Controlling home devices with the help of dtmf .

1.  Submitted to:
Dr. Ramnish
(Asst. Professor)
 Submitted by:
14152052
B.Tech( ECE)
4th year

2. AIM OF THE PROJECT
The objective of this project is to enable user to
remotely control their home appliances and
systems using a cell phone based interface.To
access the control unit ,the user should send
an authentication code along with required
function to his/her home control system via
GSM.

3. PROBLEM STATEMENT:
The proposed approach for designing this
system is to implement a microcontroller
based control module that receives its
instructions and commands from a cellular
phone over the GSM network.

4. COMPONENTS USED:
 IC-AT89S52
 IC-ULN2003
 LM7805
 CAPACITORS
 LED
 DIODE
 RESISTORS
 RELAY
 PCB
 BC547
 7805 REGULATOR

5. IC-AT89S52
The AT89S52 is a low power ,high performance
CMOS 8-bit microcontroller with 8K bytes of
inbuilt programmable flash memory. It works in
the operating range of 4v-5.5v and it has 32
programmable I/O pins.

6. IC-ULN2003
An ULN2003 is a high voltage, high current
Darlington transistor array. It consists of seven
NPN Darlington pairs that features high-
voltage outputs with common cathode flyback
diodes for switching inductive loads.

7. LM7805
FEATURES:
• Output Current up to 1A
• Output Voltages :5,6,8,9,10,12,15
• Thermal overload protection
• Short circuit protection

8. CAPACITORS
 A capacitor is used to store energy electro-
statically in any electric field.
 Capacitors are widely used in electronic
circuits to block direct current while allowing
alternate current to pass.

9. DIODE
 A diode is a very simple device and has lot
applications .A diode is a device that passes
current only in one direction .
 There are many types of diodes to handle
small current, large currents, high frequencies
and high voltages.

10. RESISTORS
A resistor is a passive two terminal electrical
resistance as a circuit element. Resistors act
to reduce current flow and at the same time
act to lower voltage ;levels within circuits.

11. RELAY
A relay is an electrically operated switch.Many
relays use an electromagnet to mechanically
operate a switch but other operating principles
are also used such as solid state relays.
Relays are used where it is necessary to control
a circuit by low power signal or where several
circuits must be controlled by one signal.

12. BC547
The BC547 is a general purpose epitaxial silicon
NPN bipolar junction transistor.

13. WORKING
In order to control the device you have to make
a call to the cell phone attached to the device
from any phone. Now the phone is picked up
by the phone on the device through auto
answer mode.
In our system, there is circuit containing
microcontroller which is the heart of the circuit.
VCC is used for the manual reset of circuit.

14. ADVANTAGES
 Quick response is achieved.
 Construction is easy.
 Easy to maintain and repair.
 Operation cost is low.
 Design is efficient and low cost.
 Economical.
 Easy to use.

15. APPLICATIONS
 This can be used in industrial applications.
 This system can be used in houses, where
people often forget to switch off electrical
appliances.
 It reduces wastage of electricity when we
forgot to switch off lights and gone outside.

16. REFERENCES
 www.wikipedia.com
 www.google.com
 www.kitsnspares.com