AntiSleep Alarm for Student

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AntiSleep Alarm for Student

Chapter: 1 Introduction

While actually giving in to our body’s natural wants such as sleep, we’re keeping the

balance beam in an upright and neutral position — generally a good thing to do. But

life comes and calls quite often, many times forcing us to put hunger, drowsiness, and

other basic human needs on the back burner in order to seal the deal and get the job

done.

So here’s the scenario, you’re sitting in your car getting ready for a big meeting that if

completed will net your company nice little multi-billion dollar deal. You’re supposed

to be going over your notes and preparing yourself for this staple achievement. But

instead, you find yourself doing the whole bobble head thing, getting dangerously to

the steering wheel with each and every bob. If only there were something to keep you

awake…

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.

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.

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AntiSleep Alarm for Student

Chapter: 2 Circuit descriptions

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

 

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AntiSleep Alarm for Student

2.2 Things Needed for Making this Antisleep Alarm

Relay Bulb Transistor or SCR Push to ON /OFF switches Resistance & capacitor Pizzo buzzer Diode IC: IC CD4020

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 relay RL1 energies 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.

Chapter: 3 Relay

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AntiSleep Alarm for Student

3.1 Introduction

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.

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AntiSleep Alarm for Student

3.2 Working

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".

Chapter: 4 TransistorsSrinivas Institute of Technology Page 6

AntiSleep Alarm for Student

4.1 Introduction

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.

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 revolutionized 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 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

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AntiSleep Alarm for Student

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

carrier devices.

4.2 Working

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.

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To minimize the percentage of carriers that recombine before reaching the collector–

base junction, the transistor's base region must be thin enough that carriers can diffuse

across it in much less time than the semiconductor's minority carrier lifetime. In

particular, the thickness of the base must be much less than the diffusion length of the

electrons. The collector–base junction is reverse-biased, and so little electron injection

occurs from the collector to the base, but electrons that diffuse through the base

towards the collector are swept into the collector by the electric field in the depletion

region of the collector–base junction. The thin shared base and asymmetric collector–

emitter doping is what differentiates a bipolar transistor from two separate and

oppositely biased diodes connected in series.

Chapter: 5 DiodeSrinivas Institute of Technology Page 9

AntiSleep Alarm for Student

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.[1] 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.

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 behavior 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 behavior 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 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.

Chapter: 6 Switches

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AntiSleep Alarm for Student

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.[1][2] 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 are touching and electricity can flow between them, or

'open', meaning the contacts are separated and nonconducting. 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.

Chapter: 7 Resistor

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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).

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

Chapter: 8 Capacitor

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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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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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Chapter: 9 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.

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.

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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 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. As of 2006, chip areas range from a few square millimeters to around

350 mm2, with up to 1 million transistors per mm2

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AntiSleep Alarm for Student

Chapter: 10 Conclusion

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.

Srinivas Institute of Technology Page 17