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From: stehle@erg.sri.com
Newsgroups: comp.dcom.telecom
Subject: Wanted: Ring Indicator (With Memory)
Message-ID: <74346@bu.edu.bu.edu>
Date: 9 Feb 91 22:32:48 GMT
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X-Telecom-Digest: Volume 11, Issue 103, Message 5 of 12


I am looking for an add-on accessory that would be placed on a
two-wire telephone line (with a T connection) that would indicate that
the ringing voltage has appeared on the line.

Ideally, an LED would be set to a flashing mode in response to the
ringing voltage.  It would stay flashing until the handset was taken
off hook; this operation would cause the LED to be extinguished and to
cease flashing.

Can you direct me to vendors of such equipment?  Can you direct me to
a schematic to build such a circuit?

I am aware of the 20 Dec 90 _EDN_ Idea for Design.  Do you have any
comments on the suitability of this circuit?  Can private telephone
systems (e.g., NT SL-1) tolerate lower on-hook DC impedances than the
Part 68 specification of 5 megohms?

E-mail replies gladly accepted at "stehle@erg.sri.com".

Thanks,


Roy Stehle   SRI International