Ppt for dtmf decoder connected to mobile phone

This home appliances control or home automation project also uses the same DTMF decoder circuit section with little modifications to control home and office electrical appliances. Just connect your cell phone headset (headphone) jack to the mobile phone and then mobile will control electrical appliances and electrical equipment through the DTMF key pad of your cell phone. Here for demonstrating, we are controlling an electrical bulb using this circuit project but you can extend this circuit to control many electrical devices with some modifications using 4×16 decoder IC

Working of this home automation electronic project
Our project uses M-8870 DTMF decoder IC which decodes tone generated by the keypad of cell phone.
When you press any key on your mobile phone while call is in progress, the other person will hear some tones corresponding to the keys pressed. These tones are based on the DTMF (Dual Tone Multi Frequency) technology.
Data is transmitted as pairs of tones. The receiver detects the valid frequency pair and gives the appropriate BCD code as the output of the DTMF decoder IC.
DTMF signal can be tapped directly from the microphone pin of cell phone device.