hi how is it possibile to wait for some rings and then activate the line to capture DTMF signals ? thank you
- posted
17 years ago
hi how is it possibile to wait for some rings and then activate the line to capture DTMF signals ? thank you
Yes.
well, i see... but i asked "how" ?
OBones ha scritto:
I know, hence why I canceled the message, I missed the "how" part.
Detecting rings is done with a RC network across the line, like on this schematic with R7/C3 (bottom right)
On this one, you get an optocoupler in the path to interface with low level voltage (12V) logic.
To activate the line, I think it's enough to put a resistor across it but can't remember the exact value. And detecting DTMF tones can be done with an MT8870 like on this schematic:
Hope this helps.
thanks, the problem i have is how to pick up the line... maybe a 600 ohm resistor ?
OB> > well, i see...
-- Yes, that will work. The second problem is that you\'re top posting. Please bottom post.
You need several circuits.
a. Ring detect circuit
b. Something to count the rings before answer
c. something to loop line and draw loop current from line/telephone exchange
d. something to couple the audio after looping
e. something to decode the dtmf
f. something to hangup.
JG
By using a ring detector, a DTMF receiver and a microcontroller.
-- Reply to nico@nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl
You mean an "infinity bug"?
Michael
Hack an ordinary answering machine?
Good Luck! Rich
a ring detector, monostable, counter, relay, line transfromer, DTMF decoder...
or use a modem. many V90 modems will decode DTMF if you ask them nicely.
Bye. Jasen
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