About Hans Kretz
Born in 1930, Hans Kretz studied in Vienna, where he built cybernetic models that demonstrated conditioned learning. Employed by Philips Austria, he first developed transistorized TVs before becoming the chief manager of the applications laboratory. In the interview, he discusses the landmarks in Austrian electronic progress, in particular the move to transistors and then to integrated circuits. He cites a number of Austrian inventions, including an avalanche detection device and a hearing aid. He also discusses the advent of automation in producing components, the transition from tubes to transistors at Philips, the development of microprocessors and the evolution of passive components. He ends with the mention of an inexpensive laser diode invented at Philips Austria that became part of their laser-disc players.
About the Interview
HANS KRETZ: An Interview Conducted by David Morton, IEEE History Center, 25 July 1996
Interview #283 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.
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It is recommended that this oral history be cited as follows:
Hans Kretz, an oral history conducted in 1996 by David Morton, IEEE History Center, Hoboken, NJ, USA.
INTERVIEW: Hans Kretz
INTERVIEWER: David Morton
PLACE: Vienna, Austria
DATE: July 25, 1996
Education and Cybernetics
I was born 1930, in Linz, in Upper Austria. After primary school and high school in Vienna I went to study telecommunication and electronics. In German we said "technique of low currents," a rather old-fashioned expression. I studied at the Technical University in Vienna, and graduated in 1960 as Diploma Engineer. My thesis was on a Cybernetic subject called the "artificial turtle." It was a model of neuropsychological functions. This is the more scientific description. I was engaged about two years to talk with a neuropsychological physician from Hungary. He told me what more or less simple animals are doing if certain stimuli are applied. And I made a block scheme out of his different remarks and descriptions. And afterwards I made the technical realization in the form of a small battery operated self-running model. It operated on different preconditions. I "taught" the model to build up so-called conditioned reflexes, as Pavlov's dog has done. From time to time it would "forget" something it had learned in previous periods and it could be shocked by strong stimulus, and so on. Afterwards I built two models. One for the young Hungarian who immigrated 1960 to the States and demonstrated his model at MIT, for instance. And people were very impressed but said the model was too small.
What was his name?
Andrew Angyan. Later on, he was a physician in Los Angeles. Now I made another model for my university, the Technical University of Vienna. This model later on came to the Technical Museum of Vienna where my model can be seen together with a picture and a short description of myself. In this technical museum you can also see another cybernetics thesis, e.g. a model of a "mouse in a maze" after the principle developed by the Greek myth of Ariadne's thread, and also the famous "Mailuefterl." It's the first fully transistorized mainframe computer in Europe. Made at the technical university under the chief management of Professor Heinz Zemanek, a pioneer not only in Austria but at least in Europe of cybernetics and as well in computer questions. One of the most experienced in that respect. I myself was half a year afterwards a scientific assistant in this scope at the university. I had lectures in London at the Royal Academy and in Karlsruhe at the Nachrichtentechnische Gesellschaft. And later on there were several publications on this specialty. On the other hand my job meant to handle most modern topics.
Philips and Transistorized TVs
After my occupation or employment at the Technical University I looked for practical job in industry. And I went to Philips, Austria, where they were looking for an application engineer for the electronics company.
My job was to handle most modern topics of technical evolution, to be aware of the state of the arts, so to say. It was a challenge, and I was very interested to get this employment, especially the application of electronics. It was my job, for instance, with semiconductors, later on with integrated circuits, operational amplifiers, and microprocessors. We divided our tasks in consumer applications and professional applications. My first task in 1960 was the construction of a semiconductor TV tuner for 200 megacycles. After some weeks I had success; it worked. And step by step I built from 1960 to 1961 one of the very first transistor TV sets in Europe. It was the intention to use this model to demonstrate transistors to each of Philips' customers. And we intended to introduce our components in the television manufacturing industry with that kind of work. TV customers in Austria were for instance, Minerva, Kapsch, Ingelen, and some smaller companies. Today we have only one, Grundig. A big TV set industry, but only Grundig. The others are gone. In '63 I made a fully transistorized large screen TV set with a19-inch screen, and I also went to the customers for introduction of this new technique.
In '64 I became chief manager of the application laboratory with up to eight employees responsible for consumer and professional activities. Later on I was responsible as well for quality aspects of using our electronic components. We had to make agreements with our customers, and I was as well in a standards organization for international harmonization. So that we increased our quality level from year to year, as it is standard today. For instance one slogan was PPM, parts per million, and no failures, i.e., zero defects was the goal we had to reach. And moreover I have had contracts to technical schools and universities. In both directions we made available our services and information and it was a quite important activity. I myself seemed to be the technical backbone or consciousness of our commercial selling division at Philips, and it was very hard work to do because the responsibility was a quite big one.
Austrian Progress in Electronics
I would like to mention some highlights we had in Austria during the last 40 years. In 1952 our Austrian company Stuzzi, a small but very effective company, made its first tape recorder. Three years later in '55 we made in our laboratory the first transistorized record player amplifier with output power of 200 milliwatts. In the following years, 1956 to '59, we made the fully transistorized mainframe computer, the first one in Europe, called "Mailuefterl," which means a May breeze, because it was not so fast as others in America like the "hurricane". It was built at the Technical University under the chief management of Professor Heinz Zemanek. The computer had a pulse frequency of maximum 132 kilocycles. It was quite large — about three by three meters and had a memory on a rotating cylinder of half a megabit. And a special activity as I mentioned at this Technical University was cybernetics with the "artificial turtle" the "mouse in the maze" and a chess playing machine and the composing machine and so on.
Back to the industry, in '56 we had the first transistor radio ever made by the industry. The company, Ingelen was the first in Europe in series production. Yet it had two tubes for the RF stages and there was a DC converter necessary for the 45 volts supply for these two tubes. And we also developed a four watt amplifier for use in car radios. Certainly a milestone of our developments was a 14 inch fully transistorized TV portable we made in our laboratory in 1961.
Another interesting step was the introduction of integrated circuits in the year 1964, where we came up with the OM 200, three transistors and two resistors in a tiny chip of two by two millimeters in size for hearing aids. Viennatone used it in their hearing aids for almost 25 years, and it was the longest-lasting integrated circuit in production for this purpose. Viennatone was also busy with artificial and electronic controlled arms. They made it possible to replace a lost arm with an artificial arm, controlled by the muscular voltages of the man who lost his arm.
"Line Wobbler" and Patent Policy
- Audio File
- MP3 Audio
Electronics in Graz and Vienna
Other highlights we had in Austria were at the universities in Graz and in Vienna. In Graz we had very interesting activities with avalanche warnings in the mountains. We made small electronic sets for the rescue of people who might be covered by a snow avalanche while skiing or mountain climbing.
Another pioneer in electronics was Professor Leopold of the Technical University in Graz who made very high sophisticated but cheap density measuring equipment, which were able to measure densities of liquids up to six or seven decimals exactly. You could measure the quality of oil while it was flowing through a pipeline. It was very important for the oil business to know which charge is coming and which is leaving. And this was only one application of this density meter. Of course in every case where you wanted to measure density as exactly as this, there was interest throughout the world, and it a good selling device. It was produced by the Graz company, PAAR. And the same company made temperature measuring equipment for temperatures up to 500 degrees Celsius, I think, with a very high accuracy, but with no computer compensation or anything like for the temperature sensing element. It only used simple operational amplifiers, but the ideas behind came from Professor Leopold, and it was a success as well throughout the world.
Now I would like to mention the Vienna University. There we have the division for general electrics and electronics, with the chief being Professor Paschke. One of the highlights was that they implanted electronic hearing aids. This was invented by a man and his wife named Hochmaier, who made a system with a microphone, an amplifier and a probe implanted in the skull behind the ear. And with the help of this system it was possible to make people hear again who had lost their hearing abilities completely. The apparatus, especially the probe in the skull, gave currents from a selective amplifier to the nerves behind the ear and it was possible to hear again. Not so good of course, but it was possible.
Now back to the industry in Austria. We had for instance in the later years a very powerful company called Frequentis, which had for many years developed air traffic control systems, for instance the first one for Vienna, later on to Stockholm, Frankfurt, London, and I know there are a lot more airports all over the world using this system, which has to be responsible for the security of the air traffic. It was a very high sophisticated system, and this company had much success in that area. While this was only a short description of what has happened in Austria.
Production and Automation
I have a couple of questions.
A couple of specific things. In your experience at Philips in components, were you involved in the manufacturing end of it?
From time to time yes, especially if there were application mistakes by our customers. I had to go with the customer to the factory and to explain what had happened at the customer's plant and what had to be improved at the factory using the components. And I had to make it clear what had to be done to get a good product.
Were there important changes during the period you were there in production technologies? I'm thinking of things like automation?
Certainly. Not only related to the production of components, but also to the set makers. For instance we delivered large quantities of picture tubes to Grundig, and we were the first in Vienna to introduce robotics for unpacking the picture tubes and to put them on the belt. And if you go to Grundig today, there are so few people working and so many robots! We in Austria were even ahead of Germany. It's really quite of interest. But it's self evident that in the technology of producing components there was a very great pressure from the set makers for improvements of components and circuits. We sometimes developed a new device, and shortly after we brought the first samples to the customers, they wanted another thing more recent, more modern, and therefore we lost a lot of money for being not as fast as small companies. That is a pity, I must confess. On the other hand it was possible for us to make mass produced products, such as small loud speakers for earphones and for telephones, at a fully automatically-working factory in Vienna, so cheap that we could sell millions and millions at a good price that was competitive around the whole world.
Transition from Tubes to Transistors
You say you, it sounds like you were also there at Philips during the transition from tubes to semiconductors. Or was that, did that happen before you got there?
It was at the time when I was employed with Philips, from '60 to '91. In the '60s we went from tubes to transistors and later on to the integrated circuits. First of all we had to use the components we got from the factory, and there were only low frequency transistors for low power, as I mentioned. The phonograph amplifier with 200 milliwatts for portable radios, today it seems ridiculous, but it worked and it was possible to operate with small batteries or even in the car. On the other hand, we had tubes for higher power for industrial applications for welding machines, and so they never had been followed by semiconductors because the tubes did their task very well. Another example is transmission tubes. We had them in powers up to hundred kilowatts and so, it's impossible to make that with semiconductors. And one advantage of the tubes was their robustness. They could stand very high overloads like lightning voltages, or heavy currents. Semiconductors were very sensitive to overloading. And it lasted about twenty years until we learned to make them less sensitive to electrical overloading. A certain new area became successful when we changed from Germanium to Silicon. These transistors were able to stand higher temperatures and to amplify higher frequencies, and later on the technology of diffused layers was so highly developed that we could make not only very good transistors and diodes but also later on proceed in developing integrated circuits.
You mentioned earlier that Philips started with point contact transistors. How long did they make those?
I think this was only for two or three years.
This was probably before your time there?
Yes, this was at '51 to '53 I guess. And one year later, we had planar transistors with a alloy diffusion, we were pioneers. These alloy diffusion transistors were able to amplify frequencies up to FM, about a hundred megacycles. And this was a big breakthrough in the development of high frequency components. We could forget the tubes and then the high voltage batteries or DC converters. It was a big step forward.
You mentioned some microprocessors. Could you tell me about how Philips got into that area?
Our opportunity to get into this area was to make a joint venture with Signetics in the United States.
But by that time hadn't Philips been making integrated circuits?
Well, but no microprocessors.
But no microprocessors.
And with Signetics we were able to have this product in our range and lots of other professional integrated circuits in the digital and the analog field. And it was a big step to professional applications. But the success of our first microprocessors, the ones that came from Signetics, were not as good as we wanted because the single chip processors came from the competitors and used bipolar technology, and we had difficulties getting the right product at the right time. But later on we developed and built integrated circuit factories in Holland and in Germany, and changed the technology to CMOS — MOS technology with lower losses and better performance, and so we regained our market position. And we were very successful for instance in telephony where low current and low power are necessary as well as in consumer electronics. We were very successful. When you ask about big computers, Philips was in this field, but a lot of the parts came from our competitors.
Why was that?
It is not possible to make all things well at the same time. Philips is a big company, but the diversification was from time to time too widespread. And you should do certain things as well as possible and not to try to make all things at the same time. But we had our strengths, for instance in the consumer electronics, e.g. TV sets. All over the world they use Philips integrated circuits because we had, with the help of the German colleagues, an advantage in knowledge, quality and special circuitry connected with TV for instance. You can find them everywhere. And afterwards we went to the Far East for instance to make the chips cheaper, but not only the integrated circuits as well as other parts, like picture tubes.
We haven't talked too much about passive components. That's a field that historians don't pay much attention to. Was that a field that changed much during the period you were there?
Certainly. Resistors for instance changed from wirewound to film resistors with high stability and high power capacity.
What is a film resistor?
Metal film. A cylinder of ceramic and a metal frame on the cylinder, deposited by physical ways. On the other hand, later on we developed, for instance, surface mounted devices. There are many of them. We have discrete resistors, capacitors and so on. We used solid electrolytics instead of wet electrolytics. These are very good for low leakage currents, long life and smaller dimensions. The demand increased for lower voltages and high capacities in contrary to the high voltage electrolytic capacitors that were common when we used tubes. We went to lower voltages and to smaller dimensions in accordance to the requirements of integrated circuits. They need low voltages, five or six volts or less, at low currents, and so the resistors and capacitors could be smaller. But there are not only these two passive components. We made, for instance, every kind of coil parts. A speciality of Philips was the core material, the Ferroxcube, a very sophisticated material for the cores of different coils up to antenna coils or high power coils for transformers for high frequencies and so on.
Another very important area is the field of sensing devices. Mostly they are passive. For instance for measuring magnetic fields, or even light, we had this so-called light dependent resistors for many applications. For controllers for heating, flame control for instance. We have the important field of resistors which are temperature sensitive which change their resistance dependent on temperature.
When or what are those used for?
The first ones are resistors with a negative temperature coefficient or NTC. Perhaps you had a tube that has an inrush of heater current when the set is switched on, so that the heater current in the tubes was too high. In tubes sets where the filaments are in series, we have to reduce the inrush of current, so we put in series NTC resistors to lower the inrush current to a normal level and after the NTC gets warm, it lowers its resistance and inrush current is not a danger for the heaters. On the other hand we have the PTC, which is a resistor with a positive temperature coefficient. We use it on color TV sets. We have to demagnetize the iron mask, and to do that we have to generate a high electromagnetic field falling gradually to zero to demagnetize the iron mask behind the screen of the picture tube. In series with the mains is the cold PTC, causing a high inrush current. After it gets warm, it will lower the current down to very small levels. And with this current you can, by help of a coil, demagnetize the iron mask. Another interesting application of PTC's of which we sold many millions was their use inside hair curlers. You can put them directly on the mains, and the temperature will remain constant in this tube. What is in it? A PTC. A self-regulating PTC which has a working point where the temperature will be constant. Proper isolation makes it very cheap and effective.
These things don't oscillate above and below the working point?
No, no. It works continuously. It's a fixed working point delivering a constant temperature. Certainly if you put it into water it will react to that. But for curling purposes it's the ideal component. We had an manufacturer in Vienna who made the curlers in Hong Kong because of cheap labor costs.
I know Philips has been very big in laser disks. Did your company make any of the laser equipment?
This is a good question. My former chief manager in the laboratory, Mr. Forsthuber, in the 1960s went to Eindhoven to move into the education field. And by the way he invented a cheap technology for making these laser diodes for mass production. It was his idea. Later on Philips made laser diodes in high quantities and made their own laser disc players, and I think was one of the first who made the video long-playing disc for short films or for interactive video display, for tourist bureaus and so on. So you can "walk" through the city and look different places and pick out your special interests. It's quite funny. And Philips was very successful in this area.
What is the key to an inexpensive mass produced laser diode? How are they made?
I don't know so much about it, but I think everything which has to be produced very cheaply has to be made self-aligning. Technology has to be developed to bring out a self-aligning optimized product. And how that is made I cannot say. But I know that they were very successful in this respect. And the principle to make pits on a plastic disc with high quality demands is very ingenious. The next step is certainly to make it with a magnetic disc in connection with laser diodes for repeated recording and replay to make tape recorders obsolete in the future.
Those are all the questions I have. Do you have any other comments you'd like to add?
Let us stop.
- 1 About Hans Kretz
- 2 About the Interview
- 3 Copyright Statement
- 4 Interview
- 4.1 Education and Cybernetics
- 4.2 Philips and Transistorized TVs
- 4.3 Austrian Progress in Electronics
- 4.4 "Line Wobbler" and Patent Policy
- 4.5 Electronics in Graz and Vienna
- 4.6 Production and Automation
- 4.7 Transition from Tubes to Transistors
- 4.8 Microprocessors
- 4.9 Passive Components
- 4.10 Laser Diodes