Want a Schematic or how to.

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fredje1
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Want a Schematic or how to.

Post by fredje1 » Wed Dec 21, 2005 6:39 am

Hello all you good people:
I am looking for a schematic that will recognize when a computer connects to a phone line Weather I am on the Phone or when the line is open or not in use. I was wondering if there is a simple solution like detecting a fax ring or modem. When you have a fax machine it can distinguish between a voice and a fax. How do they do this? Maybe this is the approach that I must use. Any way any suggestions will be of great help. I already have an off hook led that lights every time a call is being received or the line is in use. And what I want to do is to have a blue led to light when a fax or a computer comes on line on the same phone line. I wonder if I could use a Dtmf detector to do this. If so where can I get a schematic for this detector? Thank You for any information. Have a Merry Christmas and a Happy New Year.
Fje

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Externet
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Re: Want a Schematic or how to.

Post by Externet » Wed Dec 21, 2005 9:07 am

Hi.
What you are asking may not be precisely put.

..."a schematic that will recognize when a computer connects to a phone line Weather I am on the Phone or when the line is open or not in use."...

--->I don't think a computer will seize an already in-use line; and if the line is not in use, you already have...

..."I already have an off hook led that lights every time a call is being received or the line is in use."...

About ..."I was wondering if there is a simple solution like detecting a fax ring or modem. "...

--->Maybe you mean the handshaking tones instead of the word 'ring'? There is some initial tones heard when a fax machine answers; they are meant to signal a human that a non-voice device is answering. Later in the communication, the modem puts out handshaking protocols that would need a microcontroller to interpret and to act as you wish.

..."When you have a fax machine it can distinguish between a voice and a fax. How do they do this? "...

--->Because there is a computer chip inside the machine, programmed to read and detect and act upon different 'noises' accordingly.
It will take an elaborate design to come up with what you MAY want; with a dosage of programming too.

About ..."what I want to do is to have a blue led to light when a fax or a computer comes on line on the same phone line."...

---> If your computer or fax 'comes on line' while the line is in use, there is something wrong with your systems.

About ..."I wonder if I could use a Dtmf detector to do this. If so where can I get a schematic for this detector?"

---> The DTMF detector schematics are abundant on the net and data books; but you are wondering wrong, as DTMF has nothing to do with telephone line seizing.

Sorry to dissapoint you. :(

Miguel
- Abolish the deciBel ! -

zotdoc
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Re: Want a Schematic or how to.

Post by zotdoc » Wed Dec 21, 2005 9:28 am

I don't have a schematic but there is a DTMF chip. Also, Ramsey electronics has several kits that deal with DTMF and they are on the web. Sorry I can't be more help but I'm a newbie at this.

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