Home Automation using Digital Control

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Home Automation using Digital Control

ABSTRACT:
 Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of
appliances through telephone lines. It can be used to switch appliances
from any distance, overcoming the limited range of infrared and radio
remote controls.
 The circuit can be used to switch up to nine appliances (corresponding to
the digits 1 through 9 of the telephone key-pad). The DTMF signals on
telephone instrument are used as control signals.
 The digit ‘0’ in dtmf mode is used to toggle between the appliance mode
and normal telephone operation mode. Thus the telephone can be used to
switch on or switch off the appliances also while being used for normal
conversation

Block Diagram:

Hardware Requirements:
POWER SUPPLY BLOCK
555 TIMER
RELAY
MT8870 DTMF DECODER
CD4049 INVERTER
CD4013 FLIP FLOP
MCT2E OPTO-ISOLATOR
74LS154
BC547
NPN TRANSISTOR

Power Supply:
230 V AC
50 Hz
Bridge rectifier
Filter(470µf)
5v Regulator
5V DC
12V step down
transformer

555 TIMER
The 555 Has Three Operating Modes:
Monostable mode:
 In this mode, the 555 functions as a "one-shot". Applications include
timers, missing pulse detection, switches, touch switches, frequency
divider, capacitance measurement, pulse-width modulation (PWM) etc.

Astable:
 The 555 can operate as an oscillator. Uses include LED and lamp
flashers, pulse generation, logic clocks, tone generation, security
alarms, pulse position modulation, etc.
Bistable mode or Schmitt trigger:
 The 555 can operate as a flip-flop, if the DIS pin is not connected and
no capacitor is used. Uses include bounce free latched switches, etc.

CD4049-Inverter:
 The CD4049 devices are inverting hex buffers, and feature logic level
conversion using only one supply voltage (VCC)
 These devices are intended for use as CMOS to DTL/TTL converters
and can drive directly two DTL/TTL loads

DTMF Decoder:
 This circuit detects the dial tone from a telephone line and decodes the
keypad pressed on the remote telephone.
 Two distinct frequency tones make up the DTMF(dual tome multiple
frequency), and hence the name.
 The dialer and the telephone exchange communicate one way through
the DTMF communication.
 The tone generator and the tone decoder consist of a complete
communication setup.
 In this project, IC MT8870DE is used to decode the input dial tone to
the dialed numbers.

 These digital bits are interfaced to a microcontroller for any
application.
 Pulse/dial tone method is used in the modern telephone
communication.
 There is a dial tone generator on the caller side and a unique tone
consisting of two audible tone frequency is generated when the user
presses a button.
 As an example, 697hz & 1209hz will be generated when key '1' is
being pressed on the phone.
 A decoder circuit is present on the receiver side, which decodes the
tone to a digital code.

CD4013 Flip Flop:
 The CD4013B dual D-type flip-flop is a
monolithic complementary MOS (CMOS)
integrated circuit has two D-type flip-flops,
which you can use independently
 A D-type flip-flop, also called a D-type bistable,
is a subsystem with two stable states. Using
appropriate input signals, you can trigger the flip-
flop from one state to the other.

OPTO-Isolator:
 Opto coupler is a 6 pin IC.
 It is a combination of 1 LED and a transistor.
 when light falls on the Base-Emitter junction then it switches pin5
goes to zero.
 When logic zero is given as input then the light doesn’t fall on
transistor so it doesn’t conduct which gives logic zero as output.
 When logic 1 is given as input then light falls on transistor so that it
conducts, that makes transistor switched ON and it forms short circuit
this makes the output is logic zero as collector of transistor is
connected to ground.

OPTO-Isolator:

BC547:
 The BC547 transistor is an NPN Epitaxial
Silicon Transistor.
 The BC547 transistor is a general-purpose
transistor in small plastic packages.
 It is used in general-purpose switching and
amplification BC847/BC547 series 45 V, 100
mA NPN general-purpose transistors.
 Whenever base is high, then current starts
flowing through base and emitter and after that
only current will pass from collector to emitter

74LS154:
 Each of these 4-line-to-16-line decoders utilizes TTL circuitry to
decode four binary-coded inputs into one of sixteen mutually exclusive
outputs when both the strobe inputs, G1 and G2, are LOW
 The DE multiplexing function is performed by using the 4 input lines
to address the output line, passing data from one of the strobe inputs
with the other strobe input LOW. When either strobe input is HIGH, all
outputs are HIGH.
 These DE multiplexers are ideally suited for implementing high-
performance memory decoders. All inputs are buffered and input
clamping diodes are provided to minimize transmission-line effects and
thereby simplify system design.

74LS154:

Circuit Diagram:

 This system is designed to provide control of home appliances through
landline by dialing the designated number for the particular load.
Dialing can be done from the home phone or a call made to the home
number from outside. This system is designed without engaging a
programmable microcontroller but is based on digital logic using
DTMF technology (Dual Tone multiple frequency) which receives the
command from the landline phone to develop digital output.
 This digital signal is further processed to actuate switching mechanism
through relay driver to turn on/off the loads/appliances. It can be used
to switch appliances from anywhere, overcoming the limited range of
other infrared and radio frequency type controls. This proposed system
gives a new direction to the development of home automation.
Circuit Explanation:

Advantages:
 High sensitive
 Works with any Cell phone from anywhere
 Low cost and reliable circuit
 Coverage distance up to 10 meter

Applications:
 Home appliances control
 Hotel lights/ fans Control
 Shops and Showrooms appliances control
 Industrial appliances

Conclusion:
 The concept of this system can be extended in future by giving an
acknowledgement message to the user by system on the status of loads
by using GSM modem.
 Home Automation using Digital Control Project is very helpful in
Home, Industrial,Hotels and Show rooms

Home Automation using Digital Control

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Home Automation using Digital Control