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8/13/2019 Water Level Controoler
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OF
WATER LEVER CONTROLLER
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INTRODUCTION
Water is the most important Natures gift to the mankind. Without this
there is no life. Now the man understands its importance especially there
where is not available easily. It is now being managed by the proper manner
in city areas where the use of it is more than its availability. Water Level
Controller as clear from it is the top level of the overhead tanks in houses or
in industrial areas. his is a basic circuit used in all water level indicators.
!ere is a simple but effective pro"ect which can control the storage level of
water in a tank to provide water throughout the day. he circuit re#uires a
few components and can be constructed in a couple of hours. It is wired
around two readily available npn transistor which drive relay $L%& when the
water level falls below a predetermined level.
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CIRCUIT WORKING
It is wired around two readily available npn transistor which drive
relay $L%& when the water level falls below a predetermined level. 'ssume
that the tank is filled with water up to level '. the base of transistor & is
held at a positive potential through suspended metallic rod which is
connected to (&)*. he voltage developed across resistor $) is sufficient to
hold transistor & in saturation. he base of & is held at a positive potential
via level + also through N,C contact of the relay. $L& is employed to switch
the power supply to the pumping motor on or off. 's long as & conducts
the voltage at its collector with respect to ground is practically -ero and
hence transistor ) does not conduct.
When water falls below level ' & continues to conduct via level +.
+ut when it falls below level + base "unction of & is reverse biased and
voltage at the collector of & is around (&)* with respect to ground. hus
transistor ) conducts in the saturation region and activates the relay.
Now the motor gets connected to its power supply via the N,/
contacts 0which are now closed1 of the relay. 't the same time another pair
of relay contacts disconnects level + and resistor $&. 2o when water
reaches level + transistor & still does not conduct and the water level
continues to rise till level '. when water touches level ' & is forwardbiased the relay is de%energised and the power supply of the motor is cut
off. 't the same time another pair of relay contacts connects level + and
resistor $& via its N,C state. Capacitor C& provides a momentary time%delay
start. L34 indicates that the tank is being filled with three level.
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POWER SUPPLY
NEED OF POWER SUPPLY:-
5erhaps all of you are aware that a power supply is a primary
re#uirement for the test bench of a home e6perimenters mini lab. ' battery
eliminator can eliminate or replace the batteries of solid%state electronic
e#uipment and ))7* '.C. mains instead of the batteries or dry cells thus can
operate the e#uipment. Nowadays the sued of commercial battery eliminator
or power supply unit have become increasingly popular as power source for
household appliances like transceiver record player clock etc.
Summary of powr !upp"y #$r#u$% fa%ur!:-
&r$f '!#r$p%$o( of opra%$o(:gives out well regulated
(8* output output current capability of 977m'.
C$r#u$% pro%#%$o(: +uilt :in overheating protection shuts
down output when regulator IC gets too hot.
C$r#u$% #omp")$%y:simple and easy to build.
C$r#u$% prforma(#: 2table (8* output voltage reliable
/peration.
A*a$"a+$"$%y of #ompo((%!: 3asy to get uses only
common basic components.
D!$,( %!%$(,: +ased on datasheet e6ample circuit I have
used this circuit successfully as part of other electronics pro"ects.
App"$#a%$o(!:part of electronics devices small laboratory
power supply.
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DESCRITION OF POWER SUPPLY
his circuit is a small ( 8 volts power supply. Which is useful when
e6perimenting with digital electronics. 2mall ine6pensive battery with
variable output voltage are available but usually their voltage regulation is
very poor which makes them not very usable for digital circuit e6perimenter
unless a better regulation can be achieved in some way. he following
circuit is the answer to the problem.his circuit can give (8* output at about 977m' current. he circuit
has overload and terminal protection.
COPONENTS USED
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SEICONDUCTOR:
0&1 & ) ;;.. N5N
0 04iode1
0=1L34
RESISTANCES:
0&1 $&$) ;; &7? /hm.
CAPACITOR:
0&1C& ;;;&77 @A4
0)1C) ;;. &777 @A4
ISCELLANEOUS:
$3L'B ;;;;; *
ransformer ;;;;. &)%7%&)
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CIRCUIT DAIGRA
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RESISTOR
' resistor is an electrical component that limits or regulates the flow of
electrical current in an electronic circuit. $esistors can also be used to
provide a specific voltagefor an active device such as a transistor.
'll other factors being e#ual in a direct%current 04C1 circuit the current
through a resistor is inversely proportional to its resistance and directly
proportional to the voltage across it. his is the well%known /hmDs Law. In
alternating%current 0'C1 circuits this rule also applies as long as the resistor
does not contain inductance or capacitance.
$esistors can be fabricated in a variety of ways. he most common type in
electronic devices and systems is the carbon-composition resistor. Aine
granulated carbon 0graphite1 is mi6ed with clay and hardened. he resistancedepends on the proportion of carbon to clayE the higher this ratio the lower
the resistance.
'nother type of resistor is made from winding Nichrome or similar wire on
an insulating form. his component called a wirewound resistor is able to
handle higher currents than a carbon%composition resistor of the same
physical si-e. !owever because the wire is wound into a coil the
component acts as an inductors as well as e6hibiting resistance. his does
not affect performance in 4C circuits but can have an adverse effect in 'Ccircuits because inductance renders the device sensitive to changes in output.
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RESISTOR COLOUR CODE
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CAPACITOR
' capacitor is a tool consisting of two conductive plates each of which hosts an
opposite charge. hese plates are separated by a dielectric or other form of
insulator which helps them maintain an electric charge. here are several types ofinsulators used in capacitors. 36amples include ceramic polyester tantalum air
andpolystyrene. /ther common capacitor insulators include air paper and plastic.
3ach effectively prevents the plates from touching each other.
' capacitor is often used to store analogue signals and digital data. 'nother type of
capacitor is used in the telecommunications e#uipment industry. his type of
capacitor is able to ad"ust the fre#uency and tuning of telecommunications
e#uipment and is often referred to a variable capacitor. ' capacitor is also ideal
for storing an electron. ' capacitor cannot however make electrons.
SY&OL
SY&OL OF ELECTROLYTIC CAPACITOR
' capacitor measures in voltage which differs on each of the two interior plates.
+oth plates of the capacitor are charged but the current flows in opposite
directions. ' capacitor contains &.9 volts which is the same voltage found in a
common '' battery. 's voltage is used in a capacitor one of the two plates
becomes filled with a steady flow of current. 't the same time the current flows
away from the other plate.
o understand the flow of voltage in a capacitor it is helpful to look at naturally
occurring e6amples. Lightning for e6ample is similar to a capacitor. he cloud
represents one of the plates and the ground represents the other. he lightning is
the charging factor moving between the ground and the cloud.
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IAGE OF ELECTROLYTIC CAPACITOR
TRANSISTORS
' Tra(!$!%oris an !m$#o('u#%orwhich is a fundamental component in almost
all electronic devices. ransistors are often said to be the most significant invention
of the )7th Century. ransistors have many uses including switching
voltage,current regulation and amplification % all of which are useful in r(wa+"
(r,y applications.
' transistor controls a large electrical output signal with changes to a small input
signal. his is analogous to the small amount of effort re#uired to open a tap
0faucet1 to release a large flow of water. 2ince a large amount of current can be
controlled by a small amount of current a transistor acts as an amp"$f$r.
' transistor acts as a !w$%#.which can open and close many times per second.
&$po"ar /u(#%$o( Tra(!$!%or!
he most common type of transistor is a +$po"ar 0u(#%$o( %ra(!$!%or. his is made
up of three layers of a semi%conductor material in a sandwich. In one configuration
the outer two layers have e6tra electrons and the middle layer has electrons
missing 0holes1. In the other configuration the two outer layers have the holes and
the middle layer has the e6tra electrons.
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SY&OL OF NPN 1 PNP TRANSISTOR
Layers with e6tra electrons are called N-Typ those with electrons missing called
P-Typ. herefore the bipolar "unction transistors are more commonly known as
PNP %ra(!$!%or! and NPN %ra(!$!%or! respectively.
+ipolar "unction transistors are typically made of !$"$#o( and so they are very
cheap to produce and purchase.
2ow 'o Tra(!$!%or! Wor3
' bipolar "unction transistor has three terminals % &a! Co""#%or and Em$%%r
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corresponding to the three semi%conductor layers of the transistor. he weak input
current is applied to the inner 0base1 layer. When there is a small change in the
current or voltage at the inner semiconductor layer 0base1 a rapid and far larger
change in current takes place throughout the whole transistor.
5ictured above is a schematic diagram of the more common NPN %ra(!$!%or.+elow is an illustration of the same transistor using water rather than electricity to
illustrate the way it functionsF
he illustration shows pipe work with three openings & 4&a!56 C4Co""#%or56 a('
E 4Em$%%r57he reservoir of water at C is the supply voltagewhich is prevented
from getting though to 3 by a plunger. If water is poured into + it pushes up the
plunger letting lots of water flow from C to 3. If even more water is poured into +
the plunger moves higher and the flow of water from C to 3 increases.
herefore a small input current of electricity to the +ase leads to a large flow of
electricity from the Collector to the 3mitter.
Tra(!$!%or Ga$(
Looking at the water analogy again if it takes & litre of water per minute poured
into + to control &77 litres of water per minute flowing from C to 3 then the Ga$(
0or amp"$f$#a%$o( fa#%or1 is &77. ' real transistor with a gain of &77 can control
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&77m' of current from C to 3 with an input current of "ust &m' to the base 0+1.
If the output power 0current 6 voltage1 are more than & Watt a Powr Tra(!$!%or
must be used. hese let much more power flow through and re#uire a larger
controlling input current.
DIODES
' '$o' is the simplest sort of semiconductor device. +roadly speaking a
semiconductor is a material with a varying ability to conduct electrical current.
@ost semiconductors are made of a poor conductor that has had $mpur$%$!0atoms
of another material1 added to it. he process of adding impurities is called 'op$(,.
SY&OL OF DIODE
Circuit 2ymbol
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A% %. 0u(#%$o(6 fr "#%ro(! from %. N-%yp ma%r$a" f$"" .o"!
from %. P-%yp ma%r$a"7 T.$! #ra%! a( $(!u"a%$(, "ayr $( %.
m$''" of %. '$o' #a""' %. 'p"%$o( 8o(7
o get rid of the depletion -one you have to get electrons moving from the N%type
area to the 5%type area and holes moving in the reverse direction. o do this you
connect the N%type side of the diode to the negative end of a circuit and the 5%type
side to the positive end. he free electrons in the N%type material are repelled by
the negative electrode and drawn to the positive electrode. he holes in the 5%typematerial move the other way. When the voltage difference between the electrodes
is high enough the electrons in the depletion -one are boosted out of their holes
and begin moving freely again. he depletion -one disappears and charge moves
across the diode.
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W.( %. (,a%$* (' of %. #$r#u$% $! .oo3' up %o %. N-%yp "ayr a('
%. po!$%$* (' $! .oo3' up %o P-%yp "ayr6 "#%ro(! a(' .o"! !%ar%mo*$(, a(' %. 'p"%$o( 8o( '$!appar!7
If you try to run current the other way with the 5%type side connected to the
negative end of the circuit and the N%type side connected to the positive end
current will not flow. he negative electrons in the N%type material are attracted to
the positive electrode. he positive holes in the 5%type material are attracted to the
negative electrode. No current flows across the "unction because the holes and the
electrons are each moving in the wrong direction. he depletion -one increases.02ee !ow 2emiconductors Workfor more information on the entire process.1
W.( %. po!$%$* (' of %. #$r#u$% $! .oo3' up %o %. N-%yp "ayr
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a(' %. (,a%$* (' $! .oo3' up %o %. P-%yp "ayr6 fr "#%ro(!
#o""#% o( o( (' of %. '$o' a(' .o"! #o""#% o( %. o%.r7 T.
'p"%$o( 8o( ,%! +$,,r7
DIODES C2ARACTERISTICS
LED
' light%emitting diode 0L341 is a semiconductordevice that emits visible lightwhen an electric currentpasses through it. he light is not particularly bright but
in most L34s it is monochromatic occurring at a single wavelength. he output
from an L34 can range from red 0at a wavelength of appro6imately >77
nanometers1 to blue%violet 0about =77 nanometers1. 2ome L34s emit infrared 0 I$1
energy 08
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SY&OL OF LED
Circuit 2ymbol
&(f$%! of LED!
Low powr r9u$rm(%F @ost types can be operated with battery power
supplies.
2$,. ff$#$(#y: @ost of the power supplied to an L34 or I$34 is
converted into radiation in the desired form with minimal heat production.
Lo(, "$f: When properly installed an L34 or I$34 can function for
decades.
Typ$#a" App"$#a%$o(!
I('$#a%or "$,.%!: hese can be two%state 0i.e. on,off1 bar%graph oralphabetic%numeric readouts.
LCD pa(" +a#3"$,.%$(,:2peciali-ed white L34s are used in flat%panel
computer displays.
F$+r op%$# 'a%a %ra(!m$!!$o(: 3ase of modulation allows wide
communicationsbandwidthwith minimal noise resulting in high speed and
accuracy.
Rmo% #o(%ro": @ost home%entertainment HremotesH use I$34s to
transmit data to the main unit.
op%o$!o"a%or: 2tages in an electronic system can be connected together
without unwanted interaction.
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IAGE OF DIFFERENT LEDS
Tra(!formr
W.a% $! a Tra(!formr;
' transformer transfers electrical energy between two circuits. It usually consists
of two wire coils wrapped around a core. hese coils are called primary and
secondary windings. 3nergy is transferred by mutual induction caused by a
changing electromagnetic field. If the coils have different number of turns aroundthe core the voltage induced in the secondary coil will be different to the first.
ransformers convert 'C electricity from one voltage to another with little loss of
power. ransformers work only with 'C and this is one of the reasons why mains
electricity is 'C.
2tep%up transformers increase voltage step%down transformers reduce voltage.
@ost power supplies use a step%down transformer to reduce the dangerously high
mains voltage 0)
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ransformers waste very little power so the power out is 0almost1 e#ual to the
power in. Note that as voltage is stepped down current is stepped up.
he ratio of the number of turns on each coil called the %ur(! ra%$o determines
the ratio of the voltages. ' step%down transformer has a large number of turns on
its primary 0input1 coil which is connected to the high voltage mains supply and a
small number of turns on its secondary 0output1 coil to give a low output voltage.
2ymbol of transformer
Tra(!formr
2ow 'o! a Tra(!formr Wor3
'lternating current in the primary winding creates an electromagnetic field that
induces a current in the secondary winding when the field changes. 2mall
transformers use enameled wire for their windings while large transformers use
insulated copper strips. ransformers can be single winding center%tap or multi%
tap. Center%taps have a terminal at the middle point of the secondary winding
which has half the voltage of the end terminal. @ulti%taps have many terminals
along the winding whose voltages depend on their locations. he purpose of the
core is to direct the electromagnetic field through the secondary winding. 2ilicon
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steel cores are used for their high magnetic permeability. he insulated laminations
work better than solid cores by confining eddy currents which reduces their
losses.
U!! of Tra(!formr!ransformers are mainly used to convert one voltage to another. he process of
increasing the voltage is called Jstepping upK while decreasing the voltage is
called Jstepping downK. @ost electronic e#uipments need a transformer to lower
the mains voltage to a usable level. ransformers are also found in power adapters
and battery chargers. Inverters are transformers which step%up a low voltage to a
higher voltage allowing a mains powered e#uipment to run on a battery.
'dditional circuitry is re#uired to change the batteryDs direct current into
alternating current. ransformers are used for electricity distribution to minimi-e
energy loss over long distances. !igher voltages allow for lower currents whichreduces the losses caused by resistance.
RELAY
' relay is an "#%r$#a""y opra%' !w$%#.. Current flowing through the coil of the
relay creates a magnetic field which attracts a lever and changes the switch
contacts. he coil current can be on or off so relays have two switch positions and
they are 'ou+" %.row0#.a(,o*r1 switches.
$elays allow one circuit to switch a second circuit which can be completely
separate from the first. Aor e6ample a low voltage battery circuit can use a relay to
switch a )
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$elays are usuallly 254 or 454 but they can have many more sets of switch
contacts for e6ample relays with = sets of changeover contacts are readily
available. Aor further information about switch contacts and the terms used to
describe them please see the page on switches.
@ost relays are designed for 5C+ mounting but you can solder wires directly tothe pins providing you take care to avoid melting the plastic case of the relay.
he supplierDs catalogue should show you the relayDs connections. he coil will be
obvious and it may be connected either way round. $elay coils produce brief high
voltage DspikesD when they are switched off and this can destroy transistors and ICs
in the circuit. o prevent damage you must connect aprotection diodeacross the
relay coil.
he animated picture shows a working relay with its coil and switch contacts. Bou
can see a lever on the left being attracted by magnetism when the coil is switchedon. his lever moves the switch contacts. here is one set of contacts 02541 in
the foreground and another behind them making the relay 454.
he relayDs switch connections are usually labelled C/@ NC and N/F
CO Common always connect to this it is the moving part of the switch.
NC Normally Closed C/@ is connected to this when the relay coil is off.
NO Normally /pen C/@ is connected to this when the relay coil is o(. Connect to C/@ and N/ if you want the switched circuit to be o( w.( %.
r"ay #o$" $! o(.
Connect to C/@ and NC if you want the switched circuit to be o( w.( %.
r"ay #o$" $! off.
A'*a(%a,! of r"ay!:
http://www.kpsec.freeuk.com/components/switch.htmhttp://www.kpsec.freeuk.com/components/relay.htm#protect%23protecthttp://www.kpsec.freeuk.com/components/switch.htmhttp://www.kpsec.freeuk.com/components/relay.htm#protect%23protect8/13/2019 Water Level Controoler
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$elays can switch AC a(' DC transistors can only switch 4C.
$elays can switch .$,. *o"%a,! transistors cannot.
$elays are a better choice for switching "ar, #urr(%!0M 9'1.
$elays can switch ma(y #o(%a#%!at once.
D$!a'*a(%a,! of r"ay!: $elays are +u"3$rthan transistors for switching small currents.
$elays #a((o% !w$%#. rap$'"y0e6cept reed relays1 transistors can switch
many times per second.
$elays u! mor powrdue to the current flowing through their coil.
$elays r9u$r mor #urr(% %.a( ma(y IC! #a( pro*$' so a low power
transistor may be needed to switch the current for the relayDs coil.
SOLDERING TEC2NI
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5reparing the soldering ironF
Wipe the tip clean on the wetted sponge provided.
+ring the resin cored solder to the iron and tin the tip of the iron.
Wipe the e6cess solder of the tip using the wet sponge.
$epeat until the tip is properly tinned.
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SOLDERING COPONENTS INTO T2E PC&
+end the component leads at right angles with both bends at the same
distance apart as the 5C+ pad holes.
3nsure that both component leads and the copper 5C+ pads are clean and
free of o6idi-ation.
Insert component leads into holes and bend leads at about
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PRECAUTIONS
&. @ount the components at the approp places before soldering. Aollow the
circuit discription and components details leads identification etc. 4o not
start soldering before making it confirm that all the components are
mounted at the right place.
). 4o not use a spread solder on the board it may cause short circuit.