59759661 gsm based irrigation system

7/31/2019 59759661 GSM Based Irrigation System

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GSM BASED IRRIGATION SYSTEM

I.E.T.E. RAJKOT SUBCENTER 3

THE INSTITUTION OF ELECTRONICS

AND

TELECOMMUNICATION ENGINEERS

NEW DELHI

DECLARATION

GSM Based Irrigation System

I hereby declare that the work presented in this project report entitled

GSM Based irrigation System is a partial fulfillment of my AMIETE in Electronics

institution of Electronics and Telecommunication and is an authenticated record of

my own work carried out under the valuable guidance of Dr. H. N. PANDYA The

matter embodied in the report has not been submitted for the award of any other

degree or diploma.

Submitted By:-

LAKHANI ARCHITA M

(Mem. No.SG-172792)


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In sprinkler or overhead irrigation, water is piped to one or more central

locations within the field and distributed by overhead high-pressure sprinklers or

guns.

A system utilizing sprinklers, sprays, or guns mounted overhead on

permanently installed risers is often referred to as a solid-set irrigation system.

Higher pressure sprinklers that rotate are called rotorsand are driven by a ball drive,

gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial

circle. Guns are similar to rotors, except that they generally operate at very high

pressures of 40 to 130 lbf/in (275 to 900 kPa) and flows of 50 to 1200 US gal/min (3

to 76 L/s), usually with nozzle diameters in the range of 0.5 to 1.9 inches (10 to 50

mm). Guns are used not only for irrigation, but also for industrial applications such

as dust suppression andlogging.

Sprinklers may also be mounted on moving platforms connected to the

water source by a hose. Automatically moving wheeled systems known as traveling

sprinklersmay irrigate areas such as small farms, sports fields, parks, pastures, and

cemeteries unattended. Most of these utilize a length of polyethylene tubing wound

on a steel drum. As the tubing is wound on the drum powered by the irrigation water

or a small gas engine, the sprinkler is pulled across the field. When the sprinkler

arrives back at the reel the system shuts off. This type of system is known to most

people as a "water reel" traveling irrigation sprinkler and they are used extensively

for dust suppression, irrigation, and land application of waste water. Other travelers

use a flat rubber hose that is dragged along behind while the sprinkler platform is

pulled by a cable. These cable-type travelers are definitely old technology and their

use is limited in today's modern irrigation projects.
http://en.wikipedia.org/wiki/Logginghttp://en.wikipedia.org/wiki/Logginghttp://en.wikipedia.org/wiki/Logginghttp://en.wikipedia.org/wiki/Logging


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Center pivot irrigation

The hub of a center-pivot irrigation system.

Center pivot irrigation is a form of sprinkler irrigation consisting of several

segments of pipe (usually galvanized steel or aluminum) joined together and

supported by trusses, mounted on wheeled towers with sprinklers positioned along

its length. The system moves in a circular pattern and is fed with water from the pivot

point at the center of the arc. These systems are common in parts of the United

States where terrain is flat.

Center pivot with drop sprinklers. Photo by Gene Alexander, USDA Natural

Resources Conservation Service.
http://en.wikipedia.org/wiki/Center_pivot_irrigationhttp://en.wikipedia.org/wiki/Center_pivot_irrigationhttp://en.wikipedia.org/wiki/Trusshttp://en.wikipedia.org/wiki/Trusshttp://en.wikipedia.org/wiki/Trusshttp://en.wikipedia.org/wiki/Image:PivotWithDrops.JPGhttp://en.wikipedia.org/wiki/Trusshttp://en.wikipedia.org/wiki/Center_pivot_irrigationhttp://en.wikipedia.org/wiki/Image:Center-pivot_irrigation.jpg


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Most center pivot systems now have drops hanging from a u-shaped pipe

called a gooseneckattached at the top of the pipe with sprinkler heads that are

positioned a few feet (at most) above the crop, thus limiting evaporative losses.

Drops can also be used with drag hoses or bubblers that deposit the water directly

on the ground between crops.

The crops are planted in a circle to conform to the center pivot. This type of

system is known as LEPA (Low Energy Precision Application). Originally, most

center pivots were water powered. These were replaced by hydraulic systems (T-L

Irrigation) and electric motor driven systems (Lindsay, Reinke, Valley, Zimmatic,

Pierce, Grupo Chamartin. Most systems today are driven by an electric motor

mounted low on each span. This drives a reduction gearbox and transverse

driveshafts transmit power to another reduction gearbox mounted behind each

wheel. Precision controls, some with GPS location and remote computer monitoring,

are now available.

Wheel line irrigation system in Idaho. 2001. Photo by Joel McNee, USDA Natural

Resources Conservation Service.

Lateral move (side roll, wheel line) irrigation

A series of pipes, each with a wheel of about 1.5 m diameter permanently

affixed to its midpoint and sprinklers along its length, are coupled together at one
http://en.wikipedia.org/w/index.php?title=Low_Energy_Precision_Application&action=edit&redlink=1http://en.wikipedia.org/wiki/T-L_Irrigationhttp://en.wikipedia.org/wiki/T-L_Irrigationhttp://en.wikipedia.org/wiki/T-L_Irrigationhttp://en.wikipedia.org/wiki/T-L_Irrigationhttp://www.alibaba.com/catalog/100283762/Center_Pivot_Irrigation_Farm_Machines.htmlhttp://www.alibaba.com/catalog/100283762/Center_Pivot_Irrigation_Farm_Machines.htmlhttp://en.wikipedia.org/wiki/GPShttp://en.wikipedia.org/wiki/Image:WheelLineIrrigation.JPGhttp://en.wikipedia.org/wiki/GPShttp://www.alibaba.com/catalog/100283762/Center_Pivot_Irrigation_Farm_Machines.htmlhttp://en.wikipedia.org/wiki/T-L_Irrigationhttp://en.wikipedia.org/wiki/T-L_Irrigationhttp://en.wikipedia.org/w/index.php?title=Low_Energy_Precision_Application&action=edit&redlink=1


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edge of a field. Water is supplied at one end using a large hose. After sufficient

water has been applied, the hose is removed and the remaining assembly rotated

either by hand or with a purpose-built mechanism, so that the sprinklers move 10 m

across the field. The hose is reconnected. The process is repeated until the opposite

edge of the field is reached. This system is less expensive to install than a center

pivot, but much more labor intensive to operate, and it is limited in the amount of

water it can carry. Most systems utilize 4 or 5-inch (130 mm) diameter aluminum

pipe. One feature of a lateral move system is that it consists of sections that can be

easily disconnected. They are most often used for small or oddly-shaped fields, such

as those found in hilly or mountainous regions, or in regions where labor is

inexpensive.

Sub-irrigation

Sub irrigationalso sometimes called seepage irrigationhas been used for

many years in field crops in areas with highwater tables. It is a method of artificially

raising the water table to allow the soilto bemoistenedfrom below the plants' root

\zone. Often those systems are located on permanent grasslands in lowlands or

river valleys and combined with drainage infrastructure. A system of pumping

stations, canals, weirs and gates allows it to increase or decrease the water level in

a network of ditches and thereby control the water table.

Sub-irrigation is also used incommercialgreenhouseproduction, usually for

potted plants. Water is delivered from below, absorbed upwards, and the excess

collected for recycling. Typically, a solution of water and nutrientsfloods a container

or flows through a trough for a short period of time, 10-20 minutes, and is then

pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires

fairly sophisticated, expensive equipment and management. Advantages are water
http://en.wikipedia.org/wiki/Subirrigationhttp://en.wikipedia.org/wiki/Subirrigationhttp://en.wikipedia.org/wiki/Water_tablehttp://en.wikipedia.org/wiki/Water_tablehttp://en.wikipedia.org/wiki/Water_tablehttp://en.wikipedia.org/wiki/Soilhttp://en.wikipedia.org/wiki/Soilhttp://en.wiktionary.org/wiki/moistenhttp://en.wiktionary.org/wiki/moistenhttp://en.wiktionary.org/wiki/moistenhttp://en.wikipedia.org/wiki/Roothttp://en.wikipedia.org/wiki/Roothttp://en.wikipedia.org/wiki/Commercehttp://en.wikipedia.org/wiki/Commercehttp://en.wikipedia.org/wiki/Greenhousehttp://en.wikipedia.org/wiki/Greenhousehttp://en.wikipedia.org/wiki/Greenhousehttp://en.wikipedia.org/wiki/Potted_planthttp://en.wikipedia.org/wiki/Nutrienthttp://en.wikipedia.org/wiki/Nutrienthttp://en.wikipedia.org/wiki/Water_tankhttp://en.wikipedia.org/wiki/Water_tankhttp://en.wikipedia.org/wiki/Water_tankhttp://en.wikipedia.org/wiki/Nutrienthttp://en.wikipedia.org/wiki/Potted_planthttp://en.wikipedia.org/wiki/Greenhousehttp://en.wikipedia.org/wiki/Commercehttp://en.wikipedia.org/wiki/Roothttp://en.wiktionary.org/wiki/moistenhttp://en.wikipedia.org/wiki/Soilhttp://en.wikipedia.org/wiki/Water_tablehttp://en.wikipedia.org/wiki/Subirrigation


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and nutrient conservation, and labor-saving through lowered system

maintenance and automation. It is similar in principle and action to subsurface drip

irrigation.

Manual irrigation using buckets or watering cans

These systems have low requirements for infrastructure and technical

equipment but need high labor inputs. Irrigation using watering cans is to be found

for example in peri-urban agriculture around large cities in some African countries.

Automatic, non-electric irrigation using buckets and ropes

Besides the common manual watering by bucket, an automated, natural

version of this also exist. Using plain polyester ropes combined with a prepared

ground mixture can be used to water plants from a vessel filled with water. The

ground mixture would need to be made depending on the plant itself, yet would

mostly consist of black potting soil, vermiculite and perlite. This system would (with

certain crops) allow you to save expenses as it does not consume any electricity and

only little water (unlike sprinklers, water timers, ...). However, it may only be used

with certain crops (probably mostly larger crops that do not need a humid

environment; perhaps e.g. paprika's).

Irrigation using stones to catch water from humid air

In countries where at night, humid air sweeps the countryside, stones are

used to catch water from the humid air bytranspiration. This is for example practiced

in the vineyards atLanzarote.

Dry terasses for irrigation and water distribution

In subtropical countries as Mali and Senegal, a special type of terrassing

(without flood irrigation or intent to flatten farming ground) is used. Here, a 'stairs' is
http://en.wikipedia.org/wiki/Automationhttp://en.wikipedia.org/wiki/Automationhttp://en.wikipedia.org/wiki/Transpirationhttp://en.wikipedia.org/wiki/Transpirationhttp://en.wikipedia.org/wiki/Transpirationhttp://en.wikipedia.org/wiki/Lanzarotehttp://en.wikipedia.org/wiki/Lanzarotehttp://en.wikipedia.org/wiki/Lanzarotehttp://en.wikipedia.org/wiki/Malihttp://en.wikipedia.org/wiki/Malihttp://en.wikipedia.org/wiki/Senegalhttp://en.wikipedia.org/wiki/Senegalhttp://en.wikipedia.org/wiki/Senegalhttp://en.wikipedia.org/wiki/Malihttp://en.wikipedia.org/wiki/Lanzarotehttp://en.wikipedia.org/wiki/Transpirationhttp://en.wikipedia.org/wiki/Automation


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made trough the use of ground level differences which helps to decrease water

evaporationand also distributes the water to all patches (sort of irrigation).

Sources of irrigation water

Sources of irrigation water can be groundwater extracted from springsor by

using wells, surface water withdrawn from rivers, lakes or reservoirs or non-

conventional sources like treated wastewater,desalinated waterordrainage water.

A special form of irrigation using surface water is spate irrigation, also called

floodwater harvesting. In case of a flood (spate) water is diverted to normally dry

river beds (wadis) using a network of dams, gates and channels and spread over

large areas. The moisture stored in the soil will be used thereafter to grow crops.

Spate irrigation areas are in particular located in semi-arid or arid, mountainous

regions. While floodwater harvesting belongs to the accepted irrigation methods,

rainwater harvesting is usually not considered as a form of irrigation. Rainwater

harvesting is the collection of runoff water from roofs or unused land and the

concentration of this water on cultivated land. Therefore this method is considered

as a water concentration method.

How an in-ground irrigation system works

Most commercial and residential irrigation systems are "in ground" systems,

which means that everything isburiedin the ground. With thepipes,sprinklers, and

irrigation valvesbeing hidden, it makes for a cleaner, more presentable landscape

without gardenhosesor other items having to be moved around manually.

Water source and piping

The beginning of a sprinkler system is the watersource. This is usually a

tap into an existing (city) water line or a pump that pulls water out of a well or a

pond.
http://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Spring_%28hydrosphere%29http://en.wikipedia.org/wiki/Spring_%28hydrosphere%29http://en.wikipedia.org/wiki/Wellshttp://en.wikipedia.org/wiki/Wellshttp://en.wikipedia.org/wiki/Rivershttp://en.wikipedia.org/wiki/Lakeshttp://en.wikipedia.org/wiki/Reservoirshttp://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/w/index.php?title=Desalinated_water&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Drainage_water&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Spate_irrigation&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Floodwater_harvesting&action=edit&redlink=1http://en.wikipedia.org/wiki/Rainwater_harvestinghttp://en.wikipedia.org/wiki/Rainwater_harvestinghttp://en.wikipedia.org/w/index.php?title=In_ground&action=edit&redlink=1http://en.wiktionary.org/wiki/buriedhttp://en.wiktionary.org/wiki/buriedhttp://en.wiktionary.org/wiki/buriedhttp://en.wikipedia.org/wiki/Pipehttp://en.wikipedia.org/wiki/Pipehttp://en.wikipedia.org/wiki/Pipehttp://en.wikipedia.org/wiki/Sprinklerhttp://en.wikipedia.org/wiki/Sprinklerhttp://en.wikipedia.org/wiki/Sprinklerhttp://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Hose_%28tubing%29http://en.wikipedia.org/wiki/Hose_%28tubing%29http://en.wikipedia.org/wiki/Hose_%28tubing%29http://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Hose_%28tubing%29http://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Sprinklerhttp://en.wikipedia.org/wiki/Pipehttp://en.wiktionary.org/wiki/buriedhttp://en.wikipedia.org/w/index.php?title=In_ground&action=edit&redlink=1http://en.wikipedia.org/wiki/Rainwater_harvestinghttp://en.wikipedia.org/w/index.php?title=Floodwater_harvesting&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Spate_irrigation&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Drainage_water&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Desalinated_water&action=edit&redlink=1http://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/wiki/Reservoirshttp://en.wikipedia.org/wiki/Lakeshttp://en.wikipedia.org/wiki/Rivershttp://en.wikipedia.org/wiki/Wellshttp://en.wikipedia.org/wiki/Spring_%28hydrosphere%29http://en.wikipedia.org/wiki/Evaporation


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The water travels through pipes from the water source through the valves to

the sprinklers. The pipes from the water source up to the irrigation valves are called

"mainlines", and the lines from the valves to the sprinklers are called "lateral lines".

Most piping used in irrigation systems today are HDPE and MDPE orPVC orPEX

plastic pressure pipes due to their ease of installation and resistance to corrosion.
http://en.wikipedia.org/wiki/HDPEhttp://en.wikipedia.org/w/index.php?title=MDPE&action=edit&redlink=1http://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/wiki/PEXhttp://en.wikipedia.org/wiki/Plastic_pressure_pipeshttp://en.wikipedia.org/wiki/Plastic_pressure_pipeshttp://en.wikipedia.org/wiki/PEXhttp://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/w/index.php?title=MDPE&action=edit&redlink=1http://en.wikipedia.org/wiki/HDPE


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PROJECT MEANS:-

Be fore tak ing p ro jec t work fo r execu t ion , i t i s

qu i te necessary to have an exac t idea o f the word .

PROJECT

P s tands fo r Plann ing : P lann ing is the word , wh ich

dea ls w i th the idea o f ac t p roposed to be done.

R s tands fo r Resources : Resources a re the means ,

wh ich gu ide to p romote the func t ion o f the p lan . There

must be a l l necessary resources in o rder to ma in ta in

good pro jec t work .

O s tands f or Opera t ion : Opera t ion is ac tua l ly a l l the

type o f work , wh ich is to be per fo rmed by workers to

comple te the ob jec t .

J s tands fo r Jo in t e f fo r t : I t means the combined

ef fo r ts o f worker and o ther s ta f f to comple te the work .

E s tands fo r Exp la in Eng ineer func t ion : Both the bod ies

i .e . p lann ing body and eng ineer ing body work toge ther

w i th eng ineers th rough the i r techn iques fo r good

produc t ion .

C Sign i f ies Communica t ion : For the execut ion o f the

p lan , the communica t ion is very necessary .


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T Symbol izes Task o f techn iques o f the work ing :

Task o f work ing w i th co - opera t ion o f the work i ng

body and con t ro l work ing body .As a mat te r o f fac t the

word PROJECT i s used spec ia l ly fo r cons t ruc t iona l

and manufac tu r ing purpose.


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LIST OF COMPONENTS USED

FOR THE GSM BASED IRRIGATION SYSTEM

(1) DIODE

(2) TRANSISTOR

(i)PNP

(ii)NPN

(3) TRAMSFORMER 230V 12-0-12V/500 MA CAPACITOR

(i) 10

(ii) 100

(iii) 0.1

(iv) 22

(v)

(4) RESISTOR

(i) 100K

(ii) 10K

(iii) 2k2

(iv) 220k

(v) 1k

(6) Cell phone interface

(7) DTMF decoder section

(8) Moisture sensors

(9) Main controller section

(10) Indicator section

(11) Relay driver and the pump control section

(12) Power supply section


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in auto answer mode after connecting a hands free set to it. Whenever this phone is

called up, it picks up the phone after which the DTMF tones generated by the calling

cell phone will also be produced at the cell phone connected to the system. This fact

is the essence behind the working of the entire project. The DTMF tones from the

switches depressed at the calling cell phone are transmitted to the system cell

phone via the GSM network. Initially this system would seem rather costly as

whenever a pump is to be switched on or off or the status of the field is to be known,

a call has to be made. But since nowadays call costs are going so low that this is not

much of a problem. Moreover when the call cost is compared with the cost of

physical visit of the farmer to the field, it proves to be much cheaper. Also more and

more telecom service providers are giving CUG plans in which call rates are

negligible or even zero. The cell phone hands free is attached to a microphone is the

system. The mic picks up the DTMF tones from the hands free speaker. These

tones are very small in amplitude thus a single transistor collector feedback biased

amplifier stage has been employed for amplifying the signals to a specific level so

that they can be applied to the DTMF decoder for decoding.

The DTMF decoder section: this section is fed input from the single stage

transistor amplifier output. The output of the amplifier and thus the input to the

decoder are the DTMF tones from the system cell phone which are in turn the tones

which were send from the caller cell phone. The decoder is built around a very

popular ASIC the MT8870. This chip accepts DTMF tones and converts them into

BCD data corresponding to the switch that was depressed at the caller phone. Along

with this data, the decoder also generates one specific high signal called the StD

signal from its pin 15. This signal is generated whenever the chip receives any valid

DTMF tone and last for the instant for which the tone lasts. This signal is used to

convey the micro controller that a new data nibble has arrived. The decoder exactly

decodes the DTMF tones by the help of an in built oscillator that generates a very

stable frequency with the help of an externally connected crystal resonator of

3.5795MHz. the output of the DTMF decoder is fed to the controller for further

processing.


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The moisture sensors: there are three moisture sensors employed in the

system. The concept of multiple sensors is based on the fact that different parts of

the field may have different amount of moisture at the same time and that has to be

taken into consideration. As many no. of sensors can be used in the system

although here only four are employed. The sensors actually measure the soil

resistivity to gauge the amount of moisture present in it. Each sensor has been

made using a 555 timer employed as a schmitt trigger. The sensitivity of each

sensor is adjustable using a preset. Moreover each sensor has been fitted with fail

safe mechanism in the form of a 0.1uF capacitor to prevent false triggering. The

outputs of the sensors are active high which can be seen on an LED which has been

connected on the output pin of each sensor so that the status of the sensor can be

easily seen. These LEDs also help in setting the sensitivity of the sensors. The

sensors are fed from the probes that are to be inserted in the soil for measuring the

resistance between the two points at which the probes are entered. The probes can

be of any conductive material, but material which are not corrosive or prone to

rusting must be used. The best alternative is to use graphite rods as sensor probes.

These rods can be easily available by breaking exhausted dry batteries. The outputs

of the sensors are also fed to the microcontroller for further processing.

The main controller section: this section controls the entire system. It

actually integrates the individual components and then unifies their functions as one.

The controller that has been used here is the 89C2051 which belongs to the very

popular 8051 series of micro controllers from Intel. The 2051 has been utilized

because it is a 20 pin controller and thus far smaller in size than the usual 40 pin

version. The main purpose of the controller to be used in this project is that by its

usage further advancement and modification of the project becomes easy and

feasible. Moreover the component count of the entire system remains small in the

scenario when a micro controller is used. Less no of components mean less no of

failure points which increases the system reliability. The micro controller is clocked

by a 12MHz quartz crystal resonator. Other associated circuitry for the controller like

the power-on-reset network and the manual reset network are also connected to the

controller.


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The controller accepts input on its port 1 which has been configured as the

input port. The first nibble to the input port is the data from the sensors whereas the

second nibble is the data obtained from the DTMF decoder section. The StD output

of the DTMF decoder is applied as interrupt to the controller. As the entire 8051

family is built in such a way as to accept active low interrupts, the signal from the

DTMF decoder is first inverted with the help of a single npn transistor and then

applied to interrupt the controller.

The indicator section: contrary to other type of indicators, usually visual in the

form of leds, here audible indication is used. This is due to the fact that an audible

clue about the status is to be given to the user on the phone. To accomplish this two

different buzzers are implemented. One of the buzzers indicates that the pump has

been started and running. This buzzer plays a music to distinguish it from the other

continuous buzzer It stays on for the time the pump is on. The other buzzer is a

continuous one which rings when all the sensors are dry. Display LEDs are also

utilized for visual indication of the status.

The relay driver and the pump control section: this section is connected to

the output of the controller and is used to control the relay which in turn controls the

pump. There are two problems in driving the relay directly from the controller. The

first is that the outputof the controller is in the vicinity of +5V which will not be able to

drive the 12V /200ohm relay. The other thing is that the controller is also not able to

provided that high amount of current that is required by the magnetizing coils of the

relay.

The power supply section. The system requires two distinct dc voltages to

function- +5V dc for the entire circuit except the relay driver section and the relays

themselves as both are rated at 12V. The transformer used is the 12-0-12V/500mA

which is more than enough. The output ac voltage of the mains transformer is fed to

a rectifier for converting it into dc. This impure unregulated dc is applied to a large

value filter capacitor which smoothes the dc voltage. Finally the unregulated dc is

then applied to the 7805 voltage regulator chip so as to obtain the necessary +5

volts needed by the electronics circuit.


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MICROCONTROLLER

Microcontroller is a computer on a single chip. Micro suggests that the device

is small and controller indicates that the device can be used to control the events,

processes or objects. Microcontroller is becoming a key component in many

electronics products like washing machine, un-interrupted power supply, color

television, CD player, remote control, robots, CNC machines, modems, printers,

keyboards, advertisement displays. Temperature indicator and controller, pressure

monitor, elevators, engine management system in automobiles, measurements

instruments, mobile phones, security system, fire alarm system and many others.

The use of microcontroller is so widespread that it is almost impossible to work in

electronics field without utilizing it.


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Overview Of Microcontroller

A microcontroller is an integrated chip that is often part of an embedded

system. The microcontroller includes a CPU, RAM, ROM, I/O ports and timers like a

standard computer but because they are designed to execute only a single specific

task to control a single system, they are much smaller and simplified so that they

can include all the functions required on a single chip.

Early controllers were built from discrete components and they were large in

size. Later microprocessors were build and microcontrollers were able to fit onto a

circuit board. Microcontroller now places all of the needed components onto a single

chip. With the advent of VLSI technology, microcontroller chip are becoming

essentially single chip microcomputers. Microcontrollers collect data from the input

devices, process the data and make decision based on the result of process. The

input may be for sensing and measurement of some aspects of the environment and

output may be generation of one or more control signals that effect the environment

in a desirable manner. Input may be simple binary valued signal from switch, group

of binary digits from ADC, serial data from computer, pulses from infrared receiver or

signals from sensors. Output may be solenoid, relay, LCD, LED, indicators,

Optodevices, motors etc. Assembly language is stored in either internal ROM or

external ROM. Internal RAM is used for processing and temporary storage.

Microcontrollers have become common in many areas, and can be found in

variety of applications like intercom, telephones, mobiles, security system, door

openers, curtain controller, answering machines, fax, television, CNC machines,

washing machines, VCR/VCD, DVD players, remote controls, musical instruments,

sewing machine, camera, Microwave ovens, laser printers computer equipments,

instrumentation and many other home appliances. They are widely used in

automobiles and have become a central part of industrial robotics. The

microcontrollers is most essential IC for continuous process- based industries like

chemical refinery, pharmaceuticals, steels, programmable logic control system(PLC)

and distributed control system(DCS).


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Microcontrollers do not require significant processing power because they are

usually used to control a single process and execute simple instructions.

The automotive market has been a major driver of microcontrollers, many of

which have been developed for automotive applications. Because of automotive

microcontrollers have to withstand harsh environmental conditions, they may be

highly reliable and durable. Automotive microcontrollers, like their counterparts are

very inexpensive and are able to deliver powerful features that would otherwise be

impossible, or too costly to implement.

Brief History Of 8051 Microcontroller Family:-

Intel Corporation introduced an 8 bit 8051 microcontroller in 1981. This

microcontroller has 128 byte RAM, 4K bytes ROM, two timers one serial ports and

four I/O ports on single chip.8051 is a 8 bit processor because CPU can work 8 bit

data at a time. If data is larger then 8 bit, it has to be broken into pieces of 8 bit. Intel

allowed other manufacturers to make flavors of 8051 with the condition that it should

be code compatible with Intel 8051. There are 20 vendors like Philips, siemens;

Dallas, OKI, Fujitsu, Atmel, etc. are building their own versions of the 8051.

Comparison Of Some 8051 Family.

Chip ROM(bytes) RAM(bytes) Timers I/O pins

8031 -- 128 2 32

8032 -- 256 3 32

8051 4K 128 2 32

8052 8K 256 3 32

8751 4K(EPROM) 128 2 32

8752 8K(EPROM) 256 3 32

89C51 4K flash 128 2 32

89C52 8K flash 256 3 32


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Fig 1: simplified block diagram of the microcontroller

Microcontroller incorporates all features found in microprocessor Such as

ALU, General purpose registers, accumulators, program counters, stack pointer,

timing control unit, interrupts etc. In addition to these microcontrollers incorporates

ROM, RAM, I/O, serial I/O, timers etc.

Parallel Serial Input-Output Port:- Microcontroller contains parallel input output

ports to interface it with real world. For Example: 8051 contains 4 parallel input-

output ports to interface with I/O devices. The 8085 microprocessor requires

separate chips such as 8255 (programmable peripheral interface) to interface it with

I/O devices. Microcontroller also has in built serial port. Serial communication with

microcontroller is simpler.

Timers:Microcontroller has inbuilt timers. 8051 has 2 16 bit timers. Timers

provide real time interrupt to the processor for specific events. It can be used

as a counter to count number of events. Typical example is object counter.

Interrupt is generated when count value overflows.


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ROM: Microcontroller has inbuilt Read only memory (ROM) which is used to

store program code and data required during execution such as look up

tables. 8051 microcontrollers has 4K-ROM, 8751 has 4K EPROM (erasable

programmable read only memory), 89C51 has 4K flash memory. ROM is

programmed during manufacturing process. EPROM can be programmed using

EPROM programmer. It needs to erase using ultraviolet eraser. 89C51 is very

popular version of 8051 because it contains flash memory. It is ideal for fast

development since flash memory can be erased and programmed in seconds.

Erasing and programming can be done by microcontroller programmer unit itself.

RAM:Microcontroller has inbuilt Random Access Memory. It is used to store

information for temporary use. CPU can write RAM as well as read it. Any

information stored in the RAM is lost when power is switched off.

8031/8051has 128 bytes Ram while 8032/8052 has 256 byte of RAM.


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roller to contain multiple control instructions that can be executed with a single

macro instruction. Another is RISC (reduced instruction set computer ) architecture,

which implements fewer instructions, but delivers greater simplicity and lower power

consumption.

A highly integrated chip that contains all the components comprising a

controller. Typically this includes a CPU,RAM, some form of ROM, I/Oports, and

timers. Unlike a general-purpose computer, which also includes all of these

components, a microcontroller is designed for a very specific task -- to control a

particular system. As a result, the parts can be simplified and reduced, which cuts

down on production costs.

Microcontrollers are sometimes called embedded microcontrollers, which just

means that they are part of an embedded system -- that is, one part of a larger

device or system.

MicroMo Electronics: Microcontrollers:-

Specializes in the design, assembly and application of high precision,

miniature DC drive systems, components, and motion control systems.

Parallax Microcontrollers:-

Broad-line distributor web site features real-time stock status and

pricing, online ordering, RFQ, technical support, product datasheets and

photos.
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MICROCONTROLLER


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A Microcontroller (also MCU or C) is a computer-on-a-chip. It is a type of

microprocessor emphasizing high integration, low power consumption, self-

sufficiency and cost-effectiveness, in contrast to a general-purpose microprocessor

(the kind used in aPC). In addition to the usual arithmetic and logic elements of a

general purpose

microprocessor, the microcontroller typically integrates additional elements

such as read-writememory for data storage, read-only memory, such as flash for

code storage, EEPROM for permanent data storage, peripheral devices, and

input/output interfaces. At clock speeds of as little as a few MHz or even lower,

microcontrollers often operate at very low speed compared to modern day

microprocessors, but this is adequate for typical applications. They consume

relatively little power (militates), and will generally have the ability to sleep while

waiting for an interesting peripheral event such as a button press to wake them up

again to do something. Power consumption while sleeping may be just nano watts,

making them ideal for low power and long lasting battery applications.

Microcontrollers are frequently used in automatically controlled products and

devices, such as automobile engine control systems, remote controls, office

machines, appliances, power tools, and toys. By reducing the size, cost, and power

consumption compared to a design using a separate microprocessor, memory, and

input/output devices, microcontrollers make it economical to electronically control

many more processes.
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The decision of which peripheral to integrate is often difficult. The

microcontroller vendors often trade operating frequencies and system design

flexibility against time-to-market requirements from their customers and

overall lower system cost. Manufacturers have to balance the need to

minimize the chip size against additional functionality.

Microcontroller architectures vary widely. Some designs include general-

purpose microprocessor cores, with one or more ROM, RAM, or I/O functions

integrated onto the package. Other designs are purpose built for control applications.

A microcontroller instruction set usually has many instructions intended for bit-wise

operations to make control programs more compact. For example, a generalpurpose processor might require several instructions to test a bit in a register and

branch if the bit is set, where a microcontroller could have a single instruction that

would provide that commonly-required function.

LARGE VOLUMES

Microcontrollers take the largest share of sales in the wider microprocessor

market. Over 50% are "simple" controllers, and another 20% are more specialized

digital signal processors (DSPs)[citation needed]. A typical home in adeveloped country

is likely to have only one or two general-purpose microprocessors but somewhere

between one and two dozen microcontrollers. A typical mid rangeautomobilehas as

many as 50 or more microcontrollers. They can also be found in almost any

electricaldevice:washing machines,microwave ovens,telephonesetc.
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Manufacturers have often produced special versions of their microcontrollers

in order to help the hardware andsoftware developmentof the target system. These

have included EPROM versions that have a "window" on the top of the device

through which program memory can be erased by ultra violet light, ready for

reprogramming after a programming ("burn") and test cycle.

An economical option for intermediate levels of production (usually a few

score to a few thousand parts) is a one-time programmable (OTP) microcontroller.

This uses the same die as the UV EPROM version of the part, and is programmed

on the same equipment, but the package does not include the expensive quartz

window required to admit UV light on to the chip.

Other versions may be available where theROMis accessed as an external

device rather than as internal memory.

A simple EPROMprogrammer, rather than a more complex and expensive

microcontroller programmer, may then be used, however there is a potential loss of

functionality through pin outs being tied up with external memory addressing rather

than for general input/output.

These kind of devices usually carry a higher cost but if the target production

quantities are small, certainly in the case of a hobbyist, they can be the most

economical option compared with the set up charges involved in mask programmed

devices.

A more rarely encountered development microcontroller is the "piggy back"

version. This device has no internalROMmemory; instead pin outs on the top of the

microcontroller form a socket into which a standard EPROM program memory

device may be installed. The benefit of this approach is the release of

microcontroller pins for Input and output use rather than program memory. These

kinds of devices are normally expensive and are impractical for anything but the

development phase of a project or very small production quantities.
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Simulators are available for some microcontrollers, such as in Microchip's

MPLABenvironment. These allow a developer to analyse what the behaviour of the

microcontroller and their program should be if they were using the actual part. A

simulator will show the internal processor state and also that of the outputs, as well

as allowing input signals to be generated. While on the one hand most simulators

will be limited from being unable to simulate much other hardware in a system, they

can exercise conditions that may otherwise be hard to reproduce at will in the

physical implementation, and can be the quickest way to debug and analyse

problems. Recent microcontrollers integrated with on-chipdebugcircuitry accessed

byIn-circuit emulatorvia JTAGenables a programmer to debug the software of an

embedded system with adebugger.

INTERRUPT LATENCY

In contrast to general-purpose computers, microcontrollers used in embedded

systems often seek to minimizeinterrupt latencyover instruction throughput.

When an electronic device causes an interrupt, the intermediate results, the

registers, have to be saved before the software responsible for handling the interrupt

can run, and then must be put back after it is finished. If there are more registers,

this saving and restoring process takes more time, increasing the latency.

Low-latency MCUs generally have relatively few registers in their central

processing units, or they have "shadow registers", a duplicate register set that is

only used by the interrupt software.
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What is Inside an LED?

LED's are special diodes that emit light when connected in a circuit. They are

frequently used as "pilot" lights in electronic appliances to indicate whether the

circuit is closed or not. A a clear (or often colored) epoxy case enclosed the heart ofan LED, the semi-conductor chip.

The two wires extending below the LED epoxy enclosure, or the "bulb"

indicate how the LED should be connected into a circuit. The negativeside of an

LED lead is indicated in two ways: 1) by the flat side of the bulb, and 2) by the

shorter of the two wires extending from the LED. The negative lead should be

connected to the negative terminal of a battery. LED's operate at relative low

voltages between about 1 and 4 volts, and draw currents between about 10 and 40

mill amperes. Voltages and currents substantially above these values can melt a

LEDchip.


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What Causes the LED to Emit Light and What Determines the

Color of the Light?

When sufficient voltage is applied to the chip across the leads of the LED,

electrons can move easily in only one direction across the junctionbetween the p

and nregions. In the p regionthere are many more positive than negative charges.

In the n regionthe electrons are more numerous than the positive electric charges.

When a voltage is applied and the current starts to flow, electrons in the n region

have sufficient energy to move across the junction into the p region. Once in the p

region the electrons are immediately attracted to the positive charges due to the

mutual Coulomb forces of attraction between opposite electric charges. When an

electron moves sufficiently close to a positive charge in the p region, the two

charges"re-combine".

Each time an electron recombineswith a positive charge, electric potential energy is

converted into electromagnetic energy. For each recombination of a negative and a

positive charge, a quantum of electromagnetic energy is emitted in the form of a

photon of light with a frequency characteristic of the semi-conductor material (usually

a combination of the chemical elements gallium, arsenic and phosphorus). Only

photons in a very narrow frequency range can be emitted by any material. LED's that

emit different colors are made of different semi-conductor materials, and require

different energies to light them.


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Diode

Figure 1: Closeup of the image below, showing the square shaped semiconductor

crystal

Figure 2: Various semiconductor diodes. Bottom: Abridge rectifier
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Figure 3: Structure of a vacuum tube diode

In electronics, a diode is a two-terminal device (except that thermionic

diodes may also have one or two ancillary terminals for aheater). Diodes have two

active electrodesbetween which the signal of interest may flow, and most are used

for their unidirectional current property. The varicapdiode is used as an electrically

adjustablecapacitor.

The directionality of current flow most diodes exhibit is sometimes

generically called therectifyingproperty. The most common function of a diode is to

allow anelectric currentto pass in one direction (called the forward biasedcondition)

and to block it in the opposite direction (the reverse biased condition). Thus, the

diode can be thought of as an electronic version of a check valve. Real diodes do

not display such a perfect on-off directionality but have a more complex non-linear

electrical characteristic, which depends on the particular type of diode technology.

Diodes also have many other functions in which they are not designed to operate in

this on-off manner.Early diodes included cats whisker crystals and vacuum tube

devices (also called thermionic valves). Today the most common diodes are made

fromsemiconductormaterials such assiliconorgermanium.
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History

Although the crystal diode was popularized before the thermionic diode,

harmonic and solid state diodes were developed in parallel. The principle of

operation of harmonic diodes was discovered by Frederick Guthrie in 1873.[1]The

principle of operation of crystal diodes was discovered in 1874 by the German

scientist,Karl Ferdinand Braun.[2]

Thermion diode principles were rediscovered by Thomas Edison on

February 13,1880and he was awarded a patent in 1883 (U.S. Patent 307,031 ), but

developed the idea no further. Braun patented the crystal rectifier in 1899 [1].

Braun's discovery was further developed by Jag dish Chandra Bose into a useful

device for radio detection.

The first radio receiver using a crystal diode was built around 1900 by

Greenleaf Whittier Pickard. The first thermionic diode was patented in Britain by

John Ambrose Fleming (scientific adviser to the Marconi Company and former

Edison employee[2]) on November 16, 1904 (U.S. Patent 803,684 in November

1905). Pickard received a patent for a silicon crystal detector onNovember 20,1906

[3](U.S. Patent 836,531 ).

At the time of their invention, such devices were known asrectifiers. In 1919,

William Henry Ecclescoined the term diode fromGreek roots;dimeans "two", and

ode(from odos) means "path".
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are only used in niche applications, such as rectifiers in guitar and hi-fi valve

amplifiers, and specialized high-voltage equipment.

Semiconductor diodes

Most modern diodes are based on semiconductorp-n junctions. In a p-n

diode,conventional currentcan flow from the p-type side (the anode) to the n-type

side (the cathode), but cannot flow in the opposite direction. Another type of

semiconductor diode, the Schottky diode, is formed from the contact between a

metal and a semiconductor rather than by a p-n junction.

Currentvoltage characteristic

A semiconductor diode's currentvoltage characteristic, or IV curve, is

related to the transport of carriers through the so-calleddepletion layerordepletion

regionthat exists at the p-n junctionbetween 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 (places for

electrons in which no electron is present) 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 on the N-side and negatively

charged acceptor on the P-side. The region around the p-n junction becomes

depleted ofcharge carriersand thus behaves as aninsulator.

However, thedepletion widthcannot 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 and more ions are created, an increasing electric
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field develops through the depletion zone which 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. This is thereverse biasphenomenon.

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. For silicon diodes, the built-in potential is approximately 0.6

V. Thus, if an external current is passed through the diode, about 0.6 V will be

developed across the diode 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 aforward bias.

Figure 5: IV characteristics of a P-N junction diode (not to scale).

A diodes IV characteristic can be approximated by four regions of operation

(see the figure at right).

At very large reverse bias, beyond thepeak inverse voltageor PIV, a process

called reverse breakdown occurs which causes a large increase in current that

usually damages the device permanently. The avalanche diode is deliberately

designed for use in the avalanche region. In thezener diode, the concept of PIV is

not applicable.
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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 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.

The second region, 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 A range).

The third region is forward but small bias, where only a small forward current

is conducted.As the potential difference is increased above an arbitrarily defined

"cut-in voltage" or "on-voltage", the diode current becomes appreciable (the level of

current considered "appreciable" and the value of cut-in voltage depends on the

application), and the diode presents a very low resistance.

The currentvoltage curve is exponential. In a normal silicon diode at rated

currents, the arbitrary "cut-in" voltage is defined as 0.6 to 0.7 volts. The value is

different for other diode types Schottky diodescan be as low as 0.2 V and red

light-emitting diodes(LEDs) can be 1.4 V or more and blue LEDs can be up to 4.0

V.At higher currents the forward voltage drop of the diode increases. A drop of 1 V to

1.5 V is typical at full rated current for power diodes.
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Schottky diode equation

The Shockley ideal diode equationor the diode law (named after transistor

co-inventor William Bradford Shockley, not to be confused with tetrode inventor

Walter H. Scotty) is the IV characteristic of an ideal diode in either forward or

reverse

bias (or no bias). The equation is:

where

Iis the diode current,

IS is a scale factor called thesaturation current,

VD is the voltage across the diode,

VT is thethermal voltage,

and n is the emission coefficient, also known as the ideality factor. The

emission coefficient nvaries from about 1 to 2 depending on the fabrication

process and semiconductor material and in many cases is assumed to be

approximately equal to 1 (thus the notation nis omitted).

Thethermal voltageVT is approximately 25.85 mV at 300 K, a temperature close to

room temperature commonly used in device simulation software. At any

temperature it is a known constant defined by:

where

qis the magnitude of charge on anelectron(theelementary charge),
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kisBoltzmanns constant,

Tis the absolute temperature of the p-n junction inkelvins

The Shockley ideal diode equation or the diode law is derived with the

assumption that the only processes giving rise to current in the diode are drift (due to

electrical field), diffusion, and thermal recombination-generation. It also assumes

that the recombination-generation (R-G) current in the depletion region is

insignificant. This means that the Shockley equation doesnt account for the

processes involved in reverse breakdown and photon-assisted R-G. Additionally, it

doesnt describe the leveling off of the IV curve at high forward bias due to

internal resistance.

Under reverse bias voltages (see Figure 5) the exponential in the diode

equation is negligible, and the current is a constant (negative) reverse current value

of -IS. The reverse breakdown region is not modeled by the Shockley diode

equation.For even rather small forward biasvoltages (see Figure 5) the exponential

is very large because the thermal voltage is very small, so the subtracted 1 in the

diode equation is negligible and the forward diode current is often approximated as

The use of the diode equation in circuit problems is illustrated in the article on diode

modeling.

Small-signal behavior

For circuit design, a small-signal model of the diode behavior often proves useful. A

specific example of diode modeling is discussed in the article on small-signal

circuits.
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Types of semiconductor diode:-

DiodeZener

diode

Schottky

diode

Tunnel

diode

Light-emitting

diodePhotodiode Varicap Silicon controlled rectifier

Figure 7: Some diode symbols

There are several types of junction diodes, which either emphasize a

different physical aspect of a diode often by geometric scaling, doping level,

choosing the right electrodes, are just an application of a diode in a special circuit, or

are really different devices like the Gunn and laser diode and the MOSFET:

Normal (p-n) diodes which operate as described above. Usually made of

dopedsiliconor, more rarely,germanium. Before the development of modern silicon

power rectifier diodes,cuprous oxideand laterseleniumwas used; its low efficiency

gave it a much higher forward voltage drop (typically 1.41.7 V per cell, with

multiple cells stacked to increase the peak inverse voltage rating in high voltage

rectifiers), and required a large heat sink (often an extension of the diodes metal

substrate), much larger than a silicon diode of the same current ratings would

require. The vast majority of all diodes are the p-n diodes found inCMOSintegrated

circuits, which include two diodes per pin and many other internal diodes.
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value. Also called CLDs, constant-current diodes, diode-connected

transistors, or current-regulating diodes.

Esakiortunnel diodes

these have a region of operation showing negative resistance caused by

quantum tunneling, thus allowing amplification of signals and very simple

bistable circuits. These diodes are also the type most resistant to nuclear

radiation.

Gunn diodes:-

These are similar to tunnel diodes in that they are made of materials such as

GaAs or InP that exhibit a region of negative differential resistance. With

appropriate biasing, dipole domains form and travel across the diode,

allowing high frequencymicrowaveoscillatorsto be built.

Light-emitting diodes(LEDs):-

In a diode formed from a direct band-gap semiconductor, such as gallium

arsenide, carriers that cross the junction emit photonswhen they recombine

with the majority carrier on the other side. Depending on the material,

wavelengths (or colors) from the infrared to the near ultraviolet may be

produced. The forward potential of these diodes depends on the wavelength

of the emitted photons: 1.2 V corresponds to red, 2.4 to violet. The first LEDs

were red and yellow, and higher-frequency diodes have been developed over

time. All LEDs produce incoherent, narrow-spectrum light; white LEDs are

actual

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