DTMF Based Home Automation

Published  August 27, 2015   91
S Saddam
DTMF Based Home Automation System

We use many different types of communication in control applications to control home appliances, industrial appliances, and other type of automation. There are two types of communication that is we generally use - one is wired and other one is wireless. In wireless communication we transmits signal wirelessly, like using radio frequency (RF) and in wired communication in which we uses wires like copper wire. In this project “DTMF Based Home Automation System” we are going to control our home appliances wirelessly. Other important feature of this project is, that we are not going to use any microcontroller in it.


Required Components

  1. MT8870 DTMF Decoder                 -1
  2. ULN2003                                              -1
  3. Relay 5 volt                                         -3
  4. Bulb with holder or LED                 -3
  5. Connecting wires
  6. Bread board                                       -2
  7. Aux Wire                                             -1
  8. 9 volt battery                                     -2
  9. PVT or Terminal Block                      -4
  10. 100K Resistor                                     -2
  11. 330K resistor                                      -1
  12. 0.1 uf Cap                                            -2
  13. 22 pF cap                                             -2
  14. 3.57 Mhz Crystal                               -1
  15. Mobile phone                  
  16. LEDs                                                       -3
  17. 1K resistor                                           -6
  18. 7805                                                       -1


Circuit Concept and Working

DTMF controlled home appliances project works over mobile DTMF technology that exists in Dial tone. DTMF stands for Dual Tone Multiple Frequency. There are some frequencies that we used to create DTMF tone. In simple words by adding or mixing two or more frequencies generates DTMF tone (Also check: DTMF Based Robot using Arduino). These frequencies are given below:

DTMF Frequencies

In Given figure we can see two groups of different frequencies. When one upper and one lower frequencies mixed then a tone is created that tone we calls Dual Tone Multiple Frequency. In this project we control ac appliances by pressing dial pad keys like 1, 2, 3, 4, 5 and more.

Block Diagram for DTMF Based Home Automation

Here we have connected a cell phone using aux wire to the DTMF decoder circuit. Before explaining the further working of project we need to know about the output of DTMF decoder for every key pressed.

Output of DTMF Decoder

Now understand working according to given table.

In circuit diagram at Q1 LIGHT is connected, at Q2 FAN is connected and at Q3 TV is connected through relay driver IC. We have left Q4. Now when we press key 1 at the dial pad of mobile phone DTMF decodes this tone and generates a digital output given in table. Now According to given output in table Q1 is HIGH and Q1 is connected with light so LIGHT turned ON. If we want turned OFF the LIGHT, we need to press key number 8. Because in the output of key8, Q1, Q2 and Q3 LOW and Q4 are HIGH and we have not used Q4. So it doesn’t matter that Q4 is HIGH or LOW. But our operation has been performed because Q1 is LOW in key 8’s output and rest of appliances not affected. Now is we want to turned on FAN so we need to press key2 because by pressing key2 only Q2 is activated and rest of output are remain same. Now if we to OFF the FAN then we need to press key8 again like before for as LIGHT. Now if we want to TV so we need to press key4 and for tuning it OFF we need to press 8 like before. Now suppose we want to turned ON all of the appliances so we need to press key7 (see table) and for turning OFF all key8 (see table).


Now if we need to ON LIGHT and FAN so we need to press key3 (see table). And now we want to ON TV so we need to press key 7 not key4. Because we should keep remain turn ON previous appliances. Now if we want to turn OFF only LIGHT so we need to press key6. Because we should again to keep remain turn ON the previous appliances except LIGHT.


So we can control each of the appliances according to table output.


Circuit Diagram and Explanation

DTMF Based Home Automation Circuit Diagram

Circuit diagram for DTMF controlled home automation project is shown above. In this circuit we have used a DTMF decoder namely MT8890 IC which converts dial pad tone into the four bit digital output. LIGHT, FAN and TV are connected to Q1,Q2 and Q3 of DTMF decoder IC through a relay driver namely ULN2003. 5 volt SPDT 3 relays are used for controlling LIGHT, FAN and TV.


For demonstration of this project we have connected three LEDs at relay instead AC appliances. And we have also used 9 volt dc battery instead 220VAC for driving LEDs. 


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Submitted by Nikki Singh on Thu, 10/29/2015 - 15:01


Will this project work if I will make a call at the receiver and then during call,press the buttons from the transmitter side. Please help me by explaining the working of each and every component. I beg u plz help me

Submitted by Eshita on Wed, 02/24/2016 - 02:39


For simulation of this circuit which software is more efficient?

hey saddam here u use uln2003 but why u use that if u connect that directly than also it work
and i want that from pressing 1 like tv on again pressing 1 it off the tv how will i do this

Submitted by snehal thamke on Thu, 03/24/2016 - 21:28


here in dis components list they have mentioned about PVT, I just wanted to know what is PVT and what are its uses and application.

Submitted by Amitesh Singh on Sun, 04/24/2016 - 11:01


Can we control home appliances using dtmf tone, through wifi lan connection...if yes then please send me a solution, that how it will work..

Submitted by raviraj on Sun, 05/22/2016 - 19:57


sir can i use cd 8870 ic for this ckt ?? is their any change in ckt diagram

Submitted by nosd1 on Tue, 06/21/2016 - 08:13


Can you please help me understand how this is a wireless solution?? The mobile is connected to the circuit through the AUX cable as I see it. I would really like a wireless version of this. Thank You

Submitted by Odin Olaya on Thu, 06/30/2016 - 15:27


What PVT stands for and how it is used. in the diagram it is not shown though. thanks

Submitted by Avinash on Tue, 08/16/2016 - 15:00


what is PVT in the components given...?

Submitted by Avinash on Tue, 09/20/2016 - 22:31


What is the PVT mentioned in the list of apparatus..?

Submitted by ramraj on Fri, 09/30/2016 - 10:48


Hi sir can I use it for 440 volts ac supply or if not please tell me that what can I use for 440 volts ac motor start with push button please help me

Submitted by Aadesh saini on Sat, 10/01/2016 - 13:47


I need full circuit diagram, what are component is used full details .plz replay soon as possible. I want urgent

Submitted by Aadesh saini on Thu, 10/06/2016 - 22:53


what are the function of pin number 5&6 of IC MT8870?

Submitted by Sravan on Thu, 10/13/2016 - 22:48


Can we use TRIAC instead of 5v relay in this circuit?

Submitted by M Prashanth on Wed, 10/26/2016 - 19:00


I know its a lot to ask but Can you send me the final project Report of this it'll be really helpful and Thank you very much the project is really Great and its working Perfectly.

Submitted by trinity on Sat, 10/29/2016 - 23:58


I want to control the appliances wirelessly (using another phone to control the whole circuit). can any one help me out with the necessary things to add?

Submitted by Rahul on Fri, 11/11/2016 - 11:55


I made this circuit on pcb as per diagram but it's not working.
led 1,2,3 is continuously on and IC MT8870 is heating more.
please let me know what should I do?
I am waiting your response.

Submitted by shubham on Tue, 11/15/2016 - 21:22


why another 9v battery is used at relay? is it must to connect ?

Submitted by shubham deore on Wed, 11/16/2016 - 17:38


circuit is working but when I press 2 or 3 it will turn on one relay ,then if I press 4 or 5 button it will on 2nd relay, at a time all 3 relay r not conducting plz help me fast

plz reply......

Submitted by MOHIT on Fri, 03/03/2017 - 13:39


How to prevent calls from other mobile and mall functioning of DTMF decoder as any one can dial mobile connected to circuit. I want exclusive control with only specific mobile.

Submitted by harshal ghatole on Mon, 03/20/2017 - 01:43


Sir,it says,that whenever we forget to switch off the appliances,that time this circuit is used.But sir,in video,we have to keep on our appliances and off,when phone call is dialled.but when switch is already on,and if we want to switch off the appliance,then how we do that?.because,if we off the switch during phone call,after phone call ends,the appliances will remain on.so,the purpose is not achieved.please please tell me.

Submitted by Harsh Patel on Thu, 04/06/2017 - 22:53


I made this circuit on PCB it can not working. At the time of starting when i connect the supply directly 12 and 13 pin LED is start to glow without any given input. please help sir.

Submitted by kajiru on Thu, 06/01/2017 - 04:02


sir is it a must to have relays between the leds and the ic mt8870?

Submitted by Indraj kumar on Tue, 06/27/2017 - 07:07


Hello guys
I complete made this circuit but auxaux wir how to connect??????

Submitted by kiran chavan on Tue, 08/01/2017 - 00:14


Sir,i want to control the tubelight & fan which is operates on 230v-50hz power supply.can i use this ckt fr this .if yes ,what modefication is needed to do in ckt .plz reply

Submitted by Asha on Sun, 09/10/2017 - 10:20


Is we need to store program in mt8870 or it is already pre program ....how we can store .....plz explain every step

Submitted by Jmass King on Sun, 10/29/2017 - 04:58


Hello Sir.
I want to implement this project by using At328 microcontroller, can you help me how the circuit diagram will look like?,
Please,help me.

Submitted by saqib zaman on Sun, 12/10/2017 - 14:18


1. Is this all the circuit you got ??
2. Does it has any coding or not?
3. Did anyone has tried that?

Submitted by anna twinkle on Fri, 01/12/2018 - 14:51


plz help mee
i cannot get the output when we dial the number on the phone
its not working

Submitted by Silver Jack on Mon, 05/07/2018 - 19:19


Please how do I make the phone answer when called if I'm not around to pick it?