Page 24 - Analog Circuit Design Art, Science, and Personalities

George A. Philbrick

2. Analogs Yesterday, Today, and

Tomorrow, or Metaphors of the Continuum

It was naturally pleasurable for me to have been approached by the Simulation
Councillors to write an article, substantially under the above super-title, for their
new magazine. This euphoria persists even now, when my performance has in fact
begun, and is only moderately tempered by the haunting suspicion of what their real
reason might have been for so honoring me. It certainly could not be because my
views on analog computing and simulation are somewhat eccentric in relation to
much of the contemporary doctrine, although I accept and actually relish this char-
acterization. It could conceivably be in recognition of my relatively early start in the
field of electronic analog technology; this again is not denied by me, but here we
may have found the clue. The fact that I began a long time ago in this sort of activity
doesn’t mean at all that I am either oracle or authority in it. The truth of the matter is
subtler still: it only means that I am getting old. So we have it out at last. They are
showing respect for the aged. Here then, steeped in mellow nostalgia, are the
musing of a well-meaning and harmless Old Timer.
Since truth will out, I might as well admit immediately that I do not claim to be
the original inventor of the operational amplifier. It is true, however, that I did build
some of them more than four years before hearing of anyone else’s, and that their
purpose was truly simulative. These amplifiers were indeed DC feedback units, used
to perform mathematical operations in an analog structure, but the very first such
amplifier itselfbegan as a model builder, even at that stage, loomed larger than my
possible role as an inventor, and I have been dealing continually with models and
analogs ever since. Hereafter in this context I shall not speak of what I may have
invented or originated, and in fact shall not much longer continue in the first person
singular. By the same token I shall make no pretense in this article of assigning
credit to other individuals or to other institutions. There are far too many of both,
hundreds and thousands, stretching from this point back into history, to give any
accurate and fair account of the brainpower and perspiration which have made
analog computing what it is today, without leaving out many who have put vital
links in the chain.
While electronic analog equipment, using this phrase in the modern sense, cer-
tainly existed in the thirties, and in the forties became available on the open market
in several Forms, its roots really went still further back in time. It is doubted that a
completely exhaustive chronology of the contributory precursor technologies could
ever be produced, let alone by one amateur historian. Nothing even approximating
such a feat will be attempted, but it is hoped that an outline of the tools and tech-
niques which were on hand in the previous era will show that the ingredients were
already there, and that the modem analog machine was almost inevitable. As is
usual in such surges of progress, several fields of science and engineering over-

Reprinted with permission of Teledyne Components.
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