor provide a signal to the controller. Controller instant changes the direction of the motor from clock wise to anti clock wise direction. On the end of anti clock wise position we mount one more sensor; with the help of this sensor we again change the direction of the motor. One LDR / photodiode is mounted on the top of platform to sense a maximum light. When sensor sense a maximum light then resistance of photodiode become very low and, we provide a 0 signal to the micro controller to stop the motor where it is. Now motor is stop, until photodiode sense a maximum light. When photodiode is in dark then again platform rotate and search a maximum light.

BASIC NOTES ON THE CONTROLLER. HERE WE SHOW THE NOTES ON 8051 CONTROLLER. Note that 8051 and 2051 is same, only difference is pins . In 89c2051 there are 20 pins are available and in 89c51 40 pins are available. WELCOME TO THE WORLD OF THE MICROCONTROLLERS. Look around. Notice the smart “intelligent” systems? Be it the T.V, washing machines, video games, telephones, automobiles, aero planes, power systems, or any application having a LED or a LCD as a user interface, the control is likely to be in the hands of a micro controller! Measure and control, that’s where the micro controller is at its best. Micro controllers are here to stay. Going by the current trend, it is obvious that micro controllers will be playing bigger and bigger roles in the different activities of our lives. These embedded chips are very small, but are designed to replace components much bigger and bulky In size. They process information very intelligently and efficiently. They sense the environment around them. The signals they gather are tuned into digital data that streams through tributaries of circuit lines at the speed of light. Inside the microprocessor collates and calculators. The software has middling intelligence. Then in a split second, the processed streams are shoved out.

What is the primary difference between a microprocessor and a micro controller? Unlike the microprocessor, the micro controller can be considered to be a true “Computer on a chip”. In addition to the various features like the ALU, PC, SP and registers found on a microprocessor, the micro controller also incorporates features like the ROM, RAM, Ports, timers, clock circuits, counters, reset functions etc. While the microprocessor is more a general-purpose device, used for read, write and calculations on data, the micro controller, in addition to the above functions also controls the environment.

8051 micro controller The 8051 developed and launched in the early 80`s, is one of the most popular micro controller in use today. It has a reasonably large amount of built in ROM and RAM. In addition it has the ability to access external memory. The generic term `8x51` is used to define the device. The value of x defining the kind of ROM, i.e. x=0, indicates none, x=3, indicates mask ROM, x=7, indicates EPROM and x=9 indicates EEPROM or Flash. A note on ROM The early 8051, namely the 8031 was designed without any ROM. This device could run only with external memory connected to it. Subsequent developments lead to the development of the PROM or the programmable ROM. This type had the disadvantage of being highly unreliable. The next in line, was the EPROM or Erasable Programmable ROM. These devices used ultraviolet light erasable memory cells. Thus a program could be loaded, tested and erased using ultra violet rays. A new program could then be loaded again. An improved EPROM was the EEPROM or the electrically erasable PROM. This does not require ultra violet rays, and memory can be cleared using circuits within the chip itself. Finally there is the FLASH, which is an improvement over the EEPROM. While the terms EEPROM and flash are sometimes used interchangeably, the difference lies in the fact that flash erases the complete memory at one stroke, and not act on the individual cells. This results in reducing the time for erasure.

Different microcontrollers in market: •

PIC

One of the famous microcontrollers used in the industries. It is

based on RISC Architecture which makes the microcontroller process faster than other microcontroller. •

INTEL

These are the first to manufacture microcontrollers. These

are not as sophisticated other microcontrollers but still the easiest one to learn. •

Atmel

Atmel’s AVR microcontrollers are one of the most powerful in the

embedded industry. This is the only microcontroller having 1kb of ram even the entry stage. But it is unfortunate that in India we are unable to find this kind of microcontroller. Intel 8051 Intel 8051 is CISC architecture which is easy to program in assembly language and also has a good support for High level languages. The memory of the microcontroller can be extended up to 64k. This microcontroller is one of the easiest microcontrollers to learn. The 8051 microcontroller is in the field for more than 20 years. There are lots of books and study materials are readily available for 8051.

Derivatives The best thing done by Intel is to give the designs of the 8051 microcontroller to everyone. So it is not the fact that Intel is the only manufacture for the 8051 there more than 20 manufactures, with each of minimum 20 models. Literally there are hundreds of models of 8051 microcontroller available in market to choose. Some of the major manufactures of 8051 are  Atmel  Philips  Dallas Philips The Philips‘s 8051 derivatives has more number of features than in any microcontroller. The costs of the Philips microcontrollers are higher than the Atmel’s which makes us to choose Atmel more often than Philips Dallas Dallas has made many revolutions in the semiconductor market. Dallas’s 8051 derivative is the fastest one in the market. It works 3 times as fast as a 8051 can process. But we are unable to get more in India. Atmel These people were the one to master the flash devices. They are the cheapest microcontroller available in the market. Atmel’s even introduced a 20pin variant of 8051 named 2051. The Atmel’s 8051 derivatives can be got in India less than 70 rupees. There are lots of cheap programmers available in India for Atmel. So it is always good for students to stick with 8051 when you learn a new microcontroller.

Architecture Architecture is must to learn because before learning new machine it is necessary to learn the capabilities of the machine. This is some thing like before learning about the car you cannot become a good driver. The architecture of the 8051 is given below.

The 8051 doesn’t have any special feature than other microcontroller. The only feature is that it is easy to learn. Architecture makes us to know about the hardware features of the microcontroller. The features of the 8051 are  4K Bytes of Flash Memory  128 x 8-Bit Internal RAM  Fully Static Operation: 1 MHz to 24 MHz  32 Programmable I/O Lines  Two 16-Bit Timer/Counters  Six Interrupt Sources (5 Vectored)  Programmable Serial Channel  Low Power Idle and Power Down Modes

The 8051 has a 8-Bit CPU that means it is able to process 8 bit of data at a time. 8051 has 235 instructions.

H bridge circuit Here we use H bridge circuit to control the direction of the motor. H Bridge is a combination of the four transistors. Out of these four transistors two transistors is NPN and two transistors’ is PNP transistor. At a time only two transistor work to run a motor. To control the direction of motor, we use microcontroller circuit.

H Bridge is connecting with the microcontroller with the help of the optocoupler circuit. We use two optocoupler to provide a electrical isolation between motor circuit and microcontroller circuit. We use optocoupler to provide an electrical isolation between motor+ h bridge circuit and microcontroller circuit.

Microcontroller circuit work on 5 volt dc, but H bridge circuit work on the 9 volt dc. In future if we change the motor then we change the supply also, If we change supply of the H bridge circuit then there is no effect on the main processor circuit. We use 7805 regulator circuit to provide a 5 volt dc supply to pin no 20 of the controller. Pin no 4 and 5 is connected to the external crystal to provide a clock pulse to the controller. Pin no 1 is the reset pin of the controller. On this pin we connect one capacitor and resistor circuit to provide a auto reset facility. Two ports are available for controlling all the inputs and output. Port p3 and port P1 is available for the input and output. The entire input signal is provided on the port p3 and motor is connected to the port p1. Port p1.0 and port p1.1 is connected to the motor through optocoupler circuit and H bridge circuit. Light sensor and two reed sensor is connected to the port p3.0, p3.1, p3.2.

DC MOTOR Here in this project we use slow speed dc motor with gear box to reduce the speed of the platform. This type of gear motor is getting from the second hand machine. Supply voltage of this dc motor is 6 to 9 volt dc. As we vary the voltage speed is also vary. Current consumption of dc motor is 200 ma. It is also possible to use a stepper motor. If we use stepper motor then we require a high current supply. Normal stepper motor require a minimum 1 A power supply. SPECIFICATION OF DC MOTOR USED:

MOTOR

DC MIN

MAX

Size

diameter 2 inch length 2 inch

SPEED

0 RPM

100 RPM

VOLTAGE

10v

20v

Gear Assembly- Rack and Pinion

Gears : A gear is a component within a transmission device that transmits rotational force to another gear or device. A gear is different from a pulley in that a gear is a round wheel which has linkages ("teeth" or "cogs") that mesh with other gear teeth, allowing force to be fully transferred without slippage. Depending on their construction and arrangement, geared devices can transmit forces at different speeds, torques, or in a different direction, from the power source. Gears are a very useful simple machine. The most common situation is for a gear to mesh with another gear, but a gear can mesh with any device having compatible teeth, such as linear moving racks. A gear's most important feature is that gears of unequal sizes (diameters) can be combined to produce a mechanical advantage, so that the rotational speed and torque of the second gear are different from that of the first. In the context of a particular machine, the term "gear" also refers to one particular arrangement of gears among other arrangements (such as "first gear"). Such arrangements are often given as a ratio, using the number of teeth or gear diameter as units. The term "gear" is also used in non-geared devices which perform equivalent tasks: "...broadly speaking, a gear refers to a ratio of engine shaft speed to driveshaft speed. Although CVTs change this ratio without using a set of planetary gears, they are still described as having low and high "gears" for the sake of

General The smaller gear in a pair is often called the pinion; the larger, either the gear, or the wheel. Mechanical advantage The interlocking of the teeth in a pair of meshing gears means that their circumferences necessarily move at the same rate of linear motion (eg., metres per second, or feet per minute). Since rotational speed (eg. measured in revolutions per second, revolutions per minute, or radians per second) is proportional to a wheel's circumferential speed divided by its radius, we see that the larger the radius of a gear, the slower will be its rotational speed, when meshed with a gear of given size and speed. The same conclusion can also be reached by a different analytical process: counting teeth. Since the teeth of two meshing gears are locked in a one to one correspondence, when all of the teeth of the smaller gear have passed the point where the gears meet -- ie., when the smaller gear has made one revolution -- not all of the teeth of the larger gear will have passed that point -- the larger gear will have made less than one revolution. The smaller gear makes more revolutions in a given period of time; it turns faster. The speed ratio is simply the reciprocal ratio of the numbers of teeth on the two gears. (Speed A * Number of teeth A) = (Speed B * Number of teeth B) This ratio is known as the gear ratio. The torque ratio can be determined by considering the force that a tooth of one gear exerts on a tooth of the other gear. Consider two teeth in contact at a point on the line joining the shaft axes of the two gears. In general, the force will have both a radial and

a circumferential component. The radial component can be ignored: it merely causes a sideways push on the shaft and does not contribute to turning. The circumferential component causes turning. The torque is equal to the circumferential component of the force times radius. Thus we see that the larger gear experiences greater torque; the smaller gear less. The torque ratio is equal to the ratio of the radii. This is exactly the inverse of the case with the velocity ratio. Higher torque implies lower velocity and vice versa. The fact that the torque ratio is the inverse of the velocity ratio could also be inferred from the law of conservation of energy. Here we have been neglecting the effect of friction on the torque ratio. The velocity ratio is truly given by the tooth or size ratio, but friction will cause the torque ratio to be actually somewhat less than the inverse of the velocity ratio. In the above discussion we have made mention of the gear "radius". Since a gear is not a proper circle but a roughened circle, it does not have a radius. However, in a pair of meshing gears, each may be considered to have an effective radius, called the pitch radius, the pitch radii being such that smooth wheels of those radii would produce the same velocity ratio that the gears actually produce. The pitch radius can be considered sort of an "average" radius of the gear, somewhere between the outside radius of the gear and the radius at the base of the teeth. The issue of pitch radius brings up the fact that the point on a gear tooth where it makes contact with a tooth on the mating gear varies during the time the pair of teeth are engaged; also the direction of force may vary. As a result, the velocity ratio (and torque ratio) is not, actually, in general, constant, if one considers the situation in detail, over the course of the period of engagement of a single pair of teeth. The velocity and torque ratios given at the beginning of this section are valid only "in bulk" -- as long-term averages; the values at some particular position of the teeth may be different.

It is in fact possible to choose tooth shapes that will result in the velocity ratio also being absolutely constant -- in the short term as well as the long term. In good quality gears this is usually done, since velocity ratio fluctuations cause undue vibration, and put additional stress on the teeth, which can cause tooth breakage under heavy loads at high speed. Constant velocity ratio may also be desirable for precision in instrumentation gearing, clocks and watches. The involute tooth shape is one that results in a constant velocity ratio, and is the most commonly used of such shapes today. Comparison with other drive mechanisms The definite velocity ratio which results from having teeth gives gears an advantage over other drives (such as traction drives and V-belts) in precision machines such as watches that depend upon an exact velocity ratio. In cases where driver and follower are in close proximity gears also have an advantage over other drives in the reduced number of parts required; the downside is that gears are more expensive to manufacture and their lubrication requirements may impose a higher operating cost. The automobile transmission allows selection between gears to give various mechanical advantages. Spur gears Spur gears are the simplest, and probably most common, type of gear. Their general form is a cylinder or disk. The teeth project radially, and with these "straight-cut gears", the leading edges of the teeth are aligned parallel to the axis of rotation. These gears can only mesh correctly if they are fitted to parallel axles.

Helical gears Helical gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. The angled teeth engage more gradually than do spur gear teeth. This causes helical gears to run more smoothly and quietly than spur gears. Helical gears also offer the possibility of using non-parallel shafts. A pair of helical gears can be meshed in two ways: with shafts oriented at either the sum or the difference of the helix angles of the gears. These configurations are referred to as parallel or crossed, respectively. The parallel configuration is the more mechanically sound. In it, the helices of a pair of meshing teeth meet at a common tangent, and the contact between the tooth surfaces will, generally, be a curve extending some distance across their face widths. In the crossed configuration, the helices do not meet tangentially, and only point contact is achieved between tooth surfaces. Because of the small area of contact, crossed helical gears can only be used with light loads. Quite commonly, helical gears come in pairs where the helix angle of one is the negative of the helix angle of the other; such a pair might also be referred to as having a right handed helix and a left handed helix of equal angles. If such a pair is meshed in the 'parallel' mode, the two equal but opposite angles add to zero: the angle between shafts is zero -- that is, the shafts are parallel. If the pair is meshed in the 'crossed' mode, the angle between shafts will be twice the absolute value of either helix angle. Note that 'parallel' helical gears need not have parallel shafts -- this only occurs if their helix angles are equal but opposite. The 'parallel' in 'parallel helical gears' must refer, if anything, to the (quasi) parallelism of the teeth, not to the shaft orientation. As mentioned at the start of this section, helical gears operate more smoothly than do spur gears. With parallel helical gears, each pair of teeth first make contact at a single point at one side of the gear wheel; a moving curve of contact then grows gradually

across the tooth face. It may span the entire width of the tooth for a time. Finally, it recedes until the teeth break contact at a single point on the opposite side of the wheel. Thus force is taken up and released gradually. With spur gears, the situation is quite different. When a pair of teeth meet, they immediately make line contact across their entire width. This causes impact stress and noise. Spur gears make a characteristic whine at high speeds and can not take as much torque as helical gears because their teeth are receiving impact blows. Whereas spur gears are used for low speed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is important. The speed is considered to be high when the pitch line velocity (that is, the circumferential velocity) exceeds 5000 ft/min. A disadvantage of helical gears is a resultant thrust along the axis of the gear, which needs to be accommodated by appropriate thrust bearings, and a greater degree of sliding friction between the meshing teeth, often addressed with specific additives in the lubricant. Double helical gears Double helical gears, invented by André Citroën and also known as herringbone gears, overcome the problem of axial thrust presented by 'single' helical gears by having teeth that set in a 'V' shape. Each gear in a double helical gear can be thought of as two standard, but mirror image, helical gears stacked. This cancels out the thrust since each half of the gear thrusts in the opposite direction. They can be directly interchanged with spur gears without any need for different bearings. Where the oppositely angled teeth meet in the middle of a herringbone gear, the alignment may be such that tooth tip meets tooth tip, or the alignment may be staggered, so that tooth tip meets tooth trough. The latter type of alignment results in what is known as a Wuest type herringbone gear.

With the older method of fabrication, herringbone gears had a central channel separating the two oppositely-angled courses of teeth. This was necessary to permit the shaving tool to run out of the groove. The development of the Sykes gear shaper now makes it possible to have continuous teeth, with no central gap. Bevel gears Bevel gear used to lift floodgate by means of central screw. Bevel gears are essentially conically shaped, although the actual gear does not extend all the way to the vertex (tip) of the cone that bounds it. With two bevel gears in mesh, the vertices of their two cones lie on a single point, and the shaft axes also intersect at that point. The angle between the shafts can be anything except zero or 180 degrees. Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called miter gears. The teeth of a bevel gear may be straight-cut as with spur gears, or they may be cut in a variety of other shapes. 'Spiral bevel gears' have teeth that are both curved along their (the tooth's) length; and set at an angle, analogously to the way helical gear teeth are set at an angle compared to spur gear teeth. 'Zero bevel gears' have teeth which are curved along their length, but not angled. Spiral bevel gears have the same advantages and disadvantages relative to their straight-cut cousins as helical gears do to spur gears. Straight bevel gears are generally used only at speeds below 5 m/s (1000 ft/min), or, for small gears, 1000 r.p.m.[4] Crown gear A crown gear or contrate gear is a particular form of bevel gear whose teeth project at right angles to the plane of the wheel; in their orientation the teeth resemble the points on a crown. A crown gear can only mesh accurately with another bevel gear, although crown gears are sometimes seen meshing with spur gears. A crown gear is also sometimes meshed with an escapement such as found in mechanical clocks.

Hypoid gears Hypoid gears resemble spiral bevel gears, except that the shaft axes are offset, not intersecting. The pitch surfaces appear conical but, to compensate for the offset shaft, are in fact hyperboloids of revolution. Hypoid gears are almost always designed to operate with shafts at 90 degrees. Depending on which side the shaft is offset to, relative to the angling of the teeth, contact between hypoid gear teeth may be even smoother and more gradual than with spiral bevel gear teeth. Also, the pinion can be designed with fewer teeth than a spiral bevel pinion, with the result that gear ratios of 60:1 and higher are "entirely feasible" using a single set of hypoid gears. Worm gear A worm is a gear that resembles a screw. It is a species of helical gear, but its helix angle is usually somewhat large(ie., somewhat close to 90 degrees) and its body is usually fairly long in the axial direction; and it is these attributes which give it its screw like qualities. A worm is usually meshed with an ordinary looking, disk-shaped gear, which is called the "gear", the "wheel", the "worm gear", or the "worm wheel". The prime feature of a worm-and-gear set is that it allows the attainment of a high gear ratio with few parts, in a small space. Helical gears are, in practice, limited to gear ratios of 10:1 and under; worm gear sets commonly have gear ratios between 10:1 and 100:1, and occasionally 500:1. In worm-and-gear sets, where the worm's helix angle is large, the sliding action between teeth can be considerable, and the resulting frictional loss causes the efficiency of the drive to be usually less than 90 percent, sometimes less than 50 percent, which is far less than other types of gears. The distinction between a worm and a helical gear is made when at least one tooth persists for a full 360 degree turn around the helix. If this occurs, it is a 'worm'; if not, it is a 'helical gear'. A worm may have as few as one tooth. If that tooth persists for

several turns around the helix, the worm will appear, superficially, to have more than one tooth, but what one in fact sees is the same tooth reappearing at intervals along the length of the worm. The usual screw nomenclature applies: a one-toothed worm is called "single thread" or "single start"; a worm with more than one tooth is called "multiple thread" or "multiple start". We should note that the helix angle of a worm is not usually specified. Instead, the lead angle, which is equal to 90 degrees minus the helix angle, is given. In a worm-and-gear set, the worm can always drive the gear. However, if the gear attempts to drive the worm, it may or may not succeed. Particularly if the lead angle is small, the gear's teeth may simply lock against the worm's teeth, because the force component circumferential to the worm is not sufficient to overcome friction. Whether this will happen depends on a function of several parameters; however, an approximate rule is that if the tangent of the lead angle is greater than the coefficient of friction, the gear will not lock.[8] Worm-and-gear sets that do lock in the above manner are called "self locking". The self locking feature can be an advantage, as for instance when it is desired to set the position of a mechanism by turning the worm and then have the mechanism hold that position. An example of this is the tuning mechanism on some types of stringed instruments. If the gear in a worm-and-gear set is an ordinary helical gear only point contact between teeth will be achieved.[9] If medium to high power transmission is desired, the tooth shape of the gear is modified to achieve more intimate contact with the worm thread. A noticeable feature of most such gears is that the tooth tops are concave, so that the gear partly envelopes the worm. A further development is to make the worm concave (viewed from the side, perpendicular to its axis) so that it partly envelopes the gear as well; this is called a cone-drive or Hindley worm. A right hand helical gear or right hand worm is one in which the teeth twist clockwise as they recede from an observer looking along the axis. The designations, right hand

and left hand, are the same as in the long established practice for screw threads, both external and internal. Two external helical gears operating on parallel axes must be of opposite hand. An internal helical gear and its pinion must be of the same hand. A left hand helical gear or left hand worm is one in which the teeth twist counterclockwise as they recede from an observer looking along the axis. Rack and pinion A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line. Such a mechanism is used in automobiles to convert the rotation of the steering wheel into the left-to-right motion of the tie rod(s). Racks also feature in the theory of gear geometry, where, for instance, the tooth shape of an interchangeable set of gears may be specified for the rack (infinite radius), and the tooth shapes for gears of particular actual radii then derived from that.

External vs. internal gears An external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, an internal gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, an internal gear is one with the pitch angle exceeding 90 degrees.

Reed Sensor The reed switch is an electrical switch operated by an applied magnetic field. It was invented at Bell Telephone Laboratories in 1936 by W. B. Ellwood. It consists of a pair of contacts on ferrous metal reeds in a hermetically sealed glass envelope. The contacts may be normally open, closing when a magnetic field is present; normally closed and opening when a magnetic field is applied; or one normally open and one normally closed. The switch may be actuated by a coil, making a reed relay, or by bringing a magnet near to the switch. Once the magnet is pulled away from the switch, the reed switch will go back to its original position. Reed switches are used in reed relays, which are used for temporarily storing information in mid-20th Century telephone exchanges. As well, they are for electrical circuit control, particularly in the communications field; as proximity switches for burglar alarms and as switches in electronic pedal keyboards used by pipe organ players and in electronic children's toys which have sound effects that need to be activated. Description The reed switch contains a pair (or more) of magnetizable and electrically conductive metal reeds which have end portions separated by a small gap when the switch is open. The reeds are hermetically sealed in opposite ends of a tubular glass envelope. Electromagnetic switch A magnetic field (from an electromagnet or a permanent magnet) will cause the contacts to pull together, thus completing an electrical circuit. The stiffness of the reeds causes them to separate, and open the circuit, when the magnetic field ceases. Another configuration contains a non-ferrous normally-closed contact that opens when the ferrous normally-open contact closes. Good electrical contact is assured by plating a thin layer of precious metal over the flat contact

portions of the reeds; low-resistivity silver is more suitable than corrosion-resistant gold in the sealed envelope. There are also versions of reed switches with mercury "wetted" contacts. Such switches must be mounted in a particular orientation otherwise drops of mercury may bridge the contacts even when not activated. Since the contacts of the reed switch are sealed away from the atmosphere, they are protected against atmospheric corrosion. The hermetic sealing of a reed switch make them suitable for use in explosive atmospheres where tiny sparks from conventional switches would constitute a hazard. One important quality of the switch is its sensitivity, the amount of magnetic energy necessary to actuate it. Sensitivity is measured in units of Ampere-turns, corresponding to the current in a coil multiplied by the number of turns. Typical pullin sensitivities for commercial devices are in the 10 to 60 AT range. In production, a metal reed is inserted in each end of a glass tube and the end of the tube heated so that it seals around a shank portion on the reed. Infrared-absorbing glass is used, so an infrared heat source can concentrate the heat in the small sealing zone of the glass tube. The thermal coefficient of expansion of the glass material and metal parts must be similar to prevent breaking the glass-to-metal seal. The glass used must have a high electrical resistance and must not contain volatile components such as lead oxide and fluorides. The leads of the switch must be handled carefully to prevent breaking the glass envelope.

Uses In addition to their use in reed relays, reed switches are widely used for electrical circuit control, particularly in the communications field. Reed switches actuated by magnets are commonly used in mechanical systems as proximity switches as well as in door and window sensors in burglar alarm systems and tamperproofing methods; however they can be disabled by a strong, external magnetic field. Reed switches were formerly used in the keyboards for computer terminals, where each key had a magnet and a reed switch actuated by depressing the key; cheaper switches are now used. Speed sensors on bicycle wheels use a reed switch to actuate briefly each time a magnet on the wheel passes the sensor. Electric and electronic pedal keyboards used by pipe organ and Hammond organ players often use reed switches to activate the notes of the keyboard. One of the challenges with choosing switches for pedal keyboards is that since the keys are depressed with the feet, the switch mechanism is exposed to dirt, dust, and other particles. Reed switches are often the preferred choice because glass reed switches are sealed, which protects them from dirt and dust. Reed switches are also widely used in electronic children's toys which have sound effects that need to be activated when a child uses the toy in certain ways, such as opening a toy jewellery box. Reed relays One or more reed switches inside a coil is a reed relay. Reed relays are used when operating currents are relatively low, and offer high operating speed, good performance with very small currents which are not reliably switched by conventional contacts, high reliability and long life. Millions of reed relays were used for temporarily storing information in mid-20th Century telephone exchanges. The inert atmosphere around the reed contacts ensures that oxidation will not affect the contact resistance.

Advantages of Reed Switches Advantages of reed switches to the Meccano modeller are their small size, which makes them easy to mount and unobtrusive, and the fact that the operating force required to operate the switch is very small, thus doing away with cumbersome cams or cranks. Reed switches, and suitable magnets, are also cheap and easily obtainable.

Disadvantages of Reed Switches It should, however, be pointed out that reed switches do have a few disadvantages nothing is ever perfect! First, the contacts and reeds are fairly small and delicate, so they won't handle large voltages or currents which cause the reeds to spark when switched. Heavy currents also overheat the reeds causing them to lose their springiness. If the reed contacts do become welded together (due to trying to switch a high current) you can often free them by sharply tapping the reed switch against a table - but not too hard or the glass will break! It is always worth trying - you have nothing to lose because welded contacts make the switch useless. Maplin give typical voltage and current ratings for the switches that they supply. A power rating, measured in Watts (W), simply means multiplying current and voltage, but remember not to exceed the current rating - e.g., 10V at 1A = 10W, but 1V at 10A also equals 10W, but in this case the current would be too high. If you are switching large currents, it will be necessary to use a relay circuit with the reed switch operating the relay coil only.

Second, since reed switches are rather fragile, particularly if you are soldering onto the thick lead-out wires, it's easy to break the glass and seals. If you need to bend the lead-out wires, make sure that you grip them securely with pliers between the glass seal and the bend point, as shown in the top of figure 2.

Sensor A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy, all sensors need to be calibrated against known standards. Use Sensors are used in everyday objects such as touch-sensitive elevator buttons and lamps which dim or brighten by touching the base. There are also innumerable applications for sensors of which most people are never aware. Applications include cars, machines, aerospace, medicine, manufacturing and robotics. A sensor's sensitivity indicates how much the sensor's output changes when the measured quantity changes. For instance, if the mercury in a thermometer moves 1 cm when the temperature changes by 1 °C, the sensitivity is 1 cm/°C. Sensors that measure very small changes must have very high sensitivities. Sensors also have an impact on what they measure; for instance, a room temperature thermometer inserted into a hot cup of liquid cools the liquid while the liquid heats the thermometer. Sensors need to be designed to have a small effect on what is measured, making the sensor smaller often improves this and may introduce other advantages. Technological progress allows more and more sensors to be manufactured on a microscopic scale as microsensors using MEMS technology. In most cases, a microsensor reaches a significantly higher speed and sensitivity compared with macroscopic approaches.

Classification of measurement errors A good sensor obeys the following rules: Is sensitive to the measured property Is insensitive to any other property Does not influence the measured property Ideal sensors are designed to be linear. The output signal of such a sensor is linearly proportional to the value of the measured property. The sensitivity is then defined as the ratio between output signal and measured property. For example, if a sensor measures temperature and has a voltage output, the sensitivity is a constant with the unit [V/K]; this sensor is linear because the ratio is constant at all points of measurement. Sensor deviations If the sensor is not ideal, several types of deviations can be observed: The sensitivity may in practice differ from the value specified. This is called a sensitivity error, but the sensor is still linear. Since the range of the output signal is always limited, the output signal will eventually reach a minimum or maximum when the measured property exceeds the limits. The full scale range defines the maximum and minimum values of the measured property. If the output signal is not zero when the measured property is zero, the sensor has an offset or bias. This is defined as the output of the sensor at zero input.

If the sensitivity is not constant over the range of the sensor, this is called nonlinearity. Usually this is defined by the amount the output differs from ideal behavior over the full range of the sensor, often noted as a percentage of the full range. If the deviation is caused by a rapid change of the measured property over time, there is a dynamic error. Often, this behaviour is described with a bode plot showing sensitivity error and phase shift as function of the frequency of a periodic input signal. If the output signal slowly changes independent of the measured property, this is defined as drift. Long term drift usually indicates a slow degradation of sensor properties over a long period of time. Noise is a random deviation of the signal that varies in time. Hysteresis is an error caused by when the measured property reverses direction, but there is some finite lag in time for the sensor to respond, creating a different offset error in one direction than in the other. If the sensor has a digital output, the output is essentially an approximation of the measured property. The approximation error is also called digitization error. If the signal is monitored digitally, limitation of the sampling frequency also can cause a dynamic error. The sensor may to some extent be sensitive to properties other than the property being measured. For example, most sensors are influenced by the temperature of their environment. All these deviations can be classified as systematic errors or random errors. Systematic errors can sometimes be compensated for by means of some kind of

calibration strategy. Noise is a random error that can be reduced by signal processing, such as filtering, usually at the expense of the dynamic behaviour of the sensor. Resolution The resolution of a sensor is the smallest change it can detect in the quantity that it is measuring. Often in a digital display, the least significant digit will fluctuate, indicating that changes of that magnitude are only just resolved. The resolution is related to the precision with which the measurement is made. For example, a scanning tunneling probe (a fine tip near a surface collects an electron tunnelling current) can resolve atoms and molecules. Types Biological sensors All living organisms contain biological sensors with functions similar to those of the mechanical devices described. Most of these are specialized cells that are sensitive to: Light, motion, temperature, magnetic fields, gravity, humidity, vibration, pressure, electrical fields, sound, and other physical aspects of the external environment Physical aspects of the internal environment, such as stretch, motion of the organism, and position of appendages (proprioception) Environmental molecules, including toxins, nutrients, and pheromones Estimation of biomolecules interaction and some kinetics parameters Internal metabolic milieu, such as glucose level, oxygen level, or osmolality Internal signal molecules, such as hormones, neurotransmitters, and cytokines

Differences between proteins of the organism itself and of the environment or alien creatures Artificial sensors that mimic biological sensors by using a biological sensitive component, are called biosensors. Photoelectric sensor A photoelectric sensor, or photoeye, is a device used to detect the presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. They are used extensively in industrial manufacturing. There are three different functional types, opposed (a.k.a. through beam), retroreflective, and proximity-sensing (a.k.a. diffused). An opposed (through beam) arrangement consists of a receiver located within the lineof-sight of the transmitter. In this mode, an object is detected when the light beam is blocked from getting to the receiver from the transmitter. A retroreflective arrangement places the transmitter and receiver at the same location and uses a reflector to bounce the light beam back from the transmitter to the receiver. An object is sensed when the beam is interrupted and fails to reach the receiver. A proximity-sensing (diffused) arrangement is one in which the transmitted radiation must reflect off of the object in order to reach the receiver. In this mode, an object is detected when the receiver sees the transmitted source rather than when it fails to see it.

Photosensor A photosensor is an electronic component that detects the presence of visible light, infrared transmission (IR), and/or ultraviolet (UV) energy. Most photosensors consist of semiconductor having a property called photoconductivity , in which the electrical conductance varies depending on the intensity of radiation striking the material. The most common types of photosensor are the photodiode, the bipolar phototransistor, and the photoFET (photosensitive field-effect transistor). These devices are essentially the same as the ordinary diode , bipolar transistor , and fieldeffect transistor , except that the packages have transparent windows that allow radiant energy to reach the junctions between the semiconductor materials inside. Bipolar and field-effect phototransistors provide amplification in addition to their sensing capabilities. Photosensors are used in a great variety of electronic devices, circuits, and systems, including: fiber optic systems optical scanners wireless LAN automatic lighting controls machine vision systems electric eyes optical disk drives

Opto-isolator An opto-isolator integrated circuit contains an infrared LED and silicon photodiode with an integrated amplifier stage.This article is about the electronic component. In electronics, an opto-isolator (or optical isolator, optocoupler, photocoupler, or photoMOS) is a device that uses a short optical transmission path to transfer a signal between elements of a circuit, typically a transmitter and a receiver, while keeping them electrically isolated — since the signal goes from an electrical signal to an optical signal back to an electrical signal, electrical contact along the path is broken. The opto-isolator is simply a package that contains both an infrared LED and a photodetector such as silicon diode, transistor Darlington pair, or SCR. The wavelength response of each device is tailored to be as identical as possible to permit the highest measure of coupling possible. Configurations The dashed line represents the isolation barrier, over which no electrical contact can be permitted.A common implementation involves a LED and a phototransistor, separated so that light may travel through a barrier but electrical current may not. When an electrical signal is applied to the input of the opto-isolator, its LED lights, its light sensor then activates, and a corresponding electrical signal is generated at the output. Unlike a transformer, the opto-isolator allows for DC coupling and generally provides significant protection from serious overvoltage conditions in one circuit affecting the other. If high transmission ratio is required Darlington photo transistor is used, however higher transmission ratio usually results low noise immunity and higher delay.

With a photodiode as the detector, the output current is proportional to the amount of incident light supplied by the emitter. The diode can be used in a photovoltaic mode or a photoconductive mode. In photovoltaic mode, the diode acts like a current source in parallel with a forward-biased diode. The output current and voltage are dependent on the load impedance and light intensity. In photoconductive mode, the diode is connected to a supply voltage, and the magnitude of the current conducted is directly proportional to the intensity of light. This optocoupler type is significantly faster than one with photo transistor however transmission ratio is very low. Because of that it is common to integrate amplifier circuit in same package. The optical path may be air or a dielectric waveguide. When high noise immunity is required optical conductive shield may be integrated into optical path. The transmitting and receiving elements of an optical isolator may be contained within a single compact module, for mounting, for example, on a circuit board; in this case, the module is often called an optoisolator or opto-isolator. The photosensor may be a photocell, phototransistor, or an optically triggered SCR or TRIAC. Occasionally, this device will in turn operate a power relay or contactor. For analog isolation, special "analog" optoisolators are used. These devices have two independent, closely matched phototransistors, one of which is typically used to linearize the response using negative feedback. Application A simple circuit with an opto-isolator. When switch S1 is closed, LED D1 lights, which triggers phototransistor Q1, which pulls the output pin low. This circuit, thus, acts as a NOT gate.Among other applications, opto-isolators can help cut down on ground loops, block voltage spikes, and provide electrical isolation.

Most common application is for switched-mode power supplies. They utilise optocouplers for mains isolation. Because of noisy environment optocouplers with low transmission ratio are preferred. One of the requirements of the MIDI (Musical Instrument Digital Interface) standard is that input connections be opto-isolated. They are used to isolate low-current control or signal circuitry from transients generated or transmitted by power supply and high-current control circuits. The latter are used within motor and machine control function blocks.

Applications of Solar seeker Cell Solar powered automobile Inhouse Solar cells Soler water heaters Solar powered flying machines Solar powered street lights Solar electric plants

CONCLUSION At last we would say that we learnt many things during our major project. We got to know about renewable sources of energy & the urgent need of improving the solar cell industry to meet future energy needs. Solar energy has the potential to supply all energy needs but it is diffuse, cyclic and often undependable. It needs systems that gather and concentrate solar energy, Solar thermal & Photovoltaic. Hence, whatever knowledge we have gained during major project here will be an assent for our future and we are very much thankful for the co-operation of all faculty & our classmates who helped to complete our project. Abhishek Dogra Sukhdeep Singh Ekanshu Sharma Amit Dhadwal

TABLE OF CONTENT Sr. NO.

CONTENT

1.

INTRODUCTION

2.

MICROCONTROLLER

3.

H BRIDGE

4.

DC MOTOR

5.

REED SENSOR

6.

PHOTO-SENSOR

7.

OPTOCOUPLER

8.

APPLICATIONS OF SOLAR SEEKER CELL

9.

CONCLUSION