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😂😌 same

Super interesting! It remains to be seen if and how this would work for a satellite at a similar altitude but with different inclination.

No

That's KiCad. It's an open source software for electronics design. You should check it out, there is a ton of tutorials for it on YT.

Thank you! Will do!

Hi! Thank you so much for taking the time to write all of this - that's awesome! Detailed feedback like yours really is invaluable to me. Basically, I agree with all of your points. Here are some of my thoughts for context: 1. Yes, if I were to design for one specific application, it would make more sense to do it the other way around. My thoughts here were: A) Other people may want to do different things with these designs, so let's over-spec this on purpose but make it modular so more sensible folks (like yourself) may want to design more sensible charger and buck modules. I don't know if you are aware of this, but the μModules are themselves on stamp-sized modules for that reason. B) RGSat started with the EPS, so it must be right way to do it ;) 2., 3., and 4. I lol'd at the "..." xD True, and in hindsight, I was clearly overdoing it due to a lack of experience. I just wanted to avoid a single point of failure due to a $0.05 part, but I will change it in r2. Regarding power dissipation, I calculated something like 9 months of "waiting for launch and deployment time" (I am sure there is a proper word for this) for the power used by the bias resistors, but that doesn't factor in battery self-discharge. So optimizing the resistor values will be the first step when I get to optimizing power use in general. 5. I'm in fact not sure, but what would be the alternative to using a MOSFET? I'd like to avoid a mechanical relay for volume and vibration reasons. How would you design this? 6. Yeah, that's another thing I am unsure about. On the one hand, I suspect that non-BGA components will go the way THT went sooner or later, so it kind of makes sense to get used to working with BGA. On the other hand, accessibility and cost are major considerations. I am willing to spend a good part of my income on this project, but in the end, I want it to be as accessible as possible. There is a balance to strike there, I think. Again I really appreciate you taking the time to share your thoughts and I hope to continue this exchange in the future!

Thank you and welcome aboard!

Thanks for commenting! Yeah, mechanical relays seem like a bad idea in a high vibration environment. I am currently using 4 MOSFET load switches for redundancy in the first version of the EPS design.

Nice, that's great to hear! If you feel like sharing, I'd like to follow along with your project. I think RUclips needs more CubeSat content :) I wasn't aware of that Mark Rober video, will be interesting to see if it has some spillover effect.

Hi there! This design is going on a high altitude balloon at the most, but that's good to know for future, space-bound versions. Were you referring to any specific component?

@@buildacubesat nearly all due to import and export regulations and other things hence why they cost millions also sometimes the altitide limit is there to prevent missile use

​@@UKsystems Ok, I see what you mean. So when I order components from Digikey and Mouser, I have to state the intended use before I can place the order. There, I always clearly explain that I will use the parts for prototyping a CubeSat and so far, my order always went through. So this should be fine. It is true that some dual use technologies like GNSS receivers and bolometers are limited for civilian use (altitude and speed limits for the former, frame rate for the latter). When purchasing the unlimited variants, you have to fill out some more paperwork and supply more context about your use case. Usually there is some back and forth with the vendor, but so far I have not run into trouble with that either. But thanks for having my back.

@ the issue is when it randomly applies to a resistor

Haha I'm super happy that you like it 😄 Thanks again for coming on board!

@@buildacubesat We love it so much! Honored to be a part of your campaign! 🥳

Awesome! Thanks for sharing, I will install that

Thank you, I am happy to hear that you enjoy watching this series! What you said there is exactly what I thought a couple of years ago when I discovered RGSat's channel =) So if you ever decide to start your own project after all, feel free to share! 🛰

One thing I noticed is pcbway isn't going just for sub count they are actually funding really good projects

@@awdhut-e2ethey own the files so they have something to gain

@@UKsystems anyways most of the creators open source the files , but it's really great for small creators with limited resources , they want to do something big so viewership increase and they get more money but because there is no viewership so there is no money and no big project So someone is breaking the cycle

@ it is a requirement for sponsorship by them

@@UKsystems Slight correction there: All design files are open source and freely available on the Codeberg repo (there is a link in the description). So transfer of ownership is not part of the sponsoring agreement I have with PCBWay. Of course I can only speak for my channel, so maybe you have had different experiences.

I don't know what you mean by that...?

@@buildacubesat ...are you Swiss by birth?

@@ostrov11 I am

@@buildacubesat ... I'm sorry, I thought you had a Ukrainian accent.

No worries :) That's just a pretty thick Swiss-German accent

Yes! I am planning to reach out to him about a collab in the future, when the design is a bit more mature (r2 or r3).

Thank you for taking the time to comment! Yes, there is a lot to improve for r2. Two questions: Is there a reason why you would prefer 0402 over 0603 as decoupling caps (other than limited space)? And you would even go with a 4 layer board if the layout is feasible on 2 layers? For EMI performance or are there any other reasons? Thanks again!

This looks like a really good fit - and that thing is tiny! Thanks for sending this my way, much appreciated.

Yes, that's definitely on the roadmap for v2! I want to get the basics right first, so for the moment (up until the suborbital balloon flight next year), I am just using equally charged cells. Are there any balancer ICs you can recommend? As usual, there is a staggering variety.

@buildacubesat I don't have any recommendations, but projects like OreSat, PyCubed, and PROVES probably use some useful ICs (and they've already been tested in space).

Thanks! I should probably have thought of that myself after spending hours looking at these data sheets for the schematic xD Turns out there actually are layout examples for both uModules I used. So in r2 I will probably go with those... I just assembled the first charger PCB this afternoon, going to test it tomorrow :)

Ok, that's good to hear! I'm really looking forward to putting this to the test though.

I know, thanks. I have been working out lately.

Thank you very much! I didn't think this would happen in the first year of this channel

Hi! Thanks for bringing this to my attention, that's really helpful. I have some of them at hand and didn't check the specs closely enough. I don't expect anything above 24V anywhere on the board down the road. Is there a 0603 device you would recommend?

Merci :)

nutzisch du github?

Nö, i ha aues uf Codeberg, isch a zimlech sympathische Verein us Berlin. D Links si aube ir Beschribig.

Haha thanks man =D

Thanks for watching! I am using 8.0.6 and the theme options are located in Preferences -> Preferences... -> PCB Editor -> Colors

Awesome! Just watched your NASA ASCEND video, beautiful footage. Are you going to document your next launch too?

I'm on it :) there are two videos about the schematics and one about the PCB layout on my channel right now

@@buildacubesat Thankyou, it will be a great help for Electrical engineering students.

Good point! I have done that myself multiple times. It may be beneficial to advertise the purpose of such sensors more clearly though imo.

Hey! Thank you so much for taking the time to comment in this level of detail, this is super helpful! I did understand the "unspecified signal impedance requirements" in the same way you mentioned - it's just that I don't always succeed in expressing myself coherently in these unscripted parts... I appreciate you mentioning this though. So for r2 I will definitely look into impedance control and use the approach you suggested (get in tha ballpark using online calculator and then tweak track sizes and spacings to fit in the design). That's an interesting vantage point, I have never thought of connectors being much of a problem for SI, rather cable/trace length between them and EMI. So I suppose in my design, the limiting factor may actually be the number of M.2 connectors a signal may go through in the stack up. Interesting! I dont' plan to run anything in the MHz range. For I2C, the usual 400 kHz mode will be plenty I think. You also brought up something I read a few times now, but never quite understood: Why do you think LEO would be a harsh environment regarding EMI? Would ionizing radiation (solar / cosmic background radiation) have an influence? Because thinking about just how empty it is up there, it would seem to be a much more benign environemnt regarding EMI than say an average office building. About smoothing transition between pad sizes and traces: Would you tend to step-up trace widths (like Phil Salmony tends to do) or use teardrops? Thanks again for the input. I will start a Discord next season, would be awesome to see you there :)

@@buildacubesat so to be clear this is all just anecdotal advice from my relatively limited experience as a hobbyist. my main assumption around stricter requirements in space is just, a vague sense of "radiation" being a problem, and the much higher cost of failure, since a lot of otherwise recoverable or easily fixable error states are potentially mission-ending when you can't physically access the device. i think what you're saying about it being much quieter up there is probably true, and ionizing radiation is a totally different thing from EMI, so i'm likely overstating the problem, i guess i was mainly just going off the general association between aerospace and stricter standards. I have not done any research into transitioning btwn trace sizes, my main intent was just to point out that lots of applications seem to get by with just accepting those small discontinuities. but i definitely think it's worth exploring how to optimize that, i just don't know much about that myself.

my intuition would say test your i2c bus at 400kHz, but also some much lower frequency (whatever the lowest your application can afford is) and use that in the final version, just to give you a nice big margin of safety. also: some of i2c devices implement CRC checksum functionality, you can check for that and make use of it where available to give you extra assurance

@@spambot7110 Sure, I understand that and your comments are still very much appreciated :) I want to look more into EMI/SI for space next year and ideally have a CubeSat dev as a guest on the channel who may be able to share some insights. For now, until the high altitude balloon test flight in June, I am going with a 'good enough if it works' approach to keep the momentum going, and then after that, I will start going over each subsystem with a fine-toothed comb and move into a space-worthy design direction. Well-reasoned comments like yours will be great to refer back to in the future, so thanks again for taking the time.

@@buildacubesat oh i just thought of something, when you see the length matching squiggles in a trace, when it's a differential pair of traces and the squiggle is on just one of them (for skew correction), that's another impedance deviation. so, i still don't know how to quantify it, but clearly there's a way to budget for it

Hey and thanks for the comment! I'm happy to hear that :) This is a framework 13", with the 12th gen i5. I can really recommend framework laptops, definitely check them out

That would of course be great, I'm eager to find out! =) I sent this to PCBWay for manufacturing (they also make all the CNC parts) and you're right, for flight hardware a different substrate may be needed (they also offer Rogers). But that's still a few years away :) Thanks for the comment and also the telling me about that TAH episode, will definitely check it ou!

Hey! Thanks so much for the kind words, that means a lot =) It's great to know that this stuff is useful for someone getting into the space industry. Best of luck with your studies, and I'll definitely keep the videos coming! Feel free to drop any questions or topics you'd like to see covered in future videos

Yeah basically, babushka-style xD Thanks! Yes, I placed all components in a 20 x 20 mm area, so if I didn't mess up too badly, this should work.

Hi! Great to hear that you are starting a CubeSat project - no better time than the present if you ask me :) Are you going to open-source it too? I got in touch with Richard from RGSat a while back and he mentioned being super busy with work, but not having abandoned the project. So I'm keeping my fingers crossed for him to continue at some point.

@@buildacubesat Well I'm glad he didn't quit. But yeah, I do plan on making everything open source, even the ground station. I think open sourcing things like this especially the flight computer is good for the community considering commercial products are so expensive.

@@mdarnell321 100% percent agree! Make sure to send a link to your project my way, would love to follow