A closeup of the ten-step relay. It moved sluggishly and got held up on the tenth step when the carry contact (upper right) could not close, stopped by the bump on the circular cam.
I re-wired the relay coils for the improved control circuit and hooked up the new power supplies. A set of micro-switches were used for setting the time—they momentarily applied power to the relays with each button push. I could now see if the relays still worked. They did!
Well, they mostly worked. The contacts had tarnished and needed cleaning, and some of the mechanisms got stuck in one or more positions. I applied the usual treatment for things that stick—WD40, but it was not enough. The lubricant that finally allowed the decade stepper relays to move freely was something called “Nano-Oil”, a substance using “Magnetically induced Molecules of 0.09 microns”, that my son had gifted me a few years back. At the time I wondered what I would use it for, but he evidently saw my future need for it.
“Nano-oil” helped to re-lubricate the moving parts on the relays.
A short video showing the (restored) relay activation and contact movement.
I had no schematic and my memories were vague, but I recalled that there had been three types of relays, all operating at different voltages, which made for a complicated arrangement of relay contacts and coil terminals. There was yet another voltage involved in lighting up the display. I wanted to figure out how I had managed all this complexity back when I barely understood power supplies, and then figure out how to renovate it, with the least amount of re-wiring.
As I went about tracing wires, confirming contacts with an ohm-meter, I gradually built up a re-understanding of how the relays were interconnected. Some of the wires had broken and so I could only guess their destinations. I eventually figured out how the three different relay types managed to propagate the time signal from one level to the next. As I worked on this, there were more than a few times when I wondered “how could this have ever worked?”
It may not look like it, but this is a clock, one of the world’s first digital clocks, circa 1973.
When I was twenty or so, I built a clock. It was a clock that used electromechanical relays to count the seconds, minutes and hours. I was early in my electrical engineering studies and barely understood Ohm’s law, but I was aware of electromagnets, and how they could be used to make mechanical movements. Some of us call them solenoids, coils of wire that magnetically push or pull an iron piston to make and break switch contacts.
My dad, in his ham radio hobby quest for cheap electronic components for whatever future project he might undertake, had acquired various relay mechanisms. He showed them to me and explained how they used electrical pulses to move a metallic wiper to a series of successive contacts. These were telephone relays, used when you “dialed” the phone. One relay, responding to a single rotary dial action could connect you to ten possible neighbors. Cascading it with another set of relays would allow calling up 100 neighbors. More phone digits would extend it even further, you get the idea. I barely understood how to deliver current to energize a relay coil, but I could figure out how to connect the contacts to make a sequence that counted.
Another item from my dad’s ham shack inventory of salvaged components was a numeric display, something you might see in an elevator (60 years ago) indicating the current floor. It used incandescent light bulbs to project a numeric figure on the screen. Ten separate bulbs, each behind a number glyph mask; one of which was selected for the current digit value. I figured out how to connect the telephone relays to the elevator displays to make a clock.
I was quite pleased with the result and when I got it working, I showed it off to my friends. But it had several drawbacks. First, it was noisy. Relays are mechanical devices that magnetically pull metal contacts against each other, resulting in a click-clack noise as they activate and release. The relays counted seconds, so there was a click-clack noise every second. And at ten seconds there was an additional click-clack, as the next relay responded to the carry pulse. And at 59 seconds, there was a carry to the minute-counting relay. As the carries propagated to the hours, a peak acoustic disruption occurred as the clock transitioned from 12:59:59 to 01:00:00.
The other drawback was that the clock got hot. As I said, I did not yet understand the relationships of voltage, current, power and heat. I just hooked up the components to make the displayed result I wanted. The numeric display, comprising light bulbs, used quite a bit of power. And the relays required power too, and my power supply was terribly inefficient. As a result the clock, in the glass case I made for it, built up an enormous amount of heat. I tried to ameliorate it by installing an internal fan, but this seemed only to make things worse (the fan used power too).
I kept the clock as a curiosity piece, displayed on a fireplace mantel in our home. It was intolerable to run continuously, so I would switch it on to show visitors that it actually worked, and then shut it down to stop the noise. Eventually, the clock got packed up during one of our moves and stayed so.
The boxed-up relay clock was in storage for at least 30 years, but I would occasionally encounter it hiding among my workshop parts and supplies. I recently ran across it. It had endured the desecration by (and excrement of) rodents, the decay of electrical components, and the binding of mechanical joints. I wondered why I had saved it all these years.
Well, the idea of resurrecting a contraption that I built half a century ago carried a certain appeal to me. Having since learned the principles of electricity, maybe I could bring it back to life and its former geek glory!
In the next series of posts, I will describe the process of restoring this pioneering clock.
Some “before” pictures showing the deterioration of my relay clock
I finally caught up with my blog postings of past nightscape photos to reach the ones I made this last year. And I have now completed their assembly into a printed photo book.
I didn’t realize when I started this project that the pictures would span 25 years, and that they happened to straddle the transition from film photography to digital. The chronological order reveals the change in technology as I pursued my various night sky targets.
For completeness, I posted the preface and introduction as blog entries, but their real place is in the leading pages of the printed book where all the photos are collected under one cover. I was pleased to be able to give copies of it to my family and close friends this holiday season. Not all of them have coffee tables, but I hope they find a place for it.
Although this marks the end of this particular project, I doubt that I am really done. As mentioned in the epilogue, the capabilities of cameras just keep improving and so I am now excited to start the next 25 years of taking pictures of the night sky!
A riverboat returning from its dinner cruise under the light of the harvest moon.
Some years ago I was driving home from an afternoon excursion into the beautiful rural areas of Minnesota during the fall harvest. The sun eventually sank below the corn fields and the evening sky took over as the moon rose.
There was a delay in our travel home while I stopped and took pictures of this unusual composition: the moon in a twilight sky behind the steeple of a local church and its cemetery. I don’t believe there was a guiding hand directing me to that place and time, but I recognize a unique moment when I am in it.
In the years since, I have attempted to capture the moon in this magic moment, but it turns out to be a difficult project. I recently learned why at a seminar led by Mike Shaw, one of the pioneers in making modern nightscape photos. His advice and recommendations led me to try this composition on the St Croix River, the optimal timing being one day before the full moon.
The new bridge over the river was a long time in the planning, and long overdue for replacing the old lift bridge that chronically clogged the traffic in Stillwater. The old bridge is now dedicated to pedestrians and bicycles; the new bridge hosts walkways and overlooks, making for a pleasant “loop trail” from Minnesota to Wisconsin and back.
I practiced the photo shoot for several days prior to the key event and witnessed lots of fishing and boating activities on the river. I also watched big river boats taking their passengers out for dinner cruises, returning after sunset. The beautiful fall weather held, and I was able to once again photograph the rising harvest moon dressed in the beautiful colors of twilight.
I assembled a time lapse of the experience. It’s a one-minute sequence. I hope you enjoy it.
[I write this not to gain credit or accolades, but as an attempt to inspire others who may have been blessed by similar good fortune or have been more successful than expected in saving for their futures to consider what to do with their “excess”.]
My dad once told me that he was planning to “spend his children’s inheritance”. It was his lighthearted way of saying that he was not going to restrict his spending during retirement. He intended to pursue his passions for inventive projects and for philanthropic activity, especially for educational causes. And that his children should continue saving for their own financial security. None of us expected any different.
Well, he failed. Despite his efforts to create the ultimate ham radio station, and to support his grandchildren through college, he left a surplus. Not a Warren Buffet or Bill Gates level of wealth, but certainly more than we expected from a man who worked for a salary and who, while we were growing up, paid the mortgage by keeping our daily expenses to a minimum.
My printed tile map. It identifies the fat and skinny rhombus tiles so that I knew how many to make and how to place them. It was generated based on a simulation of an edge length of 250mm and a gap width of 6mm, adding up to a nice binary number.
I suspended this project in order to go on a roadtrip to capture pictures of the night sky in the beautiful deserts of the Southwest. I am currently working on them, and hope to share them soon, but the Penrose tile floor project carries a higher priority—we want our screen porch back while it is still summer!
Having prepared my tiles to the best accuracy I could coax from my woodworking tools, I now faced how to place them on the floor. As before, I considered the advice from Ken Adelman, who recommended “dis-aligning” the pattern from the rectangle of the room, to avoid difficult or awkward-looking tile fragments at the edges. He also recommended identifying a center point and creating reference lines radiating at angles that match the pentagonal symmetries of the tiling.
A timelapse of a Penrose tile installation by Ken Adelman
I am about to embark on a month-long road trip, and I am reluctant to start the next phase of this project—laying and setting the tiles, something I expect will take a considerable amount of time and attention. Instead, I need to make plans for this upcoming trip which involve excursions to remote areas of the Southwest for the purpose of making night timelapse sequences. I am skeptical that I can fully succeed at either, much less both, in the time remaining.
So for now, I will put my tiles aside, and will instead present a rendition of the tile-laying process made by my Facebook friend Ken Adelman, the person I referred to as having succeeded in Penrose-tiling his sunroom, and who has kindly counseled me in this project.
He made a timelapse of his installation that spanned several days. I have posted it to my Vimeo account and you can watch it here. I found the movement of the sun quite fascinating as the tiles were carefully placed and spaced, the shadows indicating the elapsed time involved.
Maybe I can make a similar movie, but it will have to wait until after I return from the Nightscaper Conference, where I hope to learn the modern tools of nighttime landscape photography. Technology has changed dramatically from when I embarked on my Nightscape Odyssey twenty years ago, and I am eager to keep up.
My hand-crafted P3 rhombuses, awaiting my return to install them.
The last cut on this fat rhombus tile. The blue arm at the top of the tile is a hold-down clamp. The fence is at an angle of 18 degrees and the blue gauge on the fence track is a stop that positions the tile at the exact required distance from the blade.
I placed an order for the Marmoleum planks that I intended to cut into my Penrose rhombus tiles. It is always a bit nerve racking, making calculations, optimizing the tile sizes, trying to minimize waste, and reaching a conclusion about how much raw material will be needed. What if I am off in my estimate for the sawblade kerf?
I learned late in the ordering process that the planks were not 1-foot by 3-foot; the sales rep contacted the factory at my request and reported back that they were 300 mm by 900 mm. Further, the ordering process called for the number of square feet, but the planks were packaged in bundles, and only full bundles were shipped, so the required square foot area was rounded up to the next bundle size.
For most flooring projects, this is probably just fine, but I needed to know just how many planks would be delivered so that I could ensure that I would be able to make all of the tiles in my design. In the end I learned that the bundles contained seven planks, 20 square feet of flooring, or should I say 1.89 square meters?
With the knowledge of the exact linoleum area of each plank, I could now partition them into rhombuses (rhombi?). I determined that I could get three fat or four skinny rhombuses from each plank. I counted the rhombuses in my pattern and ordered the exact number of planks required: 21 for the skinny rhombus, and 42 for the fat ones. These are nice multiples of seven; I was pleased. I placed the order, the moment of financial commitment to this project.
Later, I realized that I could have done better. If I had slightly tilted the skinny rhombus cookie cutter on the plank, they could have been a bit larger. The fat rhombuses would have been correspondingly larger, and I would have needed fewer planks and the waste would have been smaller. I contemplated revising my plan, but after discovering that the cutting complexity would be high (introducing opportunities for mistakes), and the gain was rather small– a few percent– coupled with the guidance of my partner who reminded me about false economies, I opted to stay with my original plan. I am glad that I did.
The tile-making involved many cuts on my table saw. It was important to set up each cut with a particular jig and fixture, and then cut all of the raw material that needed that setup, all at the same time, before changing the saw for the next cut. This would guarantee that all of the pieces would be congruent, with the same dimensions and angles. It was important to make them the same, but it was even more important to make them correct. A hundred identical tiles, all of which are the wrong shape, was my greatest fear. So I embraced the expression “measure twice, cut once” and fell into a paranoid checking of dimensions and angles.
I ended up creating 84 skinny rhombus tiles and 126 fat ones. It took 462 passes through the table saw to make them. I worried about the psychological lulling of attention with repetitive tasks. I have encountered experienced woodworkers, with missing finger tips, who recounted the event that severed them. Invariably it was a lapse of attention, usually because of a trivial or repetitive cut that caused them to misjudge or ignore the spatial positions of their hands relative to the saw.
Aware of these stories, while shopping for a table saw, I learned about a model that detects human contact with the blade and fires an explosive brake to instantly stop it, analogous to an airbag in a car. They are expensive, but for an inexperienced woodworker like me, it seemed like a good investment. I am quite pleased with my SawStop table saw. It is a precision tool that I hope to never trigger.
I spent most of a week cutting tiles from the Marmoleum planks. I took it in stages, and today I cut the last of them. My fingers are intact and I am eager to start placing the tiles. I am also pleased that they seem to be dimensionally correct. My precision is not to the thousandth of an inch. I might be able to claim ½ millimeter, which would be 1/50th inch. We will see how that translates to tile placement with pentagonal symmetry!
My tile size was based on an edge dimension of 250 mm, almost 10-inches. The angle of the fat rhombus is 72 degrees. Here are my checks.
The length of each side of the tile is 250 mmThis angle on the fat rhombus should be 72 degreesSkinny rhombus tiles accumulating on the workbench behind me. Hopefully they are all identical, but more importantly, matching the right size and shape.
A rectangular section of a symmetric Penrose tiling. This will be the pattern for the porch floor.
I had seen examples on the web of Penrose tiles, but they were always rather high-end installations. I recently encountered someone who had successfully created a Penrose flooring in his sunroom. I was able to ask him about the details of his project and the recurring theme in the ensuing discussion was “accuracy”. His floor was made of ceramic tiles, rhombuses carved from 1’x2’ rectangular commercial tiles with a computer-controlled water-jet cutter to one-thousandth inch precision.
I was not prepared to go to this level, so I sought less expensive materials and tooling, settling on modern linoleum, “Marmoleum”, a materal that can be obtained laminated to a medium density fiber board substrate that I could cut myself. Any lack of machine precision would be hidden by the spacing and grout lines between the tiles. At least that is my plan.
Still, it was important for the angles and dimensions of the tiles to be as consistent and accurate as possible. I made a proof-of-concept trial with sheets of plywood, cutting them on my table saw using the fence and miter gauge at the prescribed angles. This exercise showed me that the standard methods would not work. I needed a more specialized jig, one that could result in many, many congruent tile shapes being cut to precise angles and lengths. I learned that such jigs for the table saw are common, at least among the skilled woodworkers that make fine furniture and other beautiful objects.
What I needed was a “crosscut sled”, a fixture that could be crafted using the saw it would ultimately supplement, and there were many YouTube instructions on how to make one. After watching several, I opted to skip the learning curve and purchase a commercial version. It had a wonderful angle fence, riding on a machined steel guided platform running parallel to the blade, equipped with a stop that could exactly position the material for its cut.
It was perfect. I created several identical copies of the first fat rhombus, and started making the second skinny rhombus when I discovered that the jig could not reach the required angle, 54 degrees. It stopped at 50.
A customization was required and I was able to extend the range by routing a slot in the sled, and calibrating it. I now have a Penrose-compatible crosscut sled for my table saw. On to actually making my linoleum tiles!
My routing skills are not high, but I was able to extend the angular range of the crosscut sled to 60 degrees!
