Interfacing Telephone with PIC

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Weis Guy

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any ideas on how to interface Telephone with PIC? I've been thinking of using DTMF decoder like MC145436 (DTMF Decoder)..and I will be using also coin slot for this.Anyone?!
 

If for receiving DTMF tones or caller ID, then use capacitive coupling. This will do the job as well as providing galvanic isolation.

Cheers

Ravi
 



this would be my concept..i want to determine that my input on the coin slot would be accepted if the party that i would be calling picked up the call and the display will be counting on a certain time for example "0:05.00"..that concept be the same as a prepaid phonebooth..
 

For this you need to monitor the telephone line and check for line reversal. Line reversal occurs when the called party picks up the phone. One more method is to monitor the line for the ring tone. If the ring tone stops, then the called party has picked up the phone.

Use capacitive coupling to a differential amplifier and monitor the tones.

Cheers

Ravi
 

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