Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!cbatt!ucbvax!marcus@EDDIE.MIT.EDU@ihlpl.UUCP 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 Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 12 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