Page 65 - Analog Circuit Design Art, Science, and Personalities

Max Wien, Mr. Hewlett, and a Rainy Sunday Afternoon

Figure 7-3.
Hewlett's Figure I "rn 6F2SETl
..
3 detailed the
oscillator circuit.
Note Wien net-
work and lamp
(Courtesy
Stanford
University
Archives.)

is proporzicnal to the fourth power of Lhe aDsolur-e
tenperature, ard as rrost of the energy is lost through
radiation, this requirement may be easily met by not-
operating the lamp at LOO high a currert. Under these
cordltlons, the life of rhe lamp s5ould be almost infinite.

Hewlett's use of the lamp is elegant because of its hardware ~implicity.~ More
importantly, it is elegant because it is a beautiful example of lateral thinking. The
whole problem was considered in an interdisciplinary spirit, not just as an electronic
one. This is the signature of superior problem solving and good engineering.
The lamp solved a tricky problem, completing the requirements for a practical
instrument. The design worked very well. It covered a frequency range of 20 to
20,000 cycles (it was cycles then, not Hertz) in three decade ranges with dial cali-

2. Hewlctt may have adapted this technique from Meacham, who published it in 1938 as a way to stabi-
. ... _..
li7e a mart7 crvslal oscillator. Meacham'z naner. 'The Rridpe Slahilirerl Oscillator " is in reference
-
.
.- . , .... .. .. .
..
. ,.-~-.. . ...
. . . ._ -.
~
number five in Hewlett's thesis.
DISTORTION AND AMPLITUDE
Figure 7-4. CHARACTERSTICS
Hewlett's Figure
4 showed good
distortion
perform an ce.
What limited it?
(Courtesy
Stanford
University
Archives.)

to 30 100 300 1000 3000 10000 3 m
FREPUENCY C.l?S.
IN
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