INVENTOR of accutron, horologist and physicist Max Hetzel, holds transistorized circuit of Bulova's new Accutron electronic timepiece with jig and readies tuning fork for insertion between tiny coils, each containing 8,000 turns of wire. He started working on Accutron development in Bulova's Switzerland plant 8 years ago. Hetzel is now chief physicist at the company's main plant in Jackson Heights, N.Y.

Transistorized Timepiece "Hums" Instead of "Ticks"

A new sound of timea "microsonic" hum to replace the centuries-old ticking soundwas introduced recently in a new transistorized timepiece designed to make conventional wrist watches a thing of the past.

The new timepiece, called the "Accutron," looks like a wrist watch, but uses timekeeping principles never used in a wrist watch, according to its inventors, the Bulova Watch Company, Inc.

"The same instrument we can now wear as a personal timepiece on our wrists is orbiting earth as a timing instrument aboard the Explorer VII satellite," said Gen. Omar N. Bradley, Bulova board chairman, who introduced his company's new development. The task of the timer, which weighs 8 ounces and replaces 30 pounds of otherwise necessary equipment, is to turn off the satellite transmitter at a preset time.

"Because of its performance in space and the 3 years of field testing that we have put it through here on earth, we believe," Gen. Bradley said, "that Accutron is more accurate than any conventional wrist watch be it powered by spring or battery, and considerably more reliable in operation."

"Furthermore," he said, "we believe Accutron is the most significant advancement in timekeeping in more than 300 years."

Bulova supports its accuracy claim for the new watch by guaranteeing the Accutron in use to be accurate within 1 minute per month; approximately 10 times more

accurate than fine-quality wrist watches. Gen. Bradley said that Accutron was so

unlike a conventional watch that his company has been referring to it as a "micro-sonic" or electronic timepiece. The new timekeeper has none of the conventional watch components, such as main spring, escapement, winding mechanism, winding and setting stem, balance wheel, and hairspring.

An electromagnetic tuning fork that is powered and controlled by a transistorized electronic circuit replaces the balance wheel and hairspring. It is the tuning forkvibrating at 360 cycles per second within the Accutronthat gives off the slight "hum" barely audible when the instrument is held close to the ear.

Jewelry stores in 32 market cities throughout the country will start selling the Accutron in mid-November, a company marketing spokesman said. Prices of the Accutron will range from $175 to $2,-500, with most of the dozen men's models in the $250 to $400 range. The $2,500 model is in platinum.

The Bulova company originated development of the Accutron some 8 years ago in its Swiss plant. Max Hetzel, a Swiss horologist and electronic engineer who is now Bulova's chief physicist, is the inventor of the electronic timepiece.

Bulova has obtained numerous American and foreign patents on its device.

Microminiaturization and refinement of the electromagnetic and electronic components of the Accutron has been directed for the past 5 years by W. O. Bennett, vice-president of research and engineering for Bulova.

A single component that probably best represents microminiaturization within

PHASE SENSING COU 7 ^ r WIVE COIl #1

rnonnrm'^w^ 4 DRIVE C0H #?

^-ESISI

POWER CELL for Accutron is a 1.3-volt mercury cell (shown on finger) which can be replaced merely by unscrewing a cap on the back of the Accutron case. Power cell looks similar to hearing aid batteries, but is specially designed for Accutron's requirements. Replacement power cells wi l l cost $1.50. Recessed handle for setting the hands also is on the back of the case. Accutron shown is one of 12 introduced recently by Bulova Watch Company, Inc.

^-CAPAC

ELECTRONIC CIRCUIT of the Accutron acts as an on-off switch as it continuously imparts driving pulses through the drive coils to the magnetic cup arrangement on each tine of the tuning fork time standard (not shown). Voltage flows from the power cell to drive coils through switching germanium transistor when the phase-sensing coil "senses" the correct position of the tuning fork during each vibration. Frequency of vibration is maintained at 360 cycles per second. The 1.3-volt mercury power cell delivers 6 millionths of an ampere (0.000006), 8 millionths of a watt (0.000008).

the device is an index wheel that transposes vibratory motions from the tuning fork to rotary motion to move the hands. This gear is 0.095 inch in diameter (about like a pin head) and 0.0015 inch thick (about one half the diameter of a human hair); yet, it has 300 precisely machined ratchet teeth.

The tiny coils that keep the tuning fork vibrating are \/A inch long. Each coil has 8,000 turns of wire that is 0.0006 inch in diameter (only about one fifth the diameter of a hair). One pound of this wire would stretch 200 miles.

The Accutron's power source, a button-size 1.3-volt mercury cell, will keep the timepiece running for at least a year. Operation of the device requires about 8 millionths of a watt (equal to 10 billionths of a horsepower). In comparison, the power used by an electric toaster to toast a slice of toast would operate the Accutron for about 250 years. g|=

Eskimo Village To Have Dial Telephone Exchange

The traditional "mukluk telegraph" of the Arcticthe hand-to-hand and mouth-to-mouth means by which Eskimos have sent their messages for centuries pastwill get a modern assist from the new dial telephone exchange of the Trans-Alaska Telephone Company which was scheduled to go into operation at Kotzebue, Alaska, late in October.

Kotzebue will become the northernmost telephone system on the North American continent, according to J. E. Field, president of Trans-Alaska.

The Kotzebue installation, constructed under the supervision of J. V. Ditto, vice-president of Trans-Alaska, will serve about 100 subscribers in this predominantly Eskimo community. These subscribers will include a new hospital built

950 Of Current Interest ELECTRICAL ENGINEERING

THIS BUILDING, near the center of Kotzebue, Alaska, will house the community's new dial telephone exchange, built by Stromberg-Carlson Division of General Dynamics Corporation. The Kotzebue exchange, part of the Trans-Alaska Telephone Company, will be the northernmost on the American continents, and, it is believed, the only telephone system north of the Arctic Circle.

by the U. S. Bureau of Indian Affairs to provide medical care for the native population in the area.

This will be a completely modern dial exchange, built by the Stromberg-Carlson Division of General Dynamics Corporation, in Rochester, N. Y. In fact, Kotzebue will receive the first production model of Stromberg-Carlson's new "Compak I" 100-line dial exchange.

There is another innovation that will be enjoyed by Kotzebue telephone subscribersthe telephones that will go into service in the community's trading posts, business establishments, cabins, and homes will be Stromberg-Carlson's line * of "Petite" colored phones.

Actually, there is no Eskimo word for telephone, but the fluid and oft-times ingenious Eskimo tongue has solved this problem by coining the word "Okoksoon,"

THE NEW "Okoksoon," in Kotzebue, Alaska, is tried out by one of the Eskimo women in the village. It is one of Stromberg-Carlson's "Petite" telephones, selected by Trans-Alaska Telephone Company as standard equipment in the Kotbebue telephone system. One of the reasons for this choice is that the "Petite" has a dial light, making it easy to find and use the telephone during the long Arctic night.

NOVEMBER 1960

meaning, roughly, "to talk into a telephone."

Kotzebue is the second largest Eskimo village in Alaska, with a population of about 1,200, and with about 3,800 living in the area. Natives outnumber all others in the community by a ratio of about 20 to 1. The village is named after Otto von Kotzebue, Russian explorer who was the first European to land in the area, in 1816. Eskimos have lived there for thousands of years, however.

The Kotzebue exchange is just one of a number of new dial telephone exchanges being planned by Trans-Alaska, which recently signed a $1.3 million contract with Stromberg-Carlson for equipment to implement its expansion program. The company, which serves a major portion of the 49th state, has general offices in Anchorage. EE

High-Energy Electric Arc Heater

A machine with the potential capability to supply a stream of gas at temperatures as high as 20,000 F and pressures as great as 15,000 psi has been devised by the Westinghouse Electric Corporation. The machine, an electric arc heater, can operate for sustained periods of time and at an extremely low level of gas contamination.

The arc heater has immediate application in a wind tunnel for missile testing. Also, it holds promise as a chemical synthesizer and as a furnace for processing metals with ultrahigh melting points. A prototype model of the machine has been operated at a power input of 1,700 kw, but a high of 30,000 kw is planned by the company.

Dr. J. A. Hutcheson, vice-president in charge of engineering for Westinghouse, credited the new arc heater with being the first to operate continuously and at a low level of gas contamination.

"The temperature into the nozzle has been maintained at 10,000 degreesapproximately as hot as the surface of the sun," Dr. Hutcheson said. "In addition, flow from the nozzle of the unit has

Of Current Interest

reached a sonic velocity of 3,400 miles per hour. Velocities over ten times the speed of sound can be expected when the gases are expanded with a hypersonic ' exhaust nozzle.

"Applying these characteristics to a wind tunnel will help duplicate the extreme conditions met by missiles and other space craft of the future upon reentry into the earth's atmosphere.

"As a chemical synthesizer, the machine will supply the high temperatures necessary for inducing difficult chemical reactions. Nitrogen and oxygen, for instance, could be combined in the heat chamber to form nitrous oxide, a compound widely used in chemical processing. A synthesizer of this type could also find application in processing petroleum products."

Dr. Hutcheson said that the unit's potentialities as a furnace might make a number of refractory metals available in -ingot form for the first time. Normally used in powder form, metals such as tungsten are difficult to process because of their high melting points.

In all of these applications, the success of the arc heater "is generally dependent upon a low level of contamination," he said. One of the problems involved in units under development during the past 2 years is that electrodes and walls of the chamber burn and thus contribute impurities amounting to as much as 10% of the mass of the gas flowing through the system, he explained.

"The Westinghouse unit has a guaranteed maximum contamination level of 0.2%," he said. "Still further reductions in this level are contemplated.

"In addition, we believe that the Westinghouse arc heater has a uniform temperature 'profile' within the heat chamber. In other words, the temperature at the entrance to the nozzle is constant."

The basic concept for the new arc heater was proposed by Dr. Werner Emmerich, research physicist at the Westinghouse research laboratories. He conceived a scheme in which an electric arc, dissipating megawatts of electric power, can be maintained for prolonged periods of time to continuously transfer thermal energy to a gas passing through the arc. This is done virtually without erosion of the electrodes, thus all but eliminating this cause of gas contamination.

A key to the performance of the new machine lies in the design of the two electrodes which form the terminals for the arc. Each of these electrodes consists of a hollow donut-shaped ring placed horizontally, one directly above the other. Water is pumped through the hollow rings for cooling.

An electric arc is started by drawing < it across the gap between the two rings, and then rotated around the gap at a high rate of speed.

Rotation of the arc is accomplished by a magnetic field from d-c coils arranged around the outside of the heat chamber. This rotation, combined with water-cooling, prevents the electrodes from heating to a point beyond the structural endurance of the material. Repeated tests of the unit have left the electrodes undamaged, indicating a lack of contamination from this source.

The working fluid, such as air or nitro-

951