### Network

M

#### merco

Jan 1, 1970
0
hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

O

#### OBones

Jan 1, 1970
0
merco said:
hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

Yes.

M

#### merco

Jan 1, 1970
0
well, i see...

OBones ha scritto:

O

#### OBones

Jan 1, 1970
0
merco said:
well, i see...

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)

http://obones.com/2Lignes1Tel/Schema.png

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:

http://obones.com/2Lignes1Tel/ToneCommand2#/Schema.png

Hope this helps.

M

#### merco

Jan 1, 1970
0
thanks, the problem i have is how to pick up the line...
maybe a 600 ohm resistor ?

J

#### John Fields

Jan 1, 1970
0
thanks, the problem i have is how to pick up the line...
maybe a 600 ohm resistor ?

---
Yes, that will work.

The second problem is that you're top posting. Please bottom post.

Thanks,

J

#### Joe G $$Home$$

Jan 1, 1970
0
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

N

#### Nico Coesel

Jan 1, 1970
0
merco said:
hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

By using a ring detector, a DTMF receiver and a microcontroller.

M

#### Michael Black

Jan 1, 1970
0
merco" ([email protected]) said:
hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you
You mean an "infinity bug"?

Michael

R

#### Rich Grise

Jan 1, 1970
0
hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

Good Luck!
Rich

J

#### jasen

Jan 1, 1970
0
hi
how is it possibile to wait for some rings and then activate the line
to capture DTMF signals ?
thank you

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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