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GSM BASED

INTRODUCTION &WORKING:-

 

In this project we can control any electrical appliances through mobile or landline from any part of the country.  In this project one base unit is connected to the basic landline in parallel with the land line phone.. When we want to control any electrical appliances through outer phone then first we  dial the home number, bell is ringing and after few bell phone is automatic on and switch on the base unit  to operate. Now we press the single digital excess code, if the excess code is ok then unit give a  tone pulse and switch on the base unit. Now again we press the switch on/off code to on/off any electrical appliances. With the help of this code unit is on and base unit give a acknowledge pulse for on and off separately.

 

Complete circuit is divided into three parts.

1.                 DTMF DECODER

2.                 MICROCONTROLLER

3.                 AUTOMATIC ON THROUGH OUTER PHONE

 

DTMF DECODER

 

In dtmf decoder circuit we use ic 8870 ic. IC 8870 is a dtmf decoder ic. IC 8870  converts the dual tones to corresponding binary outputs.

 

DTMF SIGNALLING. Ac register signaling is used in dtmf telephones, here tones rather than make/break pulse are used fro dialing, each dialed digit is uniquely represented by a pair of sine waves tones. These tones ( one from low group for row and another from high group fro column) are sent to the exchange when a digit is dialed by pushing the key, these tone lies within the speech band of 300 to 3400 hz, and are chosen so as to minimize the possibility of any valid frequency pair existing in normal speech simultaneously. Actually, this minimisator is made possible by forming pairs with one tone from the higher group and the other from the lower of frequencies. A valid dtmf signal is the sum of two tones, one from a lower  group ( 697-940 Hz) and the other from a a higher group ( 1209-1663 Hz). Each group contains four individual tones.  This scheme allows 10 unique combinations. Ten of these code represent digits 1  through 9 and 0. . tones in DTMF dialing  are so chose that none of the tones is harmonic of  are other tone. Therefore  is no change of distortion caused by harmonics. Each tone is sent as along as the key remains pressed. The dtmf signal contains only one component from each  of the high and low group. This significaly simplifies decoding because the composite dtmf signal may be separated with band pass filters into single frequency components, each of which may be handled individually.

 

 

 

Component COST

 

 

S.No.

Item

Quantity

Rate/Unit

 Rate(Rs.)

1

89s52

1

80

80

2

74154 DECODER IC

2

120

240

3

91214 DTMF ENCODER

1

40

40

4

PRESET

1

2

2

5

RESISTENCES 10K

10

0.25

2.5

6

relay 12v 400E

4

20

80

7

motor

1

80

80

8

cyrstal

1

25

25

9

PCB

1

800

800

10

Crystal

1

25

25

11

LCD

1

250

250

12

MT 9170 OR 8870

1

120

120

13

Microswitch

4

3

12

14

battery connector

1

10

10

15

MOBILE HEADPHONE

1

80

80

16

Push to On Sw

3

12

36

17

SOLDERING WIRE

1

25

25

18

SOLDERING IRON

1

120

120

19

FLUX

1

10

10

20

CONNECTING WIRE

1

50

50

21

TR548

2

2

4

22

TR558

2

2

4

23

RESISTENCES

20

0.2

4

24

CAPACITORS

 

 

0

25

1000f

2

10

20

26

100f

1

5

5

27

470f

4

5

20

28

DIODES

8

1

8

29

LED

8

1

8

30

Crystal 12MHz

2

25

50

31

IC BASE

3

5

15

32

IC 7805 Volt. Reg

2

15

30

33

TRANSFORMER 9 V

1

30

30

34

CRYSTAL 3.579545

2

20

40

35

IC136

2

15

30

36

PLY BOARD

1

100

100

37

TAPE ROLL

1

10

10

38

Copper Clad Board

1

100

100

39

FeCl3

1

100

100

40

ZENER

0

3

0

41

Screws/bolt

2

2

4

42

OTHER CHARGES

1

1000

1000

 

 

 

 

Hardware required-

 

8051 programmer universal kit

 

CRO 20 Mhz

 

Digital multimeter

 

Software required:

 

Keil software- Microvision 2

 

ORCAD for PCB design 10.5

 

Proteus for simulation 7.4 version

 

 

 

Features-

 

Wireless connection

 

Microcontroller

 

Use of GSM mobile

 

 

Applications:

 

1.     Remote control of devices

2.     Control of Antennas direction

3.     Irrigation control

4.     Control boilers or machines in remote area.

 

Bibliography

 

www.electrofriends.com

www.8052projects.com

www.8051.com

www.toshankits.com

www.atmel.com