DTMF Decoder Circuit ON-OFF Switch

This project was created with the goal of controlling devices from a long distance by 2G network.

In the video demonstration, colored LEDs were used to simulate the devices; however, in normal conditions, the LEDs could be replaced with relays, and AC devices could be turned on/off.

The left board in the image below contains a connector that connects to the receiver phone via an improvised cable.The phone's output signal/tones pass through an amplier stage(vertical little board) before reaching the DTMF decoder IC, which takes the DTMF tone as an input and outputs four bits that correspond to the binary representation of the pressed number. The data is then passed to the board on the right via a connector, and the microprocessor recognizes which number the user pressed and acts in accordance with the program that has been implemented. The blue board at the top stores all of the sounds heard in the video, and the microprocessor determines when to play them.