NNTP-Posting-Date: Wed, 13 Nov 2002 09:18:50 -0600
From: Walt Jung <email@example.com>
Subject: Re: Historical question: negative feedback and the op amp
Date: Wed, 13 Nov 2002 10:18:40 -0500
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I recently researched this area in writing a historical
section of the ADI book, "Op Amp Applications", which is/was the focus
of a seminar series. See www.analog.com/seminar This book will be
available next week for anyone interested.
As Tony notes, it is generally true that WWII obscured much of
the early origins of the first op amp (which actually wasn't named as
such until the classic Ragazzini paper: John R. Ragazzini, Robert H.
Randall and Frederick A. Russell, "Analysis of Problems in Dynamics by
Electronic Circuits," Proceedings of the IRE, vol. 35, May 1947, pp.
444-452. (An overview of operational amplifier uses, and 1st formal
definition of the term).
The first circuit I could find which could be likened to what
we now call an operational amplifier was dated 1941, an inverting
(only) design by Karl Swartzel Jr. of Bell Labs. See K. D. Swartzel,
Jr., "Summing Amplifier," US Patent 2,401,779, filed May 1, 1941,
issued July 11, 1946. (The first operational amplifier, used as a
summing amplifier). It can be noted that this wasn't all that long
after Black's work... about a decade or so.
After the second world war, op amps were developed further,
but unfortunately nothing appears in the Bell Labs journals on the
early circuits. One needs to read the various patents (and there are
many of them) on the M9 gun director system, the context of these
developments at Bell Labs. A system level patent which describes this
system was: W. H. Boghosian, et al, "Artillery Director," US Patent
2,493,183, filed May 21, 1942, issued Jan. 3, 1950. (An artillery fire
control system using op amps for control).
The first commercial op amp was the Philbrick K2-W: See: Data
Sheet For Model K2-W Operational Amplifier, George A. Philbrick
Researches, Inc., Boston, MA, January 1953. See also "40 Years Ago,"
Electronic Design, December 16, 1995, pp. 8. (The George A. Philbrick
Researches dual triode K2-W, the first commercial vacuum tube op amp).
I am leaving on a trip today, and will be unable to follow
this thread until next week. Anyone interested in further details is
welcome to send me an email at firstname.lastname@example.org
On Wed, 13 Nov 2002 09:07:47 +0000 (GMT), Tony Williams
>In article ,
> Mike wrote:
>> Harold Black came up with his negative feedback theory in 1927, yet the
>> first op-amp wasn't invented until the 1950s.
> I think the term operational amplifier was used before
> then, in analogue computers, possibly during WWII and
> therefore not immediately publishable.