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MULTIPLE DEVICE CONTROLLER

Abstract- Dual tone multi-frequency

signaling (DTM F) is used fortelecommunication

signalingover analog telephone lines in the voice-

frequency band betweentelephonehandsets and

other communications devices and theswitching

center. DTMF technique can be used for

controll ing appli ances together via powerl ine.

Keywords-Dtmf , powerli ne, encoder, decoder

1. INTRODUCTION

Using this simple circuit you can switch on or off

upto 8 appliances remotedly via the mains line. 4 bit

dual tone multi frequency (dtmf) data is send through

the mains line to switch on or off the desired

appliances via 8 relays.

Push to on/off toggle switches S1 through S8 are

used to control appliances. If any switch is in UP

position, the encoder sends off signal data and the

respective output goes low in the decoder. If the

switch is in down position, the encoder sends on

signal data and respective output goes high to

become latched.

Eight 4 bit data words (0000-0111) are used to switch

off 8 appliances. Another eight 4 bit words (1000-

1111) are to switch on the appliances. If D bit (MSB)

is high it is on signal, and if D bit is low it is off

signal. Once switches have been set in on or off

position, data words are automatically sent

continuously.

In case the power fails, power-on-relay set works and

all the outputs of IC CD4099 (IC8) go low to switch

off all the relays. However, when the power resumes,

data is sent automatically again and the respective

relay energise. So even after power failure correct

devices are switched on/off automatically once the

power resumes.

The circuit comprises of two units,namely,a DTMF

encoderat the controlling end and DTMF decoder at

the other end where the appliances are located. The 2

units are connected via phase(L), neutral(N) and

earth(E) wires of the AC mains line,with the AC

phase being the same.

2.HARDWARE

2.1 ENCODER

The encoder circuit comprises DTMF tone generator

IC UM9089(IC2), dual binary counter IC

CD4520(IC3), and 2 16 channel multiplexer ICs

CD4067(IC4,IC5).

The main frequency 50HZ is fed to pin 2 of dual

binary counter IC3(A) via transformer X1 secondary.

The D output (MSB) of IC3(A) is connected to strobe

pin 10 of IC3(B). The 4 bit binary output of IC3(B) is

fed to the 2 16-channel multiplexer as address input.

The 16 decoded outputs of IC4 are connected to the

columns pins of the DTMF tone generator,while the

outputs of IC5 are connected via switches S1 through

S8 to the row pins of IC2. Inputs Y0 to Y15 of IC5

are connected to switches S1 to S8.

DTMF tone generator IC2 has 4 row pins and 4

columns pin, each of which is associated with a

specific frequency. When any row pin is shorted to

any column pin, the associated dual frequency tone is

generated. At any given instant of a row and column

takes place as per address present at pin 10 thorugh

14 of IC4 IC5 and the position of switch s1 through

S8. The selected column is connected to the selected

row via pin 1 of IC4 and IC5. A total of 16 dual

frequency tones, 1 for each combination are thus

possible. The output of IC2 are indicated by glowing

of RED LED. For each count, one row and one

column is connected together via IC4 and IC5 and

dual tone generator and superiposed on the neutral

mains.

Fi 1. Encoder Unit

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2.2 DECODER

It comprises of MT8870, DTMF receiver(IC7),

CD4099 8-bit addressable latch IC8, and relay

drivers.

DTMF tone generated by the coder and transmitted

through mains wires is received DTMF to binary

decoder IC7 for conversion into its corresponding

four bit output at pin 11 through 14. This output is

fed to IC8.

If D bit is high, one of the output of IC8 goes highand it latches. If D bit is low, one of the output of IC8

will go low. The Qo to Q7 outputs of latch IC8 are

fed to, via 1k resisitors, transistors T2 through T9 for

driving relays RL1 through RL8 to switch on/off the

selected device.

3. COMPONENT LIST

IC1,IC6- +5V 7805 REGULATOR IC IC2- UM95089 DTMF tone generator IC3- CD4520 DUAL binary counter IC4,IC5- CD4067 16 CHANNEL

multiplexer,demultiplexer

IC7- MT8870 DTMF receiver IC8- CD4099 8-bit addressable latch D1-D12- 1N4007 rectifier diodes

230V AC

50 Hz

DTMF

DECODER(RECIEVER)

8 BIT

ADDRESSABLELATCH

RELAY DRIVERSOUTPUT

APPLIANCES

Fig 3 . Decoder unit

Fig 2. Encoder Circuit Diagram

Fig 4. Decoder Circuit Diagram

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LED- 5mm red LED T1-T9- BC548 npn transistor Resistors (R1 to R16) Capacitors (C1 to C9) RL1-RL8- 9V,15O ohm,1C/O relays S1-S8- push to on/off switch X1-X2-230V AC Primary to 9V-0-9V,

500mA secondary transformers

XTAL1,XTAL2-3.5795MHz crystal

4.WORKING

Using the keyboard mounted on the coders panel,

you can easily switch on/off the desied appliances.

The on/off position of switches on the keyboard

indicated whether the renote appliance is on or off.

Lets assume you want to switch on appliance no. 4

and 8 connected across RL4 and RL8. When you

push down switch S4 and S8 to down position, these

produces 1011 and 1111. This encoded data is

superimposed to mains neutral via capacitor C1.

After receiving this data, IC7 places the data on its

output as well as at input of IC8. Since the output D

input (PIN3) of IC8 is high, its Q3 and Q7 outputs

go high and latch. As a result, relays RL4 and RL8

energise to turn on appliance no.4 and no.8. All other

outputs will be low, keeping the remaining6

appliances are off.

When IC7 receives data, its delayed steering output

goes high and transistor T1 conducts to make pin4 of

IC8 low. This enables IC8 to receive data.

5. APPLICATIONS

Can be used as switching device in :-

(i)Industries where many devices are to be controlled

simultaneously.

(ii)Home appliances.

6. FUTURE SCOPE

DTMF Technique can be used by HomeAutomation system.

Remote control system. Number of appliances can be increased.

7.CONCLUSION

Thus, this technique can be used to access multiple

things at a time and help in consuming time in this so

busy world.

8. Acknowledgment

We would like to thank our department for

encouraging us to search on this topic and also our

H.O.D and all the staff members for their continuous

support and help.

9. REFERENCES

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