Unassuming Apollo Panel Has Major Role in Apollo 13

[@Gazdatronik]

Whenever I encounter folks that say we never went to the moon, I point them to these videos. These devices still work, as designed, to this day, for one purpose. To get us to the moon, as safely as possible. If we never went, why bother doing such a good job making these devices? They both fire off at the same point. What an excellent analog device.

[@anullhandle]

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

[@paradiselost1914]

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.

[@n900video]

@@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?

[@MLeoDaalder]

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

[@zombieregime]

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.....

[@jlwilliams]

I find it reassuring to know that even in such a massively engineered effort as Apollo, there was the equivalent of a “junk drawer”… a place for essential bits that you can't get along without but which don't really belong anywhere. Re the name: I'll bet someone said “Let's just stick them all on one ‘miscellaneous panel’ and shove it in next to the toilet controls.” And then somebody else said, “But we can't just call it the ‘miscellaneous panel’ because that doesn't sound very official” and someone else said “Let's call it the circuit utilization panel, 'cuz we're utilizing it to hold a bunch of circuits that we don't know what else to do with.”

[@zombieregime]

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......

[@richfiles]

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

[@rkirke1]

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...."

[@Ray-ej3jb]

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

[@cambridgemart2075]

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.

[@rkirke1]

Having worked as an auto electrician in the past, this panel reminds me conceptually of the "secondary junction/fuse/relay afterthought box" hiding somewhere in nearly all 80s-90s EFI cars (usually in a really weird place). I can imagine a few engineers from different teams coming together towards the end of the design like : "So, we have a last minute addition that's pretty simple but absolutely vital, and there's no room left in the main fuse box whatsoever". "Ohhhh, you as well?" "How about we just put all the fixes in one module. There's a tiny space to fit it just between the left rear mudguard and tail light. We'll just call it the 'secondary auxiliary junction-function module' and nobody will need to know.."

[@AsbestosMuffins]

the idea that there's just a box in the CSM that had random bits of other instruments circuitry bodged into it is fascinating

[@SeanBZA]

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

[@mikebarushok5361]

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

[@kiltrash1]

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.

[@zombieregime]

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?

[@Broken_Yugo]

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

[@absurdengineering]

Can we just appreciate that the camera shots of the laptop screen, showing the scanned manual, are good enough to reproduce fragments of said manual? I know it's slightly off-topic, but man oh man, has the imaging technology of all sorts made insane leaps in the last 20 years or what :)

[@Atarian1993]

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

[@TimTheTerrible]

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.

[@stargazer7644]

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.

[@absurdengineering]

@@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 KZbin 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.

[@MichaelOfRohan]

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

[@twotone3070]

Just 3 mates in a basement having fun doing what they enjoy and taking us along for the ride, simple pleasure of friendship.

[@PsRohrbaugh]

I am so excited for 10 years from now, when you have a full stack Saturn V in your backyard 😁

[@CuriousMarc]

We are inflating it right now!

[@matthewmiller6068]

@@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.

[@dwarf365]

This stuff goes clean over my head no matter how high I jump. Doesn't stop me from trying and you make it as clear as possible. Thank you Marc!

[@CuriousMarc]

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

[@TimTheTerrible]

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.

[@PsRohrbaugh]

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!

[@fischX]

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

[@chefchaudard3580]

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

[@jcxtra]

Ever since I was a young lass and I first saw the Apollo 13 movie, it has captivated me, and I always figured I'd run out of new things to learn, I absolutely love the deep-dives you and your team are doing for both preservation of the history of this stuff and making it accessible for 'fascinated individuals' like myself. Everyone involved has such dedication to 13 (and other vintage technology) that lets me not feel as weird having a thirst for "how was it done in the past?" - Thank you.

[@natedawww]

Seems like a good candidate for the X-ray treatment!

[@mikefochtman7164]

I noticed on the schematic, a capacitor in series with 100 ohm resistor on the emitter of the flip-flop's left transistor. This would prevent this tran from turning on until the cap is charged during power on. This may be how it ensures always powering on in the 'reset' state. As long as the sensed voltage reached 'good' levels before that capacitor charges, you won't get false triggers on power on. Once charged, both emitters of the flip-flop are basically at rail voltage.

[@Zarcondeegrissom]

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.

[@Kae6502]

"Okay, we learned stuff..." and that's why i love this channel! We learn stuff about things I never knew about before. Down to the resistor, diode and voltage level. I can never watch Apollo 13, or another documentary about that Mission without thinking of this little, unassuming box of 1960's awesomeness! Thank you CM and Team.

[@JohnRineyIII]

Everywhere you look in Apollo, there’s more complexity and more cleverness.

[@jerwahjwcc]

Them: We can't rebuild a Saturn rocket. They were all bespoke and we've lost the skills to time @CuriousMarc : Hold my beer, I'm going to reverse engineer the whole thing

[@KellyMurphy]

I'm thinking there's some sort of inhibit detector using a capacitor and current detector. While the cap is charging rapidly, there is enough current to activate the inhibit, but going slow allows the voltage to equalize and not reach the inhibit current threshold to activate it. The only problem with this theory is that when you disconnect the power it also trigger, which might mean their's a drain resister that is too low of a value so draining the cap get's to much current as well and is activating the inhibit, though IMO their shouldn't be a negative current detection that would trigger an inhibit. It's possible if the module was never flown, that's the reason.

[@tekvax01]

The most important stuff always comes in the least assumed packages! Great job as always Marc, Ken, Mike, and others!

[@PhilWheatInAustin]

I am always amazed at the number and quality of drawings and schematics that you can turn up!

[@gvii]

Kind of interesting that they were just making do with what technology they had at the time. Now we are well ahead of that era, yet it takes considerable effort to reverse engineer what they did and how they did it. I always find that fascinating. Anyway, great video. Always been interested in this early spaceflight stuff, so it's super fun to see it working up close.

[@musiqtee]

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…😅👍

[@patrickradcliffe3837]

3:19 this is pretty typical DOD and NASA aerospace publications back in the day. I remember doing publication manual changes back when I was in the Navy related to discrepancies between the pub and the aircraft.

[@salman_nav]

I wish my college professors had had the absolute engineering genius that Marc and Mike (and Carl and Ken) possess. It would have made me a better engineer.

[@rsmrsm2000]

You show a piece of the history of ancient technologies, which are essential to know where we are today. In addition, it shows components that were used in the APOLLO program, which was an important milestone for humanity. I am proud of your work this amazing work. Congratulations and thank you for showing.

[@RC-nq7mg]

The Saturn V launche vehicle, CSM and LM to me are some of the most incredible technological achivements even to this day. Sandly I was not alive to see a Saturn launch, but it just blows me away that they were able to devop all of that technology to launch, power, guide, land, keep people alive in space for sustained periods of time, all in the 60's. Meanwhile what did people have at home? a black and white television running on tubes, maybe a transistor radio, or an electric can opener. The shuttle looked like a toy compared to the Saturn V.

[@musiqtee]

My tech-only guess: Could it be that an “undervolt” should *not* be triggered by total loss of voltage? Meaning that a different circuit & indicator is showing “no power” instead? Operationally, an undervolt situation is different to a total and immediate loss of a bus, probably leading to different checklist procedures. I.e. differentiating between failures in the supply or load side of the bus, and between partial or total loss of normal state. (What part of Ohms law failed here…) Could this be the reason behind the intricate (and awesome) design? Again, a wild guess on my part… 👍 Huge thanks to the whole team! ⚡️💛

[@eddievhfan1984]

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.

[@musiqtee]

@@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…😅

[@KallePihlajasaari]

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.

[@BigMouth380cal]

Great segment. I, for one, am having a hard time believing that Marc and company are fine with leaving the mystery of the undervolt sensor as is. I can't help but think there will be an update with the solution to that conumdrum.

[@zyeborm]

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

[@fburton8]

It could get Spicey?

[@Sean006]

You can almost hear the cogs whirring in their brains. Excellent stuff 👍

[@ToumalRakesh]

7:37 I mean OF COURSE his PSU voltmeter has been calibrated ;)

[@spunkmire2664]

You guys are national treasures. seriously.

[@ifitsrusteditsmine]

"Clickiness completeness". "We learn stuff everyday". I love this guys

[@robinwells8879]

Sends tingles down the spine.

[@jagmarc]

Delayed window comparator. A main bus undervoltage is a very big anomaly, so something very big would be going on to cause it. The bus could well briefly dip during a 'fuse-clearing' event, but MB staying low is very bad news. Also don't want it latched from little random triggers coming from radiation effects high energy hits cosmic.

[@GordonjSmith1]

Loving the journey you are retracing - it is fascinating is it not!

[@Dr_Mario2007]

Circuit utilization panel, in this case meant to utilize anything on the particular voltage rails, in the other words, basically a part of the power supply with fancy words tossed around (NASA is known for those fancy words and euphemisms).

[@MonochromeWench]

Seems like a situation where it might be an idea to build a new one from the schematics to see if it behaves different to the actual thing probing the exposed components to find where any differences are because you can't see everything on the actual device.

[@stevenflogerzi1955]

You can tell this came out of the Aircraft industry, Alodyned Aluminum for corrosion resistance and flush mounted rivets. This thing is rigid as a tank.

[@darrylr]

I'd like to think that "greeting earthlings" leaves out part of the space exploration curious audience.

[@jross1269]

No Asbestos this time. Great!

[@drstrangelove09]

what about the IBM computer that was in the Saturn V rocket? That might be even more interesting since it was designed by people that designed such things day in and day out.

[@SuzuranMajere]

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

[@CuriousMarc]

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

[@drstrangelove09]

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

[@drstrangelove09]

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

[@benjaminhanke79]

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

[@t1d100]

I would enjoy a video on the electronic workings of the under-volt event and how the buses were tied to get the remaining power that they needed to get home. The movie mentions those things, but not in detail.

[@bobl78]

it´s amazing this stuff brought them to the moon and back.. I would not trust my life to that stuff, even if it was all new... I think a great amount of luck was involved into the Apollo programm

[@absurdengineering]

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.

[@2adamast]

6:50 Google reacted to Marc's "Houston we have a problem" _I am sorry to hear that_

[@ronjohnson9690]

Lost in space has a new meaning now!

[@paullee107]

I'm not an engineer. At all - I do dabble in Linux, Unix, ms-dos and other fun things... I so want to play with you!! Invite me and teach me on a project! Thanks for all the content, sir. I love it.

[@steve_case]

We learn stuff every day!

[@kippie80]

Could it be that these random circuits were placed here together because they use relays? They are orders of magnitude more unreliable and have easy servicing access this way.

[@tomgeorge3726]

Could you build the sense module and measure the circuit's characteristics. Great video, nice to see some Apollo gear again.

[@ProjectSnowman]

I wonder if the delay has something to do with it being 60 years old or if it always did that. It’s kind of a nice feature to have a soft start on initial spacecraft power up. Cuts down on the heebie jeebies on the launch pad 😂

[@RocknR00ster]

Interesting circuit

[@rinislaboratories1315]

So awesome

[@inothome]

What are those caps doing in parallel with two resistors on each circuit? Looking quick with it paused and no print in front of me it's hard to trace out. But those caps will add a delay and shunt across those resistors on voltage changes.

[@WacKEDmaN]

thats gotta be the ultimate bodge wire! (wires?!)

[@michaelwebber4033]

Build it from discrete components and try it. I'd love to see that

[@erichpwagner]

The schematic shows resistor values but not the capacitor values. I wonder if the rate of rise of the reference and slugged rate of rise on the pnp of the scr structure is what caused the time sensitivity noticed?

[@cgourin]

I wonder if that blue goo, most likely insulation, has fire retardant properties inherited from the feedback of the Apollo 1 fire accident.

[@CuriousMarc]

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

[@codewiz]

What's the spin-up sound at the beginning of every video? Perhaps the turbo pumps of the F-1 engines during the ignition sequence?

[@CuriousMarc]

Turbopump spool up.

[@reneejones6330]

You could breadboard the circuit and see if you get similar behavior, then probe the breadboard to understand how it works.

[@wolfman7393]

Very cool stuff!

[@gerryjamesedwards1227]

I managed to outrun a comparator that was made using an unused op amp, it was meant to be watching a cap for when the voltage across it had dropped to a couple of hundred millivolts, this was fine with a current sink discharging it at a constant rate, but if the cap was simply discharged thru a small resistor the comparator completely missed it, and just sat there with the cap fully discharged. Perhaps the comparator in this circuit here is also being outrun by the initial power-up?

[@thomasneal4775]

Great series of videos! Have you done anything on the Navigation Optical system?

[@Joemama555]

sure used a lot of rivets on that little box!

[@Kutulu369]

I quote a wise green-blooded hobgoblin when I say, "Fascinating".

[@schmitzvonschmitzen2870]

Assuming the power bus is pulled to ground, first transistor of the comparator is in base-emitter breakdown condition, right? It might somehow affect comparators behaviour, so it wouldn`t trigger on very low voltages. Further 12V lower threshold is approximately twice base-emitter breakdown voltage of a standard silicon BJT + some drop across 6.8K input resistor. I wonder if this is a bug or a well thought of feature! Fast rising input voltage, short voltage error duration, is probably suppressed by capacitors on the input.

[@justin.campbell]

Could there be a voltage drop across the leads and connections? I suggest checking voltage at the device rather than the supply. Great video as always, I enjoy these looks into the more obscure parts!

[@rkan2]

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

[@lo2740]

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

[@devqbasic2384]

Marcs next Video be like. We bought a Saturn 5 rocket and in this Video we will Show you how to get it flight ready

[@franklinwerren7684]

Was there a way to clean off the blue goop back in the day to fix a board??? Or was it considered a throwaway item??? DE N2JYG

[@gordonwedman3179]

You could almost call that box a bodge.

[@kallewirsch2263]

It would have been interesting, how much time the electronics give you until the undervolt is reported. In other words: how short can an undervolt "pulse" be in order to get undetected. My guess would be that nobody expected the fuel cells to go from 28V to 0V in an instance. Given all the electrics and electronics, there is lots of capacity on the power lines which keep the voltage from a steep drop.

[@daylechipps7124]

Thanks!

[@CuriousMarc]

Well thank YOU!

[@KeritechElectronics]

Unassuming but did the job just fine :)

[@wktodd]

Are you allowing for the diode drop? (Is 25.6 Voltage at sensor?) It should not show a fault at start up surely.

[@PeterFacey-h6d]

Hmm. This behaviour (not lighting the lamp on quick removal of the monitored bus voltage, with the sensing unit already powered up) is impossible with the circuit shown. Are you sure you're on the right pins? I assume the capacitor to ground on the emitter of the lefthand flip-flop transistor is to force the flip-flop into the off state when power is applied, but that isn't relevant to the above behaviour.

[@CuriousMarc]

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.

[@mumiemonstret]

I have a hard time seeing it as a feature rather than a bug that the indicator doesn't light up if bus voltage suddenly disappears. Having to press the indicator reset buttons at power-up would have been a small price to pay, while not knowing if the bus had below 12 V on it seems very sketchy and out-of-character for the Apollo program to me. I suspect that there is (even) more going on here.

[@greentree180]

You guys cant be far from launching your own retro moon mission. You should have bought one of the Apollo launch crawlers that have just been dismantled

[@jasonmurawski5877]

What happened to the Apollo 1 capsule? I assume it was disassembled to try and determine the cause of the fire, but I’ve never heard anything about it. Also was apollo 1 a block 1 CM?

[@CuriousMarc]

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

[@eugenioarpayoglou]

They sure went to a lot of trouble to fake the Moon landing. *sarcasm alert.

[@ferrari2k]

I am just curious, you recreated the Main B Undervolt signal during the power-up phase of the Apollo Computer back a few years. What is the difference to this one?

[@bobwatson957]

Hi Folks. Any chance of posting the names of the nasa folk who created the diagram and the electronics if possible. Those diagrams are so beautifully drawn and electronics so advanced for there time, that I think the folk who created them need Wikipedia articles. If they don't I'll write the articles, if you can post any names. Thanks.

[@m0rjc]

Presumably there's another light somewhere that says that Bus A and B have power at all? So if the bus has completely failed that light will be absent and the astronauts will know there's no power?

[@CuriousMarc]

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).

[@m0rjc]

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

[@CuriousMarc]

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

[@jankrusat2150]

Doesn't one of your collector friends have an Apollo fuel cell? how about integrating it into the circuit? ;-)

[@alexscarbro796]

I wonder if the issue is that the PSUs are only capable of sourcing current and will not sink it. What if the positive lead is grounded, or pulled to ground, simulating a short or low resistance to ground.

[@ijunkie]

They really thought of everything didn't they?

[@benjaminhanke79]

3:27 Who's Nara? NASA archives?

[@CuriousMarc]

National government archives.

[@funnygrunt_o7]

god the apollo program is so sexy

[@FesixGermany]

Nah just kidding, it's fine 😂

[@68hoffman]

kool :)

[@user0000user]

What y'all complaining about? It's not like it's rocket science....

[@zebo-the-fat]

Rocket science is easy, rocket engineering is hard!

[@matthewmiller6068]

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"

[@xeeton]

Why does all the NASA stuff actually seem like the alien technology?

[@zyeborm]

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

[@ShainAndrews]

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

[@absurdengineering]

​@@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.

[@ShainAndrews]

@@absurdengineering Entropy entered the chat...

[@ronjohnson9690]

@@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.

[@markgreco1962]

Am I first

[@8BitNaptime]

Not on the Moon, though

[@bensmith3304]

@@8BitNaptime No, you are Mark Greco

[@AB-Prince]

no, this is patrick

[@CuriousMarc]

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

[@markgreco1962]

@@CuriousMarc I’m framing your reply😁😀

[@ExiSTEIN]