• DIN 47100 FTFY

    02/23/2022 at 20:52 0 comments

    I just learned about the DIN 47100 standard for wire colors, which includes pink. I thought it might explain why a certain vendor of hookup wire includes pink instead of grey in their 10-color kits (??). It does not, because DIN 47100 keeps grey and drops orange instead.

    Not only did it not explain that thing I was wondering about, it laid eggs in my head and fed half my brain to its evil larvae. This page will likely serve no purpose beyond an attempt to exorcise myself.

    DIN 47100: how did that happen?

    Take a look at this train wreck:

    DIN 47100 illustrated
    image: CAE Groupe
    • Let's ignore the three-color codes from 45 and up, which are apparently often ignored to favor repeating the 1-44 sequence.
    • Starts with 10 solid colors — ok.
    • The top dozen of the right column, 31-42, look perfectly systematic: pairs of green & yellow with blue stripes, red stripes, and black stripes; then pairs of grey & pink with the same stripe sequence. Blue, red, and black follow the sequence of solid colors as do green,/yellow and grey/pink.
    • Yes, the code is often used for cables of wire pairs.
    • But what about the left column? Three pair 21-26 look like the same kind of sequence as 31-36 and 37-42. Since white and brown precede the green-pink sequence it would make sense for 21-26 to precede 31, which they do, but not directly. And how to make sense of any of the rest of that?

    What a mess.

    It's clearly not random, but hints of regularity appear randomly distributed. How could that come out of Germany? To be fair, DIN "withdrew" the standard >20 years ago, but how did it live there from 1944-1998? And it lingers still — seemingly common in "LiYY" and "LiYCY" cables, of which I've learned nothing but to associate them with DIN VDE 0812 although the latter apparently does not specify color. (I say "apparently" because the standards are ̶ ̶j̶e̶a̶l̶o̶u̶s̶l̶y̶ ̶g̶u̶a̶r̶d̶e̶d̶ ̶d̶a̶r̶k̶ ̶s̶e̶c̶r̶e̶t̶s̶ ̶ ̶ paywalled.) 

    I looked it up. Judging by the sources Google likes, DIN 47100 confuses everyone. Not only do different references disagree but some have internal inconsistencies. None are authoritative, so which is closer to right? Some of the confusion relates to variability of "standard" abbreviations which apparently weren't part of 47100.

    • Wikipedia
      • apparently valid info
      • but not because supported by cited references
        • Colorhex ref is entirely completely irrelevant?
    • igus (Wikipedia article reference)
      • does not include abbreviations used in the Wikipedia table for which this is cited as reference
      • code 28 "grey-yellow" text
        • reverse of "yellow-grey" in Wikipedia
        • but image shows yellow-grey
        • relevant because that's part of the mess
    • Eland
      • includes abbreviations, but different abbreviations 
        • abbreviates brown inconsistently as BR & BN
      • code 28: "Yellow-Grey (YWGR)" (text only)
    • CAE Groupe
      • image linked above
      • code 28: "Grey-yellow" text with corresponding image
        • internally consistent at least
        • correct? (apparently not)
    • Belcom
      • abbrevs like Wikipedia, but:
      • code 17: "WHITE-GREY WH(ite)YE(llow)" - eh? (image is white-grey)
      • code 28: yellow-grey (with corresponding image)
      • code 34: YERD but image shows solid YE (gfx layers problem? looks like there is a red stripe behind the yellow ring)
    • Mueller Group
      • um, sounds German...
        • but is US-based "stocking distributor of European-made" cable
      • no abbreviations, no pictures, i.e. no fluff
      • lists only 1-44 repetition, no 45+ three-color codes, but counted as 1-22 pairs
      • pair 14 (i.e. 28/2) core B: "Yellow/gray"
        • "grAy": shibboleth for US market
      • internally consistency looks encouraging
        • ...like but not in agreement with CAE Groupe, who are actually European

    So who's right about the colors for 28/14B? Further digging in more places turns up more votes for yellow-grey than for grey-yellow, so maybe Mueller Group, and Wikipedia, have the colors right. That's colors - not touching abbreviations.

    And then there's Helukabel — bona fide Germans — who, according to a Helukabel reference page hosted by Sealcon Cable & Wire (formerly Hi-Tech Controls...

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  • Unexpected flow. Surface tension?

    07/08/2021 at 02:27 2 comments

    The bottom of the pan is flat.

    Near where the stream hits the flat surface, fast-moving water blows straight off the edge while on the opposite side slower flow piles up before it falls off. Surface tension, I suppose, subject to some threshold condition. But ?.

    Edit: "falls off" prolly means attached (surface wetting) flow over the edge & down the side -> not "blows straight off" -> the "threshold condition". ?.

  • StereoZoomoscope

    03/29/2021 at 00:35 0 comments

    A while ago I read this: #Stereo Microscope For Around $100 ! by @w_k_fay 

    And half-heartedly watched ebay for a while until this:

    StereoZoom 4 optics pod

    Then ordered some Qi Po eyepieces from China...

    eyepieces (vendor image)

    (👓 = high eyepoint -> 22 mm eyelens -> pretty neat for the $ if they're any good)

    ... which showed up today.

    Now I just need a frame and a light.

    Or maybe not:

    ... time passes ...

    You can imagine that rig (above) didn't really deliver the usability.

    And useful stands tend to cost money. (budget = less than cost of simply buying a new scope)

    And the awkward shape of the "pod" makes attaching it to something less easy.

    And hive wisdom (e.g. link at top) says get an objective lens to keep solder fume & spatter at bay -- if used for soldering, which... of course. But none of the Qi Po objective lenses fit ye olde SZ pods & ye olde B&L len$e$ co$t. I found a B&L-to-common adapter that I can't find again right now but it was ~6;30 (+ common lens), There are ring light adapters that fit and I found one with glass (or plastic?) in it that would serve the protective purpose, but ̶ ̶~̶$̶4̶0̶ ̶i̶i̶r̶c̶ ̶ ̶ $34 for whoever buys the last one:

    And so the occasional fits of looking continued...

    So I was looking at ebay again last week, and found:

    Listed as "... 2X Stereozoom ..." which means fixed 2x, not zoom. Overlooking that because I already have the zoomy pod, there's:

    • an "E-arm"
      • holds the awkwardly shaped pod
      • focus track
      • 2-axis knuckle
    • a base
      • heavy (stable)
      • another focus track
      • coarse adjustment slider/clamp (total range = long)
    • a 1x objective (just glass, to protect internals)
    • pair of 15x eyepieces
      • not much more than 10x
      • wide field but not high eyepoint
      • keep or sell with 2x pod?

    Oh, and I picked up a super cheap ring light a while ago for proof of concept. That works, tho I'll be looking for mobrighter.

    That got here a couple of days ago.

    I thought the two-stage stand looked a little Rube Goldbergish, but its versatility has already proven useful!

    TODO pix of range of articulation.

    It's a "Series K" stand, per B&L catalog. More useful than a plain vertical stand by a wider margin than I would have guessed apart from actually using one.

    The fancy stand turned up just as I was about to start work on making a stand after half a year of back-burner thinking about how to attach the pod to anything. In other words: just before I would stopped looking for one. I'll take that as a good thing because the K stand is so much more usefully versatile than the simpler up-and-down focusing stand I was about to make.

    But I went ahead and made the diy stand anyhow as an example of concrete specific application of #A Cheap Compact Linear Slide: