The project aims at controlling various loads spread over a large area remotely by using DTMF concept. The DTMF command tone thus received from the phone causes electrical load switching. The project is useful for managing industrial, domestic or agricultural loads that extend over a large area.
The project requires a DTMF decoder interfaced to audio output socket of the cell phone. Whenever a button on the keypad is pressed the frequency thus generated from it is received by the decoder and it converts the frequency into its equivalent digital code. A microcontroller of 8051 family is used which is interfaced to relays through relay driver IC. The digital code is then provided to microcontroller that identifies the phone commands and initiates the relays to actuate the respective loads by turning them on and off.