MOBILE Control_electrical Appliances

7/28/2019 MOBILE Control_electrical Appliances

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MOBILE

CONTROL ELECTRICALAPPLIANCES


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Project Introduction.

This unit talks about the basic definitions needed to understand the

Project better and further defines the technical criteria to be

implemented as a part of this project.

Why automation?

Earlier, we are looking into the face of future when we talked about automated

devices, which could do anything on instigation of a controller, but today it has

become a reality.

1. An automated device can replace good amount of human working force,

moreover humans are more prone to errors and in intensive conditions the

probability of error increases. Whereas an automated device can work with

diligence, versatility and with almost zero error.

2. This is why this project looks into construction and implementation of a system

involving hardware to control a variety of electrical and electronics instruments.

What is home/office automation?

Home/office automation is the control of any or all electrical devices in our home

or office, whether we are there or away. Home/office automation is one of the

most exciting developments in technology for the home that has come along in

decades. There are hundreds of products available today that allow us control


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over the devices automatically, either by remote control; or even by voice

command!

What can be automated?

Virtually anything in the home/office that is powered by electricity can be

automated and/or controlled. We can control our electrical devices with our

cordless phone from our easy chair. We can turn our porch lights on

automatically at dark or when someone approaches and can see who is at the

front door from any nearby television, and talk to them or unlock the door from

any nearby telephone. Have the security system turn off lights, close drapes and

setback the temperature when we leave and turn on the alarm system. The

possibilities are only limited by our imagination!

How is the system controlled in this project?

This circuit enables one to utilize a telephone for remote switching on and off of

any electrically operated device. It does not require any physical connection to

the telephone lines or lifting of the handset. The circuit is only acoustically

coupled to the telephone instrument. Consequently, . The switching operation is

performed by making use of coded telephone ring signal.

While designing it has been ensured that the circuit is free from any false

triggering by normal telephone ring signals. Since the instrument has no

hardwired connection to the telephone line it does not affect the normal operation

of the telephone set. To avoid false triggering, suitable reset feature is

incorporated in this circuit.

Why not any other device?


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In this age of automation many other devices like microprocessor or micro-

controller, infrared remote, voice controlled devices etc. are used for the

automation purposes, but they have certain limitations which are described below

1. The use of microprocessor or micro-controller involves complexities like

microprocessor operating voltages; interrupt servicing, poling, memory

access mechanism and extensive soldering. Moreover, if we use micro-

controller or a microprocessor we cant change the working as and when

desired. The problem being, while using them we have to hardwire the code

into ROM chips and in case we need to amend we have to burn a new ROM

chip to replace the earlier one. The earlier ROM becomes useless and has to

be scraped. And this has to be done on every single time we need add

something new.

2. An infrared remote control can work for a device up to a specified range of

distance after that it cannot be used for controlling the device.

3. A voice controlled device works on a single voice and cannot be used by any

other person and have a certain range of working.


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This unit talks about how the different units of the project working. How Relays and

Transistors can be interfaced to your telephone and can be used to turn ON and OFF

your home appliances such as bulbs, tube lights, lamps or heavy-duty motors.

This project is a teleremote circuit that enables

switching ON and OFF of appliances throughtelephone lines. It can be used to switch appliances from

any distance, overcoming the limited range of infrared

and radio remote controls. The circuit described in the

project can be used to switch up to ten appliances

(corresponding to the digits 0 to 9 of the telephone

keypad). This circuit is based on the DTMF controller

circuit. DTMF means dual tone multiple frequency. The

DTMF signals on telephone instrument are used as

control signals.

PROJECT WORKING


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When we press the star button in the telephone the pulse dialing is

converted in to tone dialing. We use this tone dialing in our project. Telephone

lines are connected to the DTMF decoder circuit including a DTMF decoder IC

8870, which is a 24 pin IC. This DTMF decoder converts the DTMF pulse into a

BCD signal. It means when we press the digit no.1 then output from decoder is

0001. In this ic if we want to control only one output so we use pin no 15 of this

ic. Whenever this ic decode the output then pin no 15 become high for a time .

Due to this we use a flip flop logic along with this decoder to control any thing

from the mobilephone.

When you press a button in the telephone set keypad, a

connection is made that generates a resultant signal of two

tones at the same time. These two tones are taken from a row

frequency and a column frequency. The resultant frequency

WHAT IS

DTMF?


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signal is called "Dual Tone Multiple Frequency". These tones

are identical and unique.

A DTMFsignal is the algebraic sum of two different audio

frequencies, and can be expressed as follows:

f(t) = A0sin(2**fa*t) + B0sin(2**fb*t) + ........... ------->(1)

Where fa and fb are two different audio frequencies with A

and B as their peak amplitudes and f as the resultant DTMF

signal. fa belongs to the low frequency group and fb belongs to

the high frequency group.

Each of the low and high frequency groups comprise four

frequencies from the various keys present on the telephone

keypad; two different frequencies, one from the high frequency

group and another from the low frequency group are used to

produce a DTMF signal to represent the pressed key.

The amplitudes of the two sine waves should be such

that

(0.7 < (A/B) < 0.9)V -------->(2)


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The frequencies are chosen such that they are not the

harmonics of each other. The frequencies associated with

various keys on the keypad are shown in figure (A).

When you send these DTMF signals to the telephone

exchange through cables, the servers in the telephone

exchange identifies these signals and makes the connection to

the person you are calling.

The row and column frequencies are given below:

Fig (A)

When you press the digit 5 in the keypad it generates aresultant tone signal which is made up of frequencies 770Hz

and 1336Hz. Pressing digit 8 will produce the tone taken from

tones 852Hz and 1336Hz. In both the cases, the column


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frequency 1336 Hz is the same. These signals are digital

signals which are symmetrical with the sinusoidal wave.

A Typical frequency is shown in the figure below:

Figure (B)

Along with these DTMF generator in our telephone setprovides a set of special purpose groups of tones, which is

normally not used in our keypad. These tones are identified as

'A', 'B', 'C', 'D'. These frequencies have the same column

frequency but uses row frequencies given in the table in figure

(A). These tones are used for communication signaling.

The frequency table is as follows:


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Figure (C)

Due to its accuracy and uniqueness, these DTMF signals are

used in controlling systems using telephones. By using some

DTMF generating ICs (UM91214, UM91214, etc) we can

generate DTMF tones without depending on the telephone set.


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_ __ _!__ _ _________The MC4013

IC 4013dual type D flipflop is constructed with MOS Pchannel and

Nchannel enhancement mode devices in a single monolithic

structure. Each flipflop has independent Data, (D), Direct Set, (S),

Direct Reset, (R), and Clock (C) inputs and complementary outputs

(Q and Q). These devices may be used as shift register elements or

as type T flipflops for counter and Static Operation Diode

Protection on All Inputs

Supply Voltage Range = 3.0 Vdc to 18 Vdc

Logic EdgeClocked FlipFlop Design

Logic state is retained indefinitely with clock level either high or low;


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information is transferred to the output only on the positivegoing

edge

of the clock pulse

Capable of Driving Two Lowpower TTL Loads or One Lowpower

Schottky TTL Load Over the Rated Temperature Range

PinforPin Replacement for CD4013B


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KA78XX/KA78XXA3-Terminal 1A Positive Voltage Regulator

Features Output Current up to 1A Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V

Thermal Overload Protection

Short Circuit Protection

Output Transistor Safe Operating Area Protection

Description

The KA78XX/KA78XXA series of three-terminal positive regulator are available in the

TO-220/D-PAK package and with several fixed output voltages, making them useful in awide range of applications. Each type employs internal current limiting, thermal shutdown and safe operating area protection, making it essentially indestructible. If adequate

heat sinking is provided, they can deliver over 1A output current. Although designed

primarily as fixed voltage regulators, these devices can be used with external componentsto obtain adjustable voltages and currents.


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RELAYS

In order to enable a circuit to be isolated from the system only under

faulty conditions, protective relays are used. In normal cases, it is open circuit

relay. The relay is usually provided with 4 terminals, two of which are

connected to relay winding and other two are connected to the circuit to be

controlled. It has following characteristics :

Sensitivity

Speed

Selectivity

TYPES OF RELAYS :

Electromagnetic Attraction Type : These relays are actuated by DC or

AC quantities.

Electromagnetic Induction Type : Its operation depends upon EMI

phenomena.

Thermal Relays : Its operation depends upon the heating effect ofelectric Current.

Distance Relays : Its operation depends upon the ratio of voltage to

current.

ELECTROMAGNETIC RELAY :

These relays are electromagnetically operated. The parts of these

relays are an iron core & its surrounding coil of wire. An iron yoke

provides a low reluctance path for magnetic flux, the yoke being shaped so

that the magnetic circuit can be closed by a movable piece of iron called

the armature, and a set of contacts. The armature is hinged to the yoke

and is held by a string in such a way that there is an air gap in the


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magnetic circuit. Figure shows the principle of operation of this relay.

When an electric current flows in the coil, the armature is attracted to the

iron core. Electrical switching contacts are mounted on the armature.

When the armature coil is energized, these movable contacts break their

connections with one set of fixed contacts and close a connection to a

previously open contact. When electric power is removed from the relay

coil, spring returns the armature to its original position.

Standard voltages for D.C. relay are 6,12,24,48 & 110 volts and for A.C.

relays are 6,12,24,48,120 & 240 volts.

Fig. Basic Diagram Showing the Operating Principle of a Relay


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BC546; BC547NPN 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.PNP complements: BC556 and BC557.


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RECTIFIER DIODE

Philips Semiconductors Product specification

Rectifiers 1N4001G to 1N4007GFEATURES

Glass passivated

High maximum operating

temperature

Low leakage current

Excellent stability

Available in ammo-pack.

DESCRIPTION

Rugged glass package, using a high temperature alloyedconstruction. This package is hermetically sealed and fatigue free ascoefficients of expansion of all used parts are matched. Fig.1Simplified outline (SOD57) and symbol. 2/3 page (Datasheet


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