Featured Engineer

Interview with Max Robinson

Max Robinson

Max Robinson - Retired Professor of Physics and EE, Now Having Fun with Tubes

May we ask you about your blindness?

Yes. Normally I don’t bring up the subject especially in email exchanges but my vision, or lack of it, has shaped my life and my career.

How did you lose your vision?

I was born with cataracts. That’s no big deal today but in 1940 it was a very big deal. The fact that my parents were dirt poor farmers didn’t help any. I won’t go into all the details but I accumulated 8 operations from age 6 months to 11 years. A detached retina left me with a blind right eye and 20/800 in my left.

How are you able to use a computer, read books, etc?

20/800 isn’t very much vision. For those who may not know it means that I see at 20 feet what I’m supposed to see at 800 feet. With a lot of magnification I can see the computer screen and read the text in books, provided the publisher didn’t skimp too much on font size. I can use the mouse but reading text on the screen is rather tedious and slow. To overcome that limitation I use a software package known as a screen reader. It converts the text to synthesized speech that comes out through the sound card. Also I was taught touch typing starting in the third grade. My vision seems to be deteriorating as I grow older. It was easier to read software manuals 20 years ago than it is today. Electronic magnifiers have made up for this to some extent. Vision as low as mine is very difficult to measure with any accuracy.

How did you find a job? Was it difficult?

All blind and visually impaired people have difficulty finding employment. The personnel director imagines him or herself doing the job with his/her eyes shut and concludes that it can’t be done. Seldom if ever is the potential employee given a chance to show what is possible. Those who have been blind since birth or from an early age have undergone a good bit of brain rewiring. Parts of the brain that usually process visual information become reassigned to process oral and tactile information. This is the basis of the commonly held and wrong belief that the blind have better hearing. In audiometer tests the blind do not score any higher than the sighted of similar age. The transducers are the same but there is considerably more processing power behind them. Also the blind have acquired many skills either by experience or training. These skills range from just getting around without bumping into things to soldering by touch.

There is still a lot of blatant discrimination but after I graduated there was a lot more than there is today. I was not allowed to take the PE or the GRE. I was admitted to graduate school on the basis of an oral exam before a committee of EE faculty. I had a friend from my home town who was a researcher in the radio astronomy group in the physics department. I began to cultivate this contact and by doing some volunteer work was able to demonstrate what I was capable of. I included in my master’s program a minor in astronomy to strengthen my credentials in this area. Upon graduation I was hired immediately.

The U of F radio astronomy group was listening to static from the planet Jupiter in the dekametric wavelength range. In an attempt to resolve the source they had set up a system they called post detection correlation interferometry. They were using Collins 75S1 ham receivers set to SSB mode and I pointed out that they were not envelope detecting but heterodyning down to the audio range. If they could make the conversion oscillators coherent they could do very long baseline interferometry. The department head balked at buying us a cesium standard but wanted a demonstration project with quartz oscillators to prove the concept. It fell to me to design and build the new coherent oscillator receiver tuned to 18 MHz. We started out with a 1e-9 quartz standard and the concept proved out. Calculations indicated that we needed a baseline of at least 5000 miles and longer if possible. The department already had a branch observatory in Chili and plans went forward. Unfortunately political instability in Chili put an end to the project before it ever got off the ground.

How did you get hired at Western Kentucky University?

Frank Six, who was a graduate of the U of F program, had recently been appointed head of the department of physics and astronomy at Western Kentucky University in Bowling Green, Kentucky. He wanted a Jupiter observing station to expand the possibilities for undergraduate student projects and master’s theses. I was sent to help him set up the station. I recognized this as an opportunity. This was a young dynamic department with a bunch of newly minted PhDs who looked like they could go a long way. Once again I was able to demonstrate what I could do and when I asked for a job interview they were delighted. Ethically they could not initiate the process but once I did the process went into motion. I was offered a considerable increase in salary and I would be the top dog instead of third in line as I had been at U of F. I made the jump and have never regretted it. I retired from Western in 2001.

How did you get into electronics/ engineering and when did you start?

Ever since I can remember I was always curious about how things worked and that included radios. We got our first TV set when we lived in Iowa. I guess I was 10 or 11 years old. The one and only station was WOI in Ames, the station of Iowa State University. In the evening it broadcast entertainment programs from the 4 networks. Yes, there were 4 back then but, instead of Fox, the fourth one was Dumont. During the day the station aired educational films. One was “How a Vacuum Tube Works”, including animation showing the electrons moving from the cathode through the grid to the plate. I was hooked.

Shortly after that we moved to Florida where I befriended a couple of boys who were also hooked on tubes. We built crystal sets, one-tube radios and took radios apart and put them back together. Sometimes they even worked afterword.

My interest in music led me to get an electric guitar and a tape recorder when I was about 15. The tape recorder stopped working and there wasn’t a TV shop in town who knew anything about them. This was 1956. To my parent’s horror I took it apart and succeeded in fixing it. Then I got a ham license which opened up a whole new world of circuitry. I still hold the same call sign K4ODS.

In 1960 I entered the University of Florida to major in electrical engineering. I graduated with a bachelor’s degree in 65 and a master’s in 66. I minored in astronomy which was important in securing employment as described above.

What are your favorite hardware tools that you use?

Now that I am retired I no longer have access to a university laboratory. My test equipment has to be self-financed. I have a lot of Heathkit test gear which can out perform specifications if carefully calibrated. I saved up my pennies and bought a Tektronix TDS2012 scope. My next-best instrument is a Hewlett Packard 334A harmonic distortion analyzer which I bought off eBay.

What are your favorite software tools that you use?

My most often used software tools are LTSpice and a drawing program I wrote myself which I modestly call MaxCAD.

What is the hardest/trickiest bug you have ever fixed?

I should begin by explaining my position at Western Kentucky University. I taught physics and electrical engineering part time and the other part I was the science college electrical engineer. That meant that whenever a faculty member had an electrical or electronics problem in their research labs I was called in.

Back in the 90s I received a call from a member of the chemistry department who had bought an automatic sequential analyzer with a computer interface for logging data. The package was supplied by a very small and possibly fly by night company. Included in the price was a copy of Lab Tech Notebook, a data acquisition system. Lab Tech is no longer in business although they were an honest and reliable company while they existed. Not to be confused with the other company which shall remain nameless.

I was very familiar with the Lab Tech system having used it on another much larger research project which I will cover later. Lab Tech is a graphically programmed system. That is, the user selects input blocks, processing blocks, and output blocks from a tool tray and drags them to the drawing board. The user connects the blocks with lines and the program works provided there are no mistakes. Lab Tech referred to the drawing as a setup. The input blocks were device drivers which interfaced the setup to the hardware that was connected to the computer. No driver had been supplied for the hardware and I did not have the tools for writing one. After a couple of hours on the phone with the top officials of the analyzer supplier I concluded that they had no idea of what the Lab Tech system was or how to program it. They couldn’t even supply a driver for their hardware. So I was on my own.

What with software licensing problems and all that, the only tool I had available was Microsoft Quick Basic. I wrote a program to read the analyzer’s output and display it as a bar graph on the computer screen. That made the chemist happy, which made my supervisor happy, which in turn made me happy.

What is on your bookshelf?

You have caught me in the middle of remodeling my electronics shop so most of my books are in temporary storage. I can’t give exact titles, authors and publishers. I hope I haven’t misspelled any of the author’s names. I have an almost unbroken collection of the ARRL Radio Amateur’s Handbooks from 1929 to 1976. There is a lot of history there. I also have many of the textbooks I used in the EE program at U of F including Samuel Ceely’s book on radio communications, Termin’s book on communications and W. H. Chin’s filter synthesis book. I went so far as to write a program to perform Darlington filter synthesis. I also have books purchased after graduation on op amp design, phase locked loops, and active filter synthesis. I find PLLs fascinating and use one whenever I can.

How does someone who is visually impaired build and work on circuits, especially vacuum tube equipment with its high voltages?

As for the high voltages it’s a matter of respect and knowing not to put my fingers into the chassis when the power is on.

I have a special pair of magnifying glasses that I was fitted with when I was 17 years old. I can read schematic diagrams and solder while wearing them. They do force me to get very close to the work and occasionally I do burn my nose. But that rarely happens.

What has been your favorite project? Do you have any note-worthy engineering experiences?

Both of these questions are answered by the narrative below.

My favorite project was instrumenting a fluidized bed combustion furnace. The first version was begun about 1990 and was 16 feet tall. A fluidized bed burns a mixture of coal and limestone. A forced air blower keeps the small particles in motion and it behaves like a fluid. The limestone absorbs sulfur from the coal and keeps it from going up the stack.

The project was well underway before I was called in. They had decided on a data logging and control system known as Lab Tech Notebook. As mentioned above the company is no longer in business but they had a good product and it is hard to imagine why they shut down. The system had been researched and selected by a lady in the chemistry department. As the hardware neared completion she found that programming Notebook was more than she had the time for. “Call in Max.” I received a stack of 3.5 inch disks and about 4 inches of instruction manuals. As this was a high priority project I was released from teaching duties and told to devote full time to this project.

After about a month of study I had the system in hand and was ready to program. They wanted to display various values on the screen as digital displays, trend graphs, and log the data to a file. There were temperatures, pressures and flow rates. I set up a multi- screen system that the experimenters liked very much. In the early stages they were controlling blower speeds and fuel feed rates with ten turn pots. When they said they wanted the settings of the pots logged, things got a little complicated because the fuel feed system was nonlinear. I became close friends with the chief mechanical engineer on the project whose name is John Smith, no kidding, and we and our wives remain friends in retirement.

Initial runs went well and the granting agency was pleased. Then John wanted to be able to set the air flow rate on the computer and have the blower speed controlled to establish that flow rate. If you are thinking PID loop you are right on target. The problem was that Lab Tech Notebook did not support PID loops. An upgrade to Lab Tech Control was called for and no one so much as blinked an eye when the price was quoted. It was a lot of fun setting up the PID loop. Changing values on a screen was a lot easier than unsoldering and soldering in different values of resistors and capacitors, which I have done.

The fuel feed was originally an air driven piston-and-ratchet system which was hard to calibrate and noisy to boot. I designed and constructed a stepping motor driver that solved both of those problems and could easily be controlled by the computer.

The A to D and D to A hardware interface was a system from Omega known as the Workhorse. The furnace was run for about 4,000 hours and produced megabytes of data. I don’t know what was done with all that data; it wasn’t my department.

The project was so successful that a larger version was requested by the granting agency. I retired before it came near enough to completion to need data logging. When that stage came I was called out of retirement to do my thing again. The money was right so I accepted. Upon checking the Lab Tech website I found to my dismay that they were out of business. Other systems on the market were mere toys compared to the scale of the new furnace. It was 65 feet tall and was built in an eighty foot tall tower about a mile from campus. The list of parameters to be logged was in excess of 100.

I found a distributed system bought and resold by Omega. One card in the computer would support 16 A to D and D to A modules that were daisy-chained along a digital bus cable and terminated at the far end. We wound up with two cards in the control computer. The software supplied was rudimentary at best but they did provide device drivers that I could call from a program, so I started banging the keyboard again. The system was very stable. It only crashed once and there was some doubt whether it was caused by the software or the hardware.

Long story a little less long, it ran beautifully and every one was delighted with the work that John and I had done.

What are you currently working on?

As I mentioned above I am remodeling my electronics shop. After retirement I acquired a new interest, woodworking. Yes, blind people do that too. I am not alone. There is a website at http://www.ww4b.org which has pictures of some of the work done by blind woodworkers. Pardon the digression. Actually woodworking is nothing new to me. It’s just that after retirement I bought some high quality power tools and learned the skills to go with them. My original workbench which I built more than 30 years ago looks pretty crude and is built of two-by-fours and plywood. You don’t see it in the picture because the computer workstation required much less cleaning than the workbench would have. You can see what has been done so far on the remodeling project by visiting my Fun with Tubes website. When the bench is finished you will see it there. I keep getting sidetracked by my wife Sue who keeps coming up with honey do projects. I’m in no hurry. I’m looking forward to many years of retirement.

How have you combined your love of electronics and music?

I was at the university when folk music was the big thing on campus. I sold the electric guitar and went back to acoustic where I have stayed. My love of making music has been my antidote to too much technology.

In the first half of my teenage years I thought I was going to become a professional musician. My parents were fully supportive in this. When I turned 16 the Florida state agency for the blind gave me a battery of tests and concluded that I was about equally suited to be an electrical engineer and a musician. They presented me with the facts that because there were blind musicians that I could always get gigs but they probably wouldn’t pay very well. The chances of getting a recording contract and becoming even a little famous were a million to one. On the other hand there were only a handful of blind electrical engineers in the world and it wouldn’t be easy to convince potential employers that I could do the job. I would have to be twice as good just to be considered equal. I had scored high in determination on the psychology tests so the councilors advised me to go for the EE degree. I found out later that they felt that just getting the degree would be the test for me. If I could do that I could find a job. Looks like they were right.

Meanwhile I kept music as an enjoyable hobby. I don’t know what would have happened if I had gone for the music option. It’s a classic case of the road not taken. All in all I have no regrets. Electronics and music come together in the recording studio I have assembled which you can see in the picture.

Can you tell us more about your sites “Fun with Tubes,” “Fun with Transistors” and “Max’s Music Place”?

I started Max’s Music Place http://www.maxsmusicplace.com first in an attempt to build a second career in music. I thought perhaps I could break into the field of songwriting. I had no idea of the barriers that those now in the business have placed in the path of anyone new trying to break in. By the time I retired I knew that there wouldn’t be any career in songwriting and I had found the serenity to keep writing songs and singing them on public access TV and for friends and family.

In the last year before retirement I decided to revert to tubes. It may seem strange to those now earning a living from electronics to also do it as a hobby. My career did grow out of a hobby but I must confess that I didn’t do a lot of it while working. But after I was no longer earning money from electronics it ceased to be work and once again became fun. The reason is that I have never lost the wonder. I still find it a wondrous thing that I can tune my radio to a certain station and hear someone hundreds of miles away speaking, singing or playing an instrument. I’m sitting at my computer typing as on a typewriter but instead of clacking keys making impressions on paper the characters I type appear on the screen and are spoken back to me by the screen reader. If I make a mistake I just push a key that erases the wrong letter and I type the right one in its place. Intellectually I know it’s all done by electrons and holes running around in semiconductors. But I still find wonder in the fact of those tiny particles that no human can see doing all of that in an instant of time too short to be perceived by human senses.

I set up an email list for those interested in tubes. It became more popular than I ever imagined. Its membership is nearing 500. It has attracted people from around the world and not just old fogies like me but young people as well. Occasionally the discussion would drift to transistors so I started a website and email list for transistors. There must be a lot of them because it has not taken off the way that the tube site and email list has. Not a day goes by that I don’t get a message with a question about tubes or praise for making my knowledge available for all to read.

I have learned a lot about human nature mostly from the email list. But I am amazed that, even though tubes were pronounced dead many decades ago, there is enough world wide interest in them to keep a number of tube manufacturers in business and web pages and email lists like mine still going strong.

What challenges do you foresee in our industry?

I’ll leave the challenges for the young people. I’m too busy having fun with tubes.

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