On handing in assignments on time

Now, while still waiting for assignments to be handed in from courses, thesis, etc., I stipulate a hypothesis (or whatever a mathematician would say):

  1. Let time point TA be the time that the examiner suggests as a submission date for an assignment.
  2. Let time point TB be the time at which the student finally hands in the assignment.
  3. Let time point TC be the critical time point at which assignment must be marked (as per the student).

Then, my hypothesis is

The ratio TC-TB over TB-TA will rapidly approach zero.





The transistor symbol

Together with Maple Martin I browsed through our group’s library and came across a couple of books by Prof. Kjell Jeppsson (from Chalmers University of Technology). One of the books, “Praktisk transistorteknik” (1965), triggered me – of course. Browsing through the pages, I realize that the transistor symbol he used in his figures looked unfamiliar to me. It was the 1965 version of the Swedish standard symbol for the junction transistor.

Where does the symbol come from? My short-story/interpretation.

So, in case you might be taking the course in analog electronics at the moment: this post aligns quite well with the topic we are currently reading. Take a quick glance at my impressionistic skills below. I have depicted the first point-contact transistor (to the left) and the “first” junction transistor (to the right). It is pretty obvious from where the – today, widely used – bipolar symbol comes. The symbol is found at the bottom left of the picture. Above that my redrawing of the famous Bell Labs photo. The v-shaped piece of plastic, on which the phosphor-bronze traces where applied, guides the emitter and collector to and from the germanium plate which is attached to the metal frame which the base in turn is connected to. The “housing” around the transistor is modeled by a circle around the lines.

To the right in the picture, we see a sketch of the junction transistor. A more homogeneous solution. From left to right we have the emitter, base, and collector. Here the currents go “through” the semiconductor whereas in the point contact transistor it goes on the surface (well, arguably, but true to a first degree …). Looking at the international symbol, it does not really make sense – if one has time to care about those kind of things. The Swedish standard institute (SSI) symbol, from 1965, is depicted below the junction transistor. It turns out to be a bit more of logic behind that one. The base “cuts” the emitter and collector and the current goes straight through the base. However, the symbol lost the battle.

Transistor symbols

Transistor symbols

I guess the thing was that the junction transistor was invented and patented quite soon after the delivery of the 1947 Christmas present in the shape of a point-contact transistor at Bell labs. Due to the more integrated nature of the junction transistor it was also a better choice for most users. In addition, the junction transistor has much higher gain (200 vs 20), was less noisy, and could take on higher power levels. (Not as high as for tubes which were even faster. In fact the point-contact transistor initially had a higher gain-bandwidth product.). Due to this rapid development, the old symbol made it into the books. There was no point in developing a new one (unless it was exported to another continent).

Feedback – a quick overview

Feedback is a very important concept in electronics, or systems, or biology, or … Well, feedback is important. Period. And even if we do not intentionally design with feedback – there will be feedback anyway. Through parasitic paths or through bias wires or common rails of different kinds.

Explaining (negative) feedback in detail – negative feedback is a positive thing – positive feedback is a negative thing – does not make sense here. There are essentially millions of resources out there going through all this.

Instead, in this post, I just present a picture that I did the other day. It compiles the four passive (well, …) fundamental feedback modes that you can expect to encounter. The four cases are essentially given by the dualities we have: Voltage/Current and Input/Output, i.e., 2 times 2 = 4 cases. The picture is there to illustrate the fundamental properties on a “low” level. As mentioned: there is so much, much more to dig into when it comes to feedback.

One can understand that H.S. Black had some work to do after he got inspired by Steinmetz. Steinmetz, btw, was also involved in the group pictures post the other day. They all seemed to know each other. (Speaking of that Mr. Black was also part of the team that coined the term “transistor”).

Anyway, for future quick-reference, here are four examples of feedback with some simple properties compiled in a two-by-two matrix. Beta is the feedback factor and H is the system transfer function. Some of the examples contain IV and VI conversion which in some sense obscures the feedback. I have indicated those – I hope.



Top ten cool group photos related to (mostly) electrical engineering

I’m a bit tired of pictures of football stars, politicians, and similar being identified as iconic, epic, etc. Yes, of course they are iconic: Reagan tears down walls and Kennedy lives in Berlin, etc. However, let’s go nerd and embrace ourselves and our community.

Master minds of the universe

A while ago I was at the D (Computer Science and Engineering) programme’s 40-year anniversary. John Wilander, from Apple, was there too, but unlike me he gave a presentation. He is a former D student at our university and also a former Ph.D. student at the Department of Computer Science. He talked about work culture in California and the way the engineers rule (in Silicon Valley at least..). People proudly stroll around with T-shirts: “I am an engineer”. That is less likely to happen here…

I got a bit inspired by that and wanted to evangelize a bit on top of that. So …

Here is my top ten list of cool group (arguably “group” for some of them) photos (arguably “photo” for one of them). But yet. Just imagine to stand there in the picture and the guy next to you is a Nobel prize winner, and the guy to your left and behind you. You’re a millionaire, but it does not matter, because the other guy is a billionaire, etc. I think you get the picture.

Behold: the top ten coolest group pictures of all time. And as usual – I do not claim any copyright on these pictures and I am also referring to the “original” source to the best of my knowledge and also credit them below the picture.

There is no special order of appearance.

  1. In the beginning was … Xerox

    We will start a bit slowly with the glimpse in the eye. However, people tend to forget Xerox from which – ironically – a lot of people copied technology… The mouse, the desktop publishing, and other things.

    For us in electronics engineering, we also remember Lynn Conway coming from the Xerox Parc facilities in Palo Alto. The Mead Conway revolution enabled a simplified understanding and option to fabricate chip for the “common-man”.

    In the center of the picture we have the hero of the group. The Xerox Alto machine, developed at the Xerox PARC, was one of the first computers to introduce the concept of a Desktop.

    The personal computer enters the world and we see computers with GUI and children are playing with the computer.

    [Link to Forbes]

  2. Steve Gates och Bill Jobs

    No comments needed really? The founders of Microsoft and Apple, a couple of future-to-be billionaires and philanthropists chilling in the stairs.

    This photo is taken in 1991 – a year when a 386 was da sh1t and the power-PC was discussed. Notice that during this time Jobs did not work for/with Apple. Instead, after he was kicked out in the mid 80’s, he founded the NeXT company. And as they chat, Jobs is not necessarily that future-to-be big guy. Notice that the operating system that he developed at NeXT (which was based on UNIX)later formed the basis of OS X, iOS and others.

    Even though we are today only some 30, 40 years into the computer era, is it fair enough to say that this is an iconic group photo? Well, I think it is. It shows that software is this the thing and it shows that design is also very important.

    [Linked to Melablog.it]

  3. Bell, Ford, and Firestone

    Bell, Ford, and Firestone are gathered around the American president in 1929. Why is this an iconic picture? (Bar the fact that everyone, but the president actually, are really, really famous). Well, we have a car manufacturer, a tyre and rubber manufacturer, and an electrical engineer (and inventor and much more). These people were among the most famous business men in the US at their time. They were also members of the exclusive Millionaire’s club.

    The interesting thing: Edison brought us the light bulb and other things. Mainstream electrical engineering becomes part of the new industrialization – equally important as cars and wheels.

    [From KineticBiz]

  4. Marconi, Tesla, Steinmetz, Einstein

    This picture is quite energetic. Not only brain power, but also electrical power is seen in the picture. Marconi is not in picture – in person. The people are however standing in front of a Marconi wireless station.

    The guy with the cowboy hat is a certain Prof. Einstein. The guy behind Einstein, to the right (for us), is not Nikola Tesla. (There have been some rumours about this picture). But since John Carson, the guy, is the inventor of single-sideband modulation (SSB) and looks quite much like the Serb, we will play with that thought for npw.

    More to the right, in the white suit, is Steinmetz. He was quite a prolific character of German descent. He took the name Proteus at arrival in America and then continued his career by contributing to the AC theory.

    There are some other famous people in the picture! For example Ernst Julius Berg – from Sweden. He has authored quite a few nice text books on electrical engineering that I plan to read some day. The soon more than 100 years old books are also available on-line.

    There are more people in the picture that you probably remember somewhere in the back of your head: Goldsmith, Sarnoff, and Langmuir (Nobel laurate). There is also Hull, the inventor of the magnetron among other things.

    [Used at Wikipedia, but found on cont.ws]

  5. Touching the sky

    This is a back-stage photo. It is the “green room” for the ground personnel (probably there is a NASA abbreviation for that…) supporting the astronauts traveling to the moon during the Apollo 11 mission.

    During the missions these guys were the ones pulling the threads and making things happen. These are the ones helping you to macgyver an air filter in space in case you would have a problem.

    We have a set of engineers with neck ties and characteristic 1960s glasses. They are roughly your grandfather’s age. Monitors on the wall also offer not only information on display, but act also as coat hangers and places for the umbrellas.

    (What about the guy to the left, standing over the engineers’ shoulders? No neck tie, a pipe, Steve Jobs-polo shirt! The 1970s is rapidly approaching. The right-most guy, sporting a more formal black suit, looks a bit disappointed or suspicious with the polo-shirt appearance.)

    [From Nasa]

  6. Von Neumann, Oppenheimer and a maniac

    To the right we have von Neumann. He’s quite easy to identify for us.

    The fifth from the left is Robert Oppenheimer, the physicist known from the Manhattan project and one of the inventors of the atom bomb. “Despite” his German name, Oppenheimer was actually born in the US. He studied in Europe, during his Ph.D. studies, together with some of the greatest minds during that time.

    Far behind, we have another quite famous character: the MANIAC. (No, not ENIAC). The mathematical analyzer, numerical integrator and computer was developed by von Neumann and the name was chosen to stop the trend of silly computer names (UNIVAC, ENIAC, ABC, …)

    An interesting note: von Neumann worked at his best when listening to loud music (especially German march music…) and being in noisy enviroments. This annoyed his colleagues quite much. Oppenheimer ended up in the post-war anti-communist American age of fear and got discredited. (But pardoned by Kennedy in 1963 when Oppenheimer was awared the Enrico Fermi Award. Interestingly the Award was first given to von Neumann in 1956 which further links the two.).

    [From Princeton]

  7. Go out and save the world!

    Imagine this conversation in the 1940s England:

    -“Hah, today I mowed the lawn and gave the flowers some water! Hard work for a busy man. What did you do, honey? Pedicure?”
    -“Nothing special, I just cracked some codes, intercepted a few messages, shortened the war by a few years, saved the lifes of say 3-4 million people. Just an ordinary day for a 1940s housewife.”

    Below we find a group photo from the Bletchley park. It seems to be a sunny day in England and a set of codebreakers seem to enjoy standing there to be prepared to save the world.


  8. If you can carry that, you can carry this…

    If you are an imperial super power, rule over some 75% per cent of land and where the sun never sets then you better have some control over your colonies. There are stories of England being defeated in battles just because it took 40 (!) days to carry the messages back to London. This could not stand. Morse proved that long distance telegraphy could be done across the US continent. And if it can be on land, why not under the sea? Why not pull a cable 2200 miles (3000 km, or going from the southern tip of Sweden to its northern tip – and back again) across the atlantic and then send messages that way. In 1858 that sounded like a good idea, just before the North American civil war.

    So, off we go. Construct a 2200-odd mile long cable and gently drop it on the sea bed. (Gently was the key word, since the cable snapped quite a few times while placing it). The depth at the deepest places was as much as 14300 feet, 4400 metres. Pulling a cable across a 4400 metre high mountain on-land would in it self be an achievement.

    Anyway, the cable arrived in the end to the other continent and the first messages could be transmitted on August 16, 1858. It was a message from the queen to the US president. It took 17 hours to transmit – at a fantastic speed of 0.1 words per minute. Just imagine the frustration while hitting the key. The cable did not last long since one of the operators came up with the master plan to increase the voltage to speed up the messages a bit. The cable burnt up somewhere on the ocean border.

    The voltage, btw was in the order of kilovolts, and the resistance was a total of kilo-ohms. The current return path was through the ocean itself (and earth).

    In the picture below (it is not a photo, it is a painting. And a very staged one too: even the painter is in the far background of the picture – but still…), we have among others Mr. Morse (Morse code, anyone?). A bunch of long-bearded guys with the mindset to connect the world (and make some money on the deal). Cyrus Field, even though he connected the continents, however, ended up in bancruptcy at the end of his life.

    [From New York Stated Educational Department]

  9. Fairchild semiconductor

    These guys we shouldn’t forget either. They are the traitorous eight leaving Shockley “alone” in his lab. They are chilling in the foyer of the Fairchild Semiconductor venue.

    The photo is taken in the 1950’s. The men have slick glasses, neck ties, and suits. Back then this was the standard equipment for engineers. No pocket protectors nor repaired glasses.

    Anwyay, here they are gathered and prepared to revolutionize the world and probably change it forever. Speeding up the process of microelectronics engineering has today brought us more or less everything younger than 30 years that we see around us.

    Among others in the picture we find Robert Noyce (who effectively founded the Silicon Valley), Jean Hoerni, and Gordon Moore. Knowledgeable people that have influenced us all.

  10. Alea Jacta Est

    This is probably the coolest of the coolest guys in the hood. Only guys? Well, not only…

    In the front row, we have a lady who slipped into the picture to marinate in the sun together with all the professors and gentlemen. Is she there just to get some attention?

    Well, this is Marie Curie… She attended all of the Solvay conferences until her death. And she got the Nobel Prize too – twice! That’s more than the others got. She simply rockxz. (More than half of the people in the picture have got or will get the Nobel Prize).

    During the Solvay conference in 1927 electrons and photons were discussed. Einstein stated his famous quote when discussing the Heisenberg uncertainty principle: “God does not play dice”.

    Besides Einstein and Curie, we have again Langmuir but also Planck, Lorentz, Bohr, Dirac, Schrödinger, Pauli, and Heisenberg. Quite a team!


Crystal Triode

The name transistor was not coined immediately after it was discovered. “Hey, look! It is an … a… errh… transistor!”. Instead there were other alternatives [from a Bell Labs memorandum]: “semiconductor triode”, “solid triode”, “surface states triode”, “crystal triode” and “iotatron”. (I like the last one… it’s futuristic.)

Reading those old books again: analogies

I am once again refurbishing my room to get some more air. These old gems pop up. Books from the beginning of the 1900s (which I have discussed before in previous posts) that describes electricity in a beautiful manner. Hand-drawn, explicit drawings illustrating how for example electricity can be seen as a closed water system. Width of pipes illustrate resistance. Pumps illustrate current sources and water tanks (or centrifugal pumps) illustrating voltage sources.

Parallel and series connection of resistors are illustrated by pipes and gives the reader a good idea of what is happening also in electrical networks.

The water pipe analogy sort of ends there, but at least a good starting point. Good analogies are further described here: by Dr. Douglas Wilhelm Harder. Here is it shown how capacitance can be generated using a flexible membranes in the pipes. The inductor can in turn be modeled as a rotating wheel (turbine-ish). Follow the link and notice how also an LC tank can be modelled. And the brilliant Water-emitting diode (or fountain-emitting 🙂 as coined by Dr. Harder. ).

Back to the topic: transistors

So, resistor [check!], inductor [check!], capacitor [check!], voltage source [check!], current source [check!], and diode [check!]. Analogies done. What about the transistor? Well, that’s sort of already done and in some sense quite intuitive: the tap, or a water lock or valve driven by another stream of water. These analogies have been around and an animated version is found here:

Looking a bit deeper into the transistor. These two pages from the 1954 book “Crystal rectifiers and transistors” edited by M.G. Say (Whitefriars Press Ltd.) which I have copied and reproduce here without really asking for permission. Fingers crossed that no one gets upset… In turn the pictures have been reproduced by permission from the RCA Photophone Ltd.

This page shows a neat description of the point-contact transistor and the junction transistor. Notice the “subtle” differences in the way the transistors are constructed. Also notice that these transistors pre-dates the planar process (1959) and the mesa transistor (1958).

To the left we can envision how a small current (well, a certain voltage must be applied and a varying voltage creates a current-flow) applied on the left-hand side – between the emitter and base – “pulls” electrons through the collector effectively creating a large current and amplifies the voltage. In more recent text books, these currents are just illustrated by large arrows and it gets too abstract IMO.

People do not tend to have the time to draw small round circles anymore… hmm…

The point-contact transistor was the one Bardeen, Brattain and Shockley demonstrated during Christmas 1947 (and published in June 1948). We also find the junction transistor at the bottom of the page. Perhaps a bit more complicated to decode the picture there. The junction transistor was invented by Shockley in 1950 (i.e., just four years old in the printed version of this book) and the operation is fundamentally (well…) different from the point-transistor.

The right-hand page shows the physical implementations back then (i.e. the “Diagrammatic sketches”). A bulky device encapsulated in a plastic case. The pictures quite clearly illustrate the physical differences between the point-contact and the junction transistors.

The junction transistor was more reliable (to the cost of more semi-conducting material) and could be commercialized much more quickly.

More physical descriptions of the implementation of the point-transistors are given in the book: “practical” implementations that could be integrated with the existing systems back then. (Only 60 years ago…)

So the name?

There seems to be a few different suggestions to the term transistor and I guess people’s memories tend to fail when it comes to remembering who coined the name to one of the greatest inventions in mankind. John R. Pierce is attributed to the coining of the term and as per his description (my interpretation): “there should be something with ‘trans’ in it from transconductance. It should align with the rest of our product portfolio, i.e., -istor: Transistor.”

All other explanations just sound too complex… Still though, iotatron would be a cool name!

At Bell, they actually voted for the name and there is a memorandum (where there is yet a etymological description of “transistor”) with 25-odd names on. The list included, of course, the above mentioned Shockley, Bardeen, Brattain, and Pierce, but also other giants like

  • Frank Gray (the Gray code),
  • CB Feldman (bandwidth-vs-transmission performance, i.e., Shannon’s aid to find the channel capacity),
  • ME Mohr (designed the first-ever quantizer)
  • JO Edson (contributor to the pulse-code modulation technique for speech coding)
  • WE Kock (developed some of the first electronic musical organs)
  • JN Shive (inventor of the Shive wave machine – see below, which elegantly illustrates travelling waves in electronics)
  • [Edit, how could I forget the target of one of my previous posts] HS Black (inventor of the negative feedback amplifier)

Competence hubs: Micro/nanoelectronics and Integrated circuits and systems

Workshop at the Nordic Forum

I have previously posted a concern about, for example, why so many students are not studying electronics. Why isn’t it interesting? What are we doing wrong? Similarly, the trend where fewer and fewer companies working with “core electronics” (you know what I mean) is still going strong.

Competence Hubs

Anyways, the short story: Vinnova, Sweden’s Innovation Agency, gave us a grant this Spring to investigate the possibility to form a competence centre within the topic “Micro/Nanoelectronics” or similar. Adopting the EU list of key enabling technologies (KET), Vinnova appointed a set of competence hubs to cover fields like “printed electronics”, “embedded systems”, “photonics”, and “power electronics”, and many others. The hubs were then given the task to scan Sweden and look for knowledge gaps, missing links in the value chain, activities and potential new activities within the field of the hub.

Our group at Linköping university got a hub together with Mid-Sweden University. We will focus a bit more on the ASIC-side, integrated electronics. Mid-Sweden University will cover electronics for sensors, sensors, and nanoelectronics. Mid-Sweden University will also take the role as coordinator of the two hubs.

2015-10-20 10.26.32
Prof. Jan Y Andersson (Mid-Sweden University) informing about the micro-nano electronics area referring to the “More-than-Moore” and “more-Moore” concepts. Prof. Christer Fröjdh (also Mid-Sweden University) preparing to give a presentation on key enabling technologies and cooperation concepts between industry and academia.

Nordic Forum, October 2015-10-20

We met yesterday at the Nordic Forum in the melting pot of electronics in Sweden (Kista). Roughly 40 people from most corners of Sweden (not Öland, my home island though — wonder why …). We first gave presentations on the objectives of the competence hubs and potential tasks for a future competence center. The competence center does not necessarily need to be a physical location, even though it needs to be a single coordinator in the center.

We had a set of workshops with the attendees and there were nice discussions and a few faces from my older days in industry. We discussed if a competence center is required, what it should do, what the benefits could be for the SME’s, how a 10-year plan (!) should be maintained given that that is a veeery long time for a start-up (or any enterprise for that matter).

We will compile the material in more detail. One of the deliverables from us, as a competence hub, is a detailed, written report to Vinnova in May 2016. We will intermediately compile comments, findings, and news and send out to the interested parties and stakeholders as well as publish on social media (like this one …)

Some comments

Some personal scattered comments from the workshop.

First, I have to thank Jan-Erik Lennefalk, a nestor in the industry and a colleague from Sicon, for a great idiom – which I haven’t heard before:

“Som de andra har jag gjort min elektroniska värnplikt.” or
“Like the others I’ve done my electronic conscription.”

Simply meaning that you have worked for Ericsson for a while. Or as someone said: “It was much easier before, then everything was about communication circuits and what was good for Ericsson was good for Sweden.”.

It was in general a good spirit in the meeting, I believe – possible due to the free lunch (there is no such thing as a free lunch, since we also harvested information from the attendees that we will use – almost like Facebook) as also some of the others met with previous colleagues and acquaintances.

SME’s find it difficult, with all right, to commit for longer periods of time. They need the instant benefits: what’s in it for me? what’s the added value? A coordinating role for the competence center could provide information on how to e.g. share lab resources, equipment, etc., for the SMEs.

The perhaps obvious by now: many saw a lack of resources in Sweden: lack of new engineers coming out and also the observation that even though some companies fold, quite a few of the engineers find job very soon after, implying a demand… still.