coin based water controlling system 1

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Vjit hyd coin based water controlling system |2011-2012

Department of Electrical & Electronics Engineering 1 | P a g

CHAPTER-1

INTRODUCTION:

1.1 SOLENOID TAP:

1.1.1 Definition : A Solenoid is an electromechanical device which allows for anelectrical device to control the flow of a gas or liquid. The electrical devicecauses a current to flow through a coil located on the solenoid valve. Thiscurrent flow in turn results in a magnetic field which causes thedisplacement of a metal actuator.

Solenoid valves come in various configurations and sizes. Solenoid valves can benormally open, normally closed, or a two way valve. A normallyopen solenoid valve allows a liquid or gas to flow through unless a current isapplied to the solenoid valve. A normally closed valve works in the oppositemanner. A two way solenoid valve has three ports; one port is common, one isnormally open and the third is normally closed.

1.1.2 Working of solenoid:

The main working theory of solenoid valve is that there is a fully closed cabinetinside the solenoid valve with holes in different position. Each hole is connectedwith different hose, the valve is centered with two electric magnets aside, when thepower is on, the valve will be pulled to that side though the movement of the valve,the hole which is connected to the hose will be closed / open, the oil inlet is alwaysopen, the hydraulic oil flows to different hoses and push the cylinder piston by itspressure, the piston drives the piston stem and then the equipment into movement.
http://www.wisegeek.com/what-is-a-valve.htmhttp://www.wisegeek.com/what-is-a-magnetic-field.htmhttp://www.wisegeek.com/what-is-an-actuator.htmhttp://www.pneumaticpart.com/solenoid-valve.htmlhttp://www.pneumaticpart.com/solenoid-valve.htmlhttp://www.wisegeek.com/what-is-an-actuator.htmhttp://www.wisegeek.com/what-is-a-magnetic-field.htmhttp://www.wisegeek.com/what-is-a-valve.htm


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By this means, the mechanical movement can be controlled by controlling theelectricity of solenoid valve.

1.1.3 Types of solenoid taps :

Many variations are possible on the basic, one way, one solenoid valve describedabove:

one or two solenoid valves; direct current or alternating current powered; different number of ways and

positions;

1.1.4 Applications of solenoid taps: Solenoid valves are used in fluid power pneumatic and hydraulic systems, to

control cylinders, fluid power motors or larger industrial valves. Automatic irrigation sprinkler systems also use solenoid valves with an

automatic controller. Domestic washing machines and dishwashers use solenoid valves to control

water entry to the machine. In the paintball industry, solenoid valves are usually referred to simply as

"solenoids." They are commonly used to control a larger valve used tocontrol the propellant (usually compressed air or CO 2).

Solenoid valves are used in dental chairs to control air flow.Besides controlling the flow of air and fluids solenoids are used in pharmacologyexperiments, especially for patch-clamp, which can control the application of agonist or antagonist.
http://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Irrigation_sprinklerhttp://en.wikipedia.org/wiki/Controller_(irrigation)http://en.wikipedia.org/wiki/Controller_(irrigation)http://en.wikipedia.org/wiki/Irrigation_sprinklerhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_current


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1.2 555 TIMER

1.2.1 INTRODUCTION:

The 555 timer is an integrated circuit (chip) implementing a variety of timer andmultivibrator applications. It was produced by Signetics Corporation in early 1970.The original name was the SE555/NE555 and was called "The IC Time Machine".The 555 gets its name from the three 5- K resistors used in typical earlyimplementations. It is widely used because of its ease to use, low price andreliability. It is one of the most popular and versatile integrated circuits which canbe used to build lots of different circuits. It includes 23 transistors, 2 diodes and 16resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8)(Refer to Figure 1). The 555 Timer is a monolithic timing circuit that canproduce accurate and highly stable time delays or oscillations. The timer basicallyoperates in one of the two modes monostable (one-shot) multivibrator or as anastable (free-running) multivibrator. In the monostable mode, it can produceaccurate time delays from microseconds to hours. In the astable mode, it canproduce rectangular waves with a variable duty cycle. Frequently, the 555 is usedin astable mode to generate a continuous series of pulses, but you can also use the

555 to make a one-shot or monostable circuit. The 555 can source or sink 200mAof output current, and is capable of driving wide range of output devices. Theoutput can drive TTL (Transistor-Transistor Logic) and has a temperature stabilityof 50 parts per million (ppm) per degree Celsius change in temperature, orequivalently 0.005 %/C. Applications of 555 timer in monostable m ode includetimers, missing pulse detection, bounce free switches, touch switches, frequencydivider, capacitance measurement, pulse width modulation (PWM) etc.


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1.2.2 Pin diagram of 555IC

PIN 1: GroundPIN 2: Trigger

PIN 3: Output

PIN 4: Reset

PIN 5: Control voltage

PIN 6: ThresholdPIN 7: Discharge

PIN 8: +VCC


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1.2.3 Functional Block Diagram of 555 Timer

Fig : Functional block diagram of IC555 as Astable Multivibrator


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Pin 8: +Vcc: The supply voltage of +5 V to + 18 V is applied to this pin withrespect to ground (pin 1).

1.2.4 Description of functional block diagram:

The 555 timer consists of a voltage divide r arrangement, two comparators, an RSflip-flop, an n-p-n transistor Q1 and a p-n-p transistor Q2 Since the voltage dividerhas equal resistors, the upper comparator has a trip point of UTP = V32 Thecomparator 2 has a trip point of LTP = CCV31. As seen in the Figure 2, the pin 6(Threshold) is connected to the comparator 1. This voltage comes from the externalcomponents (not shown). When the threshold is greater than the UTP, thecomparator 2 has a high output. Pin 2 (trigger) is connected to the comparator 2.This is the trigger voltage that is used for the monostable operation of the timer.When the trigger is inactive, the trigger voltage is high. When the trigger voltagefalls to less than the LTP, comparator 2 produces a high output.

Since the circuit is stable in either of two states, it is sometimes called a bistablemultivibrator. A bistable multivibrator latches in either of two states. A high Sinput forces Q into the high state, and a high R input forces Q to return to the lowstate. The output Q remains in a given state until it is triggered into the oppositestate. The S input is sometimes called the set input because it sets the Q output tohigh. The R input is called the reset input because it re sets the Q output to low

1.2.5 ASTABLE MULTIVIBRATOR:

We now take up the application of 555timer as an astable multivibrator. Anastable multivibrator is a wave-generating circuit in which neither of the outputlevels is stable. The output keeps on switching between the two unstable states andis a periodic, rectangular waveform. The circ uit is therefore known as an astablemultivibrator. Also, no external trigger is required to change the state of theoutput, hence it is also called free -running multivibrator. The time for which theoutput remains in one particular state is determined by the two resistors and acapacitor externally connected to the 555 timer

THEORY:

Figure 4 shows 555 timer connected as an astable multivibrator. Pin 5 is bypassedto ground through a 0.01F capacitor. The power supply (+VCC) is connected tocommon of pin 4 and pin 8 an d pin 1 is grounded. If the output is high initially,


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capacitor C starts charging towards Vcc through RA and RB. As soon as thevoltage across the capacitor becomes equal to2/3Vcc, the upper comparatortriggers the flip-flop, and the output becomes low. The capacitor now startsdischarging through RB and transistor Q1. When the voltage across the capacitor

becomes 1/3Vcc, the output of the lower comparator triggers the flip-flop, and theoutput become s high. The cycle then repeats. The output voltage and capacitorvoltage waveforms are shown in Figure 5


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1.3 Decade counter:

1.3.1 INTRODUCTION: Modulus for a decade counter is 10 These counters are useful in display applications. Counter with a sequence of 0(0000) through 9(1001) is a BCD

decade counter, because its ten state sequence is the BCD code. Q1=1, Q3=1 at the count 1010, so the OP of the NAND gate is LOW

and RESETs all the FFs Q1 and Q3 are connected to theNAND gate This counter has to reset to 0 when the output reads 11. .


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1.3.2 Pin diagram of decade counter 4017IC

1.3.3 PIN DESCRIPTION


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Feature of decade couter

Automatic counter correction

Tolerant of slow clock rise and fall time

Fully static operation 5 V, 10 V, and 15 V parametric rating

Standardized symmetrical output characteristicss Operates across theautomotive temperature range 40C to +125C 1

.3.4 APPLICATIONS OF COUNTERS

Frequency dividers

Digital clock.

Parallel to serial data conversion (MULTIPLEXING)

Auto parking control.

Industrial digital control system.


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CHAPTER -3

POWER SUPPLY UNIT

3.1 INTRODUCTION:

As we all know any invention of latest technology cannot be activated without thesource of power. So in the fast moving world, we deliberately need a proper powersource which will be apt for a particular requirement. All the electroniccomponents starting from diode to intel ICs only work with a dc supply rangingfrom -+5v to -+12v. We are utilizing for the same , the cheapest and commonly

available energy source of 230v-50hz and stepping down, rectifying, filtering andregulating the voltage.

3.2 BLOCK DIAGRAM:

The Block diagram of the Regulated power supply is as shown below.


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Block Diagram of a Regulated Power Supply System

3.3Transformers:

Fig: Trnsformer

3.3.1 Step down transformer

When the ac is applied to the primary winding of the transformer it can be

either stepped down or up depending on the value of dc needed. In ourcircuit the transformer of 230v/0-12v is used to perform the step downoperation where a 230v ac appears 12v ac across the secondary winding onealternation of input causes the top of the transformer to be positive andbottom negative. The next alternation will temporarily cause the reverse.The current rating of transformer is used in our project is 2amps. Apart fromstepping down ac voltages it gives isolation between the power source andpower supply circuitries.


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Fig: step down transformer

3.4 RECTIFER UNIT:

A rectifier is an electrical device that converts alternating current(AC), whichperiodically reverses direction, to direct current (DC), which is in only onedirection, a process known as rectification.

BRIDGE RECTIFIER:

Another type of circuit that produces the same output waveform as the fullwave rectifier circuit above, is that of the Full Wave Bridge Rectifier . Thistype of single phase rectifier uses four individual rectifying diodes connected ina closed loop "bridge" configuration to produce the desired output.

The four diodes labelled D 1 to D 4 are arranged in "series pairs" with only twodiodes conducting current during each half cycle. During the positive half cycle of the supply, diodes D1 and D2 conduct in series while diodes D3 and D4 arereverse biased and the current flows through the load as shown below.


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The Positive Half-cycle:

The Negative Half-cycle :

3.5 FILTER UNIT:

Filter circuits which are usually capacitors acting as a surge arresters always followthe rectifier unit. This capacitor is also called as a decoupled capacitor or a by


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passing capacitor, is used not only to short the ripple with frequency of 120hz toground but also to leave the frequency of the dc to appear at the output.

Capacitor c1(1000f/25v) is used for the reduction of ripples from pulsating.

3.6 VOLTAGE REGULATER:

A voltage regulator is an electrical regulator designed toautomatically maintain a constant voltage level. A voltage regulator may be asimple "feed-forward" design or may include negative feedback control loops. Itmay use an electromechanical mechanism, or electronic components. Dependingon the design, it may be used to regulate one or more AC or DC voltages.

7805 series ICs do not require any additional components to provide a constant,regulated source of power, making them easy to use, as well as economical, andalso efficient uses of circuit board real estate. By contrast, most other voltageregulators require several additional components to set the output voltage level, orto assist in the regulation process. Some other designs (such as a switching power

supply) can require not only a large number of components but also substantialengineering expertise to implement correctly as well.

7805 series ICs have built-in protection against a circuit drawing too muchpower. They also have protection against overheating and short-circuits, makingthem quite robust in most applications. In some cases, the current-limiting features


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of the 7805 devices can provide protection not only for the 7805 itself, but also forother parts of the circuit it is used in, preventing other components from beingdamaged as well.

3.7 NOISE FILTER :

Noise filters are used to remove any noise (unwanted signals) present in the line,Electromagnetic interference signals, radio frequency interference signals etc.,capacitor c3 (0.1f) is a low pass filter which by passes high frequency noises.

Capacitor C2 (10f/25 v) is for maintaining stability of the voltage at load side.

3.8 SPECIFICATIONS :

Resistor RL maintains line load regulations,

At the secondary side of the transformer, applied voltage 12v

Conducting drop across the diodes =2*0.6=1.2v

Without capacitor:

Vavg = (12-1.2)=10.8c pulsating dc

Frequency = 100hz with capacitor

V= Vavg*1.414(form factor) = 15.3v

Freuency = 0hz

With 7805 voltage regulator:

Vo= +5v

3.9 SCHEMATICS:


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CHAPTER 4

RELAYS

4.1 INTRODUCTION:

A relay is an electrically operated switch . Current flowing through the coil of therelay creates a magnetic field which attracts a lever and changes the switchcontacts. The coil current can be on or off so relays have two switch positions andthey are double throw (changeover ) switches.

Relays allow one circuit to switch a second circuit which can be completelyseparate from the first. For example a low voltage battery circuit can use a relayto switch a 230V AC mains circuit. There is no electrical connection inside therelay between the two circuits, the link is magnetic and mechanical.


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The coil of a relay passes a relatively large current, typically 30mA for a 12Vrelay, but it can be as much as 100mA for relays designed to operate from lowervoltages. Most ICs (chips) cannot provide this current and a transistor is usuallyused to amplify the small IC current to the larger value required for the relaycoil. The maximum output current for the popular 555 timer IC is 200mA sothese devices can supply relay coils directly without amplification.

Relays are usuallly SPDT or DPDT but they can have many more sets of switchcontacts, for example relays with 4 sets of changeover contacts are readilyavailable. For further information about switch contacts and the terms used todescribe them please see the page on switches.

Most relays are designed for PCB mounting but you can solder wires directly tothe pins providing you take care to avoid melting the plastic case of the relay.

The supplier's catalogue should show you the relay's connections. The coil willbe obvious and it may be connected either way round. Relay coils produce brief
http://www.kpsec.freeuk.com/trancirc.htmhttp://www.kpsec.freeuk.com/components/switch.htmhttp://www.kpsec.freeuk.com/components/switch.htmhttp://www.kpsec.freeuk.com/trancirc.htm


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high voltage 'spikes' when they are switched off and this can destroy transistorsand ICs in the circuit. To prevent damage you must connect a protection diodeacross the relay coil.

The animated picture shows a working relay with its coil and switch contacts.You can see a lever on the left being attracted by magnetism when the coil isswitched on. This lever moves the switch contacts. There is one set of contacts(SPDT) in the foreground and another behind them, making the relay DPDT.

CIRCUIT DIAGRAM:

CIRCUIT DESCRIPTION:

1. When coin is placed on coin box coin triggers a switch the switch triggera two transistor based timer

2. When switch is activated it provides positive supply to Q1 transistor basewhen Q1 gate base voltage it forward negative current through emitter tocollector and collector output is fed to timing capacitor(1000uf/25v)when once a capacitor charged its stores the negative current in it. Wesaid to the timing delay to R2 (100kohm). Here we said (0-1 min)


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different time period. This stored current fed to Q2 transistor. Howevercapacitor negative voltage provides supplied to Q2 transistor base itactivate the positive supply Q3 base. Q3 get positive supply it activates aNPN transistor. This transistor activates a relay connected tap. Howeverrelay activated it provides a positive supply to auto timer driver circuit.Here we used a 555timer as a Astable multivibrator mode. However therelay activated the 555timer generates a clock pulse through R1, R2 andC.

3. The 555timer pin3 generates a square wave this output is fed toCD4017 Decade counter. It indicates a timer output through LED andprovides supply to solenoid relay driving transistor. However solenoiddrive activate it provides ac supply to solenoid tap.

TIMER SECTION:

The high output signal from the sensor unit triggers the base of the pnptransistor Q1 which is implemented in reverse bias. This transistor triggersthe positive base of the npn transistor Q2.Here the transistor is activated inforward bias.hence the negative voltage appears through the collector of theQ2 transistor which is feeded to the capacitor C1,which is charged to store

negative current in it. The charged capacitor provides the negative triggerthe amplifier circuit as long as the capacitor current becomes zero.


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AMPLIFICATION SECTION:

TRANSISTOR AS AN AMPLIFIER:

In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as avoltage amplifier. In this circuit the base terminal of the transistor serves as the

input, the collector is the output, and the emitter is common to both (for example, itmay be tied to ground reference or a power supply rail), hence its name. Theanalogous field-effect transistor circuit is the common-source amplifier.

Common-emitter amplifiers give the amplifier an inverted output and canhave a very high gain that may vary widely from one transistor to the next. Thegain is a strong function of both temperature and bias current, and so the actual


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gain is somewhat unpredictable. Stability is another problem associated with suchhigh gain circuits due to any unintentional positive feedback that may be present.Other problems associated with the circuit are the low input dynamic rangeimposed by the small-signal limit; there is high distortion if this limit is exceeded

and the transistor ceases to behave like its small-signal model. One common wayof alleviating these issues is with the use of negative feedback, which is usuallyimplemented with emitter degeneration . Emitter degeneration refers to the additionof a small resistor (or any impedance) between the emitter and the common signalsource (e.g., the ground reference or a power supply rail). This impedance RE reduces the overall transconductance Gm = gm of the circuit by a factor of gm RE + 1,which makes the voltage gain

So the voltage gain depends almost exclusively on the ratio of theresistors RC / RE rather than the transistor's intrinsic and unpredictablecharacteristics. The distortion and stability characteristics of the circuit are thusimproved at the expense of a reduction in gain.

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