We are inflating it right now!

@@CuriousMarc And I fully believe the inflatable is just to throw people off until you build the real one ready for launch on your own moon landing, so they won't suspect anything.

If you call it miscellaneous panel, that sounds just useless enough for a 200lbs gorilla to stuff their boot into. But a 'circuit utilization panel'? Best stay away from it, Buzz, and keep it happy......

Circuit Utilization Panel near the toilet... Name checks out... C U P

I was half hoping Mike was going to describe it as "Transponder here, some other RF stuff we've been working on is here, then there's POOP, followed by the master event sequencer...."

Yeah! 'Misc Panel 1" - Apollo 13 we see a main bus b undervolt on mp1

I used to repair units from a naval satcoms system, one of the modules was a voltage stabiliser for the klystron EHT supply, but it contained lots of other circuitry they couldn't accommodate anywhere else.

When you got no more space, but have a box with spare pins, and a bit of volume inside, you will use it.

Ran into the same thing in 1950's and 1960's aircraft. Trace everything going through the squat switch relay box, as one example.

We used to have 'All Come Good' boxes in Television Outside Broadcast trucks for similar reasons. They were usually buried under the floor for extra fun.

The absolutely vital, 'you're not going to space today unless this thing is happy', required check circuitry bodge box of little to no documentation. I mean, honestly, if you dont have at least one in your design, are you even trying?

Reminds me of a car I had with the factory horn relay buried in the dash.

Wait, you encounter these people in the wild!? or youtube trolls lol.

I found out several years ago that a friend of mine doesn't believe we went to the moon. Due to such ignorance, I haven't wanted to speak to him since.

@@paradiselost1914 I always wondered if they just assume the Soviets, who had both the technology and the motivation to expose such an alleged fake and would probably jump on any opportunity to stick it to the US, would just sit idle and do nothing all these years if the moon landing never happened?

Which is then a trigger for them to say that it's too complex for the time. XD

I personally point them at the Russians. Sure, if the moon landing was a hoax, it would be the best kept secret in history. A secret kept in all the armed forces? Its possible. In all of NASA? ...maybe. In all the industries that were involved? Unlikely. But from the one nation on this planet that would have the most to gain, ready to spread embarrassment upon the US, from even the slightest whiff something was amiss?! Not a freaking chance!!! The best proof we went to the moon is even our greatest adversary, the Soviet Ruskies, believed we went to the moon. They have literally zero, none, nothing at all, zip, nadda, no reason to go along with our narrative, and we had nothing to threaten them with. And yet, they agreed, we went to the moon. Never mind janky BS shadows and badly reasoned questions borne out of obvious skullduggred ignorance, explain to me how we got them to play along.....Ill wait.....

Now that you mention it, it *is* rather crisp

Now that you mention it, I recall that I did do a "Hang on, pause; I want to look at that circuit..." at one point. Not quite like Deckard with his Esper, I suppose, but we're getting there.

The imaging technology has been pretty good for a long time. It's the display standards that are so much better now. For example, we had megapixel+ cameras on spacecraft in 1990, but you likely only ever saw those images displayed on a 240p NTSC television (~380k pixels) at the time.

@@stargazer7644 In 1990, you could download images from NASA and see them on SVGA displays on mainstream hardware. SD interlaced resolution was for broadcast and VCR use, but it wasn’t really a thing on “mainline” PCs by then. Heck, SD video output was a feature you had to pay extra for most of the time already IIRC. Sure, people at JPL did not see those images at SD resolutions - d’ohh of course. The interested public didn’t either. Very early 90s was when Internet “won” in Europe and “native” BITNET was disbanded. I was getting NASA imagery at a university computer lab on the way to high school in 1991-1994. Those 1MP+ space-bound sensors were all for static images then. AFAIR, there wasn’t really bandwidth nor processing power to get 1MP real-time video from outside of LEO down in 1990. And even for LEO it’d have been only a military capability I bet. Mainstream consumer digital image sensors were pretty bad until about 2010-ish. They had no sensitivity to speak of - noisy unless lots of light was available, had poor dynamic range, and were sold with optics with way too high f numbers relative to what the sensor needed. High-end prosumer and professional market had decent sensors for a lot of money around 2000, sure. Nobody was making what amounts to family videos with them though. What I mean by “family videos” is that today a billion people all around the world have devices with sensors good enough for at least solid 720p KZfaq videos without a studio setup for lighting and post-processing. Probably close to half of that billion can shoot decent 1080p. And another half of those can do so with very good optical image stabilization - that would have made many a pro salivate back in 2000, never mind 1990. Yeah, I know many YT video’s aren’t necessarily shot with smartphones, but most people wouldn’t notice much difference if they were shot on smartphones. Especially smartphones made in the last 5 years.

Commercially available scanners have come a long way but they still cant flip their own pager

Apollo has a knack for making the simplest thing extra complicated. This is no exception!

You shouldn't feel bad, I've been designing and building digital electronic devices for the past thirty years, and this stuff is all FM to me, too. And I'm not talking about Frequency Modulation either, by the way. To me this channel is not about understanding this technology so much as it is about appreciating it: this stuff strikes me as mostly being beyond the comprehension of the typical modern electrical engineer, not because modern engineers are stupid or lazy or undereducated, but rather for exactly the same reason that an ASE-certified automotive repair technician is useless when it comes to shoeing horses: we just don't do it this way anymore. These guys (Marc, Ken, Mike, et al) are archaeologists of a sort, recovering and preserving the knowledge of how things like this were done before we had arguably infinite, ever-expanding computing resources at our disposal to solve every problem in software.

To add onto what @TimTheTerrible said, I can follow along. What I can't imagine is how people thought this stuff up for the first time, in the 1960s!

​@@PsRohrbaughthey didn't invent most from scratch they borrowed a lot of madness from planes / aironautics that already existed.

I understand all that stuff. It tells you how old I am…😊

yeah, I was looking at that input 'smoothing' or noise-suppression cap as well, results in slowing down the response of the thing so it can power up or off before the input trips the alarm.

Agree, but also figuring out that “at the time” isn’t the same as “less clever” than today - just different. Modernity implies a line of progress that anthropology can’t support. E.g. a fresh look at really ancient tech like a stone tool, show an amazing web of logistics and knowledge exchange (trade, education, power…). Good tools are dug up literally a continent away from where the flint came from. When our specialists try to replicate it, a sense of humbleness point to the fact that we have underestimated how complex (and clever) we have been across millennia. What I’m saying is that although our tech has an “empirical progress curve”, we as humans barely changed across the time span of say 10k years. Imagine when rumours hit that “the others” now had bronze tools, while “we” are stuck with imported flint from Jutland. That’s a bit like the political-societal race that pushed Apollo, fearing that “they” (ussr) had something “we” didn’t have. Like Chinese fabs or AI right now…? So yes, we change society all the time, not necessarily linearly to something “better” (depends on what metrics we use). We - as humans - obviously do not change much…😅👍

I was thinking a similar thing, that if you'd lost the Main B bus entirely, you would be seeing a lot more caution-and-warning lights that would point to a power supply issue, and you wouldn't need to shed load, per se, if you didn't have any voltage at all.

@@eddievhfan1984 I’m getting all philosophical here… 😜 All the separate systems are critical in this setting. That implies failure in the most “dignitary” way possible. I.e. that any component may fail, but should keep running as long as possible, since other components rely on it. Low power, keep trying… Fuse blown, no try… A step beyond mere redundancy I guess - the nearest “Home Depot” is literally in a different world…😅

I think in general any real world failures would be gradual and trip AND LATCH the undervoltage circuit even when the BUS eventually fell to zero. I also think that all of the apparatus on the BUS would not operate if the voltage was below 12V so even if the rail fell to 11V all the other bits would fail neatly, not optimally but at least the catastrophe would be clear. This detector was to warn that the BUS was below specification but other devices would still be working but perhaps no longer at full specification. Zero voltage would probably have been easy to determine with some other stuff like AGC dead.

Not sure how they would go too much further without being destructive. Perhaps xray/CT and some master ken wizardry but that may be a poor application of finite resources. Not that i'd complain naturally lol

It could get Spicey?

There are legal issues with answering this question too comprehensively, so don't expect a very comprehensive answer.

It’s called the LVDC. We don’t have a real one, but our boy Mike Stewart is making an FPGA replica of it. At last check, he got it to run: github.com/thewonderidiot/lvdc_simulation

@@CuriousMarc yup... LVDC... cool, FPGAs are fun!!!

@@SuzuranMajere wasn't a question... it was a request

​@@SuzuranMajereI had no clue about this until I heard Marc in his VCF talk say: "... it's still under embargo."

Well thank YOU!

I actually would trust my life to that stuff. Modern car electronics? I’m getting wary to say the least. Luck affects us all equally. Apollo was just solid engineering. The fact that most of the RF stuff needed no repairs, and it’s older than I am, points a lot in the it-wasn’t-luck direction.

Pretty short leads, I doubt it's much, especially since there is not much current.

there is no load, not sure which drop you are expecting : no load, no drop.

Turbopump spool up.

The blue goop is for hermeticity which was mandated throughout Block II after the Apollo 1 fire. It obviously also had to be fireproof.

It’s a Block I. I believe it’s at NASA Langley.

Yes, as we point out in the video, this Block I schematics likely does not apply to the Block II hardware we have. However we likely have the correct Block II pinout from the NARA document, with all the revision information, including some that post date this module. See link in the video description.

The lights (and the detector) are not powered by either of the main busses. They are powered by the Battery Relay Bus, as shown in the video (power supply on the left).

@@CuriousMarc I noted in their testing it failed to trigger when the bus was below 12V

@m0rjc You’d be correct, but as we also explain in the video, it’s by design.

National government archives.

Rocket science is easy, rocket engineering is hard!

Being near a military base I've seen a number of people around lunchtime with interesting lanyards...one of my favorites was something like "Ballistic Missile Defense - This IS Rocket Science"

It doesn't really. This part feels like a pinball machine from 5 years later lol

Your lack of understanding does not increase the complexity of the world around you.

​@@ShainAndrews Is complexity an absolute quality of the universe, or relative to our understanding? :) IOW it's not a hole I'd like to dig myself into.

@@absurdengineering Entropy entered the chat...

@@ShainAndrews I remember a custodian having a 5 in. dia. ring full of keys. All I could think was, man, he must know an awful lot.

Not on the Moon, though

@@8BitNaptime No, you are Mark Greco

no, this is patrick

Yes you are. May your Main Bus B never go undervolt.

@@CuriousMarc I’m framing your reply😁😀