CHAPTER 1

INTRODUCTION

The anti-sleep driving alarm for people doing all night drives as well as security guards and others we have to sit in one place for long periods of time without any stimulating interaction. The newest high tech way to stay awake is a good purchase for you whether you ever have to drive back home after an exhausting day at work or just need to get something done and sleep is not an option. This trusty sleep alarm will keep you at full alert and is always ready to help if your head dozes off.

This has the potential to save lives on the road. Long distance lorry drivers can fall asleep by driving too long hours due to the pressures put on them to get the goods to their destination at certain times. This item has the potential to keep them awake or at least to tell them when they are over tired and need to stop driving!

All-night Drivers: accidents due to drivers falling asleep at the wheel are quite common. Maybe a long and tiring day at the office has drained your energy and all you want to do is return home and sleep. Some drivers tend not to pay attention on long stretches of a boring road they know too well and without knowing it they doze off. Protect yourself and your passengers with this anti sleep alarm.

Security Guards: This anti sleep alarm will make sure your eyes are kept wide open and on the target.

Students: Maybe they forgot the exam was tomorrow, maybe they were out partying, or maybe they just waited until the last minute. In any case, college students always have the need to burn the midnight oil. The problem is that it is extremely easy to fall asleep in the midst of studying and before you know it, morning has come and the exam is already over or you still haven't learned the material. If you don't want that to happen, then keep this reliable anti sleep alarm at your side.

In Summary:

• Reliable and comfortable anti sleep alarm.

• Great for drivers, students, office workers, security guards.

• Powerful and heavy vibrating when you doze off, turn it off when not needed

Replaceable button cell battery will last for half a year (used every day for 3 hours).

This circuit saves both time and electricity for students. It helps to prevent them from dozing

off while studying, by sounding a beep at a fixed time interval, say, 30 minutes.

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CHAPTER 2

CIRCUIT DIAGRAM

This circuit saves both time and electricity for students. It helps to prevent them from dozing

off while studying, by sounding a beep at a fixed time interval, say, 30 minutes.

If the student is awake during the beep, he can reset the circuit to beep in the next 30 minutes.

If the timer is not reset during this time, it means the student is in deep sleep or not in the

room, and the circuit switches off the light and fan in the room, thus preventing the wastage

of electricity .

2.1 Circuitry

Fig 2.1AntisleepAlarm for Students

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CHAPTER 3

COMPONENT NEEDED

Relay Bulb Transistor or SCR Push to ON /OFF switches Resistance & capacitor Piezo buzzer Diode IC: IC CD4020 IC: IC CD4093 Printed circuit board

The circuit is built around Schmitt trigger NAND gate IC CD4093 (IC1), timer IC CD4020 (IC2), transistors BC547, relay RL1 and buzzer. The Schmitt-trigger NAND gate (IC1) is configured as an astable multivibrator to generate clock for the timer (IC2). The time period can be calculated as T=1.38×R×C. If R=R1+VR1=15 kilo-ohms and C=C2=10 μF, you’ll get ‘T’ as 0.21 second. Timer IC CD4020 (IC2) is a 14-stage ripple counter.Around half an hour after the reset of IC1, transistors T1, T2 and T3 drive the buzzer to sound an intermediate beep. If IC2 is not reset through S1 at that time, around one minute later the output of gate N4 goes high and transistor T4 conducts. As the output of gate N4 is connected to the clock input (pin 10) of IC2 through diode D3, further counting stops and relayRL1 energises to deactivate all the appliances. This state changes only when IC1 is reset by pressing switch S1.           Assemble the circuit on a general purpose PCB and enclose it in a suitablecabinet. Mount switch S1 and the buzzer on the front panel and the relayat the back side of the box. Place the 12V battery in the cabinet for poweringthe circuit. In place of the battery, you can also use a 12V DC adaptor.

3.1 RELAY

3.1.1 Introduction

3

A relay is an electrically operated switch. Many relays use an electromagnet to operate a

switching mechanism mechanically, but other operating principles are also used. Relays are

used where it is necessary to control a circuit by a low-power signal (with complete electrical

isolation between control and controlled circuits), or where several circuits must be controlled

by one signal. The first relays were used in long distance telegraph circuits, repeating the

signal coming in from one circuit and re-transmitting it to another. Relays were used

extensively in telephone exchanges and early computers to perform logical operations.

Fig 3.1 Relay

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3.1.2 Working

Fig:-3.1.2 Electromagnetic Relay operation

A type of relay that can handle the high power required to directly drive an electric

motor is called a contractor. Solid-state relays control power circuits with no moving parts,

instead using a semiconductor device to perform switching. Relays with calibrated operating

characteristics and sometimes multiple operating coils are used to protect electrical circuits

from overload or faults; in modern electric power systems these functions are performed by

digital instruments still called "protective relays".

3.2 TRANSISTOR

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A transistor is a semiconductor device used to amplify and switch electronic signals.

It is made of a solid piece of semiconductor material, with at least three terminals for

connection to an external circuit. A voltage or current applied to one pair of the transistor's

terminals changes the current flowing through another pair of terminals. Because the

controlled (output) power can be much more than the controlling (input) power, the transistor

provides amplification of a signal. Today, some transistors are packaged individually, but

many more are found embedded in integrated circuits.

Fig 3.2.1.Transistor

The transistor is the fundamental building block of modern electronic devices, and is

ubiquitous in modern electronic systems. Following its release in the early 1950s the

transistor revolutionised the field of electronics, and paved the way for smaller and cheaper

radios, calculators, and computers, amongst other things.

A bipolar (junction) transistor (BJT) is a three-terminal electronic device

constructed of doped semiconductor material and may be used in amplifying or switching

applications. Bipolar transistors are so named because their operation involves both electrons

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and holes. Charge flow in a BJT is due to bidirectional diffusion of charge carriers across a

junction between two regions of different charge concentrations. This mode of operation is

contrasted with unipolar transistors, such as field-effect transistors, in which only one carrier

type is involved in charge flow due to drift. By design, most of the BJT collector current is

due to the flow of charges injected from a high-concentration emitter into the base where they

are minority carriers that diffuse toward the collector, and so BJTs are classified as minority-

carrier devices.

3.2.1 Introduction

Fig:-3.2.1 NPN BJT with forward-biased E–B junction and reverse-biased B–C junction

An NPN transistor can be considered as two diodes with a shared anode. In typical

operation, the base-emitter junction is forward biased and the base–collector junction is

reverse biased. In an NPN transistor, for example, when a positive voltage is applied to the

base–emitter junction, the equilibrium between thermally generated carriers and the repelling

electric field of the depletion region becomes unbalanced, allowing thermally excited

electrons to inject into the base region. These electrons wander (or "diffuse") through the base

from the region of high concentration near the emitter towards the region of low

concentration near the collector. The electrons in the base are called minority carriers

because the base is doped p-type which would make holes the majority carrier in the base.

3.2.2 Voltage, current, and charge control

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The collector–emitter current can be viewed as being controlled by the base–emitter

current (current control), or by the base–emitter voltage (voltage control). These views are

related by the current–voltage relation of the base–emitter junction, which is just the usual

exponential current–voltage curve of a p-n junction (diode)

,Fig.3.2.2 Voltage, current, and charge control

The physical explanation for collector current is the amount of minority-carrier charge

in the base region. Detailed models of transistor action, such as the Gummel–Poon model,

account for the distribution of this charge explicitly to explain transistor behaviour more

exactly. The charge-control view easily handles phototransistors, where minority carriers in

the base region are created by the absorption of photons, and handles the dynamics of turn-

off, or recovery time, which depends on charge in the base region recombining. However,

because base charge is not a signal that is visible at the terminals, the current- and voltage-

control views are generally used in circuit design and analysis.

3.2.3 Structure

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Fig3.2.3 Simplified cross section of a planar NPN bipolar junction transistor

Fig 3.2.3 Die of a KSY34 high-frequency NPN transistor, base and emitter connected via bonded wires

A BJT consists of three differently doped semiconductor regions, the emitter region, the base

region and the collector region. These regions are, respectively, p type, n type and p type in a

PNP, and n type, p type and n type in a NPN transistor. Each semiconductor region is

connected to a terminal, appropriately labeled: emitter (E), base (B) and collector (C).

3.2.4 BC547

NPN general purpose transistors

FEATURES

Low current (max. 100 mA)

Low voltage (max. 65 V).

APPLICATIONS

General purpose switching and amplification.

DESCRIPTION

NPN transistor in a TO-92; SOT54 plastic package.

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PNP complements: BC556 and BC557.

3.3 DIODE

3.3.1 Introduction

In electronics, a diode is a two-terminal electronic component that conducts electric current in only

one direction. The term usually refers to a semiconductor diode, the most common type today. This

is a crystalline piece of semiconductor material connected to two electrical terminals. A vacuum tube

diode (now little used except in some high-power technologies) is a vacuum tube with two electrodes:

a plate and a cathode.

Fig 3.3.1 Diode

The most common function of a diode is to allow an electric current to pass in one direction (called

the diode's forward bias direction) while blocking current in the opposite direction (the reverse

direction). Thus, the diode can be thought of as an electronic version of a check valve. This

unidirectional behaviour is called rectification, and is used to convert alternating current to direct

current, and to extract modulation from radio signals in radio receivers.

However, diodes can have more complicated behaviour than this simple on-off action. This is due to

their complex non-linear electrical characteristics, which can be tailored by varying the construction

of their P-N junction. These are exploited in special purpose diodes that perform many different

functions. For example, specialized diodes are used to regulate voltage (Zener diodes), to

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electronically tune radio and TV receivers (varactor diodes), to generate radio frequency oscillations

(tunnel diodes), and to produce light (light emitting diodes). Tunnel diodes exhibit negative

resistance, which makes them useful in some types of circuits.

3.3.2 Semiconductor diodes

Fig 3.3.2: Typical diode packages in same alignment as diode symbol. Thin bar depicts the cathode.

A modern semiconductor diode is made of a crystal of semiconductor like silicon that

has impurities added to it to create a region on one side that contains negative charge carriers

(electrons), called n-type semiconductor, and a region on the other side that contains positive

charge carriers (holes), called p-type semiconductor. The diode's terminals are attached to

each of these regions. The boundary within the crystal between these two regions, called a PN

junction, is where the action of the diode takes place. The crystal conducts conventional

current in a direction from the p-type side (called the anode) to the n-type side (called the

cathode), but not 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.

3.4 SWITCH

3.4.1 Introduction

In electronics, a switch is an electrical component that can break an electrical circuit,

interrupting the current or diverting it from one conductor to another. The most familiar form

of switch is a manually operated electromechanical device with one or more sets of electrical

contacts. Each set of contacts can be in one of two states: either 'closed' meaning the contacts

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are touching and electricity can flow between them, or 'open', meaning the contacts are

separated and non-conducting. This is called a PTM or "Push to Make" switch.

A switch may be directly manipulated by a human as a control signal to a system, such as a

computer keyboard button, or to control power flow in a circuit, such as a light switch.

Automatically-operated switches can be used to control the motions of machines, for

example, to indicate that a garage door has reached its full open position or that a machine

tool is in a position to accept another workpiece. Switches may be operated by process

variables such as pressure, temperature, flow, current, voltage, and force, acting as sensors in

a process and used to automatically control a system. For example, a thermostat is a

temperature-operated switch used to control a heating process. A switch that is operated by

another electrical circuit is called a relay. Large switches may be remotely operated by a

motor drive mechanism. Some switches are used to isolate electric power from a system,

providing a visible point of isolation that can be pad-locked if necessary to prevent accidental

operation of a machine during maintenance, or to prevent electric shock.

3.5 RESISTOR

3.5.1 Introduction

A resistor is a two-terminal electronic component that produces a voltage across its terminals

that is proportional to the electric current through it in accordance with Ohm's law:

V = IR

Resistors are elements of electrical networks and electronic circuits and are ubiquitous in

most electronic equipment. Practical resistors can be made of various compounds and films,

as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-chrome).

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Fig 3.5.1 Resistor code

The primary characteristics of a resistor are the resistance, the tolerance, the maximum

working voltage and the power rating. Other characteristics include temperature coefficient,

noise, and inductance. Less well-known is critical resistance, the value below which power

dissipation limits the maximum permitted current, and above which the limit is applied

voltage. Critical resistance is determined by the design, materials and dimensions of the

resistor.

Resistors can be integrated into hybrid and printed circuits, as well as integrated circuits.

Size, and position of leads (or terminals), are relevant to equipment designers; resistors must

be physically large enough not to overheat when dissipating their power

3.5.2 Theory of operation

Ohm's law

The behaviour of an ideal resistor is dictated by the relationship specified in Ohm's law:

Ohm's law states that the voltage (V) across a resistor is proportional to the current (I)

through it where the constant of proportionality is the resistance (R).

Equivalently, Ohm's law can be stated:

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This formulation of Ohm's law states that, when a voltage (V) is maintained across a

resistance (R), a current (I) will flow through the resistance.

This formulation is often used in practice. For example, if V is 12 volts and R is 400 ohms, a

current of 12 / 400 = 0.03 amperes will flow through the resistance R.

3.5.3 Series and parallel resistors

Main article: Series and parallel circuits

Resistors in a parallel configuration each have the same potential difference (voltage). To

find their total equivalent resistance (Req):

The parallel property can be represented in equations by two vertical lines "||" (as in

geometry) to simplify equations. For two resistors,

The current through resistors in series stays the same, but the voltage across each resistor can

be different. The sum of the potential differences (voltage) is equal to the total voltage. To

find their total resistance:

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A resistor network that is a combination of parallel and series can be broken up into smaller

parts that are either one or the other. For instance,

However, many resistor networks cannot be split up in this way. Consider a cube, each edge

of which has been replaced by a resistor. For example, determining the resistance between

two opposite vertices requires additional transforms, such as the Y-Δ transform, or else

matrix methods must be used for the general case. However, if all twelve resistors are equal,

the corner-to-corner resistance is 5⁄6 of any one of them.

The practical application to resistors is that a resistance of any non-standard value can be

obtained by connecting standard values in series or in parallel.

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3.5.4 Power dissipation

The power dissipated by a resistor (or the equivalent resistance of a resistor network) is

calculated using the following:

All three equations are equivalent. The first is derived from Joule's first law. Ohm’s Law

derives the other two from that.

The total amount of heat energy released is the integral of the power over time:

If the average power dissipated is more than the resistor can safely dissipate, the resistor may

depart from its nominal resistance and may become damaged by overheating. Excessive

power dissipation may raise the temperature of the resistor to a point where it burns out,

which could cause a fire in adjacent components and materials. There are flameproof resistors

that fail (open circuit) before they overheat dangerously.

Note that the nominal power rating of a resistor is not the same as the power that it can safely

dissipate in practical use. Air circulation and proximity to a circuit board, ambient

temperature, and other factors can reduce acceptable dissipation significantly. Rated power

dissipation may be given for an ambient temperature of 25 °C in free air. Inside an equipment

case at 60 °C, rated dissipation will be significantly less; a resistor dissipating a bit less than

the maximum figure given by the manufacturer may still be outside the safe operating area

and may prematurely fail.

3.6 Capacitor

3.6.1 Introduction

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A capacitor (formerly known as condenser) is a passive electronic component consisting of

a pair of conductors separated by a dielectric (insulator). When there is a potential difference

(voltage) across the conductors, a static electric field develops in the dielectric that stores

energy and produces a mechanical force between the conductors. An ideal capacitor is

characterized by a single constant value, capacitance, measured in farads. This is the ratio of

the electric charge on each conductor to the potential difference between them

.

Capacitors are widely used in electronic circuits for blocking direct current while allowing

alternating current to pass, in filter networks, for smoothing the output of power supplies, in

the resonant circuits that tune radios to particular frequencies and for many other purposes.

The effect is greatest when there is a narrow separation between large areas of conductor,

hence capacitor conductors are often called "plates", referring to an early means of

construction. In practice the dielectric between the plates passes a small amount of leakage

current and also has an electric field strength limit, resulting in a breakdown voltage, while

the conductors and leads introduce an undesired inductance and resistance.

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3.6.2 Operation

A capacitor consists of two conductors separated by a non-conductive region called the

dielectric medium though it may be a vacuum or a semiconductor depletion region

chemically identical to the conductors. A capacitor is assumed to be self-contained and

isolated, with no net electric charge and no influence from any external electric field. The

conductors thus hold equal and opposite charges on their facing surfaces and the dielectric

develops an electric field. In SI units, a capacitance of one farad means that one coulomb of

charge on each conductor causes a voltage of one volt across the device.

The capacitor is a reasonably general model for electric fields within electric circuits. An

ideal capacitor is wholly characterized by a constant capacitance C, defined as the ratio of

charge ±Q on each conductor to the voltage V between them:

Sometimes charge build-up affects the capacitor mechanically, causing its capacitance to

vary. In this case, capacitance is defined in terms of incremental changes:

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3.6.3 Networks

Series and parallel circuits

For capacitors in parallel

Capacitors in a parallel configuration each have the same applied voltage. Their capacitances

add up. Charge is apportioned among them by size. Using the schematic diagram to visualize

parallel plates, it is apparent that each capacitor contributes to the total surface area.

For capacitors in series

Several capacitors in series.

Connected in series, the schematic diagram reveals that the separation distance, not the plate

area, adds up. The capacitors each store instantaneous charge build-up equal to that of every

other capacitor in the series. The total voltage difference from end to end is apportioned to

each capacitor according to the inverse of its capacitance. The entire series acts as a capacitor

smaller than any of its components.

Capacitors are combined in series to achieve a higher working voltage, for example for

smoothing a high voltage power supply. The voltage ratings, which are based on plate

separation, add up. In such an application, several series connections may in turn be

connected in parallel, forming a matrix. The goal is to maximize the energy storage utility of

each capacitor without overloading it.

Series connection is also used to adapt electrolytic capacitors for AC use.

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3.7 INTEGRATED CIRCUIT

In electronics, an integrated circuit (also known as IC, chip, or microchip) is a

miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as

passive components) that has been manufactured in the surface of a thin substrate of

semiconductor material. Integrated circuits are used in almost all electronic equipment in use

today and have revolutionized the world of electronics. Computers, cellular phones, and other

digital appliances are now inextricable parts of the structure of modern societies, made

possible by the low cost of production of integrated circuits.

A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual

semiconductor devices, as well as passive components, bonded to a substrate or circuit board.

A monolithic integrated circuit is made of devices manufactured by diffusion of trace

elements into a single piece of semiconductor substrate, a chip.

Fig 3.7.1 Integrated Circuit

Integrated circuits were made possible by experimental discoveries which showed that

semiconductor devices could perform the functions of vacuum tubes and by mid-20th-century

technology advancements in semiconductor device fabrication. The integration of large

numbers of tiny transistors into a small chip was an enormous improvement over the manual

assembly of circuits using electronic components. The integrated circuit's mass production

capability, reliability, and building-block approach to circuit design ensured the rapid

adoption of standardized ICs in place of designs using discrete transistors.

There are two main advantages of ICs over discrete circuits: cost and performance. Cost is

low because the chips, with all their components, are printed as a unit by photolithography

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and not constructed as one transistor at a time. Furthermore, much less material is used to

construct a circuit as a packaged IC die than as a discrete circuit. Performance is high since

the components switch quickly and consume little power (compared to their discrete

counterparts) because the components are small and close together.

3.7.1 IC CD4020

3.7.2 General Description

The IC CD4020 is 14-stage ripple binary counter.

Fig.3.7.2 IC CD4020

3.7.3 Features

Wide supply voltage range: 1.0V to 15V

High noise immunity: 0.45 VDD.

Low power TTL compatibility: Fan out of 2 driving 74L or 1 driving 74LS

Medium speed operation: 8 MHz typ. at VDD = 10V

Schmitt trigger clock input

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Fig 3.7.3. IC CD4020

3.8 CD4093BC(Quad 2-Input NAND Schmitt Trigger)

3.8.1 Circuit Description

Fig 3.8.1 Circuit diagram

3.8.2 General Description

The CD4093B consists of four Schmitt-trigger circuits.

Each circuit functions as a 2-input NAND gate with Schmitttrigger action on both

inputs. The gate switches at different points for positive and negative-going

signals.

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3.8.3 Features

Wide supply voltage range: 3.0V to 15V

Schmitt-trigger on each input with no external components

Noise immunity greater than 50%

3.8.4 Application

Wave and pulse shapers

High-noise-environment systems

Monostable multivibrators

Astable multivibrators

NAND logic

CHAPTER 4

23

APPLICATIONS

It saves electricity when student is not in his room or he fall asleep.

While these alarms work to help keep drivers awake, some high-end manufacturers are adding sleep sensors to their cars right at the factory. A few notable systems:

Mercedes-Benz Attention Assist uses the car's engine control unit to monitor changes in steering and other driving habits and alerts the driver accordingly.

Lexus placed a camera in the dashboard that tracks the driver's face, rather than the vehicle's behavior, and alerts the driver if his or her movements seem to indicate sleep.

Volvo's Driver Alert Control is a lane-departure system that monitors and corrects the vehicle's position on the road, then alerts the driver if it detects any drifting between lanes.

Saab uses two cameras in the cockpit to monitor the driver's eye movement and alerts the driver with a text message in the dash, followed by a stern audio message if he or she still seems sleepy.

Conclusion

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This circuit saves both time and electricity for students. It helps to prevent them from dozing

off while studying, by sounding a beep at a fixed time interval, say, 30 minutes.

If the student is awake during the beep, he can reset the circuit to beep in the next 30 minutes.

If the timer is not reset during this time, it means the student is in deep sleep or not in the

room, and the circuit switches off the light and fan in the room, thus preventing the wastage

of electricity.

25