telephone based home automation system report

7/29/2019 Telephone Based Home Automation system Report

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INDEX

1. INTRODUCTION

2. FEATURES

3. HISTORY

4. GENERAL DESCRIPTION

5. BLOCK DIAGRAM

6. CIRCUIT DIAGRAM

7. COMPONENT LIST

8. WORKING

9. PCB OVERLAY

10. CODING

11. ADVANTAGES

12. APPLICATIONS

13. FUTURE ENHANCEMENTS

14. REFERENCES


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INTRODUCTION

Controlling devices using switches are common. From a few decades controlling

devices using remote control switches like infrared remote control switch, wireless

remote control switches, light activated switches Are becoming popular. But

these technologies have their own limitations. Laser beams are harmful to mankind.

Some technologies like IR remote control are used for short distance applications. In

such case if we have system which does not require Any radiations or which is not

harmful, long remote control switch!! Yes here is the solution.

Here we are introducing such a system which does not require any radiations, any

laser beam which has no limitation of range, we mean it can be used from any distance

from meters to thousand kilometers using a simple telephone line or mobile phone.

Here we are using a telephone as a media, which serves main part of this system.

By using home phone as a local phone and another phone - either landline or mobile

phone as a remote phone we are controlling devices.


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FEATURES

1. You can control up to 10 devices. It may be any electric or electronic appliances or devices

with simple to heavy appliances. Each device is given a unique code.

2. It makes accurate switching, any false switching of device are not done.

3. There is no risk for false switching.

4. Your local phone (i.e., home phone or office phone) can be used for normal use by using a

DPDT switch. So you need not use a separate telephone line for this device controlling.

5. To perform any operations through remote phone line, the user needs to dial to the local

telephone (to which the interfacing circuit is connected) then the respective code of thedevice is dialed.

6. This system detects the ringing signal from your exchange with the help of ring detector

and automatically switches ON.

7. This circuit gives an acknowledgement tone after switching ON and OFF the devices to

confirm the status of the device.

8. You can control devices from local telephone. It can also be controlled by PCO.


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HISTORY OF DTMF

Dual-tone multiple frequency (DTMF) signaling is used for telephone signaling over the

line in the voice-frequency band to the call switching center. The version of DTMF used

for telephone tone dialing is known by the trademarked term Touch-Tone, and is

standardised by ITU-T Recommendation Q.23. Other multi-frequency systems are used

for signaling internal to the telephone network


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In the time preceding the development of DTMF, telephone systems employed a system

commonly referred to as pulse (Dial Pulse or DP in the USA) or loop disconnect (LD)

signalling to dial numbers, which functions by rapidly disconnecting and connecting the

calling party's telephone line, similar to flicking a light switch on and off. The repeated

connection and disconnection, as the dial spins, sounds like a series of clicks. The

exchange equipment counts those clicks or dial pulses to determine the called number.

Loop disconnect range was restricted by telegraphic distortion and other technical

problems, and placing calls over longer distances required either operator assistance

(operators used an earlier kind of multi-frequency dial) or the provision of subscriber

trunk dialling equipment.

DTMF was developed at Bell Labs in order to allow dialing signals to dial long-distancenumbers, potentially over nonwire links such as microwave radio relay links or satellites.

For a few non crossbar offices, encoder/decoders were added that would convert the older

pulse signals into DTMF tones and play them down the line to the remote end office. At

the remote site another encoder/decoder could decode the tones and perform pulse

dialing, for example for Strowger switches. It was as if you were connected directly to

that end office, yet the signaling would work over any sort of link. This idea of using the

existing network for signaling as well as the message is known as in-band signaling.

It was clear even in the late 1950s when DTMF was being developed that the future of

switching lay in electronic switches, as opposed to the electromechanical crossbar

systems then in use. Either switching system could use either dial system, but DTMF

promised shorter holding times, which was more important in the larger and more

complex registers used in crossbar systems. In this case pulse dialing made no sense at

any point in the circuit, and plans were made to roll DTMF out to end users as soon as

possible. Tests of the system occurred in the early 1960s, where DTMF became known as

Touch Tone. Though Touch Tone phones were already in use in a few places, they were

vigorously promoted at the 1964 New York World's Fair.

The Touch Tone system also introduced a standardized keypad layout. After testing 18

different layouts, they eventually chose the one familiar to us today, with 1 in the upper-

left and 0 at the bottom. The adding-machine layout, with 1 in the lower-left was also

tried, but at that time few people used adding machines, and having the 1 at the "start" (in


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European language reading order) led to fewer typing errors. In retrospect, many people

consider that this was a mistake. With the widespread introduction of computers and bank

machines, the phone keyboard has become "oddball", causing mistakes.

In another sense, DTMF was obsolete a decade after it was instituted, as FSK methods

with fewer frequencies became cheaper, faster and more reliable. However, the technical

complexities of digital filtering were more expensive to deal with than junking an

adequate system.

The consumer product was marketed by AT&T under the registered trade name Touch-

Tone. Other vendors of compatible telephone equipment called this same system "Tone"

dialing or "DTMF".

The DTMF system uses eight different frequency signals transmitted in pairs to represent

sixteen different numbers, symbols and letters - as detailed below

#, *, A, B, C, and D

The engineers had envisioned phones being used to access computers, and surveyed a

number of companies to see what they would need for this role. This led to the addition

of the number sign (#) and star (*) keys (also known as humphries),[citation needed] as

well as a group of keys for menu selection: A, B, C and D. In the end, the lettered keys

were dropped from most phones, and it was many years before the humphries became

widely used for vertical service codes such as *67 in the United States and Canada to

suppress caller ID.
http://en.wikipedia.org/wiki/Image:Autovon_keypad.jpg


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An Autovon telephone keypad with the four precedence levels

Public payphones that accept credit cards use these additional codes to send the

information from the magnetic strip.

The U.S. military also used the letters, relabeled, in their now defunct Autovon phone

system. Here they were used before dialing the phone in order to give some calls priority,

cutting in over existing calls if need be. The idea was to allow important traffic to get

through every time. The levels of priority available were Flash Override (A), Flash (B),

Immediate (C), and Priority (D), with Flash Override being the highest priority. Pressing

one of these keys gave your call priority, overriding other conversations on the network.

Pressing C, Immediate, before dialing would make the switch first look for any free lines,

and if all lines were in use, it would disconnect any non-priority calls, and then any

priority calls. Flash Override will kick every other call off the trunks between the origin

and destination. Consequently, it is limited to the White House Communications Agency.

Precedence dialing is still done on the military phone networks, but using number

combinations (Example:Entering 93 before a number is a priority call) rather than the

separate tones.

Present-day uses of the A, B, C and D keys on telephone networks are few, and exclusive

to network control. For example, the A key is used on some networks to cycle through

different carriers at will (thereby listening in on calls). Their use is probably prohibited

by most carriers. The A, B, C and D tones are used in amateur radio phone patch and

repeater operations to allow, among other uses, control of the repeater while connected to

an active phone line.

DTMF tones are also used by some cable television networks and radio networks to

signal the local cable company/network station to insert a local advertisement or station

identification. These tones were often heard during a station ID preceding a local ad

insert. Previously, terrestrial television stations also used DTMF tones to shut off and

turn on remote transmitters.


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DTMF tones are also sometimes used in caller ID systems to transfer the caller ID

information, however in the USA only Bell 202 modulated FSK signalling is used to

transfer the data.

Keypad

The DTMF keypad is laid out in a 44 matrix, with each row representing a low

frequency, and each column representing a high frequency. Pressing a single key such as

'1' will send a sinusoidal tone of the two frequencies 697 and 1209 hertz (Hz). The

original keypads had levers inside, so each button activated two contacts. The multiple

tones are the reason for calling the system multifrequency. These tones are then decoded

by the switching center to determine which key was pressed.

1209 Hz 1336 Hz 1477 Hz 1633 Hz

697 Hz 1 2 3 A

770 Hz 4 5 6 B

852 Hz 7 8 9 C

941 Hz * 0 # D

WHAT IS DTMF ?

When you press a button in the telephone set keypad, a connection is made that generates a

resultant signal of two tones at the same time. These two tones are taken from a row frequency

and a column frequency. The resultant frequency signal is called "Dual Tone Multiple

Frequency". These tones are identical and unique.

A DTMF signal is the algebraic sum of two different audio frequencies, and can be

expressed as follows:


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f(t) = A0sin(2**fa*t) + B0sin(2**fb*t) + ........... ------->(1)

Where fa and fb are two different audio frequencies with A and B as their peak amplitudes

and f as the resultant DTMF signal. fa belongs to the low frequency group and fb belongs to the

high frequency group.

Each of the low and high frequency groups comprise four frequencies from the various

keys present on the telephone keypad; two different frequencies, one from the high frequency

group and another from the low frequency group are used to produce a DTMF signal to represent

the pressed key.

The amplitudes of the two sine waves should be such that

(0.7 < (A/B) < 0.9)V -------->(2)

The frequencies are chosen such that they are not the harmonics of each other. The

frequencies associated with various keys on the keypad are shown in figure (A).

When you send these DTMF signals to the telephone exchange through cables, the servers

in the telephone exchange identifies these signals and makes the connection to the person you are

calling.


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KEYPAD WITH 12 KEYS AND FREQUENCIES(Hz)

When you press the digit 5 in the keypad it generates a resultant tone signal which is

made up of frequencies 770Hz and 1336Hz. Pressing digit 8 will produce the tone taken from

tones 852Hz and 1336Hz. In both the cases, the column frequency 1336 Hz is the same. These

signals are digital signals which are symmetrical with the sinusoidal wave.

A Typical frequency is shown in the figure below:

Figure (B)

Along with these DTMF generator in our telephone set provides a set of special purpose

groups of tones, which is normally not used in our keypad. These tones are identified as 'A', 'B',

'C', 'D'. These frequencies have the same column frequency but uses row frequencies given in the

table in figure (A). These tones are used for communication signaling.

Due to its accuracy and uniqueness, these DTMF signals are used in controlling systems

using telephones. By using some DTMF generating ICs (UM91214, UM91214, etc) we can

generate DTMF tones without depending on the telephone set.


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GENERAL DESCRIPTION

The DTMF REMOTE SYSTEM is connected in parallel with the telephone apparatus:

this does not restrict the use of the telephone in any way. After a seven rings the circuit

lifts the receiver and sends an acknowledgement tone to signal to the caller that a four-

digit code number is to be entered. Ten seconds are allowed for the entry of each digit,

and each digit is acknowledged by a tone. If the time limit is exceeded, an error sound is

produced and the receiver replaced on-hook. An MICRCHIP PIC16Fxxx micro controller

controls the unit.

Once all four digits are received they are compared with stored code numbers. If

the digits are not in agreement with any of the stored numbers, the error sound is again

produced and the call is terminated. The circuit is then immediately ready for a new call.


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Each of the three switching outputs is assigned two sequences of digits, one to switch the

output stage on and the other to switch it off. If the same four-digit number is received a

second time, the circuit does not change state. The states of the outputs are stored in

EEPROM in the PIC and so are preserved in the case of a power failure.


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PART (COMPONENTS) LIST

R5 - 4K (1)

R4 - 270E (1)

R 8, 11 - 10K (2)R6, 9, 10, 14 - 100K (4)

R7 - 270K (1)

R13, 15 - 2K (2)

R16 - 19 - 1K (4)

C1, 2, 3, 10, 11 - 100KPF DISC (0.1UF / 104)

C4, 5 - 33PF Ceramic Disc

C6 - 0.47 UF / 250V

C7 - 1UF / 25V

C8 - 1000UF / 16V Electrolytic

C9 - 47UF / 25V Electrolytic

Y1 - 4 MHZ Crystal

Y2 - 3.579545 MHZ Crystal

D1, 2 - W04M 1 AMP BRIDGE

D3 - 5 mm RED LED

D4, 5, 8, 9 - 5 mm-GREEN LED

D6, 7, 10, 11 - IN4007 Diode

Q2, 3 - BC547

U1 - PIC16Fxxx (Pre Programmed MCU)

U2 - MT 8870 (DTMF Decorder)

U3 - MCT2E

U4 - LM7805 (3 Pin Voltage Regulator)

U5 - ULN2003A (Relay Driver)

RL1 3 - 12V PCB MOUNT SPDT RELAY

CN1 3 - 3 PIN TERMINALS BLOCK (Not Include In The Kit)

JP2, 3 - RJ11 TELE. SOCKET

J1 - DC Jack

2 Nos - 18 Pin IC Socket




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SALIENT FEATURES

Outputs - Relays x 3

Contact rating - See text

Operating voltage -12V AC / DC (nominal)

Operating current -100mA with no relays operated / 500mA with all relays

operated (Aprox)

Connections 1] 2.5mm DC power jack

2]. RJ-11 for telephone line

3] 3-way screw terminals for relay contacts

Auto line pick up

Auto hang-up line

On board serial EEPROM, its store the relay status. (No require battery back up)

Acknowledgement tone out put for the user.

Connects to standard single line phone line.

On board Ring, power, and relay status LEDs


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MICROCONTROLLER

The full circuit of the remote telephone switch is shown in schismatic we will not review

the operation of how telephone lines work or the detailed operation of the various ICs

used. See the References section for Web links where you can get this information. The

brain of the switcher is the MICROCHIP PIC16Fxxx micro controller, U1. Incoming ring

is detected via C6, D2, R15 and the opto-coupler U3 and connected to pin 11 of the micro

controller. The incoming call is answered by connecting the circuit based around Q1 and

R4 (an electronic holding coil) to the line. One output from micro controller (pin 3) is

used to output a 325Hz software generated tone into the telephone line via the Q2, Q3.

This tone is used to signal the user when commands have been completed or of any

command errors. The PIC16Fxx micro controller examines incoming signals on port B

and controls the outputs over port A. Connection to the telephone network is via RJ11

connector K2. Socket K3 is connected in parallel with socket K2 and allows a telephone

to be connected at the same time as the circuit. A voltage-dependent resistor (varistor) is

connected across these two sockets, which provides protection against voltages in excess

of 130 V.

Q 2

A C K

S T D

V C C

Q 1

R L 2

C 4

R I N G

Q 4

R 6

O H

R L 3

Q 3

C 5

U 1

5

14

1 5

4

1 6

1 7

1 8

1

2

3

6

7

8

9

1 0

1 1

GND

VDD

O S C 2

M C L R

O S C 1

R A 0

R A 1

R A 2

R A 3

R A 4

R B 0 / IN T

R B 1

R B 2

R B 3

R B 4

R B 5

R L 1

P I C 1 6 F x x x

M i c r o c o n tr o l l e r

I n t e r f a c e

Y 1


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RING DETECTOR

The DTMF signal to be processed (an AC signal with a DC offset) is brought in to the

circuit via D2 bridge rectifier with a single call, for example. Type MCT2E opt couplers

are used Because of this diode bridge; the polarity of the signal is no longer relevant. The

ring signal is an AC voltage, which passes through capacitor C6 to bridge rectifier D1

bridge rectifier. Since this voltage can be as high as 60 V, an opto coupler (U3) is used

before the input to the PIC. Capacitor C6 ensures that only the ring signal, and not the

DC offset, reaches the

Opto coupler.

+

C 7

C 6

J 1 A

R J 1 1

1 A

2 A

3 A

4 AR 1 3-

+ D 2

1

4

3

2

R I N G D E T E C T O R C I R C U I

D 3

U 3

1

2

5

4

R I N G

R 1 5

L I N E I N


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DTMF DECODER

DTMF detection and decoding is provided by U2. This chip, an 8870, is a complete

DTMF receiver, which is able to detect and decode all 16 DTMF tone pairs into a 4-bit

code. When a valid DTMF digit is detected the 4-bit code is placed on pins 11-14 and a

data available output, pin 15, is set to logic high. It is connected to the telephone line

via C2 and R9 and R14 a hexadecimal value corresponding to the two tones at its outputs

Q1 to Q4. These outputs are latched and so are only valid when the control output STD is

high. For its operation the integrated circuit requires a base of times, generated in this

case by the quartz crystal of 3.579545MHz. This crystal is very common in the market

since he is the employee for the systems of color of the TV equipment

R 7

D t m f D e c o r d e r

I n t e r f a c e

T O N E I N

Q 4

Q 3

V C C

R 1 4

Q 2

S T D

Y 2

C 1U 2

1 1

1 2

1 3

1 4

7

8

10

41

2

3

56 9

18

1 5

1 7

1 6

Q 1

Q 2

Q 3

Q 4

O S C 1

O S C 2

OE

V R E F

IN +

I N -

G S

INH

PW

VSS

VDD

S T D

S T / G T

E S T

Q 1


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ACKNOWLEDGEMENT TONE OUTPUT

When Q3 is driven by the PIC, it is switched on and off at a frequency of 325 Hz and

adds an extra alternating current of 2 mA. This causes the caller to hear a tone. This tone

is used to signal the user when commands have been completed or of any command

errors.

A C K

A C K T o n e O u t p u

R 1 1

-

+ D 1

1

4

3

2

T O T E L E

R 5J 2 A

R J 1 1

1 A2 A

3 A

4 AQ 3

2

1

3


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AUTO LINE PICKEDUP

Signal output to the telephone line is via two transistors. Q2 produces a line current of

approximately 20 mA, which corresponds to lifting the receiver

R 1 2

L I N E P I C K U PT O T E L E

R 8

O HQ 1

-

+ D 1

1

4

3

2

R 4

J 2 A

R J 1 1

1 A

2 A

3 A

4 A


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POWER SUPPLY

Two supply voltages are required for the telephone remote system circuit. A DC or AC

12 V mains adaptor is connected to bridge rectifier (D6, 7, 10, 11) via DC jack. U1 and

U2 are supplied with a regulated 5 V from a 7805 (U4) fixed voltage Regulator. The

unregulated voltage of approximately 12 V is required for relay driving circuit (U5).

C 1 1

+ 1 2 V

D 6

V D D

1 2 V / 5 V D C P O W E R S U P P L Y

D 1 1D 1 0

C 1 0

+

C 8

D 7

V C C

R 1 8

D 8

J 4

I N O U TG N D

U 4

+

C 9

+ 5 V


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PART (COMPONENTS) EXPLANATION

1] PIC 16Fxx MICROCONTROLLER

Now, the personal computer, which you are using, is working with the software. Thesoftware is the one to have written the operation order of the hardware (the personal

computer). It is possible to make do the various operations to the hardware when making

memorize this procedure at the memory and making execute it in the order. It is possible

to make do the operation, which is different with the same hardware, by changing the

software. It is very convenient.

PIC (Peripheral interface controller) is the IC while was developed to control the

peripheral device, dispersing the function of the main CPU. PIC has the calculation

function and the memory like the CPU and is controlled by the software. However the

throughput, the memory capacity arent big. It depends on kind of PIC but the maximum

operation clock frequency is about 20MHZ and the memory capacity to write the

program is about 1K to 4K words. The clock frequency is related with the speed to read

the program and to execute the instruction. Only at the clock frequency, the throughput

can not be judged. It changes with the architecture in the processing parts for same

architecture; the one with the higher clock frequency is higher about the throughput.

The point, which the PIC convenient for is that the calculation part, the memory, the

input/output part and so on, are incorporated into one piece of the IC. The efficiency, the

function is limited but can compose the control unit only by the PIC even if it doesn't

combine the various IC's so, the circuit can be compactly made.


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More information please refer Data sheet 0f PIC 16Fxx

SPECIAL MICROCONTROLLER FEATURES:

13 I/O pins with individual direction control

High current sink/source for direct LED drive

- 25 ma sink max. Per pin

- 25-ma source max. Per pin

TMR0: 8-bit timer/counter with 8-bit programmable preschooler o 1000

erase/write cycles Enhanced Flash program memory

1,000,000 typical erase/write cycles EEPROM data memory

EEPROM Data Retention > 40 years

In-Circuit Serial Programming (ICSP) - via two pins

Power-on Reset (POR), Power-up Timer (PWRT), Oscillator Start-up Timer

(OST)

Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation

Code-protection

Selectable oscillator options

Low-power, high-speed technology

Fully static design

Wide operating voltage range:


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2] DTMF DECODER MT8870

The MT8870 is a complete DTMF receiver integrating both the band split filter and

digital decoder functions. The filter section uses switched capacitor techniques for high

and low group filters; the decoder uses digital counting techniques to detect and decode

all 16 DTMF tone pairs into a 4-bit code. External component count is minimized by on

chip provision of a differential input amplifier, clock oscillator and latched three-state bus

interface.

FUNCTIONAL DECODE TABLE

L=LOGIC LOW, H=LOGIC HIGH, Z=HIGH IMPEDANCE

X = DONT CARE

Digit TOEINH

E-st Q4 Q3 Q2 Q1

ANY L X H Z Z Z Z

1 H X H 0 0 0 1

2 H X H 0 0 1 0

3 H X H 0 0 1 1

4 H X H 0 1 0 0

5 H X H 0 1 0 1

6 H X H 0 1 1 0

7 H X H 0 1 1 1

8 H X H 1 0 0 0

9 H X H 1 0 0 1

0 H X H 1 0 1 0

* H X H 1 0 1 1

# H X H 1 1 0 0

A H L H 1 1 0 1

B H L H 1 1 1 0

C H L H 1 1 1 1

D H L H 0 0 0 0

.

3] LM7805

Three terminal Positive Voltage regulators, its used to make the stable voltage of +5V

for micro controller. The LM7805 is three terminal positive regulators are available in the

TO-220/D package and with several fixed output voltages, making them useful in a wide

range of applications. Each type employs internal current limiting, thermal shut down and


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safe operating area protection, making it essentially indestructible. If adequate heat

sinking is provided, they can deliver over 1A output current. Although designed primarily

as fixed voltage regulators.

4] MCT2E / 4N35

It is used for Ring detection The MCT2E series opt isolators consist of a gallium arsenide

infrared emitting diode driving a silicon phototransistor in a 6-pin dual in-line package.

4 - E M I T T E R

6 - B A S E2 - C A T H O D E 5 - C O L L E C T O R3 - N C

M C T 2 E

1

2

5

4

6

1 - A N O D

5] SPDT RELAY 12V


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It closes the voltage less point of contact while the remote control works to control the

equipment outside. The relay takes advantage of the fact that when electricity flows

through a coil, it becomes an electromagnet. The electromagnetic coil attracts a steel

plate, which is attached to a switch. So the switch's motion (ON and OFF) is

controlled by the current flowing to the coil, or not, respectively. A very useful

feature of a relay is that it can be used to electrically isolate different parts of a

circuit. It will allow a low voltage circuit (e.g. 5VDC) to switch the power in a high

voltage circuit (e.g. 100 VAC or more). The relay operates mechanically, so it cannot

operate at high speed.


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ASSEMBLY INSTRUCTIONS

Use the component overlay on the PCB to place the components starting with the lowest

height components

First. Make sure that the diode, LED and electrolytic capacitors are inserted the right way

around.

1. Resistors and diodes

2. IC sockets do not insert ICs until after the TESTING section.

3. Ceramic capacitors.

4. DC Power jack and LM7805 regulators.. It does not require a heat sink.

5. A 4 pin zippy tact switch (SW1)

6. Transistors (Q1 Q3) and bridge rectifiers7. RJ11 telephone socket and LEDs

8. Electrolytic capacitors. Make sure you insert them the correct way around.

9. Terminal blocks. Note the terminal blocks. Also make sure the wire entry side

faces out from the PCB.

10. Relays and crystal


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FIRST TEST

When the PIC is first used after its program code has been loaded into it, all the output

stages are turned on, and all digit sequences are set to CCCC (in DTMF code). These

values are changed when the unit is first configured using DTMF tones.

Simply simply calling one self and watching the effect of the call and the received signals

on the receiving telephone and on the remote control can test the circuit. The call

acknowledgement tone should be heard in the earpiece, and a four-digit sequence should

be entered. The signal tones shown in the table should be heard, overlaid by the tones

from the connected telephone. During this process the tones entered can cause an

outgoing call to be set up, the power supply should be disconnected, but the telephone

connection need not be unplugged. Note that this means that if there is a power cut, the

telephone connection will not be blocked.

COMMANDS

1] 1111 = Relay 1 On

2] 2222 = Relay 1 Off

3] 3333 = Relay 2 On

4] 4444 = Relay 2 Off

5] 5555 = Relay 3 On

6] 6666 = Relay 3 Off

TROUBLE SHOOTING

Poor soldering (dry joints) is the most common reason for the circuit not working.

Check all soldered joints carefully under a good light. Re-solder any that look suspicious.

Are all the components in their correct position on the PCB? Are the electrolytic

capacitors and diodes the right way round? Are the ICs the right way around? Are any IC

leads bent up under the IC body? Is the regulator output = 5V?


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PCB Overlay


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DTMF REMOTE CODE


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ADVANTAGES OF PROJECT

1. The main advantage of this remote controller is its unlimited range as connection

is established using telephone lines.

2. Operation is not based on infrared transmission due to which positioning and

adjustment is not required at all.

3. Working is easy and only appliances connection to kit and kit to phone line is to

be done just like plug n play.

4. Flexibility is provided in a way that one can connect less number of appliances in

starting and later on expand the circuitry as per requirement.


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APPLICATIONS OF PROJECT

1. Using telephonic devices a person can control operation of many appliances

connected to the kit.

2. Just by using dial keypad of telephone from where the user is calling on / off

operation of the appliances can be performed.

3. The range of appliances that are controlled depends on person usage.


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FUTURE ENHANCEMENTS OF PROJECT

1. Appliances used in homes like television, music system, fans, lights etc. can be

operated using this technique.

2. Office appliances like FAX can be operated using this technique.


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REFERENCE FOR TECHNICAL INFORMATION

FROM FOLLOWING BOOKS:

1. Micro Processor Architecture by Ramesh S. Gaonkar.

2. Communication System by Tob & Shilling.

3. Micro controller by K. J. Ayala.

4. Integrated Electronics by Millman & Hawlkiwas.

5. Electronic devices and circuits by Allen Mottershead.

REFERENCE FOR ARTICLES & TECHNICAL INFORMATION ON

DTMF TELEPHONE REMOTE CONTROLLER FROM

FOLLOWING SITES:

http://www.yahoo.com (Yahoo search engine)

http://www.google.com (Google search engine)

http://www.ascom.com

http://www.metricom-corp.com/fec.html

http://www.homeplug.org/powerline/index.html

http://www.electricomconsulting.co.uk/overview.html

http://www.plugtek.com/morearticles.html

http://www. howstuffswork.com

telephone based home automation system report

Documents