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[SOLVED] dtmf controlled robot

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kunal123

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hello,

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i connect led between tip & ring 2 led's cathode at ring & led's anode at tip, when i pressed any key of cell phone keypad led glows, i think i successfully pass DTMF tone to MT8870, but not getting output, please suggest me some solution to solve these problem.
my cell phone is HTC desire c, NOKIA 2700, NOKIA C5-03.
 

I do not see any supply filter caps. Perhaps wires are too noisy, so twist the wires or use telephone cord. Stray hum can interference with signals on a breadboard.

Show schematic
 

The circuit does not show an earth return to the mobile's connector, no Vcc voltages are shown, the circuit relies on the crystal being the right frequency - is it?. Have you checked all the IC pins with a DVM against its data sheet?
Frank
 

Try connecting a 100 Ohm resistor across the jack connections. The jack on many moble phones is multi-functional and to be sensed as having a headphone attached (which is what you want) they need a small current to flow through them.

Brian.
 

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