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 (if any) are hereby acknowledged.
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
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.
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Burning Out Your Circuits Without Really Trying
By Errol J. Queen
I made an excellent human treasure locator!
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 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
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.