tl;dr: TIL cheap "A4988" stepper drivers are probably HR4988s. I don't know where the HR4988 silicon falls between theft and compatible clean-sheet design. The datasheet is appallingly copy/pasted. Like really astonishingly appalling.

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I've been using "A4988" stepper driver modules of the 0.6" x 0.8" 16-pin DIP sort pioneered by Pololu, but as re-designed by Joe Mosfet who openly published his version as (one quarter of a) "StepStick". High volume, low cost board houses churn these out for a price that's not very much different from free which makes them attractive for personal tinkering where vague provenance is acceptable.

Considering their origins, I wouldn't be surprised if the driver ICs didn't actually came from Allegro. Less euphemistically: I'd be surprised if they did.

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TIL HR4988

I've just learned that HR4988 exists, and that essentially all of these cheap "A4988" units use HR4988 driver ICs. There are datasheets in Chinese from 深圳市永阜康科技有限公司 (Shenzhen Yongfukang Technology Co., Ltd.) and in English from Heroic Electronic Technology (Jiaxing) Co., Ltd.

The Chinese version (only):

• comments on A4988 compatibility
• describes additional microstepping options up to 1/128.

The English version remains silent on those points.

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On one hand, I would like to acknowledge that giving their compatible part a distinct part number, a datasheet, and even some extra function smells more like commerce than counterfeiting.

...but...

On the other hand their datasheets are just the most appalling Junior High-level rip-off of Allegro's datasheet. Really. Apart from half a page of red-lettered "Cliffs Notes", the text and tables are either essentially all or really entirely ^A^C^V directly copied verbatim from Allegro's datasheet. With minor variations of appearance like different font, page layouts and pagination. Beyond that, all the diagrams and graphs are copied exactly. But not exactly exactly: where they could have at least given Allegro the respect of copying their vector graphics, instead they apparently just captured screenshots and copied Allegro's vector graphics as degraded raster images. The only authorial modification being to type over "A4988" with "HR4988" in the middle of the "typical application diagram", and add an incorrect minor note, in a non-matching font. Really. It's that bad. (I'm probably missing a detail here or there but not enough to blunt the point.)

Aside from the bald plagiarism, one thing the reader can know with confidence is that the graphs which show actual scope traces (right Allegro?) vs diagrammatic representations absolutely did not come from any HR4988 part.

how did that happen?

I don't know much about making chips. I don't know how much of the HR4988 silicon design is rip-off vs. original design of a work-alike part. Either way, I figure getting together whatever they had to send to a chip foundry to get working chips must take non-trivial knowledge, effort, and resource. How could they have been able to get that done and not have the wherewithal to come up with a datasheet by some means other than blatant verbatim copying? At least they could have said "it works like an A4988; configure extra microstep options like this otherwise refer to Allegro's A4988 datasheet because we did such a great job of not deviating from any of that."

tl;dr: 2009 Q2 with A4983 then A4988 since 2011

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Today is a day in July 2024. For about a decade the basic go-to stepper motor driver has been a 16-pin DIP PCB module design by Pololu, or a cheap copy thereof, typically carrying an A4988 driver ic, or a cheap copy thereof.

I say "typically ... A4988" because that's my own experience. More objectively: Pololu's descriptions for all of their not-A4988 modules refer to the A4988 part as the prototype to which each is more or less similar.

I say "about a decade" because shrug. More objectively: Allegro MicroSystems, Inc. announced the A4988 in 2010, which wasn't much more than a decade ago. Pololu's product photo shows a 2011 copyright date, which would make sense for an application of a part announced 2010.

The photo caption says "A4983/A4988" and way down at the bottom of the A4988 part description there is a note:

"Note: This board is a drop-in replacement for our original (and now discontinued) A4983 stepper motor driver carrier."

The "original" A4983 part looks almost identical (slightly different traces) with a 2009 copyright date.

From poking around in the Wayback Machine, it looks like Pololu was offering the 4983 module by 7 July 2009 after it wasn't in a 29 May capture. I haven't found a distinct new product announcement. A couple of forum posts from 19 Jun 2009 appear to almost certainly refer to this product. So, some time between 29 May and 19 June 2009.

That appears to be Pololu's first stepper driver (vs. dual H-bridge which could be used to drive a stepper) and the answer to the origin question.

At that time there was also a dual H-bridge driver having the same 0.6" x 0.8" 16 pin DIP dimensions. Pololu was offering that part by September 2008 and it remains current in slightly evolved form. Like the stepper drivers, that has power connections on one side and signal connections on the other. On the power side they both take in two supplies and drive two motor coils so the connections on that side are similar (not identical). Unlike the stepper drivers, the ic does a different thing differently controlled by different signals. So the 0.6" x 0.8" 16 pin DIP PCB carrier with power on one side, signal on the other, and a driver ic for two motor windings goes back another year. As offered by Pololu anyhow. The point being that the similar-looking thing Pololu already had before 2009, while similar in some respects, is too dissimilar to count for pushing the date of origin any further back.

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Whence the clones?

The clones all appear to use (one unit of) the "StepStick" design openly published 18 March 2011 by "Joem" on the RepRap wiki. Joem wrote: "With the recent outage of Pololu A4893 stepper driver boards, I've been wanting to build my own, and break my dependency (no offense, I <3 you Pololu!)." 

Motivated by shortage of A4983 parts (Pololu boards, not Allegro chips) and published pretty nearly exactly the same time Pololu offered the A4988 modules.

Joem showed a red PCB so all (& only?) the A4988-bearing clones were red -- apparently until red/green because a fake/real criterion and A4988-bearing clones became available in your choice of red or green. Other 0.6" x 0.8" DIP 16 modules with different drivers ICs appear to all be not red. ?.

 

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Trivia

(i.e. even more trivialer)

Currently the 4988 page shows the 2011 date board-and-quarter photo above.  In earlier captures the A4988 page shows the same 2009 date board-and-quarter photo. The A4988 product photo was updated from the pre-A4988 part to the 2011-dated part in ... 2019. Which leads to finding other things...

• 2009
  • [May 28 -- I have a note that A4983 module existed but I don't remember where I saw that]
  • May 29 <d< Jun 19: Pololu A4983 module listed
• 2010
  • April 29: Allegro...

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Output from #Minamil 3dp: another minimal CNC mill and #Minamil 2dc: a minimal CNC mill collected here because this doesn't fit in either project because it includes both. And doesn't fit in #"Desk Accessory" CNC Milling Machine because that's more about the fancy box than the CNC inside which might be either flavor or not inside a fancy box.

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Lots of "Desktop CNC" machines can fit on a desktop. But do they fit on your desk?

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#Minamil 3dp: another minimal CNC mill

#Minamil 2dc: a minimal CNC mill

#"Desk Accessory" CNC Milling Machine

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:

• 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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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". ?.

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:

Then ordered some Qi Po eyepieces from China...

(👓 = 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:

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... time passes ...

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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...

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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.

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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.

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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.

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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:

Alecs

Becks

Clegs

Decks

Erects

Flex

Grex

Hex

Ilex

Jauks

Kex

Lex

Mechs

Necks

Oryx

Pecks

Quarks

Rex

Sex

Tex

Umiaks

Wrecks

Xebecs

Yechs

Zebecs

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I haven't reviewed all of these:

https://web.cs.dal.ca/~jamie/Words/alphabets, other.html

Among those i have checked, several examples aim to misdirect, but remain intelligible between parties who know the substitutions. Less pessimal.

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Why?

Because I woke up one morning thinking of something like:

At

Bat

Cat

DAT

Fat

Gnat

Hat

Mat

Pat

Rat

Sat

Tat

Vat

...but decided against acronyms (DAT) and abbreviations (Lat. etc.). Then filled some holes with...

Did

Eid?

Id

Kid

Lid

Quid

Rid

...and the rabbit hole continued...

Maybe someday I'll expand this page. Thus throwing good attention span after bad... 

One day while I was pulling a dead laptop LCD apart...

through panel

focused on panel

no panel

Here's the top left image again. Horizontal features highlight vertical duplication.

Diffraction gratings aren't new. I thought it was notable that the 3x (rgb) difference in density bracketed some threshold for observing this effect.

I suppose the "threshold" is when the repetition spacing gets bigger than the blurriness.

Here's a laser pointer reflecting off the same panel onto a dark wall. While the vertical line obviously dominates, the shorter perpendicular period from the wider grating appears clearly.

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[...and while writing this... scrolling this edit window with the black photo above over a gray background, with OLED screen dimmed in low ambient light - shows that pixels that have been black for a while take a while to respond when turned 'on' to a low level. The black field on either side of the vertical bright stripe leaves a long dark smear that takes noticeable time to come up to gray. Not so where the vertical feature was keeping pixels warm before the dark trailing edge passed momentarily. The leading edge of white (lighter gray) text suffers no noticeable delay. Raising screen brightness reduces but does not eliminate the smear. I'm pretty sure this isn't a scroll animation effect. Galaxy Tab S2 8.0]