[comp.dcom.telecom] Light Showing Phone is Off Hook?

jessea@uunet.uu.net> (01/31/90)

I don't know much about phones, so I thought I post a message to see
what I could find out.  Here's the scenerio: I've got an internal
modem without a speaker.  I'd like to know when the modem is using the
line without picking up the receiver to check (wouldn't want to do
that, would we?).  So, can anyone tell me how I can set it up so that
I have a light or LED on when the modem has the line (of course it
will be on when anyone's on line - I think)?  This way I can tell
exactly what is going on.  

I'd also like to know if there is anyway you could rig a setup so that
lights can be displayed for an internal modem in the same manner as an
external modem.  I like to be able to see whats going on.  Thanx in
advance.


Jesse W. Asher - Dynasys - (901)382-1705       Internet: jessea@dynasys.UUCP 
6196-1 Macon Rd., Suite 200, Memphis, TN 38134     UUCP: uunet!dynasys!jessea 

tad@ssc.UUCP (Tad Cook) (02/03/90)

Jesse Asher asked how to rig up a light that would illuminate when his
modem was on-line.

Many modems have an A and A1 lead, which are on the outside pair (the
black and yellow leads on a modular connector) on the RJ11 telephone
line jack.  The A and A1 leads short together when the modem is on
line.  You may have to check your modem manual and option switches to
turn this feature on.

Just wire up a light and a battery in series with these leads, and you
will have your "modem busy" lamp.

Tad Cook
tad@ssc.UUCP

PEMURRAY@miavx1.bitnet (PETER MURRAY) (02/05/90)

>I don't know much about phones, so I thought I post a message to see
>what I could find out.  Here's the scenerio: I've got an internal
>modem without a speaker.  I'd like to know when the modem is using the
>line without picking up the receiver to check (wouldn't want to do
>that, would we?).  So, can anyone tell me how I can set it up so that
>I have a light or LED on when the modem has the line (of course it
>will be on when anyone's on line - I think)?  This way I can tell
>exactly what is going on.
 
I would also be interested in this info.  I live in an apartment with
3 other compu-nerds with modems, and someone is always picking up the
phone on someone else.  Any technical advice or schematics or ideas
are welcome.  Thanks.
 
 
Peter Murray                                    pm8moper@miamiu.acs.muohio.edu
205 Hepburn Hall                                        pm8moper@miamiu.bitnet
Miami University                                        pemurray@miavx1.bitnet
513/529-4944                                     murrayp@apsvax.aps.muohio.edu
 

kthompso@entec.wichita.ncr.com (Ken Thompson) (02/08/90)

Here is a circuit that works to indicate a phone line is on hook.
Mount the led that lights in a conveniently visible location.

                          |\ |
        <---------+-------| >|-----+-----'\/\/\/\/`-----+
                  |       |/ |     |        22k         |
                  |        led     |                    |
to phone          |                |                    |
line              |       | /|     |                    |
(green/red)       +-------|< |-----+                    |
(L1/L2)                   | \|                          |
                           led                          |
                                                        |
                                                        |
        <-----------------------------------------------+
                                                         
This is for information only.  No one is encouraged to actually use 
the circuit.   

No warranty expressed or implied.  Not liable for any direct,
consequential, or incidental loss or damage.  This circuit has
not been certified as complying with Part 68 of FCC regs.               

WARNING: Telephone circuitry contains potentially lethal voltages.  No
user serviceable parts inside.  Refer all repairs, adjustments and
modifications of any equipment to qualified service personnel.


Ken Thompson     N0ITL  
NCR Corp.  3718 N. Rock Road            
Wichita,Ks. 67226  (316)636-8783       
Ken.Thompson@wichita.ncr.com                                                 

Leonard Erickson <leonard@bucket.uucp> (02/08/90)

>Many modems have an A and A1 lead, which are on the outside pair (the
>black and yellow leads on a modular connector) on the RJ11 telephone
>line jack.  The A and A1 leads short together when the modem is on
>line.  You may have to check your modem manual and option switches to
>turn this feature on.

This "feature" is a royal pain if you have RJ-14 jacks. It clobbers
the second line every time you use the modem....

Many modems do not allow you to disable this. And *none* of the
manuals mention the possible problems of not disabling it on a
residence line!

Grrrrr...


Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short