sekoppenhoef@rose.waterloo.edu (Shawn E. Koppenhoefer) (10/16/89)
We have a phone at home that is shared between a computer and a person's voice. Furthermore... we have several telephones on that particular phone line. Is there some way of attaching an led or something to indicate by being on that the phone is IN-USE ? Something to prevent family members from interrupting the connection at the tail end of a 250K file transfer for example? I would ***REALLY*** appreciate any help in this regard! :-) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| _ _ KLEIN BOTTLE for sale... Shawn E. Koppenhoefer | | enquire within. ...watmath!rose!sekoppenhoef | - ~~~~~~~~~~~~~~~~~sekoppenhoef@rose.uwaterloo.ca sekoppenhoef@rose.uwaterloo.edu
irwin@m.cs.uiuc.edu (10/19/89)
/* Written 9:22 am Oct 16, 1989 by sekoppenhoef@rose.waterloo.edu in m.cs.uiuc.edu:sci.electronics */ /* ---------- "telephone light indicating use" ---------- */ >We have a phone at home that is shared between a computer and a person's >voice. Furthermore... we have several telephones on that particular phone >line. Is there some way of attaching an led or something to indicate >by being on that the phone is IN-USE ? Something to prevent family members >from interrupting the connection at the tail end of a 250K file transfer >for example? >I would ***REALLY*** appreciate any help in this regard! :-) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| _ _ KLEIN BOTTLE for sale... Shawn E. Koppenhoefer | | enquire within. ...watmath!rose!sekoppenhoef | - ~~~~~~~~~~~~~~~~~sekoppenhoef@rose.uwaterloo.ca sekoppenhoef@rose.uwaterloo.edu /* End of text from m.cs.uiuc.edu:sci.electronics */ As I recall, this was discussed in this forum a while back, maybe a year ago. On multiline push button phones, a light activates in the buttons when one of the lines is off hook. This is not a low cost system. For your purpose, at the least cost, the means to take care of the problem is to go to Radio Shack or other parts supply, get enough 4 conductor wire to go from the entrance block to the room where the modem is located. Also get a 2 pole single throw relay. Put the relay in the line so that it will cut off all extensions and put your 4 conductor ahead of the relay. Use two of the wires to activate the relay, the other two to carry the phone signal. Use a DC type relay, so no hum cross talks to the other two wires in your cable. When you are ready to activate the modem, pick the relay, which kills all of the other phones down stream from the phone block. You could even get fancy and pick the relay via a pin from a parallel port on the computer, such that you write to the port to set the bit, picking the relay, and again writing to the port to drop the relay, after you are through, so you do not forget. Put it in your communications software to handle it. Al Irwin Univ of Ill Comp Sci irwin@m.cs.uiuc.edu
adam@cbmcats.UUCP (Adam Keith Levin) (10/19/89)
From page 88 of the 1990 Radio Shack catalog:
Voice and Data Guard
$7.95 (New for `90)
Great for Modems and Fax Machines
Teleprotector. Stops interruptions of
phone calls or fax or modem transmissions.
Also stops answerers when picking up phone.
43-107 Avail. Oct. 15, 1989 ... 7.95
--
Adam Keith Levin -- CATS Commodore Applications and Technical Support
1200 Wilson Drive / West Chester, PA 19380 (215) 431-9180
BIX: aklevin UUCP: ...{amiga|rutgers|uunet}!cbmvax!cbmcats!adampeg@psuecl.bitnet (10/22/89)
In article <17263@watdragon.waterloo.edu>, sekoppenhoef@rose.waterloo.edu (Shawn E. Koppenhoefer) writes: > We have a phone at home that is shared between a computer and a person's > voice. Furthermore... we have several telephones on that particular phone > line. Is there some way of attaching an led or something to indicate > by being on that the phone is IN-USE ? Something to prevent family members Hello! A few years back, my roomates and I had something like this on our extension phones in a dorm suite. We built the circuit based on what someone else in the dorm was using--I can't say I knew how it worked (I know very little about phones!). As I recall, the circuit was simply-- |------->|-----| red lead ------resistor-------| |------ green lead |-------|<-----| where the -->|-- are LED's. Note that they are connected in opposite directions. If I remember right, the LED's flashed alternately when the phone rang (nifty with two different color LED's! :) and one would stay on when the extension was off-hook. It seems rather obvious how this would work--if phones work in an obvious manner! Anyway, this is certainly a cheap approach. The resistor value you will have to find experimentally--start large! I think the phone ringing voltage is ~100 volts, so maybe 5k ? And finally, it may be illegal to connect this circuit. It never caused any trouble with our phone system, but I can't guarantee it won't affect yours. Maybe you could try it for a while and see what happens. Best of luck! Paul