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From: rmrin@inuxh.UUCP (D Rickert)
Newsgroups: sci.electronics,talk.bizarre
Subject: Re: "Magic Eye" tubes
Message-ID: <591@inuxh.UUCP>
Date: Wed, 22-Jul-87 17:32:23 EDT
Article-I.D.: inuxh.591
Posted: Wed Jul 22 17:32:23 1987
Date-Received: Sat, 25-Jul-87 01:47:11 EDT
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Organization: AT&T Consumer Products, Indianapolis
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Xref: mnetor sci.electronics:1039 talk.bizarre:2604

> < The "Decatron" tube, which consisted of a round tube with ten
> < anodes, equally spaced about a circle.  It was nothing more than
> < a multiple neon lamp, since it displayed no digits, but each anode
> < was labeled on the panel.  Example: a Baird-Atomic nuclear scaler
> < that I once used.
> 
> Actually the Decatron was quite ingenious.  It not only indicated, but
> also did the counting.  A major plus in pre-IC days.  They were not
> particularly fast, I seem to recall a figure of a few hundred KHz.
> They consumed little power, just a few mA at hundreds of volts.
> 
> 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.
> 
> Paul Wilcox-Baker
> Tel 415 549 3854
> Telex ITT 470844
> Dual Systems Corp
> 2530 San Pablo Ave
> Berkeley CA 94702

Yup, many years ago I did a lab project in which we used a Decatron
for motor speed control!  The idea was for the circuit to keep the
same little dot continuously lit if the motor speed stayed constant
at the set point.  A wonderful mix of analog, digital, and power
technology.  I think we may have even had a mag amp somewhere in
the circuit (you know, solid state Neanderthal style).