Enoch’s Thoughts

September 16, 2023

Oasis Format Test

Filed under: Uncategorized — etblog @ 9:38 am

Photo of Crosses from Classroom Wall

Teacher: Dr. David Barnett
Subject: The Life and Writing of C.S. Lewis

  • David began the first of his three presentations on C. S. Lewis by asking the class what their thoughts were on Lewis’s writings. He then explained how he had became interested in Lewis’s works in midlife, when he returned to graduate school in Louisville, KY. As part of his studies, he visited England for a summer to compare the organizational styles of two different educational institutions, the traditional Oxford University and the progressive Open University of London. While there, he had the opportunity to visit the Eagle and Child Tavern, where C. S. Lewis and his literary group The Inklings had met weekly to discuss how their personal beliefs affected their writings. It was there, and through his friendship with member J. R. R. Tolkien, that Lewis re-engaged in the Mystery of the Faith.
  • David began his study of C. S. Lewis by reading his autobiography, “Surprised by Joy”. Throughout his life, Lewis longed for peace, which he described as joy. Lewis was born in Northern Ireland in 1898. His parents were voracious readers and filled their house with books. Lewis had a very keen mind and was fully literate by the age of 3, reading adult-level books by the age of 5. The death of his mother when he was 9 contributed to his loss of faith. After a few years at several boarding schools, he was tutored privately until he was 18, then began his studies at Oxford University in 1916. After receiving degrees in Greek, Latin, Philosophy, History, and English Literature, he became a professor at Oxford in 1924. Through his discussions with The Inklings, Lewis moved from atheism to theism, and then in 1931, to becoming a believer in the God of Grace, Grace being the undeserved, ever-present pursuit of humanity by God.
  • Lewis became an Christian apologetic writer and speaker. Could Jesus be accepted as just a good person? No, there were only three options: Jesus was either (1) who he said he was – God, (2) a lunatic, or (3) a fiend. Why had Jesus come? God has landed on this enemy-occupied land in human form to teach us how to live and die.
  • Lewis wrote in several different genres, depending on the time period in his life: poetry, fantasies, apologists, and a multitude of essays. Lewis wrote between 80 to 90 publications while teaching literature, giving interviews with BBC, and writing weekly newspaper editorials.

Key Themes: Chronological snobbery (that new ideas are better than old ones, such as the 2,000 year old belief in Jesus), imagination (“the cosmic pointer”), objective values vs relativism, myth, immorality, comprehensiveness, and desire.
Next Sunday, David will explore Lewis’s books “The Chronicles of Narnia”, “Mere Christianity”, “God in the Docks”, and “Surprised by Joy”.
For those who would like to review David’s full talk, a video recording is available on the Oasis web page at http://iideaco.com/oasis/.

Carole Mitchell – still healing from earlier leg injury
Don McConnell – brother of Dave, ongoing health issues
Michael Johnson – brother of Jerry, ongoing health struggle, and now trying alternative treatment

Lovely Oasis gathering at Robert Shippey’s home Sunday, and the opportunity to wish Robert a happy birthday! (See photo at bottom.)

Emporium is Sept 22-23, profits going to Love Your Home
Thank you note from CASA is attached at the bottom of this e-mail.
Butler Center Renovation Ribbon Cutting is this Saturday, September 16th, 10:00-11:30am, community program at 10:30am
Dinners for Sonlight Youth Choir: The Oasis class will once again be providing dinners for the Sonlight Youth Choir. The remaining dates are September 17, October 1, October 15, and October 29. More information is available at at http://iideaco.com/oasis/sonlight.html. Here’s a direct link to the sign up sheet if you prefer to sign up there, or you may e-mail regarding this. Please sign up for your date now!

March 6, 2022

Cars (Part 1)

Filed under: Uncategorized — etblog @ 10:04 pm

A recent conversation with my kids about the current popularity of big trucks got me started thinking about my first truck. I drove a 1971 GMC half-ton, 8-foot-bed, from 1971 until sometime around 1990, as near as I can recall. Manual transmission, “three-on-the-tree” shifter, 307 cubic inch V8. The only “options” it had were disc brakes, and a heater. I screwed a Radio Shack AM/FM radio to a piece of wood which was shoved under the driver’s seat, and wired to a speaker and antenna. At some point I dubbed the trick “Mescalito”, a curious reference to a lyric from a song called “Panama Red”, a drug-related song by the New Riders of the Purple Sage. (Curious, since I really didn’t “do drugs.”)

But I’m getting ahead of myself. Perhaps the first question is, how did I wind up with a pick-up truck?

As a careless, car-less Ga Tech student, I rode the Greyhound bus between Atlanta and Columbus for the first few years, a three-hour trip through a bunch of small towns. The walk from my dorm to the bus station was about a mile, and my parents would meet me at the station in Columbus. I was not particularly in the market for a vehicle, but sometime around 1971, I purchased 50% of a 1963 Austin Healey Sprite for $25. It was parked, dead, in the right west-bound lane of North Avenue sorta near Moreland. It belonged to a roommate of Alan Hoskins (see my music history, 1969), and he was happy to get rid of it for $50, as-is, where-is. I went in on it with my former dorm Resident Advisor, a fellow Physics major who had become a good friend, Dyches V. Boddiford from Sylvania, GA.

We used Dyches’ big Oldsmobile and a rope to pull the Sprite from North Avenue to the parking lot of the Ga Tech Physics building, where I was “working” part-time in the machine shop. The first problem we discovered with the Sprite was that I had tied the tow rope around a radiator pipe instead of a frame member, so that needed to be repaired.

The next day was a brisk Fall day, so I started by adding some warm water to the battery, and cleaning its terminals, and it actually cranked! But it made an awful racket. In my hasty wisdom, I decided that the clutch needed to be replaced, so over the next few weeks, I figured out how to pull the engine out using a hydraulic lift, only to discover that the clutch was fine.

Over a couple more weeks, I re-installed the engine, and eventually discovered that the noise was due to a loose pulley on the generator. (Another lesson learned.) Once I replaced that, it ran fine. Well, mostly.

I pretty quickly bought out Dyches’ share, drove it around Atlanta for the next few months and learned a lot. Like that I needed to add oil frequently. And that using American brake fluid instead of Castrol in a British brake system ruins all the rubber parts, requiring the whole brake system to be drained and the rubber parts replaced.

One day I loaned the Sprite to roommate, and eventual brother-in-law, Bunchie, and he almost got flattened by a semi as he tried to enter the downtown connector at the North Avenue on-ramp, which had no merge lane. (At the time, the connector consisted of just two lanes in each direction!) The Sprite didn’t have near the pickup of Bunchie’s old GTO.

Eventually, I summoned the nerve to drive it a hundred miles to Columbus. Cool: no Greyhound for me! Except I had to stop several times to add fluids, resulting in the ill-fated brake fluid incident. But I made it home in one piece! When my safety-conscious Dad saw the Sprite, which really was a small vehicle complete with a cloth top, that’s when he decided to pay me for a couple of Summers of house painting and electrical work by buying me a somewhat safer vehicle.

Which explains how I came to drive a 1971 GMC. My best recollection is that the price of the brand-new truck right off the dealer’s lot was right at $2,000.

I don’t remember when I learned about tags, titles and insurance, but eventually the truck was fully mine, with all that implied. I soon built a removable plywood box to cover the bed, and didn’t learn until someone rode in the back that the roof would bow up at any speed above 40 MPH. I think that was the same trip we discovered that the truck’s exhaust system had a leak that heated up the front edge of the bed hot enough to melt plastic.

My first “load” in the truck was a keg of beer that someone asked me to deliver to a second-floor of a warehouse for a party. I made a couple of rookie mistakes: I didn’t check out the route by walking it first, and I decided to back up the narrow ramp to deliver the keg. So I ended up burning out my clutch trying to back up the narrow ramp, only to discover that there was plenty of room on the second floor to turn around. And it would have been wiser to drive up and back down anyway!! Braking on the way down is much less wear than trying to clutch on the way up. Several lessons learned.

I ended up replacing the clutch in Hankamer’s back yard, with help from his wife Barbara who pressed the clutch pedal so I could align the throw-out bearing from under the truck. (More about Hank here.)

The whole time I owned the truck I frequently used it to haul stuff (apparently in contrast to most modern truck owners.) At the time, there was a popular but snarky bumper sticker that said, “Yes, this is my truck. No, I won’t help you move.” That was not me. I remember hauling a heavy old tractor engine bolted onto an angle iron stand for my Uncle John, and of course I hauled a fair amount of music gear.

One notable Saturday morning in 1974, I loaded up the truck bed with sound and music equipment for Revelation, the youth singing ensemble I was playing guitar and bass for at the time. We were going to downtown Atlanta that morning to set up and practice for a big evening gig. As we were about to leave the church in Buckhead to head downtown, the singers were all piling into the church van. John Condra, the Minister of Music, casually said, “Carl’s by himself — does anyone want to ride in the truck?” And this cute little lady named Jayne said, “I like trucks. I’ll ride with him.”

We got to the downtown hotel, the group set up and rehearsed, and then they all dispersed to go back home. I looked around for Jayne, and someone said she had gone to the pay phones to call her Mom to come pick her up. I sprinted to the row of payphones, put on my brakes as I rounded the corner, and casually as possible, sauntered up and volunteered to take her home, and she accepted.

We talked the whole way to Doraville, where I met her Mother and her Aunt Dot. She picked up her Revelation outfit, and we drove back to my apartment in Buckhead to kill time before the gig. She washed dishes while I played guitar and sang folk songs for her.

We rode downtown, did the gig, and then rode back to Doraville. We really hit it off, talking constantly about things I can’t even remember.

After seeing her at church the next day on Sunday, I asked her, “Would it be overdoing things if we went out Monday night?” She replied, “Yes, but let’s over-do it.”

By the way, she quickly learned to drive Mescalito’s three-speed transmission. What a gal.

So Mescalito and a music minister turned out to be the catalysts for a relationship which has lasted for more than 4 decades.

There are obviously more car stories to tell, including an explanation for my affinity for Chevy Astro vans, but I think I’ll save those for Cars, Part 2.

July 28, 2021

Ga. Tech Summer 2021 Capstone project judging

Filed under: Uncategorized — etblog @ 2:24 pm

This is a brief summary of my participation in yesterday’s Capstone Summer mini-expo at Ga. Tech (July 28, 2021), my third as a virtual judge.

It was supposedly a hybrid event, but other than hearing some possibly relevant background chatter during one presentation, I don’t know how they did the live presentation. I participated virtually using Gatherly again (see previous Notes from a Virtual Capstone Expo.)

This virtual Capstone session worked about the same as the previous two, perhaps a little smoother. That may be because this time I had to compress my participation due to a late-scheduled music rehearsal, so I took advantage of several opportunities the expo set-up offered. I received my five judging assignments by e-mail mid-morning, and also received the link to the pre-prepared presentations, each of which which included a poster and a video.

The normal expo procedure is for each team to start their presentation at the quarter-hour, starting at 4:15, and ending at 5:45. Since that was a tight squeeze for my schedule, I decided to get a head start by reviewed the 5 videos, and I was then able to “pre-judge” the teams based on the videos and their posters.

Following the introductory welcome, the presentations started, and I was able to wander between presentations and get additional information beyond what I learned from the videos. The RocketJudge system allows you to change your ratings and comments freely during the entire judging interval — your final version is what gets automatically transmitted to RocketJudge when the judging interval ends.

I think one reason I was able to wander around independent of the schedule without interrupting the flow, was because attendance was relatively low, and also because of how the Gatherly display works: I could see at a glance how many people were listening to a particular team, and pick one that looked like a small group, perhaps just the team members themselves.

There turned out to be a grand total of 8 teams presenting. (Hence, “mini”.) Three projects were sponsored by TTI, manufacturers of Ryobi and other tool brands, three by Delta Airlines, and two were independently conceived and funded. I judged 2 Deltas, one Ryobi, and two indies.

Here’s a quick review of the teams and projects I judged:

Parking Pals – Aircraft Parking
This team was asked to design a system to ensure parking chocks are properly placed whenever an aircraft stops at the gate, and to similarly ensure the checks have been removed and stored in their charging caddy. They use pressure switches and wireless, mesh-like networking to report their status.

Lav Rats – Vertical Default Toilet Seat
This team was asked to solve the problem of unwanted liquid left on airplane toilet seats; the solution had to fit the existing space, be more or less automatic, but could not use any electrical components.

Rowbotics – RowMotion
This team decided to attach sensors to a rowing ergometer to provide feedback to the rower on whether they were using the correct form. The design the came up with used a rotation sensor on the main shaft and a belt-driven transducer attached to the bottom of the sliding seat to feed into a small visual display.

Smart Structures – Smart Structures
This team decide to explore ways to improve “3-d concrete printing” which is used to make durable and inexpensive houses. They designed a continuous mixer system to provide a steady but flexible flow of concrete to the “print head”, and also explored the use of Aircrete, a lighter weight form of concrete. They compared the strength of Aircrete to regular concrete.

Origami Chainsaws – String Trimmer Anti-Vibration System
TTI asked this team to reduce the vibration transmitted to users of their new electric string trimmer. There were multiple production parameters and restrictions that their solution needed to meet. As part of evaluating their solution, they had to invent a rig to suspend the test trimmer and measure the amount of vibration for the original design, plus two modification options they considered.

Additional details

At the time of this writing, expo projects current and past were available here:


January 1, 2021

What Makes Sense

Filed under: Uncategorized — etblog @ 7:54 pm

As children, we’re taught that the human animal has five senses: vision, hearing, touch, taste, and smell. Since then, I haven’t thought about them very much. But when I recently started to write a post on audio cables and connectors, I was pondering the differences between audio and video, and here’s where I ended up.

Our senses are so instinctive for most of us that we hardly think of them, but they are pretty amazing in many respects. From an engineering perspective, they include redundancy and some functional overlap, but each sense also serves a unique purpose, with a unique set of characteristics.

These descriptions and comments are based mostly on my own observations and interpretations. Occasionally I looked something up, and have so noted, usually by way of a link.

In this post, I look at the senses from the following perspectives:

  1. How motion is involved in the operation of the senses
  2. How we augment the senses
  3. How the senses compare in determining distance and direction
  4. How we store and retrieve sensory information

I conclude by talking briefly about audio as a seque to that previously mentioned post about cables and connectors.

1. Motion

In a broad, external context, all of our senses can be summarized as “the ability for specialized nerve endings to detect movement.” (I’ll leave the details of how sensing information gets from your nerve endings to your brain for another time, and maybe another author.)

Let me explain my thinking.

  • Taste and smell work by detecting molecules which move into contact with the nerve endings in your nose (via air motion) and your mouth (via your eating utensils). We know from experience that these two senses are closely related. In fact, a friend of mine who was recovering from the Coronavirus recently mentioned that, as her sense of smell began to return, it worked better when she opened her mouth, “as if I am tasting the air.”
  • Touch is enabled by nerve endings in your skin, and I think it can reasonably be divided into two sub-senses, the ability to sense contact or force, and the ability to sense temperature. Sensing physical contact occurs when any object moves against your skin. Temperature sensing also occurs through the movement and contact of air with your skin. But other movements also affect the sensing of temperature. The evaporation of moisture produces a decrease in skin temperature, and long-wavelength electromagnetic waves of radiation bumping into the skin produce an increase in skin temperature. It’s pretty miraculous that light waves produced by the Sun can travel 93 million miles through the vacuum of space, through six or so miles of atmospheric gases, and even a few fluffy clouds, to warm your skin as you stand outside.
  • Hearing sound is also triggered by movement; in this case, when a sound occurs near you, the air molecules around your ear move, pressing in on your ear drum, which moves a couple of tiny bones against a small “canal” filled with liquid. The liquid moves tiny nerves inside the canal, which send signals to your brain, and you hear speech, music, or noise.
  • Sight occurs when electromagnetic waves in the visible spectrum enter your eye, passing through your cornea, into an opening in the front of your eye (the iris), through a lens which focuses the waves, through the liquid in your eye (humor me here, please) until they strike the rod- and cone-shaped detectors in your retina. The rods and cones send this information to your brain, and you can see!

There are other movement-related phenomena which don’t usually make the “5-senses” cut, but are also important. When you move your body parts using your muscles, nerves in the muscular structure tell your brain how far, how fast, and how hard you are moving your limbs. This important sense, called proprioception, is what allows you to touch your nose with your eyes closed (assuming you haven’t over-indulged in any sensory-altering activities.)

And the nerves in your ear canals also detect which way your head is tilted, and they respond to movements of your body within the Earth’s gravitational field. This sense provides balance, which keeps you from falling over (again, assuming you haven’t over-indulged), and helpfully lets you know when you have ridden something (roller coaster, mountain road, etc.) that causes you to be nauseated.

For the purposes of this commentary I shall omit the aptly-named “extra-sensory perception”, as well as the sense that somehow detects when someone is looking at you, or when you have said something your spouse doesn’t approve of, even when they are behind you. (If you are interested in ESP, let me recommend the book Extraordinary Knowing by the late Elizabeth Mayer.)

To conclude this section on motion, I would note that the very concept of motion is dependent on time, speed, and distance (a drone leaves Boston flying toward Chicago at a rate of 300 kilometers per hour….), and speed is dependent on the medium through which one travels. To keep this diatribe at a sane length, that’s all I’ll say about that.

2. Sensory augmentation

I think of taste and smell as fundamentally based on chemistry, while touch, sound and sight feel more physics-oriented. I know some very fine chemistry folk, so I would not dare malign the discipline, but even simple chemical reactions are complex when compared, for example, to the Newtonian physics of how a pool ball ricochets off of a table cushion (one of my favorite parts of the discipline).

Perhaps this difference between chemistry and physics partially explains why we don’t have commercially available products to improve our senses of smell or taste (OK, I see you there, MSG).

But over the years we have figured out how to augment touch, sight, and sound for our benefit.


For a start, we use clothing to cover our skin sensors. Clothes not only keep us warm, but can protect us from sunburn. Work gloves protect our skin from blisters and abrasion. Shoes and boots protect our feet. And as an extreme example, armor was developed to protect a fighter’s skin from harmful contact, similar to armor’s modern equivalent, the Kevlar vest.


Pictures of Ear trumpets from Wikipedia
Ear Trumpets (Wikipedia)

Glasses, contact lenses, and now laser surgery are commonly used to bend light rays before they enter our eyeballs to compensate for variations in our vision.


Our ability to hear has been enhanced by a broad spectrum of inventions ranging from the ear trumpet to modern hearing aids, and even to medical devices implanted in the aforementioned ear canal (cochlear implants). In the other direction, ear plugs, ear muffs, and now noise-suppressing headphones protect our ears (and our focus) from destructive and/or annoying sounds.

3. Distance and Direction

Our different senses interact with our brain to provide useful indications of distance and direction.

3.1 Taste and touch

Taste is almost completely based on physical contact; you taste something when it touches your taste buds, so the distance you can taste is effectively zero, and the direction is mostly meaningless. Of course, the distribution of different types of taste buds may provide a small sense of “direction” but it’s relatively minor compared to the other senses.

Skin contact is similar — you are aware of something touching you when it actually touches you. (There are ways to trick the senses, but they are minor factors in this context.) And a single skin contact nerve is not directional; any touch is more or less perpendicular to the skin. However, when your brain assembles the signals from touch points all over the body, it draws some directional conclusions. You can determine which direction even a gentle breeze is blowing by using signals from the different touch sensors around your body. This ability to combine multiple sensors to produce additional information is notable, and is used with other senses, too.

Your skin’s ability to detect heat (or its absence) has a much broader range, as evidenced by the distant sun warming your body. And although that sense for a single nerve is also non-directional, your brain again assembles the sensors around your body to determine whether you are facing the campfire or have turned your back to it, even with your eyes closed.

Let’s focus a little more on the distance aspect. The fact that your skin can feel the heat from the sun is a combination of two things: (1) the ability of your “heat detectors” to sense electromagnetic radiation in a certain spectrum, and (2) the ability of electromagnetic radiation to traverse the vacuum of space as well as the gases which comprise our planet’s atmosphere. We’ll touch on this more as we move through the other senses.

3.2 Smell

Your nose is generally non-directional — a cloud of molecules in your vicinity will make their way into your nostrils as you breathe. You can move your head and body around while sniffing to get a better bead on the source, but it is imprecise by nature.

The distance your nose can smell is almost completely determined by external factors, primarily the strength of the original aroma, and the wind direction. As far as I can tell, it’s pretty much impossible to tell the difference between a faint aroma nearby and a strong smell at a distance.

Somewhat related, loss of smell is one of the curious symptoms of COVID-19. A recently published Harvard paper explains that the problem is not neural, but is a temporary malfunction of the nasal cells that normally detect smells. (The original article is here, probably the first time I have ever cited anything from that particular source.)

3.3 Hearing

Hearing is both distance- and direction-sensitive. The shape and positioning of our outer ear flap efficiently funnels moving air into our ear drum, but it also affects the relative amplitude of the frequencies that make up a sound. High frequencies tend to be directional, meaning that they don’t turn corners as well as low frequencies. Noises behind our ear sound different, and we can sense the difference as we rotate our head toward the sound.

We also get hints about the distance of a sound due to its relative volume combined with its frequency spectrum. Air and humidity tend to attenuate the high frequencies — listening to a neophyte bagpipe player practicing at the other end of a football field is not too painful.

Experienced sound system operators know that the low-frequency sub-woofers and bass drivers can be placed nearly anywhere, since their waves are effectively non-directional, but they have to elevate the high-frequency speakers on stands, stage trusses, or ceiling mounts for clear sound. The rule of thumb is that an audience member must be able to see the speaker to hear it (since your ears and eyes are so close together.)

We know that, in practical terms, a loud noise (thunder, explosion, rock band) can be heard several miles away through the air. The distance at which hearing works is limited by its dependency on a fluid to transmit sound waves. (Yes, I tricked you a little when I said “air” above; sound also passes through water, and presumably other fluids.) Air works the best for Earthling ears, but water apparently works for whales, otherwise they wouldn’t sing. And water also transmits sound for boats, ships, and submarines (also serious fishing persons), which (who) use sound waves (called sonar ) as a means of locating objects (and fish) under water.

Returning to land-based life-forms, having two ears provides us with significant benefits. The volume of a sound (see below) as registered by each ear provides an additional indication of whether the sound is coming from your left, your right, or straight ahead. This definitely feels like a survival skill — it helps you know which way to jump when you hear the snap of a twig, the sound of a snake rattle, or a low growl. In addition having two ears provides redundancy. If one of your ears stops working for any reason, you may lose some directional indications, but you will still be able to hear something!

The frequency range of human hearing starts at around 10 cycles per second. Air moving slower than that is felt by the skin (and your internal organs!) rather than heard with your ears. At the upper extreme, a set of young fresh ears can hear high frequency sounds up to around 20,000 cycles per second (a practically named metric that is now known as Hertz.) Sounds above that certainly exist, but we call them “ultra-sonic” sounds (see chart below).

Sound frequency chart from Wikipedia
Sound Frequency Chart
Noise chart from NIOSH
Noise chart

Returning to volume, the intensity of sound pressure is most commonly measured in decibels. Sustained sounds above a certain limit can cause temporary or permanent loss of the ability to hear, as shown in the adjacent chart from the National Institute of Occupational Safety and Health, part of the Centers for Disease Control (CDC).

Now let’s compare hearing to vision.

3.4 Sight

Sight is generally considered the most important sense. Pardoxically, it is also the most complex sense. Here are some characteristics of eyes that differ from ears.

  • your ears are fixed (other than the amusing ability to wiggle them that some people have), while your eyes can move left, right, up and down.
  • Your ears simply process the sound waves that strike them, while the lenses in your eyes can change focal length to better perceive near and distant objects.
  • The iris in your eye opens and closes to control the intensity of light striking your retina, which allows you to see in a variety of illumination levels, while your ears have no such dynamic adjustment capability.
  • Your eyes have two primary kinds of sensors: rods, which see grey-scale, and cones which see color in high resolution. The cones are in the middle of the visual field; they see with high resolution, but require relatively bright light. As your eyes adjust to the darkness, the rods take over. When trying to spot a faint object at night, it helps to look away from it slightly, because the rods are denser on the periphery of the visual field. (There is a third type of sensor, recently discovered, described in this article on photoreceptor cells. Who knew? Besides Wikipedia. of course: “These cells are thought not contribute to sight directly, but have a role in the entrainment of the circadian rhythm and pupillary reflex.”)
  • If a sufficiently bright light hits your eyes, or an object flies toward one, your eyelids close instinctively. for protection.
  • Your eyes also converge to allow better focus on objects less than 20 feet away.
  • Your eyes close when you sleep, partly for self-protection, and presumably to give the vision-processing part of your brain a break.

Even more than hearing, sight is distance-sensitive and direction-sensitive. Your youthful eye’s lenses can focus on an object as close as an inch away. Sometime around middle age your lenses lose their flexibility, which explains the popularity of reading glasses among people when they reach that age. The act of focusing on an object is one of several indicators your brain receives to provide you with an indication of the distance of the object. I worked on 3D television a few years ago, and its focus (heh) was on one of the main “binocular” aspects of depth perception, namely the fact that your eyes see slightly different images when you look at a three-dimensional scene. Note that this is another example of your brain combining information from multiple sensors to produce additional information is notable

Other factors that provide distance and depth perception (relative distance) include:

binocular effects (requiring the use of both eyes)

  • disparity – your left and right eye see slightly different images
  • parallax – when you focus on a near object, the background appears different to your two eyes
  • vergence – when you look at a near object, your eyes converge; when you focus on a more distant object, they diverge

monocular effects (noticeable using just one eye)

  • relative size – when you look at a row of parked cars, the more distant cars appear smaller
  • texture gradient – the texture of near objects is more detailed that that of far objects
  • occlusion – near objects block portions of farther objects
  • perspective – a straight road appears to converge to a point as it nears the horizon; (learning this is an important key to making realistic sketches)
  • contrast differences – similar to texture gradient; objects in the foreground have higher contrast, and
  • motion parallax – when you’re riding in a car looking out the side window, nearer objects seem to pass quickly, while more distant objects (like a far-away tree line) seem to be moving slower

The ability to sense distance is important to sports players, who need to perceive distance quickly and accurately in order to kick, hit, or catch a ball. But it also allows you to do such mundane things as pour liquid into a glass at arms length without spilling it, and efficiently navigate in your world without running into things.

Direction of vision is quite different from direction in hearing. In short, you can hear things around corners, but you can’t see things around a corner (without help, anyway, from a periscope, mirror or fiberscope). Not only can you not see around corners, you can only see things located in front of your eyes. You can’t see things that are too far above, below, or behind them. Fortunately your eyes can move in their sockets, your head can turn, and your peripheral vision is pretty amazing compared to a camera lens, for example.

3.5 Senses in space

As an amusing little side trip, let’s pause to do an “astronaut check” on our senses; what senses work in space?

  • Vision? Fortunately you can see pretty well, since electromagnetic waves (light) can pass through the vacuum of space (assuming you have a clear cover on your space helmet).
  • Hearing? not so much; your hearing requires a fluid, preferably similar to Earth air, which outer space it notoriously short of; that exploding starship you can see through the spaceship portal or camera is completely soundless to you, unless some ill-fated person on board the ship is broadcasting the sounds to you via radio waves.
  • Temperature? It turns out that managing the temperature extremes in space is a significant engineering challenge. The energy from a nearby sun is absorbed by your space suit and potentially transmitted through your suit’s pressurized air, but the suit is also an efficient radiator of heat into an airless void. There’s an article here from Quora via Forbes that provides a little more explanation.
  • Touch, and smell are hampered by your space suit; you might smell yourself while in your suit, and you can fortunately feel your astronaut tools through the gloves (at least a little bit).
  • And taste, already noted for having a distance of zero, works about the same in space.

5. Storage and retrieval of sensory-based information

Over the centuries, humans have invented methods for storing and retrieving some kinds of information. Consistent with my previous comments about physics and chemistry, we have yet to find a scalable way to store and retrieve smells, tastes, or even touches (that would definitely be creepy), but we do pretty well with sight and hearing. (Although there is promise; as I was writing this, I ran across a Gizmodo article that describes a lickable device that creates different taste sensations on your tongue.)

5.1 Analog storage

In this context, by analog storage I mean any method of capturing sensed events that does not require the use of modern computing equipment.

The recording of visual images probably started with cave dwellers marking their walls for decoration, or record-keeping. Audio “recording” probably started with the verbal transmission of stories and songs, building on a spoken language.

The development of written language led to the ability to record stories and other written information. Monks re-wrote stories as a means to reproduce them.

Crude photographic technology (vision) has been around since the early 1800s, slightly beating out Edison’s invention of the phonograph in 1877 (hearing). Commercially available products for recording and playing back synchronized audio and video became available during my lifetime. While I was a student at Georgia Tech, our department purchased one of the first Sony Video Tape Recorders which used 1/2″-wide magnetic tape.

Modern analog recording devices still capture high resolution video and audio, typically using tape recording based on magnetism. Despite this, the recording and playback process always changes the content in detectable ways. This was pretty obvious with the first photographs — while they served a valid purpose, they would never be confused with the original subjects. The same is true about audio recording. Early recorded music was like an elephant doing ballet: the accomplishment was not how well it did it, but that it did it at all.

Today, recorded audio and video, and amplified audio produce pretty high-quality versions of the original content, but you can always tell a difference. A light-based image or video camera can only capture what is it pointed at. Smartphone cameras have significantly improved the quality of snapshots and home videos, but you don’t confuse them with reality. Since the “is it live or is it Memorex?” days, audio systems have also improved. A top-of-the-line 5.1 amplifier/speaker system (left, center, right, left rear, right rear, and subwoofer) makes for an enjoyable and exciting theater-like experience in your home, but, you aren’t likely to confuse the sound with reality. Recordings provide a way for us to share and recall real-life experiences, but they don’t replace them.

5.2 Digital storage

In this context, by digital storage I mean the method of capturing sensed events that uses modern computing equipment using digital encoding techniques. As an example, this Wikipedia article describes digital audio encoding.

Claude Shannon of Bell Labs gets the credit for defining binary digits as a way to measure information. Appropriately, in our modern digital lives, our file sizes reflect the amount of information required to store and reproduce different types of content.

5.3 Information storage comparison

Image of a text file showing song lyrics and chords
Text file of lyrics and chords
  • The lyrics of a song in a text file might require 1,000 to 2,000 bytes of character information.
  • A music score which captures the melody, harmony, and timing as symbols might require 30,000 bytes of data.
  • An audio recording of a song, encoded using an efficient compression method such as as MPEG3, might require 2,000,000 to 3,000,000 bytes. This captures the audible vocal nuances, and the background instruments.
  • A video recording of the same song might require 100,000,000 to 200,000,000 bytes. This captures a camera’s view of the scene, likely including some close-ups, some wide shots, perhaps closed captioning of the lyrics, and even some Ken-Burns-type effects on promotional posters or other still images mixed in.

It’s intentionally obvious from my descriptions that each format requires more “information” as you move down the list. It’s also true, although perhaps less obvious, that the creation, editing, storage, and distribution processes get more complicated, too.

Focus on Audio

From my perspective, audio recording and reproduction strike a nice balance between quality and accessibility. I don’t mind editing and formatting video content, but the sheer scale is often daunting. As I was writing this sentence, I was also uploading a 24-minute video to the internet to share with my family. It took me about 6 hours to edit the video, and it took about ten minutes on a decent internet connection to upload it.

For some reason, there are more readily available options for editing, amplifying, and distributing audio content, and most of the older technologies still work pretty well.

Photo of Zoom H1 pocket-sized audio recorder
Zoom H1

That’s not to say the technology has been stagnant — my 5-year-old shirt-pocket-friendly Zoom H1 stereo recorder has been a faithful friend, capable of recording 12 hours of high-quality stereo audio on one AA battery. It apparently has a new sibling, the H8, which can record 4 channels fed by 4 XLR inputs, in addition to their standard dual microphone capsule. (I’ve been afraid to check the price!)

This focus on audio technology brings me back to the original intent of this discussion, which was to lead into an overview of audio cables and connectors. Faithful readers who have made it this far won’t be surprised that this post has gone way beyond that. But if you happen to be interested in knowing more about audio cables and connectors, (not to mention the names for the 4 different genders of XLR connectors), here’s the link: http://iideaco.com/cables.

November 15, 2020

The Load-Out

Filed under: Uncategorized — etblog @ 4:15 pm

In early October, probably for the tenth time since it came out, I listened to the Jackson Browne album Running on Empty. It’s an incredible “road” album from start to finish. The last two songs have been stuck in my head ever since.

As a very amateur musician, I don’t really have the chops to play on the road. But I’ve been fortunate enough to have many road-related opportunities. And, in the process, I discovered my favorite part of gigging.

Electronic Organ
Thomas-by-Heathkit Organ

My first “roadie” job happened when I was in my early teens. I had built a small electronic organ from a kit, and a few of us neighborhood guys had formed a band and learned some songs. We somehow talked the youth minister at our church into letting us play after the Sunday night service, at “Fellowship.” So my Dad helped me load the organ into the truck, and take it to the church. Unfortunately, the preacher’s wife had a different opinion, and stopped the jam before it got started.

The next summer, our youth choir traveled to a couple of “old folks’ homes” to sing for them. We carried a two-channel, tube amplifier which was originally intended for permanent mounting, a couple of speakers, and two microphones. Yep, I was the guy who knew how to hook it all up.

Over the next few years, I learned to play guitar, mostly from my cousin Jimmy, then I picked up the bass, both of which required amplification, so I hauled amps, guitar cords, and power cables, just so I could play. These rather humble beginnings gave me the opportunity to learn some practical lessons about sound equipment, such as how to avoid feedback, what to plug in last to avoid loud noises, and how to troubleshoot.

Over the years, mostly thanks to church youth choir trips, I became acquainted with more complicated sound amplification systems. For me, these youth choir trips were miniature versions of the tours arranged for “real” musicians like Jackson Browne. For two weeks every summer, we piled into a couple of Greyhound-like buses, and drove across the country, performing almost every night. We carried sound gear and instruments in the luggage bins.

One Tree Hill original
One Tree Hill original quartet

Then came Patrick. Patrick was a paraplegic who wrote songs about his personal lessons learned, and performed them as a ministry. Occasionally he played a gig large enough that he needed someone to run sound for him, so he recruited me. His solo gig grew into a quartet (shown above) in which I played bass. He named the quartet One Tree Hill (well before the television show of the same name, which we were proud to out-live).

Band on a small stage
One Tree Hill at Starbucks

Eventually One Tree Hill grew into a full band. Over nearly 20 years, with a varied cast of band members, we recorded a handful of CDs with Patrick’s original songs, and played a lot of gigs. One busy year we played 75 gigs. Some of our gigs were for less than a dozen people, where we played without sound equipment, or just a small system.

Brian, Patrick, Carl on stage
Brian, Patrick, Carl on stage at The Potter’s House

But our favorite locations were larger drug rehab facilities, where they thought we were famous, and we played an hour-long set for a hundred people (usually men) ready to hear encouraging words and rocking music.

Here’s how a typical gig would go. Patrick and I would meet at the church where we stored our equipment. I would roll the gear out and load it into our trailer which was hooked to his van equipped with hand controls. We had a couple of sub-woofers, two tall Mackie 3-way powered speakers, five floor monitors, three racks of amps, effects, and equalization, two guitars, my bass, GK bass amp rack, and 4×10 bass cabinet, several crates of speaker, patch, and power cables, a case of microphones and XLR cables, and a heavy canvas duffel bag full of mike stands. It took about 30 minutes to load the trailer, three trips each with a carefully-packed “Rock-and-Roller” cart.

One Tree Hill at Eddie's Attic
One Tree Hill at Eddie’s Attic

Patrick would drive to the gig, park somewhere near the auditorium entrance, and I would start rolling gear from the trailer to the stage. P would balance his guitars on his lap and roll himself on in. Usually we had to get someone to help me lift him onto the stage. (When we played at Eddie’s Attic in Decatur, we pulled him up 13 narrow steps, but fortunately they had a great house sound system.)

Once Patrick was on stage, he would set up mike stands, mikes, cables, and his guitars while I set up the main and monitor speakers, and set up the sound board on a stack of equipment racks. Then I ran power cables and speaker cables, while Patrick plugged in the mike and instrument cables.

Most of the time I did a full-house equalization of the sound system, checking for frequencies in the room that were particularly hot, or dead, and adjusting the third-octave main equalizer to flatten out the response. This generally made the rest of sound check go much smoother.

About this time Brian would show up and set up his acoustic and electric guitar rig, and our drummer/percussionist (whichever and whoever we had at the time) would show up and set up his gear.

Sound check outdoor gig
Sound check for outdoor gig

By the time I finished setting up my basses (electric and upright) the female singer (when we had one) would show up and we would start sound check. Since I ran the board from stage during the show, sound check was pretty critical. I would walk back and forth from behind the board to the audience area, trying to get a good balance and a good level, having to make some assumptions about how the system would sound when the room was full of people.

Full Stage Set-up One Tree Hill
Full stage outdoor set-up

My floor monitor signal source was set to “post-fader”, so it would reproduce the channel mix as it was sent to the house speakers. That way I could tweak the balance between voices and instruments while I played from the stage. With less-professional performers, that set-up could have been challenging, but the quality of our musicians made that job really easy. Brian mixed himself seamlessly between rhythm and lead parts, Patrick played and sang very consistently, and all of the percussionists and female singers we played with had good ears, and could balance themselves well.

When the gig was over, it was time to reverse the whole process. All the cables had to be carefully wrapped and stowed so the next set-up would be snag-free. I always packed up my instruments and amps first so I didn’t have to worry about them being damaged.

We sometimes got offers to help from the audience, and we learned to ask them to give us a few minutes to wrap and crate, then they could help us move gear out to the trailer, where I supervised loading like a Tetris Master.

Finally, we drove back to the church and unloaded the trailer. A full gig somewhere in the Atlanta area would take five to six hours from meeting Patrick to load the equipment to finishing unloading at the end. Midway in the band’s active period, Patrick moved to a location where we could leave most of the live sound gear locked in the trailer between gigs. We still had to move instruments and studio gear back and forth, but that saved a few hours a gig.

In the middle of the One Tree Hill era, the church we were attending started a “contemporary” worship service which, like most of them, met in the Family Life Center gymnasium. The sound system had to be set up early on Sunday morning, and taken down after the service. There was a tricky bit related to the portable stage, which was set up by church workers, and the way we were using the pieces made them uncomfortably wobbly. I figured out a way to stabilize them which involved straps and “come-alongs,” with some assembly required.

Cable-puller aka coma-along

The assembly and audio set-up was sufficiently complex that I wanted to do it myself, and did so every Sunday for an entire year. Eventually I needed to hand it off (to another engineer, naturally) so I wrote and drew a 4-page document with all of the steps required to safely and effectively assemble the set-up.

As One Tree Hill wound down, I found other places to play and people to play with. But the nature of “picking” for an audience as an amateur means having to schlep gear — instruments always, amps sometimes, sound systems less often.

Bitsyland playing a market and a party
Bitsyland playing a market and a party

I really enjoy playing, and seeing and hearing an audience’s response. But more than that, I enjoy the pleasure of making good music, with or without an audience. My family members, including Cousin Jimmy and our musical friends, often schedule a pickin’ where we just play for and with each other. We’ve been known to play for hours, until our fingers get sore.

But for some bizarre reason, probably related to some faulty wiring deep in my psyche, my very favorite thing to do is to pack up and load out. Maybe it’s the feeling of completing a task. Maybe it is the sense of relief from the pressure I feel to play my parts correctly.

The Jackson Browne album Running on Empty was recorded in 1977. I find it to be a fun execution of a clever concept. Most of the tunes were recorded live during one of the tour concerts. A few of them were recorded on the Silver Eagle tour bus as it rolled to the next gig, or in a hotel room. (In the background of some songs you can hear the sound of big rigs as they pass the tour bus during the recording.) One of the songs starts with the bus version of the recording and segues into the live version.

Having never been on a road tour like that, I can’t say for sure, but the album feels realistic. Jackson Browne is a powerful songwriter, and there are a couple of really good love songs mixed in with the theme tunes. There are a few songs with subject matter that is awkward for me, but, again, I feel like it reflects the reality of that sort of life on the road.

But I really resonate with the last two songs, because they are about packing up and loading out, about enjoying playing, about roadies and equipment, and the sound of an empty auditorium after the crowd has gone home. And about going to the next city to do it all again.

As my body has logged more and more mileage, and birthdays feel like they are flying by, I’m glad I can still find a place to pick, the energy to schlep gear, and the joy of packing it all up when the gig is over.

The shenanigans described here would not have been possible without kind and benevolent support over the years from my co-workers, my bosses, my family, and most of all, my Infinitely Patient Spouse. I am grateful.

Interested readers can find a crude summary of my musical history here.

You may also find some historical remnants and versions of One Tree Hill’s web page here.

There is also a gallery of miscellaneous photos I assembled in 2020 using photos provided by Brian and Patrick. In addition, Brian has posted some One Tree Hill videos on his YouTube channel.

Somewhere I have some of my own photos, and the 4-page chart I made for the worship service set-up, but I’ve decided to publish this without waiting any longer to find them. Watch this space for updates 🙂

August 15, 2020

I’m Positive

Filed under: Uncategorized — etblog @ 12:47 pm

Several decades ago I read a novel by Russian novelist Aleksandr Solzhenitsyn. I was in my precocious young adulthood, and my world view was simple: the Soviet Union, and Russia in particular, were the enemy, and there was nothing good there. Solzhenitsyn was an exiled dissident, so I was interested in his perspective.

Knowing he had been exiled, I was surprised when I read a passage in which he affectionately described the beauty of the Eurasian steppes, and the countryside of his homeland. I was struck by the realization that the dreaded country of Russia could include scenes of nature that would tug at the heart of an exile many years later. That realization has stuck with me ever since, that a place can be beautiful regardless of the national boundaries and polity that encompass and seem to define it.


Today I find myself in an uncomfortable time. Between politics and pandemic, climate changes and economic concerns, hatred and greed, life often feels overwhelmingly depressing. As a concerned citizen, I need to be aware of what’s going on around me, near and far, so I can react accordingly — donate, vote, petition, act.

But a steady diet of chaos, evil, and confusion doesn’t feel healthy.

An antidote

As one antidote, I am trying to be positive. To be sure, I’m not ignoring reality, or putting on rose-colored glasses. I’m simply looking around for small evidences of beauty, normalcy, and stability that the actions of the universe reveal to me.

Recently I noticed two things that provided me with a few moments of relaxation and encouragement. They were not dramatic, but that’s sort of the point: I can derive pleasure from small things.

I don’t expect you to be “wowed” by these examples. But I hope they will encourage you to broaden your own perspective, and seek joy in small delights.


Hickory nut shards
Hickory nut shards

Two days ago, I walked, barefooted and painlessly, down my back stairs to my “pandemic office” at around 7AM. Three hours later, as I came back up the stairs, I was struck with an unexpected sensation: pain. Specifically, pain in the soles of my feet as I navigated the stair landing. Keen observer that I am, I quickly deduced that I was stepping on sharp fragments of hickory nuts.

In the short time I was downstairs, some local squirrels apparently decided that finally the hickory nuts were ready to eat. Whole nuts have been falling on the deck for the last few weeks, but apparently the ones in the tree were not fit to eat, until rightnow!

At the time, I thought that was mildly amusing, but little more; I filed it away in my “interesting things I’m not likely to write about” brain folder.


Butterfly on a bush

Then yesterday I saw the butterflies. Jasper and I were in the part of the back yard I call the “frisbee field” playing catch as we do most every day. At one end of the field, there are a couple of butterfly bushes . They have been modestly showing off their delicate purple flowers for the whole summer. But today was the day two butterflies decided it was finally time to cavort around the flowers, and (I presume) pause to drink some nectar, or whatever it is that butterflies do when they land near a flower.

Between the timing of the squirrels and the timing of the butterflies, I was reminded that the seasons are changing, despite the everpresent heat of August in North Georgia. Oh, I’ve already noticed other, more subtle changes recently — the slow displacement of the shadows in the yard as the sun gradually moves lower in the sky, and the two scrawny trees in the backyard that always start dropping leaves just a few days after the Summer solstice, like they want to be first in the annual Falling Leaves Contest.

But for some reason this year, it was the confluence of the squirrels and the butterflies that reminded me that there is more to life than the significant (but definitely not all-important) issues that threaten to give me a bad case of the blues if I fail to figure out how to counter-balance them with positive observations.

It was while watching the butterflies cavort that I thought of Solzhenitsyn, and the beautiful steppes of his Russian homeland, and decided I would focus for a few moments on the important benefits of observing the world around me, finding beauty and joy, thinking positively, and writing about it.

Ukranian Steppe photo
Ukrainian Steppe

July 22, 2020

Notes from a Virtual Capstone Expo

Filed under: Uncategorized — etblog @ 5:26 pm

The Georgia Tech Capstone Expo is typically held twice a year, usually Spring and Fall. The event provides Seniors across a variety of majors the opportunity demonstrate projects and devices that they have designed and implemented. I’ve participated as a volunteer judge for the last few years. The Expo is normally held in the McCamish Pavilion, the basketball arena on the Tech campus, where it fills the main entry and service floor, plus the basketball court, much of the second floor, and even a large outdoor tent for larger projects which are not suitable for indoors. It is quite a spectacle, and always inspiring.

This summer, in acknowledgment of the challenges introduced on campus by the Covid pandemic, the Mechanical Engineering (ME) department hosted a “mini” virtual version of the Capstone Expo. A few weeks ago I signed up to judge, and was very curious how a virtual version would work, especially having participated in a wide variety of video conferences, telepresence meetings, virtual seminars, town halls, and corporate broadcasts over the last few years, and especially in the last few months.

The lead-up to the Expo used some familiar tools: Eventbrite for ticketing, a new vendor, rocketjudge, for the judges’ voting app, and a post-event survey application. The students all participated remotely, and they used BlueJeans for their planning and design meetings.

Obviously I was most curious about the tool they selected for the actual Expo interaction. The circumstances were challenging. The viewers and judges were told in advance that they would need to participate using a computer with microphone and camera, running the Chrome web browser. The judges were provided with a rubric to guide our assessments, and we were given a link to the list of participating teams. Each team created a single poster for display (just as in the face-to-face Capstones) and a short video describing and, if possible, demonstrating the problem and solution. (This took the place of the physical models and devices normally used in a face-to-face Capstone.) This information was made available to judges and attendees earlier in the afternoon of the the Expo.

We were allowed to log in starting at 3:30 PM, with the opening remarks and official kick-off scheduled for 4:00 PM. Following that, each team would do a presentation of their project every 15 minutes (4:15, 4:30, 4:45, etc.) until the conclusion at 5:45. The winners were scheduled to be announced at 6:00 PM. The teams left time for Q&A at the end of each presentation. This was more formalized than a face-to-face Capstone, in which presentations generally occurred on a more ad hoc basis, when one of more people stopped at a team and expressed interest. In some cases, there were also sidebar conversations going on between an attendee and a team member.

So how would this work considering we were all going to have to use a previously unseen tool to emulate a very dynamic environment?

The short answer is, “Much better than I expected.”

Here’s an overview. This is completely based on my memory, so some of the details may be off, but it should be pretty close. It made quite an impression on me.

When I logged in, a screen appeared in my Chrome browser window. I’ve drawn it out, below, for two reasons: (1) I didn’t realize until it was over how well it worked, and how much I wanted to describe it, so I didn’t take any screen shots. I was busy attending, and judging, a conference!! (2) I don’t want to post anything graphical that might be considered intellectual property, even though this write-up will only be distributed to a few folks.

Outline of Gatherly main page

The screen and the functionality were created by Gatherly (gatherly.io), which turns out to be an Atlanta-based start-up. Based on a quick web search, gatherly.io appears to be one of a very few tools designed for this type of application.

Due to my own schedule conflicts, I didn’t manage to get signed on until about 3:50. At that time, the large presentation window was mostly blank, and I could see myself (and the mute status of my audio and video) in the self-view window, The lower-right window was a scrollable list of attendees by name, and the room plan view had several types of icons scattered about, and was titled “Lobby.” In the lower left of the Room view was a wider gray area marked Elevators.

I could see the icon that represented me at the “entrance” to the room. I discovered that when I moved my mouse, a line extended from my icon to wherever my mouse was pointing to.

In addition to the small people icons, there were larger, numbered grey circles that I soon figured out were groups of attendees. Hovering my mouse pointer over a grey circle popped up a list of the people in the group. Clicking on the group was equivalent to walking up and “joining” the group. The large window showed video images of the group participants. I could “walk” around the lobby by simply clicking. There was a nice time delay that made it look like I was actually walking!

Not quite being ready to commit, I didn’t actually join any groups, but just hung around in the lobby. Eventually, the host appeared in the main screen and began to welcome us and explain how things were going to work. He directed us to the “News” tab in the lower right corner for generally applicable information. After some additional housekeeping announcements, he announced that we were free to begin.

I was assigned to judge three teams, which would take at least 45 minutes to hear all three presentations. All three of my teams were on the “Upper” floor, so I “walked” to the elevator by clicking, and was presented with a choice (elevator “button”?!) of U or L. I clicked U, and the Room Plan view changed to show the six team locations in the room. (It turns out that there were 11 teams total for this ME “mini-Capstone” — five on the lower floor, and 6 on the upper.)

The only snag I hit was when I tried to listen to the first team’s presentation. I clicked on the space marked out for the team, but not on any of the other people who appeared to be gathered there. If I had been a little more sociable in the lobby I probably would have figured it out earlier, but eventually I clicked on the “group” that was hovering on the team space, and “joined” the team, in mid-presentation, I would note. But it was a little like walking up to a physical presentation already in progress.

Once I “joined” the presentation, the main window displayed their one-page poster, and the scrollable participant window showed all of the people in the group, presenters and observers. I had to scroll back and forth to figure out who was talking whenever they changed speakers, but that wasn’t a huge problem. The presenters were easy to spot because their names began with their project location identifier (U6, for example.)

At this point I remembered that they had asked those of us who were judges to start their names with a “J” when they signed in, but I never saw anyone who had remembered to do that in the directory.

The first project I visited was a team that had designed an automated way to swap out charged battery packs for delivery drones. I listened to their presentation, asked a few questions, and made my initial assessments on the judging app.

Then I virtually wandered over to the next team and did more or less the same thing. Their product, sponsored by a mining corporation, automated the preparation of test samples for analysis. Their design included a detailed stress analysis of their grinding apparatus, fluid flow calculations for the liquid distribution system, and outlining the computer code required to manage the overall automated system.

One of the things I enjoy about the face-to-face Capstones is getting to chat on an individual basis with some of the individual team members. They always have something interesting to say. This virtual version was no exception. The presenters were aware of who the visitors were, thanks to the display interface. (This is an improvement over the “trying to make out the name on the name tag” interaction of a face-to-face.) One presenter even acknowledged two of us by name when they started the presentation. The Q&A portion was very natural, with no noticeable audio delay, just like talking in person.

I repeated the process one more time for the third team. This project was about a robot test “track” for a legendary ME class which requires students to build and program robots to perform a specific task. Their design allowed the track to be reconfigured for each semester to introduce new challenges, and to take advantages of improvements in the robot products that the whole class uses. After some real Q&A, we shared a little humor about whether their design would accommodate robots which could levitate. “Oh yeah, we can handle a hoverbot!” one student quickly replied.

During one of these presentations, I figured out what the “local chat window” was useful for. When you join a group, a unique chat window for that group appears in the local chat tab. Team members posted notes, follow-up answers, web links, and so forth. It all felt very natural.

After I finished entering grades for all three, I looked over the list of projects and found one that sounded interesting on the lower floor. This was a project to help mobility- and strength-impaired persons do their laundry. It used a wheeled basket with a tilt mechanism to dump the clothes into the washer or dryer, as appropriate, and a power-assisted claw mechanism to remove the clothes from the washer or dryer.

When I joined the group, there was a judge asking some very good questions of the group. Since I wasn’t assigned to judge them, I just listened, and came up with a few comments. Rather than interrupt, I just began typing my comments into the local chat window. About the time I finished my first comment, the judge thanked them and “walked” away, and they began to respond to my first comment, which proposed community laundromats as a possible market as well. My second comment was that the claw looked like so much fun that you could probably get kids to do the laundry. And my third comment was about whether they had done a safety analysis.

I was fascinated at how natural the typed comments and verbal responses felt in this context. Almost as if I were standing there texting questions to them.

In summary, the design and implementation of the meeting tool was impressive. I can think of so many ways that the solution could have been awkward, or time-consuming, or unclear. But the attention to design detail seemed pretty obvious.

This is even more amazing when you consider the fact that Gatherly.io is a start-up, and that the ME department had to figure out how to pull this off in just a few months.

The Expo organizers posted a few statistics at the end of the session. In addition to the 11 projects and teams, there were 35 judges, 75 participating students, and more than 150 virtual attendees.

The first place winner was “Hive Deliveries”, the first group I visited. Second place went to Sanitation Assistance Machine, an automated ultraviolet surface de-contaminator. And the Laundry project I visited won third place in the People’s Choice voting.

All in all, I would consider it a successful event.

November 9, 2019

Why my first simulation included the use of a shovel

Filed under: Uncategorized — etblog @ 3:06 pm

Early in my Superior Steel days, I was given the job of replacing one of Mr. Pete’s old relay-based control systems with a new Texas Instruments 5TI Programmable Controller. (Mr. Pete was Wendall Kitchens’ dad, and the founder of Superior Steel. He built all of the electrical controls, and his retirement was one of the factors that led Wendall to hire me.)

This particular control system managed the weighing and dispensing of the ingredients for making concrete blocks. There was a conical bin suspended over the mixer that was hung on a mechanical scale system. As materials were added to the bin, the needle on a big Cardinal Scale rotated to indicate the weight of the material in the bin.

Diagram of a modified mechanical scale dial
Scale diagram

To automate this process, Mr. Pete came up with the idea of gluing a small magnet (about 1/8″x1/8″x3/4″) to the front of the rotating needle indicator. Then he added several aluminum rod pointers to the face of the scale which could be adjusted to point to specific weight values. Each rod had a magnetic reed switch attached to its back side. As the scale needle rotated, the proximity of the magnet as it passed by a pointer would cause the tiny reed switch to close, completing a circuit. The Scale diagram shows some of the components described here, and their relative locations.

He ran tiny wires from the reed switch pointers to the control panel, and used them to automate the operation. With a single press of a button, the sand conveyor would start adding sand to the bin until the scale’s needle reached the first pointer. The sand conveyor would cut off and the aggregate conveyor would start adding fine rock until the second pointer was reached, at which time the cement conveyor would start adding cement until the third pointer was reached. The bin would then dump its contents into the mixer. Water was added using a water meter, and the rest was more or less manual. The operator would watch it mix until it looked right, then dump the mixture into the block-making machine, and start the weighing process again.

I prepared for writing the program by studying Mr. Pete’s D-sized drawing (about 36″x24″) of the circuit, which consisted mostly of relays and timers. Relays are generally used to take the output of a low-power device, such as the reed switches, and allow it to control a more powerful device, such as a large conveyor motor or a pneumatic valve attached to a cylinder actuator. Timers are used to add preset delays to the process.

A sample diagram of a relay circuit in ladder format
Ladder diagram

Fortunately, the 5TI used relay-based ladder logic as its programming “language”. Ladder logic depicts a circuit as two vertical lines (the plus and minus or hot and neutral voltages) which are connected by horizontal “rungs” which introduce logic in the form of series and parallel contacts (logically equivalent to AND and OR). You “program” the 5TI by entering a list of elements which emulate relays. The 5TI supported inputs, outputs, relays and timers. The Ladder diagram shows an example of a push-button-controlled relay,a timer, and an indicator lamp. (Analysis of this logic is left as an exercise for the reader.)

In my first few weeks at Superior Steel, I had successfully done some troubleshooting of control panel malfunctions using a volt meter and Mr. Pete’s circuit diagram, but when I tried to understand the whole thing, there were a couple of relays whose purpose I didn’t understand. [Narrator: cue the dum-dum-DUM music.] But I had a pretty good idea of how everything was supposed to work, so I moved on.

Since this was the first time I had tried to do a relay-to-5TI conversion, I wanted it to go right. So I built a SIMULATOR! It was a metal chassis with a handfull of toggle switches (to simulate inputs) and neon lamps (to simulate outputs).

Programming console with buttons and alphanumeric indicators
5TI programming console

I connected the 5TI programmer to the 5TI unit and entered the ladder-logic equivalent to the physical relays and timers as I understood them into the 5TI. The photo of the 5TI controller shows what buttons were available, and gives you an idea of how the programming worked. Once I entered the logic steps, I disconnected the programmer and connected the 5TI electrical inputs and outputs to the simulator switches and lights.

Finally, I stepped through the sequence using a switch to start the sequence. I watched the light symbolizing the conveyor for the first material as it lit up, then I used the switch simulating the first scale pointer reed switch to indicate that the first set-point had been reached. The first conveyor light turned off, and the second conveyor light turned on. After a few seconds, I used the switch simulating the second scale pointer reed switch to indicate that the second set-point had been reached. I went through the whole sequence, and it seemed to work as intended.

Satisfied that everything was ready to go, I delivered the 5TI and its input/output chassis to the concrete block plant, and their electrician wired everything in place according to my instructions.

At last the day came to commission the system and mix the first batch.

As the owner and his operator stood watching, I pressed the start button. Lights flashed, a motor starter clonked, the conveyor started up, and the first material began to flow into the bin, just as planned. When the scale needle swung up to the first pointer, the first conveyor stopped, and the second conveyor started, just as expected.

Then something completely unexpected happened. The scale began to fill much more quickly than expected. The needle passed the second pointer, and kept rising. While I was trying to figure out what the heck was going on, the operator was shouting, “Turn it off, turn it off!”

By the time I could get it stopped, sand and rock had overflowed the scale bin, onto the floor, and into the mixer.

We stood there trying to figure out what had gone wrong. The operator pointed out that, just a few seconds after the second conveyor had started, the first conveyor had started back up, dumping excess material in the rapidly filling bin.

My first thought was that the 5TI had run the program wrong. In retrospect, that would have been a pretty ominous explanation. Fortunately that was not what had happened. After a little thought, I realized what the problem was. And what those extra relays were for in Mr. Pete’s original drawing!

I also learned, in memorable fashion, why a simulator is only as good as the accuracy of its representation of reality.

What happened was this: when the second conveyor began to add material to the scale, and the scale needle began to rise, the magnet no longer kept the first reed switch closed. So the program ‘thought’, “I need to add more of the first material.” And so it did.

Mr. Pete’s unexplained relays were latches. Each relay was wired so that, as the measuring cycle went through its steps, when it was activated by the scale pointer, it would hold itself on until the end of the process. It served as an electrical memory that indicated, “We don’t need any more of this material on this cycle, even if the scale pointer switch opens back up.” (The first line on the ladder diagram is a similar latching circuit for the “Start” pushbutton.)

So why didn’t I catch this logical fallacy on the simulator? Because the switches I used were toggle switches, not momentary switches. To simulate the actual operation of the scale circuit, I would have had to have turned off the first switch to emulate the action of the reed switch as the scale needle increased. If I had thought of it.

Back at the concrete block plant, it fortunately only took a few minutes to add latching relays to the 5TI program.

It took somewhat longer to convince the owner and the operator that it wouldn’t happen again next time.

And it took even longer to shovel up the excess rock and sand from in and around the mixer. They didn’t ask me to help, but since it was fundamentally my fault, I grabbed a shovel and did my part.

I can’t say that I never mis-used a simulator after that, but I will say I was considerably more cautious.

If you are interested in more information on the 5TI or ladder logic, here are a few references:

A 5TI article on a cool electronics archive site (and the source of the 5TI programmer photo):


A description of ladder logic diagrams:


And, as usual, Wikipedia has a very comprehensive article on Simulation: https://en.wikipedia.org/wiki/Simulation

The father of Information Theory, Claude Shannon, gets the credit for showing how series and parallel relay contacts are equivalent to AND and OR logic operators. https://en.wikipedia.org/wiki/Claude_Shannon

March 22, 2019

Delights and Disappointments

Filed under: Uncategorized — etblog @ 8:32 am

Last year, a work friend asked me to talk to members of his Technical Development Group on any topic. I decided to talk about my “personal relationship with technology,” which, now that I have written that phrase, sounds a little peculiar, so it fits right into Enoch’s Thoughts (as explained several paragraphs into my very first posting.)

As often happens, I found it more convenient to initially document the talk on a web page, to which I hereby direct you, hoping you derive as much enjoyment reading it as I did writing it. Please see http://iideaco.com/dnd/.

June 24, 2018

Soldier’s Joy — a tale of music and romance

Filed under: Uncategorized — etblog @ 2:19 pm

Earlier this month, four of us old pickin’ buddies got together one weekend at my cousin Jimmy’s mountain cabin. On Sunday morning, Brant and I were playing a few old fiddle tunes on the front porch with his hand-built mandolin and my guitar, and I happened to tell him the story of learning to play Soldier’s Joy, which turned into a bit of a saga. When I finished, he said, “You need to write that down.” So here goes.

In the mid-70s, some promoter apparently decided that Atlanta needed a bluegrass version of Woodstock. It would be held at the Fairgrounds on Labor Day weekend, it would last for 48 hours, and the tickets would include the option to camp out.

Blaylock Album Cover

Blaylock Album Cover

A banjo player and music store owner named Bill Blaylock decided that this event would be a good opportunity to showcase his unique approach to banjo playing as featured on his record, “A Gentleman and His Banjo.” Cousin Jimmy had taught Bill’s son in middle school, which is how Jimmy got to know him. So when Bill needed pickers that summer for the album and for the festival, he recruited Jimmy, and Jimmy recruited me.

Over the summer, Jimmy and I traveled to Marietta once a week to learn the songs Bill wanted to play. I was playing an upright bass borrowed from Bill’s music store, and Jimmy was playing his Gallagher six-string guitar.

To be honest, my relationship with the upright bass fiddle was awkward at best. I had briefly played a bass belonging to First Baptist Church of Atlanta when I was a college freshman. The only instruction I received at the time was, “It’s the same notes as the top 4 strings on the guitar.” The student chorale I sang in, and played with, mostly performed show tunes, and I had a fun time, despite the fact that the bass’ warped bridge would occasionally go flying across the room if I played too enthusiastically. I have no idea how it sounded, but they didn’t make me quit, so it must have at least been palatable. Or perhaps just entertaining.

Bill’s bluegrass songs were a little simpler than the show tunes, but the fact that we were going to be playing on a big stage, with a big sound system, and a big crowd, was a little nerve-racking.

The weekly practice routine came at an opportune time for me. A few months before, my fiancee had hit “pause” on our wedding plans, then took a summer job as a missionary to a Native American tribe on a reservation out West. Her first (and last) communique to me from Arizona was a “Dear Carl” letter, which sort of left me at loose ends. A summer full of picking was a welcome distraction. Who needs romance?

One of the tunes we learned for Bill was Soldier’s Joy, a very popular fiddle tune with an ancient Scottish heritage. Like many fiddle tunes, the chords seem to change at unexpected times, but the “B” part of the tune has a distinctive walk up on the bass that made it easy for me to remember over these many years. During the Civil War, Soldier’s Joy referred to a combination of whiskey, beer, and morphine that soldiers drank to reduce pain from war wounds.

In addition to learning lots of new music that summer, a couple of otherwise minor events still stand out in my mind even though nearly half-a-century has passed.

To set the scene for the first event, picture us rehearsing after-hours in the music store, with the main store lights turned off. I’m standing off to one side with the bass while Bill and Jimmy sit in folding chairs, accompanied by a small bottle of Coca-Cola (Bill) and a tobacco spit cup (Jimmy; you can take the boy out of the country, but you can’t ever take the country out of Jimmy.) The only lights on are the ones in the back hall of the music store, and several of Bill’s friends are sitting in the hall watching and listening to us play, and otherwise trying not to interrupt.

It was a very cool scene, with the dim light streaming out of the hall, putting Bill and Jimmy and their instruments in silhouette from my perspective, and I’ve often wished I had taken a photograph. But that was long before a camera would fit in your pocket.

On one particular song, Jimmy was using a capo to raise the chords up to the correct key. The capo he was using was mostly a nylon strap rather than the big steel spring kind. When we finished that song, Bill started right into another, and Jimmy quickly flipped off the capo and dropped it beside his chair.

Immediately, a wave of chuckling began to emerge from the listeners seated in the hall; the chuckling grew louder, until we finally had to stop playing to see what was going on. It took a few charade-like gestures from down the hall, but we finally figured out that Jimmy had dropped his capo into his spit-filled tobacco cup. (Yep — yuk!)

The second event that stands out in my mind involves the actual show. The Bill Blaylock trio were scheduled to play three or four sets over the course of the festival. In addition, at the last minute, Bill told us that he had signed us up to accompany another performer for several sets.

Roni Stoneman with Grandpaw Jones

At the time, Roni Stoneman was billed as the world’s fastest banjo player. In addition, she also played the part of a rural country wife on Hee-Haw, a redneck version of the Ed Sullivan Show. In a typical comedy sketch, she was depicted as a tired housewife, ironing clothes in a run-down house, with a couple of teeth blacked out, and an accent that exaggerated her already strong Southern drawl, exchanging laconic lines with Roy Clarke or Grandpaw Jones.

On stage, however, she was a consummate professional who knew exactly what she wanted. A few weeks before, her manager had sent Bill a list of songs that she would be playing, mostly standard bluegrass numbers, so he could make sure we knew how to play them. Just before her first set, the three of us got together for the first time to go over the tunes, and she made sure we knew what she wanted — a straight up rhythm section in four-four time, bass on beats one and three, guitar on the back beat, no runs or leads from us. She would play through each song multiple times, and at the last turn-around of the song, she would lift her cowboy-boot-clad foot as a signal that the end of this song was nigh.

As best I can remember, the actual playing at the festival was fun and rewarding. The crowd was smaller than expected, but sufficient to encourage us. One of the Blaylock sessions was early in the morning of the second day, and the fog-muffled, pre-dawn grayness, combined with the sleepy-eyed campers clustered near the stage, made the set feel and sound like something from another era.

I think it was during our second set with Roni Stoneman that the second memorable event occurred. (Try to remain calm – remember, it was a very minor event.) We were a few songs into the set, and starting to relax a little, feeling a little more comfortable with the whole scene. Roni was playing the fire out of a song, and me and Jimmy were keeping the rhythm going. Her fingers were just flying, and for some reason I did a little walk-up, like C – G – C – G a b – C – G – C.

Without missing a note, she swiveled her head around to glare at me, and yell (out of microphone range), “NO RUNS!!”, then turned back to the audience with her 100-Watt grin, and continued to pick the fire out of her banjo.

Needless to say, I didn’t play another run the rest of the session with her!

Unfortunately, despite all the fun Jimmy and I were having, the festival ended prematurely. As Jimmy and I were driving back and forth between sets, we had noticed a definite lack of Woodstock-sized crowds. As I recall, there were a lot of other large and small events happening in Atlanta that Labor Day weekend, competing for folks’ attention — a Braves baseball game, a big race at Road Atlanta, and many other similar opportunities for late summer entertainment.

About half-way into the festival, we had played a couple-three sets with Bill Blaylock, maybe two sets with Roni Stoneman, and had watched Doug Kershaw, the “Ragin’ Cajun,” dance from one end of the stage to the other, sawing madly on his fiddle. Charlie Pride was scheduled to play, but I don’t remember whether he did. (The big-name stars were flown in from a nearby hotel by helicopter, to avoid the traffic crunch that never quite happened.)

Anyway, Jimmy and I were standing next to Bill in one of the underground tunnels that led up to the stage entrance, when legendary banjo player Earl Scruggs came rolling up in a golf cart. I believe his son Randy was with him, and maybe Earl’s stage manager. They were all discussing with Bill whether Earl should go on out and play his set as scheduled, and the final consensus was that he should not. I remember someone saying something like, “It don’t look good — it’s liable to get nasty out there.”

I later heard that the sound crew, observing the low attendance, decided to ask for their payment immediately, or they would shut down the system. It seems that the promoters had not received enough money from the gate to pay everyone they were indebted to, and had even tried some tricks, like giving the sound crew a check with only one signature when two were required.

Eventually, some sort of announcement was made, the sound crew shut down the sound and lighting systems, and the whole thing ended, “not with a bang, but a whimper.”

But it was not all bad. Jimmy and I had the chance to play a lot of music, and to see some famous pickers. And, just before the festival, my ex-fiancee called to say that she had some of my belongings to return, would I be at home that weekend. I just casually mentioned that, no, I was going to be playing at a big bluegrass festival all weekend, that maybe Tuesday would work.

Coincidentally, Ted Turner was just starting up his cable television station, and he was looking for content to broadcast. The bluegrass festival was local and available, so he broadcast the whole thing (as long as it lasted) live.

Also coincidentally, I had mentioned to my ex-fiancee that we might be on channel 17, and she actually watched us play, recognizing me by my ever-present cowboy hat.

So when she brought my stuff to my apartment on Tuesday, we had plenty to talk about. And talk we did. In fact, one thing led to another, and we’ve been married over 40 years.

And Bitsyland, the Americana string band I play bass with now, still includes Soldier’s Joy in its repertoire.

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