DTMF DECODER (IC 8870)
Decodes DTMF audio signal to 4 bit binary TTL level output with LED indication.
Suitable for use with microcontroller applications.
· Decodes DTMF as 4 bit binary
· TTL level output for direct connection to microcontrollers
· Low power 5V DC operation
· LED indication of outputs
· Based on MT8870 IC
· Remote Control systems
· Caller ID applications
· FM receiver based remote control
· Remote control using Mobile phone
Operating Voltage 5 V DC Regulated power supply input
Operating Current 100 mA
Connect regulated +5V DC supply for operation of board.
Outputs D1-4 and VT are active highoutput at 5V level.
If any LED is on means , that output is at high level.
VT LED blinks once a new DTMF tone is received.
The binary data appears at D1 to D4. Details of this output is given in table below .
Input signal can be from an audio source like microphone amplifier, FM radio receiver, wired phone line.
Please note when connecting land line phone signal, do not connect ground wire of board to phone line directly. Use a 100nF (0.1UF) capacitor in series to phone line wires at ground.