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From: marcus@EDDIE.MIT.EDU@ihlpl.UUCP
Newsgroups: mod.telecom
Subject: Hands Free duplexing circuit.
Message-ID: <8612110700.AA22666@ucbvax.Berkeley.EDU>
Date: Fri, 5-Dec-86 00:13:26 EST
Article-I.D.: ucbvax.8612110700.AA22666
Posted: Fri Dec  5 00:13:26 1986
Date-Received: Sun, 14-Dec-86 10:48:00 EST
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Organization: The ARPA Internet
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Approved: telecom@xx.lcs.mit.edu

I am interested in building a better home intercom system, or at least
planning it.  With the fairly great number of phones out in the world
with "hands free" features, it seems that a similar circuit could be
made for intercom use.  Many of the phones use a VOX circuit to switch
between half-duplex modes of operation.  I really don't care for that if
it could possibly be avoided.  What possibility is there for subtracting
the speaker's output from the microphone's input or something similar to
operate in a FDX mode?  Are there any ICs made for phones that would be
of much use here?  Any suggested circuits or sources?

Marcus Hall
..!ihnp4!ihlpl!marcus