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From: dgc@math.ucla.edu (David G. Cantor)
Newsgroups: comp.dcom.telecom
Subject: Re: Building a Phone Line Simulator
Message-ID: <15150@accuvax.nwu.edu>
Date: 1 Dec 90 00:41:15 GMT
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X-Telecom-Digest: Volume 10, Issue 860, Message 4 of 11


In Telecom V10, #854, Todd Inch  <gtisqr!toddi@beaver.cs.washington.
edu> suggests a circuity for a simple phone line simulator: Here is
(in my opinion) a minor improvement:


|                |         This differes from the original by the
|                |         addition of the (load) resistor.  The
|                |         "battery" can be any DC supply from about
|                |         6 volts to 50 volts and the resistance
|    Line  1     |         should be chosen so that about 20 ma
|                |         flows when the lines are shorted.  That is,
|                |         R = 50 V, where R = restance in ohms and
|                |         V = voltage of supply.  Note that the telco
|                |         standard has V=48 and R around 2400.  None
|                |         of this is critical.  A slightly  better
--battery-\/\/\/ |         simulator is made if the batter is shunted
|                |         by a capacitor, on the order of 10 microfarads.
|                |
|                |
|                |
|                |
|    Line 2      |
|                |
|                |
|                |