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PICList Thread
'help re a telephone circuit'
1999\08\17@073748 by Duilio Foschi

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I want to build a test circuit that will enable me to detect when a phone
goes off-hook and detect the DTMF tones thru a modem.

I was told to use the following circuit:

(please enlarge your screen to display it)

phone

|      |
|      |
|
+--------------o-----------o--------------------------------------------o---
----------------o
|                     |           |
|                   |
|                     |           |
|                   |
|                    +-+          |
+-+                  |
|                    | | R=100K   |
| |                  |
|                    | |          |
| |R=1K              |
|                    +-+          |
+-+                  |
|                     |           |
|                   |
|   R=1K              |           |
|                   |
|   +-----+           |       +|\ | 741       1N4148   1N4148
/                   |
o---|     |----o---------------| \|+          |\|       |\|      +-----+
|/                  ----- 12V
|   +-----+    |      |        |  \-----------| |-------| |------|
|-----|  2N2222A           ---
|              |      |        |  /           |/|       |/|      +-----+
|                     |
|              |      O--------| /|-                             R=10K
>                    |
|              |      |       -|/ |
\                   |
|             + +     |           |
o---o hook          |
|        R=560| |     |           |
|     detect        |
|        ohm  | |    +-+          |
+-+                  |
|             | |    | | R=10K    |
| |R=560ohm          |
|             +-+    | |          |
| |                  |
|              |     +-+          |
+-+                  |
|              |      |           |
|                   |
|
+-------o------o-----------o--------------------------------------------o---
----------------o
|      |
|      |

modem


I know very little about telephone circuits:

1. will it work ?
2. can I lower the voltage, say to 9V ?
3. is there a better circuit ?


Thank you

Duilio Foschi

1999\08\17@204422 by Steve Ridley

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Hi Duilio

I can't read your schematic. I have never had any luck reading ascii
schematics I receive as email. However I have an off hook detect circuit
that I think is simpler then what you have suggested here just going by the
number of components. Mine uses an opto coupler and does ring detect among
other things so you would have to sort out the bits you need from the other
stuff. If you are interested I can send you a schematic privately as an
Orcad file or I could paste it into a Word document or something.

Steve

{Original Message removed}

1999\08\17@222122 by Dennis Plunkett

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At 10:37 18/08/99 +1000, you wrote:
>Hi Duilio
>
>I can't read your schematic. I have never had any luck reading ascii
>schematics I receive as email. However I have an off hook detect circuit
>that I think is simpler then what you have suggested here just going by the
>number of components. Mine uses an opto coupler and does ring detect among
>other things so you would have to sort out the bits you need from the other
>stuff. If you are interested I can send you a schematic privately as an
>Orcad file or I could paste it into a Word document or something.
>
>Steve
>

Judging from his other comments this will be too complex, or he has seen
that, or will not be a single chip soultion
<Go on flame me>
But it would be nice if people would place all thier requirements in one go
rather than letting out little pieces of it here and there. Like the
inevitable carrot for the horse, removed before he gets to it, yet another
hurdle is placed in the way of those whom whish to help.

I am not having a good day, sigh, I think I need another job, anyone need
me in Victoria? Currently studding my Masters. (No doubt that my thesus
will be flamed too!)


Dennis


>{Original Message removed}

1999\08\17@225317 by Gordon Varney

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>
> Judging from his other comments this will be too complex, or he has seen
> that, or will not be a single chip soultion
> <Go on flame me>
> But it would be nice if people would place all thier requirements in one
go
{Quote hidden}

Check out CP Clair Data Book. Optoelectronics
Every thing you need is there.
connect/disconnect
ring detect
off hook detect

Dennis,
Please give us a head start, what is your thesus about, it may be a good one
to flame ;-))))
My thesus was about lasers (I havent touched on since) Good luck

Gordon

1999\08\17@233711 by Javier

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Hi
I4m interested in the circuit !!
look in the Tomi Engdahl archive you can find lots of telephone circuits
Bye
Javier

-----Mensaje original-----
De: Steve Ridley <spam_OUTsteverTakeThisOuTspamINSNET.COM.AU>
Para: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU <PICLISTspamKILLspamMITVMA.MIT.EDU>
Fecha: Martes 17 de Agosto de 1999 21:44 p.m.
Asunto: Re: help re a telephone circuit


{Quote hidden}

>{Original Message removed}

1999\08\18@013624 by Dennis Plunkett

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At 21:55 17/08/99 -0500, you wrote:
{Quote hidden}

It will be about design and test in manufacture.

Dennis

1999\08\18@013636 by Duilio Foschi

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Dennis,

>Judging from his other comments this will be too complex, or he has seen
>that, or will not be a single chip soultion

I am sorry if I seemed rough in my previuos comments.

I hope that you will find the job you want and that you can have better days.

Ciao

Duilio

1999\08\18@013658 by Russell McMahon

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>I can't read your schematic. I have never had any luck reading ascii
>schematics I receive as email.

If you use WIN95 then -

- Open notepad (NOT wordpad)
- Go to email.
   Ctrl-A (highlight all)
   Copt (Ctrl-Ins or whatever)
- Got to Notepad
- Paste (shift-ins or whatever)

Voila.

Failing this, pasting to your favourite word processor and using a constant
width font MAY work.
This doesn't work with eg WORD 7 but obviously does width Notepad.


regards


               Russell McMahon

1999\08\18@015044 by Duilio Foschi

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Dennis,

>Check out CP Clair Data Book. Optoelectronics
>Every thing you need is there.
>connect/disconnect
>ring detect
>off hook detect

where do I find the book ?

Thank you

Duilio

1999\08\18@092543 by Gordon Varney

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----- Original Message -----
From: Duilio Foschi <.....foschidKILLspamspam.....SUMMER.ETRURIA.NET>
To: <EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU>
Sent: Wednesday, August 18, 1999 12:02 AM
Subject: Re: help re a telephone circuit


{Quote hidden}

Try (http://www.cpclare.com).

Gordon Varney

1999\08\18@094032 by Gordon Varney

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> >
> > where do I find the book ?
> >
> > Thank you
> >
> > Duilio
>
>
> Try (http://www.cpclare.com).
>

Specifically the multifunction datacom IC's

TS117

is a wonderful part.

Gordon Varney

1999\08\18@105036 by Matt Bonner

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Russell McMahon wrote:
>
> Failing this, pasting to your favourite word processor and using a constant
> width font MAY work.

This is probably the main reason some ASCII art is unreadable.  Also,
don't use TABS (use spaces instead) since not all tab stops are set
identically.

--Matt

1999\08\19@042922 by Duilio Foschi

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I'd like to thank all who answered my help cries.

Thank you

Duilio

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