Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!tut.cis.ohio-state.edu!rutgers!sunybcs!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: power from phone line
Summary: ON-hook power versus OFF-hook power
Keywords: phone, power, remote
Message-ID: <3550@kitty.UUCP>
Date: 10 Dec 89 16:25:38 GMT
References: <3542@kitty.UUCP> <548@scorn.sco.COM> <3547@kitty.UUCP> <1989Dec9.220311.15928@phri.nyu.edu>
Organization: Recognition Research Corp., Clarence, NY
Lines: 21

In article <1989Dec9.220311.15928@phri.nyu.edu>, roy@phri.nyu.edu (Roy Smith) writes:
>> If you are going to design a commercial product, then you are in trouble
>> because Part 68 will not allow ANY usable amount of leakage from tip to ring
> 
> 	Is this a new rule?  Universal Data Systems (now part of Motorola,
> I think) used to make a nice little 1200 bps modem called the 212LP, where

	Perhaps I did not make myself clear.  I was referring to "leakage",
which means the amount of current flow in an ON-hook (i.e., telephone line
idle) state.  In an OFF-hook state, one can draw as much current as the
subscriber loop will allow, typically between 20 and 100 mA.

	It appears that the orignal poster was referring to designing a
telemetering device for data acquisition which would require power on a
*continuous* basis, and therefore would draw power from the telephone line
while it was ON-hook.

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