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Mobile Controlled Electrical Appliances

Project Introduction:-

This project talks about the basic definitions needed to understand the project better and further defines the technical criteria to be implemented as a part of this project. This project is a teleremote circuit that enables switching ‘ON’ and ‘OFF’ of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote controls. The circuit described in the project can be used to switch up to ten appliances (corresponding to the digits 0 to 9 of the telephone keypad). This circuit is based on the DTMF controller circuit. DTMF means dual tone multiple frequency. The DTMF signals on telephone instrument are used as control signals.

Why automation?

Earlier, we are looking into the face of future when we talked about automated devices, which could do anything on instigation of a controller, but today it has become a reality.

1. An automated device can replace good amount of human working force, moreover humans are more prone to errors and in intensive conditions the probability of error increases. Whereas an automated device can work with diligence, versatility and with almost zero error.

2. This is why this project looks into construction and implementation of a system involving hardware to control a variety of electrical and electronics instruments.

What is home/office automation?

Home/office automation is the control of any or all electrical devices in our home or office.

Whether we are there or away. Home /office automation is one of the most exciting developments in technology for the home that has come along in decades. There are hundreds of products available today that allow us control over the devices automatically, either by remote control; or even by voice command.

What can be automated?

Virtually anything in the home/office that is powered by electricity can be automated and/or controlled. We can control our electrical devices with our cordless phone from our easy chair.

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We can turn our porch lights on automatically at dark or when someone approaches and can see who is at the front door from any nearby television, and talk to them or unlock the door from any nearby telephone. Have the security system turn off lights, close drapes and setback the temperature when we leave and turn on the alarm system. The possibilities are only limited by our imagination.

How is the system controlled in this project?

This circuit enables one to utilize a telephone for remote switching ‘on’ and ‘off’ of any electrically operated device. It does not require any physical connection to the telephone lines or lifting of the handset. It does not require any physical connection to the telephone department. The switchinig operation is performed by making use of doded telephone ring signal.

While designing it has been ensured that the circuit is free from any false triggering by normal telephone ring signals. Since the instrument has no hardwired connection to the telephone the line it does not affect the normal operation of the telephone set. To avoid false triggering, suitable reset feature is incorporated in this circuit.

Why not any other device?

In this age of automation many other device like microprocessor or micro-controller, infrared remote, voice controlled devices etc. Are used for the automation purposed, but the have certain limitation which are described below :-

1. The use of microprocessor or micro-controller involves complexities like microprocessor operating voltages; interrupt servicing, poling, memory access mechanism and extensive soldering. Moreover, if we use micro-controller or a microprocessor we can not change the working as and when desired. The problem being, while using them we have to hardwire the code into ROM chips and in case we need to amend we have to burn a new ROM chip to replace the earlier one. The ear ROM becomes useless and has to be scraped. And this has to be done on every single time we need add something new.

2. An infrared remote control can work for a device up to a specified range to distance after that it can not be used for controlling the device.

3. A voice controlled device works on a single voice and cannot be used by any other person and have a certain range of working.

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

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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:           

f(t) = A0sin(2*П*fa*t) + B0sin(2*П*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.  

The row and column frequencies are given below: 

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

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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:

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 signalling.

Due to its accuracy and uniqueness, these DTMF signals are used in controlling systems using telephones. By using some DTMF generating IC’s (UM91214, UM91214, etc) we can generate DTMF tones without depending on the telephone set.

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Component List

Integrated Circuit:-

IC-8870 : DTMF Decoder IC-74154 : BCD to Decimal Decoder. IC-4049 : Hex Inverter IC-4013 : D flip-flop IC-4017 : Counter IC-555 : Timer IC-7809 : Voltage regulator IC-7805 : Voltage regulator IC-7812 : Voltage regulator

Transistor:-

BC-548 : Medium power transistor

Resistors:-

R1 : 1k R2 : 10k R3 : 100k R4 : 22k R5 : 330k R6 : 56k

Diodes:-

IN-4007

Capacitor:-

C1 : 4700MFD,25V. C2 : 1000mfd,25v. C3 : 0.1mfd,100v. C4 : 0.01mfd,100v.

Transformer:-

12-0-9,1A.

Relay:-

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6V, 100E

Crystal:-

3.579mh

MISCELLANEOUS:-

WIRE 2 meters. VEROBOARD. SOLDER WIRE. SOLDER PASTE HEAT SINK. CIRCUIT BOX. SCREWS. BULB HOLDERS. BULB HOLDER STAND.

BLOCK DIAGRAM

Working of the circuit:-

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This unit talks about how the different units of the project working. How relays and Transistors can be interfaced to your telephone and can be used to turn ‘ON’ and ‘OFF’ your home appliances such as bulbs, tube lights, lamps or heavy-duty motors.

This project is a tele remote circuit that enables switching ‘ON’ and ‘OFF’ of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote controls. The circuit described in the project can be used to switch up to ten appliances (corresponding to the digits 0 to 9 of the telephone keypad). This circuit is based on the DTMF controller circuit. DTMF means dual tone multiple frequencies. The DTMF signals on telephone instrument are used as control signals.

When we press the star button in telephone the pulse dialling is converted in to tone dialling. We use this tone dialling in our project. Telephone lines are connected to the DTMF decoder circuit including a DTMF decoder IC 8870, which is a 24 pin IC. This DTMF decoder converts the DTMF pulse into a BCD signal. It means when we press the digit no. 1 then output from decoder is 0001. Circuit automatically sense and convert the DTMF signal into BCD signal.

Output from IC 8870 is connected to the next stage, which is a BCD to Decimal converter circuit. For this purpose we use BCD to Decimal converter IC 74154. This IC converts the BCD signal into Decimal signal. It means when press the digit 2 in the keypad then 2 number output of the decimal decoder is active in this stage.

The output of the BCD to Decimal decoder circuit is active low; therefore, we convert this low signal into high signal with the help of inverter circuit. In this project we have used hex inverter circuit, which is IC 4049. Hex inverter circuit converts at a time six input signal. Since we have ten outputs in this circuit, therefore, we have used two hex inverter ICs. Output of the inverter is high now.

Output of the IC 4049 is in the form of pulse signal, now to convert the pulse signal into toggle signal we have used a flip-flop. The flip-flop used in the circuit is IC 4013. This IC is a dual flip-flop IC since it has two inputs and two outputs. These flip-flops are of D-type, i.e., the input data appears at the output at the end of the clock pulse. This mans that when the output of the previous stage is low, the output of the flip-flop is low and when the output of the previous stage is high then the output of the flip-flop is high. If we use ten outputs of the IC-4049 and want all the outputs connected to flip-flop then we have to use minimum five flip-flop ICs in the project.

Output of the flip-flop is connected to the base of NPN transistor through 1k ohm resistor. Emitter of every transistor is connected to the negative voltage and collector is connected to the relay coil. Relay is electromagnetic switch. Relay operation voltage is 9V DC. The rectifier circuit before regulator IC-7805 provides this 9 V DC. Relay further ON/OFF any electrical appliance connected to it.

Now when we press the number 1 of the telephone keypad then one number dial is ON and the corresponding relay is switched ON and the electrical circuit is completed. Now again

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when we press the no. 1 then flip-flop output is shifted to zero and the relay is OFF and so the electrical appliance connected to it.

When the circuit is used to switch the relays from the telephone instruments to which it is connected physically, the mode of operation of the telephone line can be changed by using the star button. But when switching is done from some other telephone instrument the working of the circuit is a little different. In that case a coupler circuit assists the working of the project. This coupler circuit consists of an optocoupler IC 417 , a timer IC 555 and a decade counter IC 4017.

When a call is established and telephone starts ringing the optocoupler IC detects the ring. This IC is connected to the IC 555 timer IC and for every ring it makes timer IC to generate a pulse. The timer IC is connected to the decade counter and with every pulse generated by the timer IC, the decade counter makes one of its outputs high. A relay is connected to one of the output of the counter IC, that connects the coupler circuit with the DTMF decoder circuit, whenever, that output is high. That means the circuit counts a preset value of rings and then it connects the telephone line to the DTMF decoder circuit to perform switching action.

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Different type of ICs:-

IC 74154:-

PIN DISCRIPTION:-

IC 74154 is a BCD to decimal converter. This IC is a 24 pin IC. Pin no. 20,21,22,23 are the BCD input pins of this IC, pin no.2,3,4,5,6,7,8,9,10,11 are the output pins, pin no 24 is connected to the positive 5 volt supply and pin no. 12 is the negative supply pin. Pin no 18 and pin no. 19 of this IC is enable pin. If the data available on the pin no. 19 is negative then output is negative for a time. The negative pulse is given by the NPN transistor collector pint. IC 74154 is a special package may be used to provide a 1 low output out of 16 output of may be used to send input data to one selected output of 16, the remaining 15 staying high.

SUBSTITUTE IC:-

No other substitute easily available.

IC 4049:-

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PIN DESCRIPTION:-

IC 4049 is a hex inverter IC. Pin No. 1 Is connected to the positive supply. Pin no. 7 is connected to negative supply. Pin no. 3,5,7,9,11 are the inputs of the IC and pin no. 2,4,6,10,12 are the input pins of this IC. Since the output of IC 74154 are low hence IC 4049 is used to invert the output of IC 74154, i.e. to convert the low output of the decoder IC into high output.

SUBSTITE IC:-

IC 7404

IC 8870:-

IC-8870

PIN DESCRIPTION:-

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IC 8870 is a DTMF (dual tone multiple frequency) decoder. It converts dtmf pulse into the equivalent BCD signal. Pin no. 18 and 10 of this IC are connected to the positive supply. This positive supply is from the 5 volt regulator circuit. Pin no. 9,5,6 are connected to the negative supply. Signal fro the telephone line is in the form of dtmf pulse is applied to pin no. 2 of this IC through 2.2k ohm resistor and 0.1 mfd capacitor. This signal is also connected to pin no. 3 through 100k ohm resistor. Pin no. 7 and 8 are connected to a crystal of frequency 3.7945mh. pin no. 16 and 17 of this IC is resat pin . pin no 11,12,13,14 are the BCD output of this IC.

SUBSTITUTE ICs:-

IC 9170, IC 3170

IC 4013:-

PIN DESCRIPTION:-

IC 4014 is a dual flip-flop IC. Pin no. 14 of this IC is connected to the positive supply. Pin no. 7 is connected to the negative supply. Pin no. 3,11 are clock input of this IC. Pin no.1 and 13 are the output of the IC. Pin no. 10 and 4 are connected to the reset pin . pin 2 and pin 5 and pin no. 9,12 are join together. In this IC there are two clock pulses therefore this is a dual flip-flop IC. Output from IC 4049 is given to the flip-flop IC to convert the pulse signal into toggle. If we use ten outputs of 4049 and want all the outputs connected to flip-flop then five 4013 IC must be used.

SUBSTITUTE IC:-

IC 7474

IC 4017:-

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PIN DESCRIPTION:-

IC 4017 is a counter IC. Pin no. 16 is connected t the positive supply. Pin no. 8 is connected to the negative supply. Pin no. 13 and 7 are the output pins and connected to the relay through NPN transistor. Pin no. 1,2,3,4,5,6,9,10,11,12,14,15 are not connected.

SUBSTITUTE IC:-

IC 7490

IC 555:-

PIN DESCRIPTION:-

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The 555 timer is an extremely versatile integrated circuit, which can be used to build lots of different circuits. Pin no. 4 and 8 of the timer IC are connected to the positive power supply. Pin no. 1 is connected to the negative power supply. Pin no. 2 is the input of the IC and pin no. 3 is the output of the IC.

SUBSTITUTE IC:-

No substitute (available as 555 IC only with different manufacturers).

POWER SUPPLY FOR DIGITAL CIRCUITS

Summary of circuit features:-

Brief description of operation: - Gives out well regulated +9V output, output current capability of 100mA.

Circuit protection: - Built-in overheating protection shuts down output when regulator IC gets too hot.

Circuit complexity: - Simple and easy to build.

Circuit performance: - stable +9V output voltage, reliable operation.

Availability of components: - Easy to get, uses only common basic components.

Design testing: - Based on data sheet example circuit, I have used this circuit successfully as part of other electronics projects.

Applications: - Part of electronics devices, small laboratory power supply.

Power supply voltage: - Unregulated DC 8-18Vpower supply.

Power supply current: - Needed output current 1A.

Components cost: - Few rupees for the electronics components plus the cost of input transformer.

DESCRIPTION OF POWER SUPPLY:-

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This circuit is a small +12 Volts power supply, which is useful when experimenting with digital electronics. Small inexpensive wall transformers with variable output voltage are available from any electronics shop. Those transformers are easily available, but usually their voltage regulation is very poor, which makes them not very usable for digital circuit experimenter unless a better regulation can be achieved in some way. The following circuit in the answer to the problem.

This circuit can gived +12V output at about 1A current. The circuit has overload and terminal protection.

The above circuit utilizes the voltage regulator IC 7812 for the constant power supply. The capacitor must have enough high voltage rating to safely handle the input voltage feed to circuit. The circuit is very easy to build for example into a piece of Vero board.

Pin diagram of 7812 regulated IC

Pin 1 : Unregulated voltage input

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Pin 2 : Ground

Pin 3 : Regulated voltage output

Component list:-

1. 7812 regulator IC.2. 4700 uf electrolytic capacitor, at least 25 V voltage rating.3. 1000 uf electrolytic capacitor, at least 25 V voltage rating.

DECODER FUNCTION:-

The first IC shown is a BCD to decimal decoder IC. Pin 20,21,22,23 are used as BCD inputs into the IC. Pins 1,2,3,4,5,6,7,8,9,10,11,13,14,15,16,17 are the sixteen decimal outputs. These outputs are active low so they are at high when they are not activated. If the BCD inputs exceed sixteen none of the outputs will be activated and not go low.

Decoder is a combinational circuit. In combinational circuits, the output at any instant of time depends upon the input present at that instant of time. This means there is no memory in these circuits. A binary code of n bits is capable of representing up to 2n distinct elements of the coded information.

A decoder is a combinational circuit that converts binary information from input lines. If the n bit decoder information has reused or don’t care conditions, the decoder output will have less than 2n output.

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The decoder present here is called n to m line decoder where m<n their purpose is to generate the 2n (or less) minterms of n input variables. The name decoder is also used in conjunctions with some code converters such as a BCD to seven segment decoder.

Some IC Decoder is constructed with NAND gates. Since a NAND gate produces AND operation with an inverted output, becomes economical to generate the decoder minterms in their complemented form most if not all IC decoders include one or more enable inputs to control the circuit operation 3 to 8 line decoder with enable inputs constructed with NAND gates. All outputs are equal to 1 if enable input is 1, regardless of value of input.

A decoder with an enable with an input can function as demultiplexer. A demultiplexer is a circuit that receives information on a single line and transmits this information on one of possible output line is controlled by the bit value on n section lines.

Scope of industrial automation solutions:-•    Motor control•    Machine logic control•    Man/Machine interface•    Position control and monitoring•    Systems integration•    Software aiding automation control products and systems•    Automatic temperature and humidity control

Scope of Home automation software:- •    Home appliances like washing machine, Ac's etc•    Wall modules and sockets•    Lighting•    Window blinds•    Integrating the above with software and user interfaces that run on television, touch screen displays, telephone, mobile phone and computer.

Benefits of Home/Industrial automation solution:-

•    Repeatability•    Enhanced control and monitoring•    Quality control•    Waste reduction

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•    Safety and security•    Increased productivity and cost reduction•    Lower energy bills