Inventor of AT&T’s Datakit, the First Virtual Connection Switch, Dies at 85

IEEE also mourns the loss of other members

4 min read

Alexander “Sandy” Fraser

Developer of the first virtual circuit network switch

Fellow, 85; died 13 June

Fraser developed the Datakit, the first virtual circuit network switch, while working at AT&T Labs in Florham Park, N.J. The telecommunications technology is used by all major U.S. telephone companies.

He invented other pioneering technologies as well, including the file system for the Titan supercomputer (prototype of Atlas 2), cell-based networks (precursor to asynchronous transfer mode), and the Euphony processor, which was one of the first system-on-a-chip microprocessors.

He began his career at Ferranti, an electrical engineering and equipment company in Manchester, England. He left there in 1966 to join the University of Cambridge as an assistant director of research. After three years, he moved to the United States to work for AT&T Bell Labs in Holmdel, N.J. While there, he helped develop the Moving Picture Experts Group Advanced Audio Coder, which compresses music signals. First used in Apple’s iTunes program, it now can be found in all smartphones.

Fraser held several leadership positions at the company during his 30 years there. He became director of the Computing Science Research Center in 1982 and five years later was promoted to executive director. In 1994 he became associate vice president for the company’s information science research department. In 1996 he helped establish AT&T Labs in Florham Park. It is the company’s research and development division, of which he was vice president for two years.

He decided to focus more on research and left his position as vice president. AT&T named him chief scientist, and in that position he worked on developing architecture and protocols for a large-scale Internet so that customers could connect to it from their homes.

In 2002 Fraser retired and founded Fraser Research, in Princeton, N.J., where he continued his networking work.

He earned his bachelor’s degree in aeronautical engineering in 1958 from the University of Bristol, in England. He went on to receive a Ph.D. in computing science in 1969 from Cambridge.

Byung-Gook Park

Vice chair of IEEE Region 10

Fellow, 62; died 20 May

Park was an active IEEE volunteer and was serving as the 2021–2022 vice chair of IEEE Region 10 at the time of his death. He was the 2014–2015 chair of the IEEE Seoul Section.

He was a member of several committees at conferences including the IEEE International Electron Devices Meeting, the International Conference on Solid State Devices and Materials, and the International Technical Conference on Circuits/ Systems, Computers, and Communications.

He served as editor ofIEEE Electron Device Letters and editor in chief of theJournal of Semiconductor Technology and Science.

From 1990 to 1993, he worked at AT&T Bell Labs in Murray Hill, N.J., before joining Texas Instruments in Dallas. After one year, he left the company and joined Seoul National University as an assistant professor of electrical and computer engineering. He worked at the university at the time of his death.

His research interests included the design and fabrication of neuromorphic devices and circuits, flash memories, and silicon quantum devices.

Park authored or coauthored more than 1,200 research papers. He was granted 107 patents in Korea and 46 U.S. patents.

He received bachelor’s and master’s degrees in electronics engineering from Seoul National University in 1982 and 1984, respectively, and a Ph.D. in EE in 1990 from Stanford.

David Ellis Hepburn

Past vice chair of IEEE Canada’s Teacher-in-Service Program

Life senior member, 91; died 25 March

Hepburn was a strong proponent of preuniversity education and enjoyed helping shape the next generation of engineers. He was involved with IEEE Canada’s Teacher-in-Service Program, an initiative that aims to improve elementary and secondary school technical education by offering teachers lesson plans and training workshops. He served as vice chair of the program’s committee. He was honored for his contributions with the 2017 IEEE Canada Presidents’ Make-a-Difference Award.

He was an active volunteer for TryEngineering, a website that provides teachers, parents, and students with engineering resources. These include hands-on classroom activities, lesson plans, and information about engineering careers and university programs. He wrote six lessons, which cover transformers, AC and DC motors, magnetism, binary basics, and solar power.

While a student at Staffordshire University, in England, he was an intern at electrical equipment manufacturer English Electric in Stafford. Five years after graduating in 1952, he joined utility company Hydro-Québec in Montreal as a systems design engineer. In 1965 he went to work for consulting firm Acres International in Montreal. His first assignment there was with the design and construction team for the Churchill Falls underground hydroelectric power station, in Labrador, Nfld.

In 1969 he was tasked with helping to build transmission lines in Bangladesh that connected the country’s eastern and western electrical grids. He and his family lived there for two years.

After that, Hepburn continued to work on international projects in countries including Indonesia, Nepal, and Pakistan.

Following his retirement in 1994, he worked as a consultant for organizations including the World Bank and the Canadian International Development Agency. He also volunteered for the Canadian Executive Service Organization, a nonprofit that provides underserved communities worldwide with mentorship, coaching, and training in sectors such as alternative energy, forestry, and manufacturing. He volunteered on projects in Guatemala and Honduras.

Markus Zahn

Professor emeritus at MIT

Life Fellow, 75; died 13 March

Zahn was a professor of electrical engineering for 50 years. He taught at the University of Florida in Gainesville in 1970 and worked there for 10 years before joining MIT, where he spent the remainder of his career.

He researched how electromagnetic fields interact with materials, and he developed a method for magnetically separating oil and water, as well as a system that detects buried dielectric, magnetic, and conducting devices such as land mines.

He was director of MIT’s 6-A program, which provides undergraduate students with mentoring and internship opportunities.

Zahn, who was granted more than 20 U.S. patents, worked as a consultant for Dow, Ford, Texas Instruments, and other companies

He received bachelor’s, master’s, and doctoral degrees in engineering from MIT.

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The Inner Beauty of Basic Electronics

Open Circuits showcases the surprising complexity of passive components

5 min read
Vertical
A photo of a high-stability film resistor with the letters "MIS" in yellow.
All photos by Eric Schlaepfer & Windell H. Oskay
Blue

Eric Schlaepfer was trying to fix a broken piece of test equipment when he came across the cause of the problem—a troubled tantalum capacitor. The component had somehow shorted out, and he wanted to know why. So he polished it down for a look inside. He never found the source of the short, but he and his collaborator, Windell H. Oskay, discovered something even better: a breathtaking hidden world inside electronics. What followed were hours and hours of polishing, cleaning, and photography that resulted in Open Circuits: The Inner Beauty of Electronic Components (No Starch Press, 2022), an excerpt of which follows. As the authors write, everything about these components is deliberately designed to meet specific technical needs, but that design leads to “accidental beauty: the emergent aesthetics of things you were never expected to see.”

From a book that spans the wide world of electronics, what we at IEEE Spectrum found surprisingly compelling were the insides of things we don’t spend much time thinking about, passive components. Transistors, LEDs, and other semiconductors may be where the action is, but the simple physics of resistors, capacitors, and inductors have their own sort of splendor.

High-Stability Film Resistor

A photo of a high-stability film resistor with the letters "MIS" in yellow.

All photos by Eric Schlaepfer & Windell H. Oskay

This high-stability film resistor, about 4 millimeters in diameter, is made in much the same way as its inexpensive carbon-film cousin, but with exacting precision. A ceramic rod is coated with a fine layer of resistive film (thin metal, metal oxide, or carbon) and then a perfectly uniform helical groove is machined into the film.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor more robust, ideal for specialized cases such as precision reference instrumentation, where long-term stability of the resistor is critical. The glass envelope provides better isolation against moisture and other environmental changes than standard coatings like epoxy.

15-Turn Trimmer Potentiometer

A photo of a blue chip
A photo of a blue chip on a circuit board.

It takes 15 rotations of an adjustment screw to move a 15-turn trimmer potentiometer from one end of its resistive range to the other. Circuits that need to be adjusted with fine resolution control use this type of trimmer pot instead of the single-turn variety.

The resistive element in this trimmer is a strip of cermet—a composite of ceramic and metal—silk-screened on a white ceramic substrate. Screen-printed metal links each end of the strip to the connecting wires. It’s a flattened, linear version of the horseshoe-shaped resistive element in single-turn trimmers.

Turning the adjustment screw moves a plastic slider along a track. The wiper is a spring finger, a spring-loaded metal contact, attached to the slider. It makes contact between a metal strip and the selected point on the strip of resistive film.

Ceramic Disc Capacitor

A cutaway of a Ceramic Disc Capacitor
A photo of a Ceramic Disc Capacitor

Capacitors are fundamental electronic components that store energy in the form of static electricity. They’re used in countless ways, including for bulk energy storage, to smooth out electronic signals, and as computer memory cells. The simplest capacitor consists of two parallel metal plates with a gap between them, but capacitors can take many forms so long as there are two conductive surfaces, called electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that is frequently found in appliances and toys. Its insulator is a ceramic disc, and its two parallel plates are extremely thin metal coatings that are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are attached using solder, and the whole assembly is dipped into a porous coating material that dries hard and protects the capacitor from damage.

Film Capacitor

An image of a cut away of a capacitor
A photo of a green capacitor.

Film capacitors are frequently found in high-quality audio equipment, such as headphone amplifiers, record players, graphic equalizers, and radio tuners. Their key feature is that the dielectric material is a plastic film, such as polyester or polypropylene.

The metal electrodes of this film capacitor are vacuum-deposited on the surfaces of long strips of plastic film. After the leads are attached, the films are rolled up and dipped into an epoxy that binds the assembly together. Then the completed assembly is dipped in a tough outer coating and marked with its value.

Other types of film capacitors are made by stacking flat layers of metallized plastic film, rather than rolling up layers of film.

Dipped Tantalum Capacitor

A photo of a cutaway of a Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum metal. The pellet is made from tantalum powder and sintered, or compressed at a high temperature, into a dense, spongelike solid.

Just like a kitchen sponge, the resulting pellet has a high surface area per unit volume. The pellet is then anodized, creating an insulating oxide layer with an equally high surface area. This process packs a lot of capacitance into a compact device, using spongelike geometry rather than the stacked or rolled layers that most other capacitors use.

The device’s positive terminal, or anode, is connected directly to the tantalum metal. The negative terminal, or cathode, is formed by a thin layer of conductive manganese dioxide coating the pellet.

Axial Inductor

An image of a cutaway of a Axial Inductor
A photo of a collection of cut wires

Inductors are fundamental electronic components that store energy in the form of a magnetic field. They’re used, for example, in some types of power supplies to convert between voltages by alternately storing and releasing energy. This energy-efficient design helps maximize the battery life of cellphones and other portable electronics.

Inductors typically consist of a coil of insulated wire wrapped around a core of magnetic material like iron or ferrite, a ceramic filled with iron oxide. Current flowing around the core produces a magnetic field that acts as a sort of flywheel for current, smoothing out changes in the current as it flows through the inductor.

This axial inductor has a number of turns of varnished copper wire wrapped around a ferrite form and soldered to copper leads on its two ends. It has several layers of protection: a clear varnish over the windings, a light-green coating around the solder joints, and a striking green outer coating to protect the whole component and provide a surface for the colorful stripes that indicate its inductance value.

Power Supply Transformer

A photo of a collection of cut wires
A photo of a yellow element on a circuit board.

This transformer has multiple sets of windings and is used in a power supply to create multiple output AC voltages from a single AC input such as a wall outlet.

The small wires nearer the center are “high impedance” turns of magnet wire. These windings carry a higher voltage but a lower current. They’re protected by several layers of tape, a copper-foil electrostatic shield, and more tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They handle a lower voltage but a higher current.

All of the windings are wrapped around a black plastic bobbin. Two pieces of ferrite ceramic are bonded together to form the magnetic core at the heart of the transformer.

This article appears in the February 2023 print issue.

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