Dtmf based device control

1. Head office: 3nd floor, Krishna Reddy Buildings, OPP: ICICI ATM, Ramalingapuram, Nellore
www.pvrtechnology.com, E-Mail: pvrieeeprojects@gmail.com, Ph: 81432 71457
DTMF BASED DEVICE CONTROL
ABSTRACT
The project is aimed to design a system using which the devices can be controlled
wirelessly in a home or in industry by using DTMF technology.
In this project we can control the devices at homes or industries
from our mobile without any contact. For this we are using DTMF [Dual Tone Multi Frequency]
technique which is an in built feature to few mobiles. This project is designed in such a way that
the Industrial or home devices are interfaced to the microcontroller [8051] through the relays
along with one mobile which supports DTMF by using DTMF decoder. A normal mobile phone
will be used as a remote control. A call is established between the controlling mobile and the
remote mobile. Now any key pressed on the remote mobile will generate a complex frequency,
which can be heard on the mobile placed. That frequency can be detected by controller by means
of DTMF decoder. Keys assigned for control can be User Defined. Depending on the keys
pressed the micro controller can be programmed in such a way that it can control any devices in
homes or industries.
This project uses regulated 5V, 500mA power supply. 7805 three terminal voltage
regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac
output of secondary of 230/12V step down transformer.

2. Head office: 3nd floor, Krishna Reddy Buildings, OPP: ICICI ATM, Ramalingapuram, Nellore
www.pvrtechnology.com, E-Mail: pvrieeeprojects@gmail.com, Ph: 81432 71457
TECHNICAL SPECIFICATIONS:
HARDWARE:
Micro controller : AT89X series
Crystal : 11.0592 MHz
LCD : HD44780
Relays
Loads
DTMF decoder
Mobile
SOFTWARE:
Keil micro vision
Proteus
UC flash
APPLICATIONS:

3. Head office: 3nd floor, Krishna Reddy Buildings, OPP: ICICI ATM, Ramalingapuram, Nellore
www.pvrtechnology.com, E-Mail: pvrieeeprojects@gmail.com, Ph: 81432 71457
 Industrial applications
 Domestic applications
BLOCK DIAGRAM:
Power
Supply
16X2
LCD
DISPLAY
8
0
5
1
Relay2 Load2
Relay1 Load1
Relay3 Load3
DTMF
decoder
Mobile

4. Head office: 3nd floor, Krishna Reddy Buildings, OPP: ICICI ATM, Ramalingapuram, Nellore
www.pvrtechnology.com, E-Mail: pvrieeeprojects@gmail.com, Ph: 81432 71457
POWER SUPPLY BLOCK DIAGRAM:
Stepdown
Transformer
Filter Regulator OutputBridge
Rectifier