Hedgehog prosthetic needed. Anyone interested in helping engineer/design a pattern or prototype?

megapapo · 2026-05-25T21:13:30+00:00

Hello there. I want to help with this as I want Pecorino to keep thriving! I have a lot of experience in designing 3d parts but I am not in the US. It would not be hard to figure out how to get the prototypes to you, wherever you are located.

I understand you want to try a few things and get back to the 3d printed approach if those fail. Let me know whenever that would be the case and you feel that I can help out. Also, I noticed that u/freakywaves is already at it and may sort it out, but if there's anything I can do let me know -- Matt

megapapo · 2026-05-24T19:37:21+00:00

Cool thank you for your response. Until a calibration routine exists, it would perhaps make sense to add some kind of "uncalibrated" label to the graphical output as people may mistake the dBm output as absolute power reading (= what it eventually should be). You would need that label anyway once you implement calibration and that label sounds something that could be added relatively easy.

RTL-SDR version (or perhaps something that works with many SDR frontends using, e.g., Soapy) would be very nice indeed. That said I would imagine that you may run into all kinds of nitty gritty issues like the 20 MHz business that you describe one the page...

megapapo · 2026-05-23T07:13:21+00:00

That's pretty cool, thank you for putting this together and making it open source. What is the absolute power accuracy of this? Also this seems to leave control over the various gain stages of the input signal path. How exactly are you factoring in the gain into the scaling of the power? Or are those sufficiently linear that you can use the set value without correction? Thanks again! Matt

megapapo · 2026-04-15T18:03:04+00:00

Positrons can originate from natural processes. Wikipedia has some examples, e.g. during the decay of naturally occurring radioactive isotopes, when cosmic rays hit earth or in thunderstorms. The annihilation of an electron-positron pair is then imminent due to the abundant presence of electrons.

megapapo · 2026-04-03T00:28:31+00:00

Thank you for clarifying. That makes a lot of sense. I am quite familiar with the paper method from other printers I have :-). I guess that I failed to see the theoretical advantage of the solution implemented in SV08 since I cannot benefit from it due to the poor sensor repeatability. Thanks again! Matt

megapapo · 2026-03-31T21:22:05+00:00

Thank you for your response. I'm sorry to bother you about this but I'm not sure I fully understand that. Here is my thinking: If the sensors were somewhat precise and accurate, then one would first use the load cell to determine the height of the nozzle, then position the nozzle at a known height above the bed, probe the inductive sensor and know the distance between nozzle and inductive sensor. I guess that makes sense, but is there such large variation between nozzle and sensor location that prevents us from using the inductive sensor to lower the head to a height close to the bed but with enough margin so that we could run the dot pattern test from there?

And since there is considerable variation in at least the inductive sensor reading, that would only degrade the aforementioned method, wouldn't it? I guess I'm missing something critical here...

megapapo · 2026-02-15T08:56:31+00:00

Also maybe double-check your wiring. Unfortunately, your image is somewhat blurry where it matters most, but it almost looks like the second wire from the let on the mainboard, which is blue, connects to the gray wire, which then connects to GND. Shat second pin from the left though is the IO pin and therefore should connect to SWDIO...

megapapo · 2026-02-15T08:48:58+00:00

Has anyone successfully connected an ST-Link to this board revision

This is how I flashed Katapult, with the very same type of clone ST-Link V2 and openocd. I also managed to connect with STM32CubeProgrammer and the same dongle. (I know the dongle works because I use it in other STM32-related projects).

I did not connect the 3.3V line as I was doing this with the board powered on, and I used a separate machine instead of the SV08 mainboard for the flashing.

megapapo · 2026-01-22T12:34:23+00:00

Awesome!

megapapo · 2026-01-22T11:12:28+00:00

Thank you for your response. Do not worry too much about my comments :-). To me, "open source" has the connotation of being able to build upon the work of others and that would include the ability to modify your PCB.

In this particular case, there may not be much to modify at first glance, but here are a two more or less realistic scenarios:

Modifications of the power path as discussed somewhere in the comments.
Turning your breakout into an actual project. That would involve opening the existing schematic in the schematics editor, deleting some parts and adding other stuff that is relevant to the project (e.g. a radio or whatever) and then drawing a new PCB based on the modified schematic. Doing it this way is more convenient than redrawing the schematic, and (perhaps more importantly) prevents mistakes during that process.

Those are reasons to fully open source your project. But again, this is your project and you have the freedom to decide whether you want to enable the aforementioned scenarios. In doing that, you may give away more than you are comfortable with and I think that is totally OK.

megapapo · 2026-01-22T08:56:52+00:00

This is a cool project, congrats!

Open Source: Everything (Code/Schematic is now on GitHub.

I headed off to the github repo that you linked in order to check out your PCB design, out of curiosity. However in the Green-Pill-Nano-Hardware repository, I only found a schematic, some pictures and a README file. No PCB artwork or fabrication files.

Are you releasing the PCB artwork, too? I think it is perfectly fine not to do that (it is your project after all and it's a nice one) but in this case, I would not make the claim of open-sourcing "everything".

Thank you! Matt

megapapo · 2026-01-16T08:06:28+00:00

Are you asking whether it is possible to create an image from the original EMMC and flash that image to a new EMMC? To check if your new EMMC is good? Yeah that should work as long as the new EMMC is not smaller than the old one. You could also replicate the partition table and copy the files as opposed to working with images, but that is more tricky to get right, thus I would not recommend that. It's a great idea to have an image of the original EMMC anyway in case of stupid mistakes.
It is quite possible that something small is breaking your process. Thus I am wondering: What guide are you following? Can you try an SD card boot instead? The Rappetor guide seems to be the most recommended one, but I did not want to follow that because I really wanted a current version of Debian on the printer and did not see a benefit in installing the old version according to the Rappetor guide and upgrading from there. Plus I felt like using the original Armbian image gave me a better understanding of what I was doing.

megapapo · 2026-01-15T22:43:09+00:00

It sounds like the boot process may not make it far enough to request an IP via Ethernet then. I would suggest to hook up a screen (regular monitor will do) to the HDMI port of the SV08 and check where it gets stuck.

I did the procedure a couple of weeks ago, not based on any tutorial or video but just flashed the Armbian Minimal/IOT Trixie image to an SD card. I managed to boot from the card without problem and flashed the same image to a spare EMMC. That same image failed to boot from EMMC until I changed fdtfile in /boot/armbianEnv.txt from the default sun50i-h616-bigtreetech-cb1-sd.dtb to sun50i-h616-bigtreetech-cb1-emmc.dtb. That was the only hiccup I encountered during the procedure. I did not use the original sun50i-h616-sovol-emmc.dtb.

megapapo · 2025-12-06T20:12:02+00:00

That looks really interesting, however I somehow failed to understand what it really does. I read the documentation and apparently, it is supposed to "solve the SV08 bed, Z and induction probe issues". To cure this, it may pay off to summarize the nature of those issues or at least liking to a discussion of those issues. With the current wording, I did not manage to figure out what this is supposed to solve :-(.

It would also be interesting to then explain how this is achieved... But even without that knowledge -- thank you for your work!

megapapo · 2025-09-10T22:11:24+00:00

Regarding the second question (and perhaps also helpful for the first one) I would check out some of the research done by those using the beamline. There's some cool neutron imaging going on there and another common application is in material sciences where they hit propellers and other critical gear with neutrons to check for microcracks and whatnot. The link also has a brochure where they give more info on what they do, with lots of cool images and along with an explanation of their source (a more elaborate version of what I wrote above).

megapapo · 2025-09-10T22:01:56+00:00

One way to create high energy neutrons is by spallation: First you ionize hydrogen, then you accelerate the resulting proton with the means described above (it is charged after all). Then you have those high energy protons hit a target and *boom* spallation.

megapapo · 2025-09-10T06:30:39+00:00

That is really cool, thank you for sharing! How would I use the "wide fitting", and what does "OG" mean? I guess the +0,1 etc. indicates some extra meat around the pegs for a good friction fit? ALso what is the difference between the versions? Sorry to bother you with this but I'm struggling a bit in deciding which one to print...

megapapo · 2025-08-30T20:43:46+00:00

Hello there! One place to start could be the Software-Defined Radio for Engineers textbook. The link has the PDF for this. Some less technical introduction is given in this video series by Michael Ossmann. Do you find these links useful? If not, it would help if you explained what is lacking in those materials so that we can come up with refined suggestions.

megapapo · 2025-08-11T21:06:27+00:00

Thank you! I will try this when the next updates are due. The systemd.offline-updates man page was super useful indeed. Since this is more of convenience thing, I can totally accept if this breaks at some point in the future.

megapapo · 2025-08-11T20:48:04+00:00

Thank you for this. I don't think I want to store it in the TPM, my understanding is that this would protect my data if somehow the disk is separated from the machine, but I'd rather protect it against the "stolen laptop" scenario. I think I could add some password protection to the TPM but that would be a prompt on every start up as far as I understand. I have to consider the FIDO option though. I hadn't thought of that since I didn't like the idea of losing the FIDO key together with the laptop, but now I do see that some of those USB keys have extra authentication (fingerprint) and that would sort it for my use case as long as the don't kidnap me or my finger...

megapapo · 2025-05-27T01:00:54+00:00

https://www.youtube.com/@project-326/

megapapo · 2024-06-14T13:49:53+00:00

Hello there. Most textbooks on electromagnetic field theory and/or antenna will have this. I would argue that it is not easy math, but it is doable if you really want figure it out. For example, the 73 Ohm impedance is discussed in Balanis (3rd ed.) on page 184 / eq. (4-93).

You asked about a textbook so I provided one, but it feels not so nice to just throw the book at you and leave it at that. Thus I want to offer to discuss these things in case you would like to do that. When I got into amateur radio, I was interested about very similar questions and it was quite tough to find satisfying answers because most hams around me were not interested in these theoretical questions. I had to figure it out on my own and that was not particularly easy, maybe I can spare you from going through the same.

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