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From: BRUCE@ccavax.camb.com (Barton F. Bruce)
Newsgroups: comp.dcom.telecom
Subject: Re: For Telecom-ers Who Live up North
Message-ID: <15228@accuvax.nwu.edu>
Date: 4 Dec 90 08:00:31 GMT
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X-Telecom-Digest: Volume 10, Issue 866, Message 4 of 9


In article <15113@accuvax.nwu.edu>,  CAPEK@YKTVMT.BITNET (Peter G. 
Capek) writes:

> interesting device called a Telefreeze.  It connects to a phone line
> and makes the line go "off hook" when the ambient temperature goes
> below a preset limit.  The idea is that you would periodically call

That is an OLD trick, but a slight modification may make sense.

You may prefer to NOT have your summer home line be busied out, but
instead let it answer the phone and hang up very fast, probably faster
than answer supervision can propagate back. Even if it does cost you
for the call, when it happens, you will be glad to know there is a
problem.

Instead of having the low temp thermostat simply short the line, have
it connect a pair of back to back zeners across the line. 68 volt ones
normally work well when the CO battery is 48v. If you are on a DLL ckt
with 72 or 96 volts, pick diodes a bit higher.

Ringing superimposed on battery will trip when a zener fires, but the
line will then go on hook instantly.