Re: Off Topic - Telephone design info.

[Stephen C. Phillips]

 Jon, 

 I bought a SAMS book from Radio Shack (Tandy - to 
those oversees) about a dozen years ago that explained 
simple telephones, and a little more.  Tip  Ring 
comes from the old plugs the operators had to use to 
manually connect calls, the was a Tip, an insulator/ 
gap, and a Ring, followed by another insulator.  At 
least that's the explaination I was given when I started 
in this business 15 years ago.  TREG would be a better 
forum for this question.  I hope this helps.  

 Best regards, 
 Stephen C. Phillips 
 All opinions are my own.  

At 11:34 AM 7/22/97 MST, you wrote:
 
 I'm not quite on the correct list for this but -
 
 Do any of you know of a good book that details how the phone systems 
 work (what's a ring, what a tip, etc).
 
 Also a book that covers what regulations are involved to gizmos that 
 connect to the phone lines in a home.
 
 Basically, if I could learn how to design a telephone I'd know what I 
 need for an upcomming project.
 
 Thanks,
 
 Jon Bertrand
 j...@cirris.com

Re: Class I laser . U.S. vs EN 60825

[Stephen C. Phillips]

 Bob, to reply quickly, 

 Not speaking for Cisco, and not having any specific 
knowledge of that product or that approval, and without 
checking the 2 spec's for comparison at this time... 
I'm recalling that the measurement aperture size is 
different for the 2 spec's (10mm vs. 15mm??), so even 
if the pwr limits may be the same at a given wavelength, 
for classification, the measurement is, I believe, 
performed differently, thus - different measurement 
values can be obtained for the same product per the 
2 different specifications.  

 I'm sure someone here will look into this deeper  

 Best regards, 

 Stephen C. Phillips 

 These opinions are my own, and not those of Cisco Systems.  

At 01:18 PM 6/2/97 -0400, you wrote:

I came across a safety notice from Cisco indicating that under a certain
failure mode one of their single Mode FDDI cards will exceed  EN 60825
limits for a class I laser device, but still meet U.S. limits.

I thought the limits were the same. Can anyone explain?


Robert Brister

EHS Senior Associate
Digital Equipment Corporation
(508)493-8141
FAX:(508)493-8353