This document describes a GSM based home automation system using DTMF signals. It involves a DTMF decoder, microcontroller, and relays. The system allows controlling electrical devices via mobile phone by sending DTMF tones. When a button on the phone is pressed, the corresponding DTMF tone is decoded by the microcontroller. The microcontroller then activates the necessary relays to control the electrical loads. This allows remote control of appliances and robots through the mobile phone network without needing a separate remote controller.

1. GSM based Home Automation
Name : Rajneesh Salgotra
EnRol : 163/2010
Roll : 31
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2.  GSM
 DTMF
 DTMF DECODER
 MICROCONTROLLER
 RELAYS
 COMPLETE CIRCUIT
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3.  Now a days , GSM services easily available to
everyone .
 And You need not to carry a different remote
controller .
 Mobile Stations are already a multipurpose
devices , so why not to incorporate one more
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4.  Dual-tone multi-frequency signalling (DTMF)
is used for telecommunication signalling
Between telephone handsets and other
communications devices and the switching
centre .
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1209 Hz 1336 Hz 1477 Hz
697 Hz 1 2 3
770 Hz 4 5 6
852 Hz 7 8 9
941 Hz * 0 #

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1209 Hz 1336 Hz 1477 Hz
697 Hz 1 2 3
770 Hz 4 5 6
852 Hz 7 8 9
941 Hz * 0 #

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O
U
T
P
U
T
INPUT

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10.  We have the decoded Hexadecimal Number
corresponding to the pressed key
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NOW Microcontroller to take
Decision .

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I
R
O
C
O
N
T
R
O
L
L
E
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12.  Problem :
The output of Microcontroller is of very low
power highly insufficient to operate electrical
loads .
So we use relays for controlling electrical heavy
loads through Microcontrollers .
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AC POWER

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+Vcc

15.  Remote controlled ROBOTS and APPLICANCES
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16.  No feedback
 GSM connection for the operation
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17.  http://pdf1.alldatasheet.com/datasheet-
pdf/view/77085/MITEL/MT8870.html
 Mazidi, Muhammad Ali, The 8051 Microcontroller and
Embedded Systems
 SOLID STATE RELAY HAND BOOK
 http://chipscity.com/downloads/Projects/GSM%20based%20C
ontrol%20System.pdf
 www.wikipedia.com
 8051 MICROCONTROLLERS by SATISH SHAH
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