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From: gene@cooper.UUCP
Newsgroups: sci.electronics
Subject: Re: Full duplex intercoms?
Message-ID: <802@cooper.UUCP>
Date: Thu, 26-Mar-87 16:45:53 EST
Article-I.D.: cooper.802
Posted: Thu Mar 26 16:45:53 1987
Date-Received: Sat, 28-Mar-87 11:02:56 EST
References: <1922@ihlpl.ATT.COM> <562@puff.WISC.EDU> <3972@fritz.UUCP> <18003@ucbvax.BERKELEY.EDU>
Organization: The Cooper Union (NY, NY)
Lines: 21
Summary: ffull duplex intercoms

>                                 Does anyone know of any intercoms which are
> full duplex ... ?

Sure. Take two junk telephones (that still work, just maybe a dead bell or
something) connect them in series with a 9V battery, and Voila! an intercom!
Of course, there may not be an easy way to call the other end, as with a
ringer, but the connection is FULL duplex with just two wires (red and green)
going from station to station. (A few years back, we did this in work to
talk from the stock room to the selling floor. It worked then...)


					Gene

					...!ihnp4!philabs!phri!cooper!gene

	"Mourn for us, so pressed with fear.
	 Chained and shackled, we all found
	 Freedom choked, in dread we lived
	 Since Tyrant was enthroned."

				- RJAH