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From: larry@kitty.vanP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: "Magic Eye" tubes
Message-ID: <1844@kitty.vUCP>
Date: Wed, 15-Jul-87 22:50:45 EDT
Article-I.D.: kitty.1844
Posted: Wed Jul 15 22:50:45 1987
Date-Received: Sat, 18-Jul-87 08:14:42 EDT
References: <1495@frog.UUCP> <35ffa63b.b8ab@apollo.uucp> <6@spar.SPAR.SLB.COM> <10018@dual.UUCP>
Organization: Recognition Research Corp., Clarence, NY
Lines: 36
Summary: Cold cathode tubes

In article <10018@dual.UUCP>, paul@dual.UUCP (Baker) writes:
> There was a whole range of rather odd neon type devices available at one
> time, that could be used for counting and other logic.  These typically
> had a trigger electrode that "fired" the device and started conduction
> between the main electrodes.  Reducing the current through the main path
> would turn the device off again.  There must be some people on the net
> who actually designed with these things.

	Western Electric was well known for using cold cathode tubes in
telephone switching ciruits during the 40's, 50's and early 60's.  These
were essentially three element tubes having a cathode, an anode, and a
"starter anode".  The anode -> cathode voltage was usually + 130 volts,
and the tube would conduct sufficient current to operate a relay.  Only
a small about of current was applied to the "starter anode" to cause the
tube to go into conduction mode.
	Compared to the "non-WECO" world, these cold cathode tubes (like
the WECO 346C) were of bizarre design.  For example, in addition to being
filled with an inert gas these tubes contained a radioactive material
to facilitate ionization.  The earlier tubes contained radium bromide,
with later tubes containing krypton-85.
	A common example of using these tubes was for timing circuits
in the middle of relay-logic switching apparatus.
	In the mid 1950's, these cold cathode tubes reached their
zenith when WECO designed a prototype "electronic" (I used the term
loosly) telephone switching system which used cold cathode tubes as
the switching matrix.  This ESS :-) machine was fully described in the
"Bell System Technical Journal".  Contained in the article were
photographs, including one of the weirdest looking telephone set I
have ever seen!  The telephone set resembled a checkwriter with a
handset.  I don't recall the exact BSTJ issue, but anyone interested
in history or electronic trivia should check it out.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
<>  vanP:  {allegra|ames|boulder|decvax|rocksanne|watmath}!sunybcs!kitty!larry
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