Soyuz spacecraft digital clock teardown | Hacker News Reader

Soyuz spacecraft digital clock teardown

righto.com

120 pointsnucatus34 comments

> You might expect the power supply to be a simple buck converter. However, the power supply uses a more complicated design to provide electrical isolation between the spacecraft and the clock. I'm not sure, though, why isolation was necessary.

A reason very simple, you don't want a short through the clock to set your space, or aircraft on fire!

A big reason why a lot of avionics still works on HF AC power, and not DC is that it makes isolation, and providing arbitrary voltages very easy.

> A reason very simple, you don't want a short through the clock to set your space, or aircraft on fire!

Why not use a simple fuse?

Then, even if you would've had a contact from an isolated phase to anything, there will be no short at all.

You can also watch the companion YouTube video series, at https://www.youtube.com/playlist?list=PL-_93BVApb5-951yH6TlP...

Frankly I can't recommend the rest of his channel enough. I found the teletype restoration series[0] particularly interesting. It's fascinating watching the process of troubleshooting and performing repairs of all this vintage technology.

[0] https://www.youtube.com/playlist?list=PL-_93BVApb5-9eQLTCk9x...

I have a bust ASR33 (dropped off a removalist truck) and probably need to talk to these guys...

The board construction and component quality is exceptional and pro. Reminds me of HP gear (and later, Apple 2) of that time. Clearly created with pride - these are tech treasures.

Edit: Here's a series of Curious Marc videos about the clock. https://www.youtube.com/watch?v=JBIhzEZkWEA&list=PL-_93BVApb...

Previous discussion:

https://news.ycombinator.com/item?id=22077019

Important thing worth mentioning: here in the USSR in many cases electrical engineers' bonuses were paid according to the count of parts used. So there was a natural motivation to overcomplicate things.

Major Error Detected. Soviet resistors are not ubiquitous "Green Cylinders". Greens are %5 and reds are 10%.

I thought Soviet resistors went to the gulag

Dad?

It's out east, past Ohm(sk)

You'd think you're joking, but the founders of the Soviet space program started their work in NKVD research prisons, convicted not even for resisting.

https://en.wikipedia.org/wiki/Sharashka

One possibility for the TTL design rather than something more integrated is that such coarse chips are much less susceptible to damage from hard radiation, and this clock must have been a very important part of the spacecraft control systems.

> Why is the clock so complicated? In this blog post, I examine the clock's circuitry and explain why so many chips were needed.

Thousands of words follow before getting to the answer. What is the point of such a tease in a technical blog post with no advertising?

Do people think this makes good writing? Have authors internalized the clickbait style they read in so much other media? It's too common to be accidental.

Or maybe he's stating the thesis for his post and then backing it with technical detail before writing his conclusion. Have readers become so accustomed to instant gratification that they can't take the time for a thorough analysis with facts and technical detail to back up the author's claim?

Academic writing uses abstracts, and it is not because they are so accustomed to instant gratification. It is because it makes for clearer reading and a more efficient allocation of effort.

This is not academic writing though. This is an interesting story posted on somebody's blog. If I tell my friends a cool story, I would need to walk them through the story and drop the punch line/conclusion at the end. I also enjoy it very much when somebody tell me a story that way. Not everything, even technical teardown, needs more efficient allocation of effort.

Interestingly, this is the second time I see this kind of comment recently and turns out it's from the same person. Maybe I'm on HN too much.

I brought up the academic example specifically to rebut DWakefield's argument that the main reason the reader would want abstracts/summaries is because they cannot delay gratification; I wasn't arguing that blogs should have it because academics use it.

Clearly, this is my axe to grind

Nothing wrong with providing a summary and later expanding it in a full treatment. There is no need served by holding reader in surprise till the ending like a piece of fiction.

I see "story telling" as an anti pattern in non fiction, jounralistic and technical writing.

As is standard most serious writing formats, the answer to the question(s) posed at the start can be found in the conclusion. You are free to read the conclusion any time you want. For example, I've heard that the best way to read academic papers to read these sections in this order: abstract, intro, conclusion, methods. You can read other sections if you would like, but the core of the papers' message will be in those 4. The rest of the paper provides details.

I do think that more structure would make the blog post easier to read and navigate, but since the information you were seeking is easily found within the structure that exists, I don't think your critique makes much sense.

The standard for most serious writing formats is an abstract where the important results of the paper are summarized, and an introduction where the author lays out the structure of the document. And in something shorter without as many sections, you still say the important bits up front.

As the second paragraph of my comment makes clear, the point isn't to critique this particular blog post, it's to wonder why, when the author raises the question, he doesn't then just immediately summarize the answer in one sentence, and why this is so generally common across so much writing. I really do think this is a general phenomenon rather than an isolated issue.

(Also, just as a datapoint: On this separate HN thread I pulled out the conclusion of the OP and posted it as a comment. Even though it was very easy to find since it was simply the last two sentences of the post, readers apparently found my comment extremely helpful and it was upvoted more than 100 times. https://news.ycombinator.com/item?id=25742276 )

Unfortunately, the common pattern for an academic abstract is something like:

In this paper, the Soyuz clock is analyzed in detail and the underlying reason for its high complexity is described.

You still usually have to access the full paper to get the reason itself...

I agree that this happens all the time in academic writing and it's terrible.

If you only want an answer to that question, I guess so, but answering that question is far from the only purpose of the post, as stated. I found it far from clickbaity. The title of both the article and the HN post imply it's more a story about how they tore it down and all sorts of internal details.

It's not that I just want the answer, I want to know the answer so I can judge whether the lengthy exposition is likely to be interesting and so worth reading.

Do you not consider the explanation of the various functions of the clock - and the examination of the components implementing those functions - to be part of that answer? Because I do; pretty hard to answer "why?" if you can't even answer "what?" and "how?".

The author successfully summarizes the answer in the section labeled "conclusions", so no, this is not the explanation. That summaries do not contain all the info of what's summarized does not mean they are useless or impossible.

the beauty of written content, you can skim the whole text in a few seconds, see if it interests you, jump to the conclusion, go back and read it all... in a world that's turning completely to video content, I'd say we can forgo the supposedly not so good style.

OTOH, he doesn't seem to really answer the real question: why they still used TTL when much more highly integrated CMOS technology was already available in consumer market? I guess it's something very specific to aerospace strict standards, and as far as I can tell he didn't say much about it.

Aren't older TTL more resistant to radiation because of physically large chip structures? It could be that those chips were already space-tested or radiation-hardened.

yeah, I believe it should be something like that. Anyways I think the author created some anticipation of giving an explanation about the reason of all those chips and the conclusion was just something like "there are many ICs because it uses TTL and each TTL IC doesn't do much so you need many of them". Ok... but why does it use TTL? that's the interesting question, isn't it?

If you follow the youtube video posted at the end of the article, you will see that there are another two separate youtube videos as followup of the first one where some of technical details are discussed.

Your clickbait detector maybe set a little bit too far on the sensitive side...

True clickbait tends to follow the "bait" with a lot more vacuous material, unlike this article.

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