The Decoded Output for Row and Column Frequencies Key The microphone wire signals can be processed with the decoder IC to generate a binary series as a parallel o/p such as Q1, Q2, Q3, & Q4. Here the red wire is an input of the DTMF circuit. The microphone consists of two wires namely red wire and green wire. The signals from the DTMF can be tapped straight using microphone pin in the cell phone. The above circuit can be built with a DTMF decoder IC namely M8870 to decode the keypad tone of a cell phone. The DTMF decoder differentiates the tones of DTMF & generates the binary series equal to a key pushed in a keypad of DTMF. Therefore this keypad is used for recognizing the dialed number by the caller in the telephone exchange rooms. The applications of DTMF keypads almost include in mobile phones and landlines. Finally, it will be examined and progressed with a computer which changes caller to the subscriber at the end. The digital codes are the address of the subscriber at the destination. The telephone exchange switch room uses a DTMF decoder to decode the frequencies of the caller into digital code. It is conveyed through the communication media or telephone line. The operation of Dual Tone Multi-Frequency is when a caller produces a call tone that includes two frequencies.

Dual Tone Multi-Frequency Decoder Circuit Working The required components of this circuit mainly include M8870 decoder IC, Resistors- 70kΩ, 100kΩ, and 390kΩ, two capacitors- 0.1♟, and crystal oscillator– 3.579545MHz. The bits which are decoded can be associated with a microprocessor or a computer for future application. The entire communication includes the touch tone inventor as well as a tone decoder. The tone of the DTMF is a type of one way communication among the user and the telephone exchange switch room. This IC uses a technique of digital counting for deciding the tones frequencies, as well as to confirm that they communicate to normal frequencies of DTMF.

The decoder IC decodes the DTMF input to five digital outputs. This circuit can be built with a decoder IC MT8870DE for the recognition of DTMF indications. This DTMF decoder circuit recognizes the phone tone from the phone line and then decodes the pressed key on the keypad of the telephone.

Dtmf sound