larryl@EDDIE.MIT.EDU (l.j.lang) (10/16/88)
In article <telecom-v08i0150m11@vector.UUCP>, jetzer@studsys.mu.edu (jetzer) writes: > In article <telecom-v08i0148m08@vector.UUCP>, mgrant@cos.com (Michael Grant) writes: > > A long while ago someone posted a question about how to build a simple > > circuit which would light a LED (or a simple lamp) when an extension > > was lifted elsewhere in the house. The requirements are: > > > - The LED lights when another extension is lifted, showing that it > > is in use. > > - The LED must be powered off the phone line. > > - No extra wires must be run to the telephone. > > - The circuit should be reasonable small so that it can fit inside a > > desktop style phone. > > > No one was able to come up with a simple schematic to do this that > > worked. The upshot was that one could buy such a device for about $30 > > I would also be interested in such a device - my roommate has this > nasty habit of picking up the phone while I'm using my modem. > Actually, I'd be happy even if it required some extra wires or external > power - just as long as it would detect any phone on the line being in use. > I might even be willing to let $30 for such a device (maybe). Where is > one available? > > Mike Jetzer I built something like this once. It consisted of an outboard box, essentially a continuity tester, with a power supply and LED. The LED would light up whenever an extension (besides my own) was lifted. The way it worked is simple: Phone cable has four wires, two active (red and green) and two inactive (yellow and black). When you lift a phone off-hook, several switches change position, some open, some close. I took apart every phone in the house, found terminals connected to a switch that closed when the switch hook was lifted, and connected the black and yellow wires to those terminals. Then I hooked my detector box to the yellow and the black wires near my phone. When any rewired switch hook was lifted, the LED lit up. [I didn't rewire the switch hook of the phone in my room, since I only wanted to know when remote phones were lifted. I was a lot more secretive in those days. :-)] Thus, the circuit looked like this: Off-hook On-hook Extension Extension (Switch (Switch closes) still open) __>| __> | | | | | | | | | Black --------|---------------|--)------------|----)----- | | | | | | Yellow --------)---------|--------|-----------------|----- | | | | |-9V--LED-| (Lights up) Detector Box Some comments: 1. You must rewire every phone where you want to detect off-hook. This shouldn't be too difficult, especially if you have phones with spade lug internal connections, rather than screw terminal or (worse) soldered connections. Also, most phones come with pretty good schematics, which is convenient, though you can just use a continuity tester (such as the detector box) to find a close-when-off-hook switch by trial and error. 2. The black and yellow wires must run to every phone. You'll want to check for their continuity before you begin this project. (Yellow can be especially dubious-it didn't run every where in my house.) 3. It requires external power. I just didn't want to mess with the 48 VDC power from the phone line. Too many problems with incoming and outgoing signals (e.g. ~90 VAC ring). 4. I doubt the phone company would approve. I make no claims about this, except that I used it without incident for several years. I never checked it with NJ Bell, the FCC, Underwriters' Lab, or even my parents. I can't see why it would cause any problems, but if it does, don't say I didn't warn you. 5. I only used one detector box. I don't know what the implications would be of using more than one. This is a pretty cheap solution. I spent less than $20, and I used a fancy project box for the detector. If you like the Larry Lang Extension Detector (LLED), I would gladly accept the $30 Mike and Mike said they'd each be willing to pay! Let me know if you use this, or if you have any questions. Cheers, Larry Lang =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= bellcore!nvuxr!larryl Room NVC 1G-410, 331 Newman Springs Road, Red Bank, NJ 07701 My employer (Bellcore) has nothing to do with this idea. I designed it before I came here, so they didn't buy it for their $1 patent fee.
chip@vector.UUCP (Chip Rosenthal) (10/27/88)
In article <telecom-v08i0150m11@vector.UUCP>, jetzer@studsys.mu.edu (jetzer) writes: > In article <telecom-v08i0148m08@vector.UUCP>, mgrant@cos.com (Michael Grant) writes: > > A long while ago someone posted a question about how to build a simple > > circuit which would light a LED (or a simple lamp) when an extension > > was lifted elsewhere in the house. The requirements are: > > > - The LED lights when another extension is lifted, showing that it > > is in use. > > - The LED must be powered off the phone line. > > - No extra wires must be run to the telephone. > > - The circuit should be reasonable small so that it can fit inside a > > desktop style phone. > > > No one was able to come up with a simple schematic to do this that > > worked. The upshot was that one could buy such a device for about $30 > > I would also be interested in such a device - my roommate has this > nasty habit of picking up the phone while I'm using my modem. > Actually, I'd be happy even if it required some extra wires or external > power - just as long as it would detect any phone on the line being in use. > I might even be willing to let $30 for such a device (maybe). Where is > one available? > > Mike Jetzer I built something like this once. It consisted of an outboard box, essentially a continuity tester, with a power supply and LED. The LED would light up whenever an extension (besides my own) was lifted. The way it worked is simple: Phone cable has four wires, two active (red and green) and two inactive (yellow and black). When you lift a phone off-hook, several switches change position, some open, some close. I took apart every phone in the house, found terminals connected to a switch that closed when the switch hook was lifted, and connected the black and yellow wires to those terminals. Then I hooked my detector box to the yellow and the black wires near my phone. When any rewired switch hook was lifted, the LED lit up. [I didn't rewire the switch hook of the phone in my room, since I only wanted to know when remote phones were lifted. I was a lot more secretive in those days. :-)] Thus, the circuit looked like this: Off-hook On-hook Extension Extension (Switch (Switch closes) still open) __>| __> | | | | | | | | | Black --------|---------------|--)------------|----)----- | | | | | | Yellow --------)---------|--------|-----------------|----- | | | | |-9V--LED-| (Lights up) Detector Box Some comments: 1. You must rewire every phone where you want to detect off-hook. This shouldn't be too difficult, especially if you have phones with spade lug internal connections, rather than screw terminal or (worse) soldered connections. Also, most phones come with pretty good schematics, which is convenient, though you can just use a continuity tester (such as the detector box) to find a close-when-off-hook switch by trial and error. 2. The black and yellow wires must run to every phone. You'll want to check for their continuity before you begin this project. (Yellow can be especially dubious-it didn't run every where in my house.) 3. It requires external power. I just didn't want to mess with the 48 VDC power from the phone line. Too many problems with incoming and outgoing signals (e.g. ~90 VAC ring). 4. I doubt the phone company would approve. I make no claims about this, except that I used it without incident for several years. I never checked it with NJ Bell, the FCC, Underwriters' Lab, or even my parents. I can't see why it would cause any problems, but if it does, don't say I didn't warn you. 5. I only used one detector box. I don't know what the implications would be of using more than one. This is a pretty cheap solution. I spent less than $20, and I used a fancy project box for the detector. If you like the Larry Lang Extension Detector (LLED), I would gladly accept the $30 Mike and Mike said they'd each be willing to pay! Let me know if you use this, or if you have any questions. Cheers, Larry Lang =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= bellcore!nvuxr!larryl Room NVC 1G-410, 331 Newman Springs Road, Red Bank, NJ 07701 My employer (Bellcore) has nothing to do with this idea. I designed it before I came here, so they didn't buy it for their $1 patent fee.
embick@tetra.nosc.mil (Edward M. Embick) (10/28/88)
{{{ Ooooops. Although credited to me, the message this is in response }}}
{{{ to was written by Larry Lang <larryl@nvuxr>. This message appeared }}}
{{{ during the mailing list outage, and at that stage my software was }}}
{{{ munging "From" lines. Appologies to Larry and all. -chip }}}
In article <614@vector.UUCP> chip@vector.UUCP (Chip Rosenthal) writes:
>I built something like this once. It consisted of an outboard box,
>essentially a continuity tester, with a power supply and LED.
>The LED would light up whenever an extension
>(besides my own) was lifted. The way it worked is simple:
>Phone cable has four wires, two active (red and green)
>and two inactive (yellow and black).
^^^^^^^^^^^^^^^^^^^^^^^^^^^
The second pair of wires are normally used for a second phone line,
such as sysops have installed for their BBS's. This solution is NOT
one that would maintain the integrety of you phone system!
------------------------------------------------------------------------------
Ed Embick (If God wanted me to write legibly, He wouldn't have invented email)
Computer Sciences Corporation ____ ____ ____
4045 Hancock St. MILNET: embick@tetra.nosc.mil // // //
San Diego, CA 92110 \\___ ___// \\___
(619) 225-8401 x287dtynan@ames.arc.nasa.gov (Der Tynan) (10/29/88)
{{{ Again...the quoted text is from the message Larry Lang wrote. }}}
{{{ However, the quoted text wasn't written by Larry, but rather }}}
{{{ quoted by him from a message he was responding to. -chip }}}
In article <610@vector.UUCP>, chip@vector.UUCP (Chip Rosenthal) writes:
-
- The LED would light up whenever an extension
- (besides my own) was lifted. The way it worked is simple:
- Phone cable has four wires, two active (red and green)
- and two inactive (yellow and black).
- When you lift a phone off-hook, several switches change position,
- some open, some close. I took apart every phone in the house,
- found terminals connected to a switch that closed
- when the switch hook was lifted, and connected the black and yellow wires
- to those terminals. Then I hooked my detector box
- to the yellow and the black wires near my phone.
- When any rewired switch hook was lifted, the LED lit up.
-
- Larry Lang
-
- My employer (Bellcore) has nothing to do with this idea.
Aeeesh!!! This is *deadly*. Beware this fix. The phone company often, if
not always, uses the black and yellow wires for a second phone line.
Connecting them together in a telephone is BAD NEWS. One day you install a
second line, lift up the receiver and bang! There goes one exchange interface.
- Der
--
Reply: dtynan@sultra.UUCP (Der Tynan @ Tynan Computers)
{mips,pyramid}!sultra!dtynan
Cast a cold eye on life, on death. Horseman, pass by... [WBY]pbowden@EDDIE.MIT.EDU (Pete Bowden) (11/01/88)
I have wired an "in-use" light into a 9-line key telephone so that I
can tell if any telephone units (or mostly modems in my case) were in use
(I have 9-lines in my residence -- 7 of which going into a BBS). Anyway,
I didn't design the circuit and I don't have it right here -- but if you
wish to experiment here's what it included...
1) 10 micro ferad capacitor
2) a zener diode (around 10 volts if I am remembering)
3) a light (whatever the light is in the standard key telephone is what
I am using)
On the positive wire (if it doesn't work on the first wire, try the second)
before the telephone units which you wish to have light up the light install
the capacitor and diode in parallel with the line, along with the light.
We'll TRY a drawing...
----LIGHT----
| |
--Capacitor--
| |
----Zener----
| |
+------------------------------------X
(Telephone line...) > Telephone Unit(s)
------------------------------------X
-
This circuit does use a slight amount of power and you may have problems
if you try to run several lights -- but it doesn't seem to affect the quality
of my line in any noticable amount. A friend who IS more into the electronics
recommended the use of an optal isolator in place of the Capacitor and Zener
but didn't go into detail.
___
-'/ > / |"Pete" Bowden, P.O. Box 905, Santa Maria, CA 93456-0905
/___/___ --/--___ | Sysop--LOIS BBS 805-928-6969 (4 public dialups)
/ /___> / /___> |
/ _/\____/\_/\____/ | ...{csun,sdsu}!polyslo!pbowden
You have PLENTY of time to finish this assignment.
What do you mean you have other classes?berger@clio.las.uiuc.edu (11/02/88)
That's really pretty excessive. The polarity of the phone line changes
when any phone is off-hook. It's not too hard to build a circuit that
takes that into account. I've built them before - but they require
external power. I'll try to remember to bring in a schematic. It
should cost under $ 5 in parts.
Mike Berger
Science, Technology, and Society
University of Illinois
berger@clio.las.uiuc.edu
{convex | pur-ee}!uiucuxc!clio!bergerron@ron.rutgers.edu (Ron Natalie) (11/08/88)
By his own definition the second pair would not be hooked to the second line since he intercepts it for the signalling. Assuming anything is on the second pair is risky, since the phone company has used all number of things on the line from power to special local hacks. If the idea of accidentally shorting a second line bothers you, use a 100 ohm resistor in the loop. This should be innocous even if the modified phone was plugged into a two line jack. -Ron
dave@rutgers.edu (Dave Levenson) (11/12/88)
In article <telecom-v08i0171m02@vector.UUCP>, berger@clio.las.uiuc.edu writes: > That's really pretty excessive. The polarity of the phone line changes > when any phone is off-hook... No. This is only true in a very small number of elderly step-by-step central offices. In most of the public switched telephone network, Tip is positive w.r.t. Ring, all of the time. You can pay extra, in some areas, for services that reverse the polarity with the called party answers, or when the originating party dials a toll call, etc.. -- Dave Levenson Westmark, Inc. The Man in the Mooney Warren, NJ USA {rutgers | att}!westmark!dave