Home /office/industry electrical appliances controlling by phone call and confirmation through voice feedback-VOICE PLAYBACK

Home /office/industry electrical appliances controlling by phone call and confirmation through voice feedback


  Present world is being ruled by technologies and there are many advanced technologies especially in the field of electronic are coming out to make our lives more comfort, user friendly and luxurious with low cost. In this project we will control the electrical appliances from anywhere in the world by using our mobile and this system also gives voice feedback about status of appliances whether they are getting switched ON or OFF.

This project will be implemented on DTMF technology with ARM7 based advanced micro controller LPC2148.

Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines in the voice frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF used in push button telephones for tone dialing is known as Touch-Tone, which was first used by AT&T in commerce as a registered trademark.

The DTMF decoder will be interfaced to the microcontroller section. If the user wants to control any of the devices, he has to press predefined number from his mobile. All the devices, which are to be controlled, will be connected to the controlling section. Each device is assigned with a unique predefined number. The microcontroller, in return, plays a voice message about device status and this voice message will be listened through that mobile only so that user can get confirmation about device.

To play the voice messages we do not need any separate voice module because we can play that voice from ARM7 LPC2148 micro controller directly by saving pre recorded voice message in micro controller’s memory in the form of binary.

TRIACs are used to control the AC loads and MOC3021 ICs are used for driving TRIACs 


Software Tools:

  • KEIL IDE for developing micro controller code
  • ORCAD for designing schematics
  • FLASH MAGIC for dumping the hex file into controller

Hardware Tools:

  • ARM7 Micro controller.
  • Audio amplifier.
  • Speaker. 
  • DTMF decoder
  • BT136 TRIACs
  • MOC3021 TRIAC drivers
  • Regulated +3.3v and +5v Power supply.


  • Easy to use, children, old aged people, physically challenged people can also operate.
  • Safe and secured. 
  • Shock protection.
  • Low cost.


  • Home automation
  • Office automation
  • Industry machine controlling system
  • Access control systems