Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!philabs!cmcl2!floyd!vax135!ariel!houti!hogpc!houxm!mhuxa!mhuxi!cbosgd!ihnp4!ixn5c!inuxc!pur-ee!uiucdcs!uiuccsb!whaley From: whaley@uiuccsb.UUCP Newsgroups: net.aviation Subject: Re: Querry on headsets: using stereo or - (nf) Message-ID: <2376@uiucdcs.UUCP> Date: Fri, 8-Jul-83 23:35:28 EDT Article-I.D.: uiucdcs.2376 Posted: Fri Jul 8 23:35:28 1983 Date-Received: Tue, 12-Jul-83 21:08:06 EDT Lines: 20 #R:ut-ngp:-39700:uiuccsb:5900002:000:1152 uiuccsb!whaley Jul 8 13:26:00 1983 Resistance of "real" or "expensive" headphones is often 600 ohms. It is possible to buy transformers to convert the audio to 8 ohms for regular stereo phone for under 2 dollars if you know where to look. What I have done is go into radio shack (a place I don't recommend, as they usually sell very inferior stuff), and look at their audio transformers. They sold one at one time that converted 1000 ohms center tapped to 8 ohms. It was intended for push pull transistor amplifier output coupling. (If you don't understand that, don't worry.) I used the center tap with one end connection, getting half the 1000 ohms, or 500 ohms. That is close enough to 600. 8 ohms isn't close enough and can damage the aircraft audio panel. On a Grumman tiger an 8 ohm earphone caused one radio to break into oscillation, while the other was unaffected. 600 ohms is quite standard for some types of application, and there are real 600 ohm to 4, 8, and 16 ohm transformers. The one I bought had the advantage of being small and cheap; it was so small I taped it into the patch cable I had made to go from the 1/4 inch phone plug to the 1/8 stereo phone plug.