FEATURES The 555 Timer at 50
together, since they are made at the same time
and under the same conditions. In other words,
they match very well. I used that feature to
build a novel oscillator, which turned out to be
extremely stable.”
Within a year, other manufacturers were
copying the design. “Everybody was stealing
from everybody else,” Hans recalled, “and
in those days, nobody paid any attention to
patents.” In fact Signetics didn’t even apply for a
patent, fearing that if they tried to enforce it, they
would start a war with other, larger companies.
Today, anyone can build a copy of a 555 timer.
The Legacy
The 555 established Hans Camenzind as an
authority on analog integrated circuits. By 2006,
he had designed 140 standard and custom chips.
He also wrote two amazing books: The definitive
Designing Analog Chips, and a brilliant general
introduction to electricity titled Much Ado About
Almost Nothing, which included thumbnail
biographies of all the pioneers. Both books are
still available online through print-on-demand.
The 555, of course, has acquired legendary
status. You can even buy a kit to build your own
macro-scale replica from discrete components
(see sidebar).
The chip has some well-documented defects.
Its use of bipolar transistors results in a nasty
voltage spike when its output transitions (see
Figure
C
), and it is power-hungry. But a CMOS
version has fixed those issues.
Hans Camenzind died in 2012 at the age of
78. Today, the storefront where he designed the
timer is occupied by a real-estate broker (see
Figure
D
). The alley is arrowed in the picture
of Murphy Avenue in Figure
E
. Maybe one
day Sunnyvale will honor Hans with a plaque
beside his old workplace, but in the meantime
his genius lives on in tens of billions of chips
containing copies of his hand-made circuit.
The writer thanks the Camenzind family for their
generous help, and Jack Ward of the Transistor
Museum, where audio files of Hans Camenzind
are archived at semiconductormuseum.com/
Transistors/LectureHall/Camenzind/
Camenzind_Index.htm.
The very first 555. (From the Camenzind photo
collection.)
A voltage spike that occurs when bipolar 555 output
goes high can disturb other components. (Reproduced
from the book Make: Electronics by Charles Platt.)
Location of the alley leading to the storefront. (Adapted
from Google Street View.)
20 makezine.com
Camenzind collection, Charles Platt, courtesy Pia Camenzind, Google/Charles Platt, Signetics, Eric Schlaepfer, EMSL, Windell Oskay
B
0.20
0.4
0.6
0.8
0
4
8
12
16
Microseconds
Volts
The storefront where Hans Camenzind developed
the 555, photographed in 2022. (Courtesy of Pia
Camenzind.)
C
D
E
M82_018-21_555timer_F1.indd 20M82_018-21_555timer_F1.indd 20 7/11/22 12:38 PM7/11/22 12:38 PM
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