"zazula@uazhe0.physics.arizona.edu"@arizona.edu (01/30/91)
..a phone in another part of the house has been picked up? I want to do this via the phone line in my room. I guess this is the same idea that is used on the phones with the little lights on the bottom that light up when someone else picks up a phone on the same line. Thanks alot! (in advance) Ralph Zazula University of Arizona Department of Physics UAZHEP::ZAZULA (DecNet/HEPNet) zazula@uazhe0.physics.arizona.edu (Internet) [Moderator's Note: We have this question from time to time, and always I recieve numerous schematics, etc. Perhaps some of you will answer direct to Mr. Zazula and assist him. PAT]
Dan_Jacobson@att.com (01/30/91)
On 30 Jan 91 06:25:10 GMT, zazula@uazhe0.physics.arizona.edu wrote: Z> ... a phone in another part of the house has been picked up? I Z> want to do this via the phone line in my room. Easy: get the cheapest $2 phone you can find, and turn its ringer switch "on". Voila, you can hear all kinds of activity, from just the other phone being picked up, to the whole conversation -- all without taking your phone "off hook". Just don't have your ear to the phone when it rings. [Disclaimer: not all cheap phones do all this]. Dan_Jacobson@ATT.COM Naperville IL USA +1 708 979 6364
gbaldwin%unix20@sunup.west.sun.com (Gordon Baldwin) (02/06/91)
>I'm trying to find a device that lights up when a phone extension is >picked up. That way I can know if a phone line with multiple >extensions is in use without picking up the phone itself ... >[Moderator's Note: We have discussed this many times in the Digest. >Would one of you readers with a schmatic send it along to Craig, with >a parts list, etc. Thanks. PAT] Could I also get the info/schema! I have a two year old that loves to play with the phone, and it would be nice to not have a light so that we know the phones are in "play mode." Gordon Baldwin ELDEC Corp sherpa2!gbaldwin@sunup.west.sun.com
jon_sree@world.std.com (Jon Sreekanth) (02/07/91)
In article <16525@accuvax.nwu.edu> zazula@uazhe0.uphysics.arizona.edu writes: .... [See previous message if you need to review the question. PAT] Regarding commercial units that do this (I've heard mention of a Radio Shack box) Does anyone know what their REN is ? Just yesterday, a consultant told me that the REN was calculated as a worst case of several measurements, one of which was DC on-hook resistance. A device of REN 1.0 has 25 Meg ohm of DC resistance. Since the customer of a 'privacy LED' box presumably has several other extension phones, such a box would need to have about 50Meg ohms of DC resistance in its DC comparator (which is how I assume they detect an off-hook extension), in order to have an REN of 0.5 (which seems to be a reasonable design goal.) Was this consultant right ? (Have the FCC 68 rules changed recently?) If so, does anyone know if commercial units have such high resistance? It's moderately challenging, I'd assume. Regards, Jon Sreekanth Assabet Valley Microsystems Fax and PC products 346 Lincoln St #722, Marlboro, MA 01752 508-562-0722 jon_sree@world.std.com
ole@csli.stanford.edu (Ole J. Jacobsen) (02/09/91)
My favorite device for showing a line in use can be purchased from your local AT&T phone store. These little white boxes (powered by a 9V battery) are hideously expensive, something close to $20, but they do the job very well. According to the box the REN is "0.0A" (I'm not kidding!) Ole J Jacobsen, Editor & Publisher ConneXions--The Interoperability Report Interop, Inc., 480 San Antonio Road, Suite 100, Mountain View, CA 94040, USA Phone: (415) 941-3399 FAX: (415) 949-1779 Email: ole@csli.stanford.edu
tds@honet9.att.com (Antonio Desimone) (02/09/91)
> I'm trying to find a device that lights up when a phone extension is > picked up. That way I can know if a phone line with multiple > extensions is in use without picking up the phone itself ... > [Moderator's Note: We have discussed this many times in the Digest. > Would one of you readers with a schmatic send it along to Craig, with > a parts list, etc. Thanks. PAT] Could I also get the info/schema! Resisting the urge to post a "me-to" note, I looked in the archives on lcs.mit.edu for something on this topic and didn't find anything. Maybe this would be a good candidate for the archive? Or did I just miss it? [Moderator's Note: If someone sends along a copy of the reply to this I will post it in the archives. PAT]