Path: utzoo!attcan!uunet!snorkelwacker!tut.cis.ohio-state.edu!cs.utexas.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: kthompso@entec.wichita.ncr.com (Ken Thompson)
Newsgroups: comp.dcom.telecom
Subject: Re: Light Showing Phone is Off Hook?
Message-ID: <3608@accuvax.nwu.edu>
Date: 7 Feb 90 16:02:41 GMT
Sender: news@accuvax.nwu.edu
Reply-To: Ken Thompson <kthompso@entec.wichita.ncr.com>
Organization: NCR Corporation, Wichita, KS
Lines: 33
Approved: Telecom@eecs.nwu.edu
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 10, Issue 83, message 1 of 8


Here is a circuit that works to indicate a phone line is on hook.
Mount the led that lights in a conveniently visible location.

                          |\ |
        <---------+-------| >|-----+-----'\/\/\/\/`-----+
                  |       |/ |     |        22k         |
                  |        led     |                    |
to phone          |                |                    |
line              |       | /|     |                    |
(green/red)       +-------|< |-----+                    |
(L1/L2)                   | \|                          |
                           led                          |
                                                        |
                                                        |
        <-----------------------------------------------+
                                                         
This is for information only.  No one is encouraged to actually use 
the circuit.   

No warranty expressed or implied.  Not liable for any direct,
consequential, or incidental loss or damage.  This circuit has
not been certified as complying with Part 68 of FCC regs.               

WARNING: Telephone circuitry contains potentially lethal voltages.  No
user serviceable parts inside.  Refer all repairs, adjustments and
modifications of any equipment to qualified service personnel.


Ken Thompson     N0ITL  
NCR Corp.  3718 N. Rock Road            
Wichita,Ks. 67226  (316)636-8783       
Ken.Thompson@wichita.ncr.com