The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Words to design by, live by, work by …
A friend mutters that every time something goes wrong with her house, which (to be fair) isn’t all that often.
However, if you’ve got the itch to fix things, a house will certainly keep you scratching: nearly everything we own has a part or patch from the Basement Laboratory Repair Division!
She has similar sayings about cars, cats, bicycles …
Father Vaughn always posed that deceptively simple question when asked for help with a new problem.
What he knew, and what we eventually discovered, was that the most recent Thing-That-Changed generally had something to do with what was now broken. Even if the difference didn’t seem related in any way, tracking down its effects was always a highly productive use of your time.
His question applies to non-technical problems, too… especially when you think nothing has changed.
That’s in addition to whatever it’s supposed to be measuring, of course, but it’s amazing how temperature effects creep into those last few digits without you noticing anything different.
The differences between precision, accuracy, and resolution remain relevant, if commonly misunderstood. In particular, precision is not the same as resolution. A good introduction is there.
I stand in awe of the analog IC design folks who can build temperature compensation into a chip by tweaking junction areas and currents. A tip o’ the cycling helmet to ’em!
The Great Green, one of my better IBM managers, used the ratios of key numbers to quickly evaluate proposals. Conversely, if a proposal didn’t have any key numbers, he knew the author was blowing smoke.
He attended a school budget meeting many years ago, wherein someone kvetched about the cost of and need for a semitrailer of paper every year. He estimated the number of sheets, divided by the number of students, then divided by the number of days in a school year. The answer came out to about one sheet of paper per student per day, which seemed like a perfectly reasonable number to him…
Two fundamental Principles of Rope:
The First Principle should be obvious, but all too often I find myself trying to thread a wire through a structure… and eventually realize I’m attempting something that’s isomorphic to pushing a rope. Doesn’t work, never has, never will.
The Second Principle comes in handy with hoses and cables. If you separate the tangle into two parts, any part without an end is topologically either a knot or a loop, but won’t contribute much to the untangling. Conversely, any part with an end can be reduced to a straight section (possibly leading to a tangle in the other part) by fiddling around for a while.
Someone famous once observed that being a gourmet consists almost entirely of being able to make approving noises and say “That was very good!” after eating a morsel that would cause ordinary folks to throw up.
The lab tech who coined that aphorism, obviously a man with an earthy sense of humor, also experimentally determined that the women he dated couldn’t tell the difference between fancy wine in ornate bottles and cheap wine in screw-top gallon jugs. So he kept a couple of ornate bottles around which he refilled as needed from the jugs. He simply pushed the corks back in and did a credible job of re-sealing the top with paper and wax.
We worked together on the IBM Video Disk project, then served time together in the East Fishkill Factory. Lost touch over the years and I think I just saw his obituary go by… sic transit, etc.
Once Upon A Time, back in the IBM Video Disk project, a friend (herein known as LLT) built a demodulator for the video data streaming off the disk. This being the development phase of the project, cost was not much of an object, so he used a quartet of high-speed TRW TDC1003J digital multiplier-accumulators running in pipelined parallel to handle the data rate.
While a 175 ns MAC isn’t a big deal these days, it was a state of the art TTL chip back then: a finned-heatsink 64-pin DIP package that cost approximately a bazillion dollars. The board was maybe two feet on a side in classic Wire-Wrap style.
We called them Multifryers: each chip drew 750 mA at 5 V. That board had many cooling fans.
Then, One Fateful Day, came a request to quantify just exactly how much it would cost to build a production version of the player. LLT pointed out that the demodulator board itself would cost more than a really spiffy car, but to no avail: he had to come up with a cost estimate for a fairly large production volume of the as-built hardware.
So LLT calls up TRW and asks for a quote on thus-and-so-many parts, with delivery to-be-determined. There’s a long silence, after which they tell him they’ll have to get back to him on that.
Time passes.
Eventually he gets the quote. He had to tell them to not start building the factory right away, because the project was most likely doomed. Much relief was expressed…
The Smell of Molten Projects in the Morning 