
Inside the digital clock from a Soyuz spacecraft - eaguyhn
http://www.righto.com/2020/01/inside-digital-clock-from-soyuz.html?m=1
======
sandworm101
>> 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.

Because soviet spacecraft, as with all spacecraft at that time, were designed
to survive all sorts of failures. The clock is an absolutely essential part of
the spacecraft. It needs to keep running even when everything else is failing,
especially when everything else is failing. A space clock needs to be both
integrated into a dozen other systems, and able to cut itself from those
systems when necessary. Cosmonauts in a failing capsule, waiting to fire the
return burn necessary to get home, won't be looking out the window. They will
be looking at that clock.

------
blattimwind
> These are mostly 14-pin "flat pack" integrated circuits in metal packages,
> unlike contemporary American integrated circuits which were usually packaged
> in black epoxy. There are also some 16-pin integrated circuits, encased in
> pink plastic.

It's worth pointing out that flatpacks (both ceramic and EP) were and probably
still are a mainstay of military and aero electronics. These were never used
in consumer electronics. Apart from microprocessors and EEPROMs, consumer
electronics never really used ceramic or hermetic metal packages for cost
reasons. Perhaps the most common components would be TO-3 power transistors
and small metal can transistors before TO-92 and similar packages obsoleted
all of those.

> Many of the components in the power supply look different from American
> components. While American resistors are usually labeled with colored bands,
> the Russian resistors are green cylinders with their values printed on them.

High grade or high precision resistors usually had their value printed on
them, though. Meanwhile, only larger SMD resistors have markings today (I
think they stop applying them below 0604 imperial).

> The Russian diodes have orange rectangular packages (below), unlike the
> usual cylindrical American diodes.

Semiconductor packages were all over the place in the past; I've seen cube-ish
moulded diodes, resistors and capacitors in European stuff.

Overall this thing looks a lot like something from the mid 60s, not so much
mid 80s. In that case, American stuff from the same period looks pretty
similar, quite possibly due to copious copying by the Russians.

> One nice thing about Russian ICs is that the part numbers are assigned
> according to a rational system, unlike the essentially random numbering of
> American integrated circuits.

On a related note, I really like IEC/ISO schematics for this reason, because
we have a graphical language to describe logic and this means logic devices
appear as a composition of symbols which explain the function of the gate to
anyone who knows this language. On American schematics only the most basic
gates (AND, OR, NOT, ...) have symbols, everything more complicated than that
is generally drawn as a box with the part number ('193) in it and the pins
just labelled with their abbreviations.

~~~
dfox
Wrt. to flatpaks it is somewhat interesting to note, that very often when
there is some kind of ASIC (think alarm clock or calculator or even “PDP-11 on
a chip”) in 80's soviet consumer electronics it is packaged in metal/ceramic
hermetic flatpack with legs bent and THT soldered.

------
ericwood
_While American resistors are usually labeled with colored bands, the Russian
resistors are green cylinders with their values printed on them_

 _One nice thing about Russian ICs is that the part numbers are assigned
according to a rational system, unlike the essentially random numbering of
American integrated circuits._

This makes so much sense, it's a shame this style of labeling didn't catch on.
It would have made my EE labs in college so much easier.

~~~
gen3
I’m color blind. The markings would make everything so much easier. Having to
check with someone else to make sure I get my colors right is such a pain. I
hope I can order some.

Edit: If anyone can find labeled resistors for a reasonable price, I would be
grateful.

~~~
lb1lf
This is why I loved it when introduced to SMT devices. Rather than those pesky
colour bands, values were stamped on in a rational manner - two digits value,
one digit power of ten. Say, 106 for a 1MOhm resistor, 102 for a 100Ohm one.

My lab productivity soared.

~~~
gen3
I found some of them. They look super helpful. How do you breadboard things
with them?

~~~
lb1lf
You mostly don't - I had a decent setup for etching, so I just quick-and-
dirtied a layout, put down a few extra pads where I suspected I might need
some, processed a board and gave it a go.

The one important thing is to not pinch on the pincers - buy a good pair... :)

~~~
gen3
One last question: Where do you order them from? The labeled kits I see are
around $120 and I’m on a college student budget. Thanks for answering my
questions.

~~~
lb1lf
When I was on a student budget, I mostly asked my lab tutor kindly if I could
help myself to the parts stocked by my university - the lab people were so
happy someone actually _wanted_ to build something that I was basically given
free access to the parts bins.

Additionally, regional distributor ELFA had bins of 1000 1% 0805 resistors for
~$10/ea, so I just purchased a couple of bins at a time as I needed them until
I had an E12-ish set.

If there is one nearby, I'd strongly suggest you visit a maker space - chances
are they have SMT kits already.

------
flipflipper
>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.

I believe this is to maintain a single point ground, usually the chassis on a
spacecraft. The chassis of the clock is probably connected to the isolated
side's ground, which avoids ground loops when the clock is integrated into the
S/C.

More detail on grounding and isolation in S/C is covered here:
[https://standards.nasa.gov/standard/nasa/nasa-
hdbk-4001](https://standards.nasa.gov/standard/nasa/nasa-hdbk-4001)

~~~
analog31
I wonder if there would be a fair amount of current flowing through the
"ground" of the craft as it went through the ionosphere and then into whatever
ion flux the sun is spitting out. They might have to be really careful about
treating the whole chassis as a circuit.

------
Waterluvian
Okay that physical globe as an item on the Soyuz dashboard is amazing. I need
to know more about that. I imagine it's gimballed and a computer moves it to
the GPS or dead reckoned position as the Soyuz orbits over the Earth.

What a really cool output device.

~~~
kens
That's the Globus IMP and dates back to 1964. Wikipedia has details:
[https://en.wikipedia.org/wiki/Voskhod_Spacecraft_%22Globus%2...](https://en.wikipedia.org/wiki/Voskhod_Spacecraft_%22Globus%22_IMP_navigation_instrument)

~~~
eigenvalue
Wow, what an amazing device! I’m surprised this isn’t better known in the
West. I’d love to understand better how it actually worked in a detailed way.
Mechanical computers are so cool.

~~~
kens
If anyone has a Globus indicator sitting around, I'd be happy to open it up
and reverse engineer it :-)

~~~
bigiain
That would be _so_ cool!

BTW, do you have any measurements of that clock you could share? I'm seriously
considering mocking one up just for the cool factor... It'd be nice to get it
at least approximately the right size. (I'm also considering building a
working model Globus indicator too. Maybe I'll just size everything based on
the most suitable globe I can find...)

------
rdtsc
> Russian resistors are green cylinders with their values printed on them. The
> Russian diodes have orange rectangular packages (below), unlike the usual
> cylindrical American diodes

They have color coded Russian resistors, probably just for smaller sizes.
Diodes have a variety of shapes, but I don't remember seeing rectangular
packages like that one either. Some of those component might have also been
specially sourced high tolerance components that might be different than what
you'd find in consumer electronics?

> The logos on the integrated circuits reveal that they were manufactured by a
> variety of companies.

Oh very interesting. I have been wondering about what those logos meant when I
used to play with electronics back in the day. They even have a link to the
full list
[http://madelectronics.ru/book/prominfo/2009-04-16-08-29-39-3...](http://madelectronics.ru/book/prominfo/2009-04-16-08-29-39-318.htm).

------
Luc
The conclusion seems a bit strange.

 _Why does the Soyuz clock contain over 100 chips instead of being implemented
with a single clock chip? Soviet integrated circuit technology was about 8
years behind American technology, so TTL chips were a reasonable choice at the
time._

Because in the paragraph above:

 _I expected the Shuttle computer to use 1980s microprocessors and be a
generation ahead of the Soyuz clock, but instead the two systems both use TTL
technology, and in many cases almost identical chips._

~~~
kens
The point is that the Shuttle's TTL chips were more advanced as far as
performance, using Fairchild's FAST line. The Shuttle also used many TTL chips
that were more complex. This is consistent with the CIA's claim that American
ICs were 8 to 9 years ahead. But it's interesting that the Shuttle was still
using TTL, and many of the chips were very basic, like the quad NAND gate
chip. So the difference between the two boards was surprisingly incremental,
rather than a jump to MOS chips or microprocessors.

~~~
metaphor
> _The point is that the Shuttle 's TTL chips were more advanced as far as
> performance, using Fairchild's FAST line._

This. The author points out the 54F00, seemingly distracted by the 54'00 part
and similarities in TTL glue logic layout that the F part is completely
dismissed without acknowledging that these chips had sub-4ns edge rates and
were indeed fast while remaining compatible with older TTL families. Throw in
high SMD density on a multi-layer controlled-impedance PCB designed to survive
brutal operating environments when PCs and CAD were still in their
infancy...even today, it's humbling to contemplate just how much work would
have been required to qualify such a design.

> _But it 's interesting that the Shuttle was still using TTL..._

These systems had super long lifecycles and were required to be extremely
reliable. I'd be surprised if the contractor that was responsible for the
design would have been allowed to integrate any IC that wasn't listed in a
QML.

~~~
egdod
FYI, that’s the author you’re talking to.

~~~
metaphor
Hadn't realized; thanks for pointing that out.

------
cstross
> Due to the end of the Space Shuttle program, Soyuz is now the only
> spacecraft capable of carrying a crew into orbit

So I'm guessing the Shenzhou program doesn't count?

[https://en.wikipedia.org/wiki/Shenzhou_(spacecraft)](https://en.wikipedia.org/wiki/Shenzhou_\(spacecraft\))

(Yes, I know the OP goes on to say "and used for flights to the ISS". Still
irritatingly inaccurate.)

~~~
kens
Thanks for the comment; I've removed the offending sentence. (edit: cstross is
right and doesn't deserve downvotes.)

Wikipedia says "Soyuz has served as the only means for crewed space flights in
the world since the retirement of the US Space Shuttle in 2011", so I guess
that's wrong?

[https://en.wikipedia.org/wiki/Soyuz_(spacecraft)](https://en.wikipedia.org/wiki/Soyuz_\(spacecraft\))

~~~
daveslash
Thanks Op. How did you come into possession of this clock?

Edit: And does it still work?

~~~
kens
CuriousMarc [1] bought the clock at a space auction. We hope the clock still
works. We plan to power it up and get it working, but first I needed to
reverse-engineer the circuitry to figure out how to power it.

[1] [https://youtube.com/curiousmarc](https://youtube.com/curiousmarc)

~~~
egdod
That’s wild. How much did it cost?

------
0xff00ffee
> While American resistors are usually labeled with colored bands, the Soviet
> resistors are green cylinders with their values printed on them.

Smart! The color band system has +ve and -ve, but overall I hate it. But
better than caps with their 104 = 100,000 pf/nF?

I've known the US color band system since I was a kid, but damn the base color
of the resistor epoxy has a huge impact, as does the low wattage high
precision: you need a magnifier to read all 5 bands on a 4mm resistor.

------
m0zg
Even back then, the Soviet space program had the electronics to make this much
less complicated. Remember, in 1986 they had the Buran shuttle which flew to
the orbit and landed fully autonomously, under computer control.

The clock was probably developed much earlier, and then perhaps slightly
modernized with LEDs and such. Developing a new clock for spacecraft would
probably take a year or two, for all the testing and certifications, so nobody
bothered.

~~~
orbital-decay
Less complicated isn't always good. There was no problem driving the clock
display with the onboard Argon-16 of course, but the clock was decoupled into
a separate device to not have a single point of failure, and also to replace
the old onboard chronometer which was even more complex and failure-prone.

~~~
m0zg
That's not what I meant. I meant using more specialized ICs or a separate
microprocessor. It's not like cost was much of a concern there.

------
ohadron
It's amazing to think that this device was produced several years after the
class simple casio watch we all know.

Same functionality more or less, probably a fraction of the weight and cost.

I'd attribute the difference to how military/government projects pan out and
not necessarily to the less advanced soviet IC abilities. There are many
similar examples in western military equipment.

~~~
dfox
Assuming this thing was designed in early 80's (which it probably was given
the LQ470-like DIL 7segment LED displays) there certainly was soviet made NMOS
ASIC that implemented most of the functionality in single package. But
similarly to contemporary western counterparts it required bunch of funky
supply voltages (albeit the supply rails used by soviet alarm clock ASICs are
nowhere near the supply funkiness of Sanyo's essentially AC powered alarm
clock ASICs) and were nowhere reliable enough to be used in space.

~~~
blattimwind
The LED display could have been an upgrade on an older design. I assume Soyuz
always had a clock.

------
kens
I just noticed that HN has the mobile link to my article, so the images are
fairly small. You can click on an image to see a larger version, or go to the
regular site: [http://www.righto.com/2020/01/inside-digital-clock-from-
soyu...](http://www.righto.com/2020/01/inside-digital-clock-from-soyuz.html)

~~~
blt
Minor note: in footnote [15], the 1974 and 1986 CIA report links both point to
the same pdf.

~~~
kens
Thanks; I've fixed the link.

------
blakes
Here is the video where they open up this very clock for the first time:
[https://www.youtube.com/watch?v=JBIhzEZkWEA](https://www.youtube.com/watch?v=JBIhzEZkWEA)

------
WalterBright
I designed and built a digital clock around 1976. It has around 40 ICs in it.

It never worked right :-)

------
gautamcgoel
Great piece of history. Can someone explain the difference between TTL and
CMOS chips?

~~~
kens
I'm not sure how much explanation you want. The short answer is that TTL
(transistor-transistor logic) is an older logic family, while CMOS
(complementary metal oxide semiconductor) is what's used nowadays, such as in
microprocessors.

In more detail, first there were bipolar transistors (NPN and PNP) and later
MOS transistor (NMOS and PMOS). Bipolar transistors are your basic
semiconductor transistors with three layers of semiconductor. MOS (metal oxide
semiconductor) transistors have an insulating oxide layer between the silicon
and the metal (or polysilicon) on top. MOS transistors were developed later
than bipolar, and started to become popular in the 1970s.

One type of logic that you can make from bipolar transistors is TTL
(transistor-transistor logic). TTL is better than earlier logic families such
as resistor-transistor logic (RTL) or diode-transistor logic (DTL). TTL was
cheap, reliable, fast, easy to use, and popular with minicomputer
manufacturers. TTL has two main problems, though. It uses a fair bit of power,
and you can't make it very dense. I.e. you can't put a lot on a chip.

MOS, on the other hand, has the advantage that you can make very dense
circuits from it. (I.e. Moore's law applies.) NMOS was used for early
microprocessors such as the Z-80 and 6502. The problem with NMOS is that it
uses resistors (sort of) in the logic gates, and these waste power.

The solution was CMOS, complementary MOS. You use both NMOS and PMOS
transistors (the complementary part), and you can get rid of the resistors,
and your chip uses very low power. The problem with CMOS is it's more
complicated because you need two types of transistors, and twice as many (sort
of). However, the need for low power won out in the mid-1980s and
microprocessors such as the 80386 started using CMOS. Use of CMOS has
continued to the present.

I'm oversimplifying the history somewhat. The books "To the digital age" and
"History of semiconductor engineering" go into much more detail.

~~~
gautamcgoel
This was great context, thanks for the explanation!

------
ben7799
This article is great... much thanks to the author.

This kind of stuff is fascinating.

