Saturday, September 1, 2012

Electronics Developments

During college and my time in the Air Force I was aware of developments but just barely. I did not subscribe to the electronics magazines. The applicable world of consumer electronics appeared to be stereo audio, television and Citizen's Band radios.

But late in my enlistment a new development was taking place which I was in danger of totally missing. New large scale integrated circuits were making possible small computers. I saw some information about them but, like many others, thought 'why would you need a computer'?

A fellow instructor was dabbling in them and had received a kit ... putting his own computer together! I almost gave a patronizing laugh. But I was intrigued a little and bought a book on Microprocessors just to get a small taste of the field.

My enlistment in the Air Force ended and I move back to my hometown, not sure what I was going to do but it seemed that continuing in Electronics was the logical thing to do. While I was still searching for a job and had answered many newspaper solicitations I received a letter from a recruiter for General Dynamics in Fort Worth, Texas. It seemed that he had been in the Seattle area interviewing applicants and had thought, in response to one of my applications, he could just drive to Yakima, thinking it was a Seattle suburb, for the interview. But seeing it was a couple hours and a mountain pass away he had decided to just follow up with a letter, so I called him. They made arrangements for airline tickets to Fort Worth so that I could interview at the plant.

I flew to Fort Worth. They had almost a production line to deal with finalizing applications and doing interviews. My experience in the Air Force was almost exactly what they were looking for and the interviewer was becoming excited. The job would be teaching the use of test equipment for the new F-16 aircraft. This was nearly a copy of my teaching in the Systems School for the F-111 aircraft.

'Almost' ... 'nearly'. Then he asked the question, what background did I have in computers? The test stations I had taught in the Air Force had manual settings or at best paper tape controlled setups. There were no computerized test stations. I mentioned that a fellow instructor had been using a home built one. The interviewer said that doing that would have been a perfect background. If I had done that I would have been hired on the spot. I was disappointed but I was taken for a tour of the F-16 plant, an incredible time. But on my flight back home I realized what I was missing out on. You don't have to hit me twice between the eyes to get my attention.

Radio Shack was bringing out a small home computer, the TRS80. I bought one and was on my way learning BASIC, Assembly Language and Pascal, three programming 'languages' available for this computer. While BASIC and Pascal were higher level languages, Assembly Language required a more in-depth knowledge of the actual microprocessor (the central computing chip), the electronic schematic of the complete computer and an understanding of the supplied operating system program. I delved into manuals and printouts of programs. I modified the circuitry of the TRS80 to provide additional capabilities.

While my first job for an electronics distributor didn't involve computers, either large or small, I learned more about the organization of the business of consumer electronics. Part of the time I was in "shipping - receiving". But all the time I was studying my small computer at home. (I had married and my wife didn't think too much about "that damn box" but she learned that it was important to be so she lived with it.)

My second job was with a machine builder. While I was primarily doing wiring and troubleshooting I also got to help with the small electronic process controllers the company built from small - though not microprocessor - chips. I learned a lot about signal timing and the flow of information. I helped when a change was needed to the circuitry. I determined that it could be solved, temporarily until a new circuit board could be designed, by another chip being soldered on top of a similar chip, though with some of its pins being wired differently.

We were also using a "5TI Sequencer" from Texas Instruments, basically a fairly large (physically) PLC. I was allowed to read - but not touch - the program. At that point the program was hand drawn like other electronic diagrams (no Autocad yet) and a new program (or modifications) were entered, one step at a time, with a 'large calculator looking' device with a keyboard and flashing LEDs. We did have a tape backup unit which was used to load a program when it was an identical copy of a previous one saving a lot of time.

After marveling at the 'ladder diagram' which documented the logic of the program I asked what all the 'capacitors' were for, since the logical symbols used in the 'ladder diagram' resembled the electronic symbols for capacitors. That generated a great laugh from everyone but me wondering what I had said. Finally, on a field trip to a plant I had the temerity to call back and suggest a modification to the program, just one contact, which I thought might help. I was allowed to perform the modification and the synchronization between two sections of the machine became much better. I was hooked.

The company was developing plans for a new computerized controller for the machine but I was to have no part in its development or use. I was on the road about 50 percent of the time while my family was growing up without me. It was time for a move.

Thursday, February 23, 2012

Systems School

I had just (it seemed) been through this school and now I was re-joining it as an instructor. I had been taught about forms of voice radio (VHF and UHF frequencies). navigation (TACAN and Inertial Navigation) approach control (ILS), and radar identification (IFF). Now I was to teach these subjects.

My first assignments were to reacquaint myself with the materials to get ready to teach these subjects. I thought back to the remark by my fellow students that I would never succeed because I had no 'war stories' to tell.
I was among instructors who had years invested in teaching this material but it seemed, without anything against them, that they were mostly just presenting the same old information. I had been through this and I didn't get any enthusiasm for the subjects. Now this is fairly hard to imagine in these dry electronic subjects but it seemed that enthusiasm is just what was missing.

I had already introduced, in Fundamental Electronics, a glimpse of my instructor style. I had presented the 'Mary Circuit'. A particular circuit in digital electronics (named the Exclusive-OR or XOR circuit) which receives two inputs, each of which can be ON or OFF. The output of this circuit is ON only if ONE, and only ONE of the two inputs is ON.

So I had introduced the 'Mary Circuit' - Mary has accepted an invitation to the prom. In fact she had accepted invitations from two different boys, Joe and Tom. Now it is 'Prom Night' and Mary is up in her room. Does she go down to the front door if no one is there? No. Does she go down to the door if just Joe is there? Sure. Does she go down to the front door if just Tom is there? Sure. Does she go down if both Joe AND Tom are there? Noooo!!! Thus the Mary Circuit.

So I received inquiries in Systems School about this 'Mary Circuit'. They were very literal and not very receptive of innovations. This would change.

The navigational signal presented by a TACAN (Tactical Air Navigation) antenna was very complex. It provided, in one signal, both direction and distance information to any aircraft which utilized its signal. The signal presented one indication when its rotating signal pointed East, with additional signals which indicated how far from East it had moved. Simultaneously it presented information to an aircraft how far away from the antenna the aircraft was. Obviously this was a very complex signal.

But this signal was to be taught with a few diagrams in a workbook. This was unacceptable. I, instead, had students in front of the class, spinning with an flashlight pointing out toward the class, another flashlight pointing upward and emitting 'beep' sounds when pointing in a particular direction. The students, after many hilarious minutes, came to understand how they could determine their relative bearing from the antenna (student wielding the flashlights) by listening to the beeps and watching the rotating flashlight. Similarly they could determine their distance from the antenna/student by listening to the pattern of other beeps.

The understanding of this signal was allowed, in the official teaching guide, a full day for presentation. In one hour my students could not only identify the different components of the signal but their importance in providing the information intended. In fact other classes, composed of cross-training older students, asked specifically for me to present the class. 'Students' older than me ended the presentation in laughter but also with full understanding of the subject matter.

Some of the components of teaching - engagement of the students, the importance of humor in attracting attention - which I had learned in my college classes - came to full use in these classes.

At some future time I may relate my use of the 'Official Invisible Air Force Bowling Ball' in teaching the principles of inertial navigation.