[comp.dcom.telecom] Telephone Headset Information Wanted

richer@HQ.Ileaf.COM (Al Richer) (03/25/91)

Hi folks...

 Having been a "lurker" on comp.dcom.telecom for a while, I
immediately knew where to come for information on anything
telecom-related. This is one that I'm sure other folk have run into,
but I've never seen anything published here on it.

 I have a telecom headset, manufactured by a California company who
flat-out refused to give me any information on it. It consists of an
electrostatic microphone, a magnetic earpiece and an amplifier box
connecting the two to an RJ-11 handset plug. The amplifier of the set
seems to derive power from the handset line, but in what fashion I'm
not terribly sure. There seems to be a bridge rectifier, as well as
some analog IC circuitry in the box to provide variable amplification
to the earpiece, as well as DC bias for the mike.

 My question is this:

 I want to adapt this little darling for use with a portable
transciever. Could anyone give me some idea of what voltage is being
provided, and on which pins of the RJ11?? From there I can puzzle out
the various connections. My main concern is that I want to avoid
damaging the internal circuitry of the amplifier box, as all of the
parts are either unmarked or have nonsandard markings.

 Thanks in advance.

 N.B.: Yes, I have checked the Telecom Archives. No joy.


Alan J. Richer              Mail:  richer@hq.ileaf.com
Interleaf, Inc.             All std. disclaimers apply 			
9 Hillside Ave.                  Your mileage may vary