SILICON CHIP
Publisher & Editor-in-Chief
Leo Simpson , B.Bus.
Editor
Greg Swain , B.Sc.(Hons.)
Technical Staff
John Clarke, B.E.(Elec.)
Robert Flynn
Advertising Manager
Paul Buchtmann (02) 982 9553
Regular Contributors
Bryan Maher, M.E. B.Sc.
Jim Yalden, VK2YGY
Garry Cratt, VK2YBX
Jim Lawler , MTETIA
John Hill
Jennifer Bonnitcha, B.A.
Bob Young
Photography
Bob Donaldson
Edltorlal Advisory Panel
Philip Watson, MIAEE, VK2ZPW
Norman Marks
Steve Payor, B.Sc., B.E.
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ISSN 1030-2662
2
SILICON CHIP
PUBLISHER'S LE
R
Putting speed into
perspective
Did you ever stop to think how blase we have all become when thinking about electronics and technology? Try as we might, the march of
technology is so remorseless that even quite dramatic developments
tend to pass unnoticed. This thought came to mind this month when we
were processing the first article on our new audio oscillator.
At first sight, the specs of this unit appear to be fairly routine; pretty good but not spectacular. But in amongst those specs are the figures
for rise and fall times of the square wave output which are quoted at
less than 30 nanoseconds for the rise time and less than 20
nanoseconds for the fall time. These are pretty respectable figures
and ones we are quite pleased with but that is not the real issue.
The point is that these figures are really incomprehensible. When
you start thinking in terms of nanoseconds you can have no real concept of what it means. None of us can. One nanosecond is one thousand millionth of a second!
Trying to divide one second into such small intervals is pretty much
on a par with thinking about the number of seconds in 32 years. If you
don't believe me, work it out on your calculator.
The truth is, of course, that when we talk and think about time intervals in terms of nanoseconds, we are not really thinking about normal
time at all. In effect, we are thinking in terms of time standing still.
And we use instruments such as high speed oscilloscopes to show us
extremely high speed pictures of intervals "frozen in time". How else
can we comprehend what is happening?
Twenty years ago, it was most unusual to talk in terms of nanosecond time intervals as far as commonplace electronic equipment was
concerned. Now such intervals are taken for granted, in computers
and in all manner of consumer electronic equipment. Yet we are utterly blase about it all.
One more point to consider: the devices which produce these very
fast waveform transitions are very cheap. They include the 74C14
CMOS Schmitt trigger device which can be obtained for less than two
dollars. Had we used a high speed CMOS version, the 74HC14, we
possibly could have halved those rise and fall times. But that would be
virtually meaningless, wouldn't it?
Leo Simpson
