This document describes a DTMF-based home appliance control system that allows wireless control of devices in a home using a user console with numbered keys. The system uses a DTMF decoder, microcontroller, and wireless transmitter and receiver to encode and transmit user selections via DTMF signals and control appliances accordingly. Key components include an AT89S52 microcontroller, MT8870 DTMF decoder, relays, LEDs, buttons, and other basic electronic components. When a key is pressed, the DTMF signal is encoded and transmitted to the receiver, then decoded by the microcontroller to trigger the correct appliance, allowing remote control of devices like lights and appliances from anywhere.

1. DTMF BASED HOME
APPLIANCE SYSTEM
Made by-
Daksh Raj Chopra

2. Contents
• Introduction
• Circuitry
• Components Used
• Block Diagram
• Circuit Diagram
• Working of the Circuit
• Applications
• Project Picture

3. Introduction
This project we propose a unique System mobile controlled robot
utilizing Dual Tone Multi Frequency (DTMF) that is paired with a
wireless module to provide seamless wireless control over many
devices in a house. This user console has many keys, each
corresponding to the device that needs to be activated. The encoder
encodes the user choice and sends via a FM transmitter. The FM
receiver receives the modulated signal and demodulates it and the user
choice is determined by the DTMF decoder. Based upon this the
required appliance is triggered.

4. Circuitry
• DTMF DECODER
• MICROCONTROLLER
• EXCESS CONTROL CIRCUIT
• AUTOMATIC ON THROUGH OUTER PHONE

5. DTMF Decoder

6. 8051 Microcontroller
The AT89S51 is a low-power, high-performance CMOS 8-bit microcomputer
with 4K bytes of Flash Programmable and Erasable Read Only Memory
(PEROM). The device is manufactured using Atmel’s high density non-volatile
memory technology and is compatible with the industry standard MCS-51™
instruction set and pinout. The on-chip Flash allows the program memory to
be reprogrammed in-system or by a conventional nonvolatile memory
programmer. By combining a versatile 8-bit CPU with Flash on a monolithic
chip, the Atmel AT89S51 is a powerful microcomputer which provides a
highly flexible and cost effective solution to many embedded control
applications. The AT89S51 provides the following standard features: 4K bytes
of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, five
vector two-level interrupt architecture, a full duplex serial port, and on-chip
oscillator and clock circuitry.

7. 8051 Microcontroller
• Compatible with MCS-51™ Products
• 4K Bytes of In-System Reprogrammable Flash Memory
– Endurance: 1,000 Write/Erase Cycles
• Fully Static Operation: 0 Hz to 24 MHz
• Three-Level Program Memory Lock
• 128 x 8-Bit Internal RAM
• 32 Programmable I/O Lines
• Two 16-Bit Timer/Counters
• Six Interrupt Sources
• Programmable Serial Channel
• Low Power Idle and Power Down Modes

8. Components Used
• Microcontroller - AT89S52
• DTMF Decoder – MT8870
• ULN 2003
• Relay
• Led
• Resistors
• Pull – Up Resistor
• Capacitors

9. Components Used
• Crystal Oscillator
• Push Button
• Mic
• Voltage Regulator
• Bulb Holders
• Bulbs
• Plug
• AC Power Supply

10. Block Diagram

11. Circuit

12. Working
• IN this project our first part is DTMF decoder. The DTMF IC receives
the DTMF pulse and then converts it into binary coded decimal. Pin
No. 18 of the IC is connected to positive supply. In this circuit we use
+5 volt regulated power supply for the smooth working. DTMF signal
is applied to the pin No. 2 and 3 of the IC through resistor and
capacitor network. Capacitor of 0.1 uF works as a dc blocking
capacitor. Pin No. 5, 6, 9 is connected to the Ground pin. Pin No. 7
and 8 is connected to the 12.095 crystal. Pin No. 16 and 17 is
connected to RC network work as an auto reset, when we switch on
the power supply.
• BCD output is available on the pin No 11, 12, 13, 14 and this output is
connected to the microcontroller 89C51.

13. Working
• Our next part of the circuit is 89C51. 89C51 is a 40 pin IC. Pin No. 40
of the IC is connected to the positive supply. Pin No. 9 is rest pin. One
capacitor and resistor network is connected to pin No 9. This
microcontroller has a total of four input output ports each 8 bit wide.
• Another pins of the port 3 is also connected for another useful uses.
P3.3 Acknowledge of code lock
P3.4 Time indication of the code lock
P3.5 Led indication of sound output for on/off signal
P3.2 Output frequency for opto-coupler input.

14. Industry Applications
• The need for the above project was that this project firstly it saves our time. If you are
stuck in traffic you can switch on your microwave oven on slow cooking mode. By the
time you reach your home your food will be ready. You don’t have go to each room to
check whether the lights are on/off. You can do with a click of single button. Secondly, it
save our money in the long run. There are some appliances like a television which we
switch off but not its power supply. There is a Led still glowing in it which uses electricity.
If we have this television attached to our project then we can switch off its power supply
whenever we want and there are many other devices like this. Thirdly, it for self-
maintenance and security. Security as in if we by chance forgot to switch off any of lights
then we can switch off from our phones. Lastly, we all know that all this will make our life
easy and trouble free.
• Industrial applications for the project made are that one can control home appliances
from anywhere in the world even we are sitting a cup of tea in United States of America.
Secondly, it reduces wastage of electricity as discussed earlier that if we forget to switch
off the lights. Last but not the least it is very low cost compared to other technologies
like GSM.

15. Project Picture

16. Thank You
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