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REMOTE CONTROL OF DEVICES USING CELLPHONESREMOTE CONTROL OF DEVICES USING CELLPHONES
Shuhab-u-Tariq (1SI03EC109)Shuhab-u-Tariq (1SI03EC109)
INTRODUCTION
Telephone operated device control circuit which enables switching ON & OFF of appliances through telephone lines.
It senses the telephone ring. Automatically switches call to this system, after
pre-defined rings. Switches ON/OFF the load depending upon the
key pressed by the caller.
BASIC BLOCK DIAGRAM
RING DETECTOR & SCHMITT TRIGGER SECTION
RING COUNTER CUM SWITCHING UNIT
This Section counts the number of rings and lifts the cradle automatically after pre-defined number of rings.
IC 4017 is used to count the number of rings.
The triggering action is carried out by relay driver circuit, which comprises of two Darlington transistors with a relay.
Q1
Q2
Q6
Q3
RESET
CLOCK
CLOCK ENABLE
COUT
Q9
Q4
Q8
Q7
Q4
Q9
C0
Q0
Q5
R
CK
CE
Q8
+Vcc
Q5
Q1
Q0
Q2
Q6
Q7
Q3
IC 4017 DECADE COUNTER
11
9
12
13
14
15
16
8
7
6
5
4
3
2
1
10
GND
CIRUIT DIAGRAM OF RING COUNTER CUM SWITCHING & CONTROLLING UNIT
3 Q0
2 Q1
4 Q2
7 Q3
10 Q4
1 Q5
5 Q6
6 Q7
9 Q8
11 Q9
R2
R3
R1
16
IC1 4017
15
13
14
S1
+5 V
CLOCK INPUT fromSchmitt Trigger
RESET SWITCH
D1
8
TR1
R4
TR2
N/O
N/C
+12V
RLC1
R5
D2
LED
To Telephone Line
RING COUNTER SECTION SWITCHING SECTION
DTMF DECODER & BCD TO BINARY CONVERTER MODULE
• DTMF – Dual Tone Multiple Frequency
Resultant signal of two tones at the same time for any key pressed
f(t) = Asin(2*П*fa*t) + Bsin(2*П*fb*t)
Pin Diagram of MT8870
Pin Diagram of IC 74154
DTMF to Binary converter
Function Decode Table
LATCH & LOAD DRIVER SECTION
This section executes the command send by caller by latching the load to previous state on/off.
Terms and components used here: D flip-flop - It is incorporated in IC4013 2003-driver IC- High voltage and high current driver IC is used to drive low impedance relay.
D flip flop an overview
D Q
CLOCK
CLOCK
TRANSIENTDATA
SINCE LAST POSITIVE GOING CLOCK DATA HELD IN LATCH
STATE OF D INPUT CLOCKED TO Q OUTPUT ON RISING CLOCK EDGE
FIG 3
Timing diagram
0
1
0
1
0
1
0
1
D INPUT
CLOCK INPUT
Q OUTPUT
Q OUTPUT
TIME
FIG 4
IC 4013
VCC Q2 IN.Q2 CLK2 RST2 D2 SET2
Q1 IN.Q1 CLK1 RST1 D1 SET1 GROUND
D.CHAR THERS C.VTG RST 1 O/P1 TRGER GROUND
14 13 12 11 10 9 8
1 2 3 4 5 6 7
CIRCUIT DIAGRAM
Q1
Q2
149 13
11 12
IC1B
86
7
IC3
2
1
4
3
8
9
5
15
16
13
12
6 11
14
7
100
GND
5 1
3 2
IC1A4 10
149 13
11 12
IC2B
86
7 Q
Q5 1
3 2
IC2A4 10
R1
+5V+12V
N/O
N/C
N/O
N/C
+5V
Sw1
+5V
RL1
N/O
N/C
RL2
N/O
N/C
RL3
N/O
N/C
RL4
to Telephone
Line
Q3
Q4
Input signlas
POWER SUPPLY UNIT
230AC
X1
C1
D21
C2 C3
IC17812
D11
9V
C4
IC17805
+12V
+5V
CONCLUSION
Low power consumption, and compact in size.
From any distance appliances can be controlled, overcoming the limited range of infra-red and radio remote control.
High reliability, due to the usage of semi conductors.