Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!casbah.acns.nwu.edu!accuvax.nwu.edu!nucsrl!telecom-request
From: optilink!elliott@uunet.uu.net (Paul Elliott x225)
Newsgroups: comp.dcom.telecom
Subject: Re: Headset Installation Help Needed
Message-ID: <16719@accuvax.nwu.edu>
Date: 6 Feb 91 04:22:13 GMT
Sender: news@accuvax.nwu.edu
Organization: Optilink Corporation, Petaluma, CA
Lines: 65
Approved: Telecom@eecs.nwu.edu
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 11, Issue 96, Message 3 of 10


In article <16649@accuvax.nwu.edu>, barefoot@hobbes.catt.ncsu.edu
(Heath Roberts) writes:

> I bought an telephone-type headset at a garage sale, and haven't been
> able to get it to work. I suspect that I'm not connecting something
> correctly.

> There's an over-the-ear mic boom, and an in-the-ear receiver,
> connected via a connectorized cord to an electronics box. The box says
> "UNEX Controlonics Corp., Westford, MA" and then what looks like a
> model, "Ventel II, Operator" It also has an FCC reg. number and a REN
> of 0.

If memory serves, Ventel is a manufacturer or distributer of phone
paraphernalia
 
> There's an RJ plug (same as normal handset cords) on the other end of
> the box. The box came with a coil cord and a twin-phone plug.
> Connecting it to a phone doesn't do anything. 

Well, Try it again!  Actually, if it is similar to the ones I've
designed, it should plug right into the phone in place of the handset
cord.  Make sure you lift the handset off the hook buttons (this is
kinda like asking "Did you plug it in?", but just thought I'd mention
it).

> Since it's not a
> line-type connector, I haven't tried plugging it into an active line.

Definitely don't do that.

> I understand that the tip connetors on the twin plug is receive, and
> ring is transmit (or vice versa) so the device is pretty clearly not
> intended to plug into a normal two-wire circuit.

The headset amp uses the hybrid inside the phone to do the two-to-four
wire conversion.

> My best guess to what's happening is that the box expects some power
> supply that a normal phone isn't going to provide. It's a nice headset
> and I'd like to be able to use it. Anyone have any helpful
> information?

The phone actually will provide about five volts (depends on the
current drawn) across the transmitter (microphone) connections, and
this is the power that the headset box uses to power the boom
microphone (probably an electret).  It may also steal some power to
amplify the receiver (earphone).  At least mine did.

Of course, you said it didn't work when you plugged it into the phone,
so maybe I don't know what I'm talking about.  Or it's broken.  They
are usually fairly simple inside, you might be able to fix it.

[A personal note: I regularly annoy my wife and kids by excitedly
pointing it out when I see one of "my" headsets on T.V. (Miami Vice
liked them a lot).  Also got to see one in use in orbit on the Space
Shuttle; NASA was trying out a few different types of communications
headsets.

I guess I have to take my glory where I find it ;-) ]


      Paul M. Elliott      Optilink Corporation     (707) 795-9444
            {uunet, pyramid, pixar, tekbspa}!optilink!elliott