May 1970 Popular Electronics
[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Popular
Electronics was published from October 1954 through April 1985. All copyrights are hereby acknowledged. See all articles from
Acrylic wall-to-wall carpeting really came into vogue in the
late 1960s to early 1970s - just in time for the arrival of
miniaturized microelectronics (is that redundant or just superfluous?).
Gate widths were being shrunken rapidly as the birth of the
Moore's Law era was in its infancy (born in a 1965 paper
written by Intel engineer and co-founder Gordon Moore). The
result was copious quantities of electronic gadgets being zapped
when the unsuspecting user would walk across the Van de Graaff
generator in the form of floor covering and reach for a dial
or switch. A couple thousand volts could easily build up on
a body clad in lime green polyester pants (remember the era),
then fzzzzt, there goes the clock radio or AM/FM tuner. Vacuum
tube circuits from a decade earlier never even felt the shock.
Welcome to the world of EMP vulnerability.
Burning Out Your Circuits Without Really Trying
By Errol J. Queen
The age of semiconductors brought with it the many
advantages of subminiaturization, cool operation, and improved
performance in everything from sophisticated FM tuners to electronic
light dimmers. Diodes and transistors are not without problems,
however; as I recently discovered.
I made an excellent human treasure locator!
I am an audio-visual enthusiast and take great pains to put
on semi-professional slide shows for friends and relatives who
visit us frequently. A Kodak Carousel projector is connected
through a Sound Synchronizer to a transistorized tape deck and
amplifier. The Synchronizer unit receives trip signals from
one track of the stereo tape, in turn changing the slides in
coordination with pre-recorded commentary and music. Colored
lamps light the projection screen prior to the show's beginning;
and by means of a light dimmer, the room lights and colored
spots are slowly dimmed as the first slide comes on.
Recently. in redecorating our family room, I made the mistake
of having acrylic wall-to-wall carpeting put in. I was unaware
of its highly electrostatic nature, particularly on cool winter
evenings. Sparks can play havoc with apparatus containing semiconductors.
When my wife or I walked across the room and then touched
any metal surface, an intense spark was created. While not dangerous
because of the infinitesimally low current, the voltage was
probably near 100,000 volts with sparks as long as an inch and
a half. We even found that we were able to locate metal surfaces
behind the wall plaster (such as plumbing and conduits) by walking
about and probing with a finger until a spark jumped into the
wall. My wife insisted that perhaps there were treasures buried
beneath the floor and asked that I crawl along the carpeting
as a human treasure locator!
In all seriousness, the electrostatic nature of acrylic was
such that within a week I saw sparks fly into my FM tuner, lamp
dimmer, and FM-AM clock radio. Each in turn suffered semiconductor
damage, which was costly and emotionally disconcerting. At that
point, I felt I would have to make a serious decision sell
the carpeting at a tremendous loss, or sell the semiconductor
equipment at a loss of dollars and pleasure. I searched the
catalogs and concluded that tube-type tuners and clock radios
were rapidly becoming a thing of the past - what with their
problems of size, heat dissipation, and lack of demand.
My problems were finally resolved when I called in the firm
which sold the carpeting. They recommended one of several available
sprays, which, when applied, reduce the charge buildup on such
fibers. Powders are. also available for the same purpose. They
can be brushed into the rug, with the excess vacuumed up immediately.
If you own or plan to buy transistorized radios, amplifiers,
tuners, tape decks, light dimmers, or other appliances, make
sure your carpeting is static-free.
Posted September 12, 2012