Page 28 - Analog Circuit Design Art, Science, and Personalities

George A. Philbrick

Figure 2-1.
This was George's
vision of the
mighty analog
tree. It remains
relevant almost
three decades
later. Courtesy of
Teledyne
Components.

design, manufacture, and test. Applications are even on the increase for scientific
research. where in a sense such equipment began. We shall not try to list the many
embodiments and applications in this text, but have included some of them in a
figure to be found nearby, which has been prepared to bear out the morphology of
our burgeoning field.
Analog representation in terms of modem apparatus is a far cry from scale models,
but the model concepts still seem incomparably fruitful. In direct models, which
retain the physical medium of their prototypes, scaling is the biggest part of the
game. Similitude conditions must be faithfully adhered to. and an appreciation of
these conditions imparts a feeling for models which is never lost. Actually the use
of direct scale models has not decreased, and is still a powerful technique in such
areas as hydraulics and structures: natural and man-made. Much ingenuity has been
lavished 011 such models; they must by no means be looked down upon by the users
and designers of more fashionable modelling items.
In a scale model the transformation of dimensions is typically direct and simple,
especially if shape is preserved. Even when the scaling involves distortions of
shape, such as relative compression and bending, the transformations generally
carry di,tance into distance, velocity into velocity, and so on. with only numerical
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