Random - nolanhergert/notes GitHub Wiki
https://hackernoon.com/apples-icons-have-that-shape-for-a-very-good-reason-720d4e7c8a14
Great list of methods evaluated here: https://thecavepearlproject.org/2023/03/17/waterproofing-your-electronics-project/
- They recommend clear heat shrink with clear epoxy underneath. Both are clear to see failures on the way.
- Hot glue works for about a year, when the glue tends to pull away from board and not be as waterproof. Still shock proof though.
- One from PSU professor at Crowd Supply talk a while back
- Allow >10 seconds after power on before sleeping to reprogram CPU. Can implement using a bit that is maintained by RAM in deep sleep and cleared with power cycle. Or a pad/button on PCB that overrides sleeping.
- Lots more stuff...
- Designing Electronics That Work. Free PDF of older version, but there's a new version coming out.
- Also maybe Circuit Designers Handbook, recommended for production optimizations. Probably not there yet.
Requirements:
- Only allow a battery to connect to a charger
- Robust to frantic pulling and pushing, maybe a hammer blow or two from dropping
Nice to have:
- Require a key installed on battery/charger in order to work with a keyed battery/charger. Some kind of thing that sits down but is cleverly flipped up as the other keyed connector comes in?
- https://hackaday.com/2022/01/28/3d-printed-jig-makes-custom-springs-a-snap/
- There are automated machines too, although takes more work.
Helpful to have spring steel (piano wire), since it maintains springiness. If you use normal steel wire, then you need to "reset" and quench it still.
You could use plain copper wire or better still enameled copper wire (magnet wire) if you just want the electrical component coils and this should work fine.
If you want to “make” springs then that’s not quite what’s happening here.
They’re using piano wire which is “spring steel” to prevent the piano from de-tuning too quickly.
So it’s already spring steel and you bending it past its yield point to form a new shape. This actually weakens it a bit but it’s fine to do with any gauge of metal that we hackers call a “spring”.
If you were to use a common (low carbon) steel wire you could do the same and then heat it to a dull red glow and then drop it into a metal bucket of water to temper it (make it springy). There’s a bit of a black art to this but if your not healing till it glows bright yellow then you should be OK. Overheating it makes it brittle and it snaps forming sharp points or edges.
If you don’t heat it enough then it wont get “springy”. Most of the black art is about what temperature your taking it to and how quickly you cool it. So just a dull red glow is fine and you kinda stuck with a fast cool down with a bucket of water but it’s much safer handling doing it this way rather than burning some part of your body with red hot metal.
Wow, so cheap SMT LEDs can be sensors too! For light and temperature.
https://github.com/paulhdietz/LEDSensor/ and his presentation here: https://github.com/paulhdietz/LEDSensors
Uttapam (fried pancake (fermented dough?!) with tomato, onion, good stuff)
Rotti / other name, like fresh tortillas.
Why ghee again? Ahh, no water / milk solids, so more like oil than butter. Smells nuttier and more interesting too.
Photochromic, polarized, blue on outside, clip on flip up sunglasses with a frame for $2.79 delivered for free. That ain't right. But it's surprising how cheap it is. It probably does cost the factory about that amount. Temu is just throwing money at shipping.
He used this site for fulfillemnt from China: https://chinadivision.com/
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It's important to visit factories to get a feel for how they do what they do. Why is MOQ this amount? How can you get the price that cheap? What design constraints are you assuming? For the toy factory making a toy that talks back, they get pennies per chip because they do the black blob and more specifically, building an ASIC that only does that thing. No flashed code. Hard coded for those sounds. Only for quantities of 100K and you can't mess it up!
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He remembers when fidget spinners were just coming out. They were the hot toy, everyone was copying the design, and the prices of ball bearings were going up! Enough that
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Some/most factories are trying to take clones of working ideas, cost optimize them further, and sell in volume as it's half the price of whatever and looks the same. He brought new, good but unproven ideas to a toy factory and they didn't care unless it looked like DJI's latest drone or was done by a big hot company already. Eventually others copied his idea and worked around the patent, and did well with the idea. However the factory owner likely is a multimillionaire and the inventor Aaron is not. Who made the best decision with what to do with their time?
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Another example of another toy. Yale (another factory owner) put $25K and more into tooling, but they lacked the marketing so it came out a flop. Might have been similar idea to above.
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Lives in Shenzhen because he gets to hang out with innovators and hardware makers, get wined and dined by factories, prototype ideas quickly with JLCPCB, etc. Nobody wants to do that in Spain. Just want to relax. Although he still spends six months there, maybe because of his visa to not be a resident in Shenzhen.
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Frequently the factories will buy the same PCB and firmware from the original supplier of an idea and only tweak the case design. The factory team below said, "we are good at hardware, you can do PCB and firmware design right?" Squares with this.
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To buy on taobao, use its image capture mode and it will automatically see the product and search for similar images
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Want to visit JLCPCB now! And specifically ask about how/when they make money or when they intentionally lose money, if they are subsidized, what their motivation is,
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Lots of great stories..
Not sure it's the most innovative factory, was a bit accosted. However they say they are doing a good job of getting costs down with designing the product for automation.
- Invents their own takes on USB cables and battery banks, and sold their products for Disney and others. Make for $1-2, Disney sells for $20. But they are frustrated because Disney didn't come back to them for another order and their healthy income is made from repeated orders. Maybe the product didn't sell, or they went to another factory, not sure.
- Everyone comes to the fair looking for new ideas. There are fairly few of them in practice. Factories want to make products for people. Distributors come looking to make licenses to sell / put their brand on it and market in their country.
- It's cheap to make a patent in China, they are familiar with the process and have done it before. Manufacturers tend to respect it too, as they have been sued by this factory and others and have lost.
- They do NDAs too. So the factory won't screw the buyer and sell their own way. Not sure if there's an agreement the other way, exclusive supplier? I think so.
- They don't really want to be in the business of selling either. They would prefer I design, send them the finished files, they cost optimize, and then other people sell. If there is a patent, makes it a lot easier. People come to them! If that strategy works so well, why do Apple and Dyson and others have their own stores too in addition to Amazon and Best Buy and Costco, etc? And why does Ikea not sell anywhere else?
Watch Roomba / dragon innovation guy on picking a factory? If he has it
Lots of nice people, feels like 60% young women. Probably the company is preferring them as salespeople. Prepare to be semi-aggressively pitched while you're walking by if you want "backup camera" or "battery bank". It's weird!
If someone doesn't know english that well, people from other booths come over to help translate my questions.
Had great chats, people are open to probing questions.
One guy is mostly forced to inherit his father's membrane design company and there's lots of competition, especially after 25% duties on US imports. Very frustrating.
Spent 45 minutes just at silicone place, feeling and looking at designs. Brought home a subset of useful samples.
Another place (NingBo Deamak Intelligent Technology Co. Ltd., contacts are Rain Zhu and Anna) makes their own designs for lights and handles all of the upfront costs themselves and make it up in MOQ with the customer (>30K units). Crazy risky. How do they prove MOQ, 1/2 cost up front?
- They patent their designs and actively take copiers to lawsuits. They would lose their NRE if not!
I think the engineers would appreciate direct feedback in person. Hopefully I can visit in person!
So many (20-30x) booths for the same "boring" stuff sometimes, right next to each other (at least 20-30x. Car head units, electric bikes/scooters
You contacted him on wechat too, but spoke in person
Sounds like China govt will help you automate your factory, esp if you will become number 1 in world. Not sure how widespread this is
The supplier wants to see that you can do the marketing and sales side too before they will respond. Make a brochure and a pitch video that is viewable in China? --Alternatively try too reduce their nre
If you aren't getting questions answered right, you can ask to speak with engineer.
I have gotten my questions closed for various reasons. This one https://electronics.stackexchange.com/questions/682410/why-would-old-chime-generators-go-out-of-tune was closed for being opinion-based. I mean, sure it's speculation, but there are very technical reasons why it would be the case! https://electronics.meta.stackexchange.com/questions/7066/why-is-this-opinion-based
Additionally, wanting me to make a more specific question (in order to meet the ideal of only having one answer) is begging the question. If I knew the exact question to ask, I would have my answer already!
Anyways, this answer in the EE meta forum on how "subjective questions are good" gets at the heart of things. It's funny that the other answer is almost the opposite. https://electronics.meta.stackexchange.com/a/5949/71181
I'm not going to bother trying and contesting it, I have better things to do.
Kids passing by in the morning, with hourly chime
6pm chime and trains passing
Pretty nice view. Occasionally a cloud will light up with lightning too, like a shooting star.
https://twitter.com/waneella_/status/1580208796869464065/photo/2, or https://www.dropbox.com/scl/fi/gpoky92nh7wmj3rpt7os2/waneella_-1580208796869464065-GIF-1.mp4?rlkey=o8llk4qdyqealm6j5kzqt4t0v&dl=0
The 45-year-old electronics store shopkeeper on the outskirts of Kyoto suburbs still knew the English word for closed crazy
A father a little older than me whose days starts at 8am and he ends work around 7:30pm. Works out several times a week, and listens to english training recordings on his bike ride home. And I can't find brain/time to learn a little bit of Japanese?
- Now "manning up" isn't a great reason to do something, but maybe that is what will work for me... at some point.
- And they are learning and remembering my name, despite me being here only a month >.<
Native japanese person living in Kyoto
It started with asking if the SNL sketch of a Japanese Game Show (https://www.youtube.com/watch?v=JLVmybhXqtU) was offensive to Hiro. We started watching a few minutes, and then stopped and discussed.
Currently it's cool in Japan to be white-skinned and speak English well. Everyone has to learn English in school, starting in elementary school. If you don't learn it, something is assumed wrong with you mentally. There are some ads in the trains with white westerners on them (beauty ads mostly). So a white westerner can be somewhat accepted as a tourist despite not bothering to learn anything about Japan or Japanese before coming. Wouldn't an American person have a somewhat negative view of someone coming to the US and not knowing any English? "They're dumb", "I'm not going to bother helping you!".
The people in power get to poke fun of "lesser" nations without many consequences. And white westerners have lots of privilege that they don't even realize.
If an American actor gets asked to be part of a Japanese movie but their role is not quite right (fits japanese images of westerners), it's considered offensive and an outrage in the US. However, when Ken Watanabe or __________ tries to influence studios to allow him to better represent a Japanese person, it's a losing battle apparently, and that's the end of it.
Coco movie supposedly does a good job of trying to be authentic when it comes to Dia De Los Muertos, but an American likely won't realize some of the subtle details unless fully explained. Also, that it made the US news tells you something about how bad of a job American studios typically do in representing other cultures for a US audience.
He showed me a video about bowing traditions in Japan (https://www.youtube.com/watch?v=XDLnyW7qWu0, others by Namikibashi: https://www.youtube.com/playlist?list=PL1bPUuanfGk9e24ugeOT4BOlgl5nVrp9c). It's funny for native Japanese as it starts with the familiar and heads off the deep end. I think Westerners would recognize this too. However, there are hidden jokes in there. The music at the beginning is music reserved for the emperor (gagaku)! Not "normal" Japanese music. And only a Japanese person that has traveled a little bit will know that it's the type of music that Westerners would expect to set the stage for something Japanese (similar to "oriental riff" or chop suey font for Chinese / SE Asia), and that disconnect is funny. So I'm sure there are lots of things in there that a westerner wouldn't realize.
I later asked if he could show me some videos/comics that stereotyped Americans and painted them in a bad light. He was happy to :)
- The US left a large station in Okinawa, such that it took over most of the island! Plus soldiers know they have immunity once they are in the base, so they regularly commit crimes outside the base and then escape to the base. Despicable. https://youtu.be/1Wzi7blrYUQ?si=JUNbTDMXwvI7f5Mf
- Commander Perry begging Japan to open up. https://youtu.be/W5B2icDl28s?si=pJYNY_ckStuhNTHO
I was explaining my surprise at the diversity of house/building designs, manhole covers, etc, in one town in suburban Japan. And as is often the case, it allowed me to ask the question of myself, why are American buildings and products so typically boring? They are still charged money to design the sorta custom house, the make the molds, etc, but but the Japanese person will pay it whereas the typical American won't. Why?
- More middle-class people in Japan, a bit more frugal than the U.S., so they can afford to
- In so many areas (traditional kimono design, salaryman outfit today) things are so rigid and defined. You must fit in! However, many people would have custom essentially outside pocket designs (they were each handmade), or inside the kimono (the back of it). There's creativity that wants to get out! That helps also explain why there are so many clocks, calculators, manga characters, etc. People are seeking out stores that have more variety, more options for each person, and they are willing to pay for it.
- I found my answer!
It actually began in the 1980s, when a Japanese bureaucrat figured that if manhole covers were more captivating, perhaps taxpayers would be more likely to support costly sewer projects.
These customized covers cost up to 3,000 versus about 500 for the boring version. But it seems like money well spent. After all, it's cleaned up the image of the sewer.
"Japanese manholes reflect the Japanese mentality," said Yamada. "Even if it costs more, we want to make something beautiful."
- From nice video and article by CBS News: https://www.cbsnews.com/news/street-art-japanese-manhole-covers/
Great images of a variety of manhole covers: https://youarts.quora.com/Discover-Japan-Manhole-Covers
He made a very interesting observation as to a common narrative in Hollywood, even still today. White American person goes to faraway place, suspects everyone as bad but finds the true bad guys and kills them. Then sort of assimilates into the culture but ultimately becomes much better than the culture. And that's all you need to know about that culture. America wins. I could see that for James Bond, The Last Samurai, Batman, Bourne to some extent, other superhero movies. But thankfully that leaves space for latent demand for other narratives to do really well, such as Jackie Chan, Everything Everywhere All At Once, Crouching Tiger Hidden Dragon, and South Park Guys (Team America World Police)
Back when there were only 10-12 TV channels in Japan, they were all public. However, the system by which to collect funding was done based on whether you had a physical antenna installed and presumably were using the TV. NHK broadcasting would outsource fee collection to various regional companies that would have people that would go around and see if that house had an antenna and would collect either a monthly or yearly or lifetime fee (not sure which) to use the publicly accessible channels. Why not just use a flat tax for every household? Probably because corruption of the contracts between companies <-> government kept things going that way. And they probably wanted to be fair to people and based on usage.
Why were people so pro-Japan in WWII era? Japanese people were much more chill in Edo era, and they probably succumbed to the propaganda that they might get colonized.
Corners in neighborhood streets aren't that safe, but my point is that it slows down cars. Sadly enough, the number of kids that die due to ball going out into the street is a good deal lower than the number of kids / adults that die from suicide.
Why high suicide rates? The dual societal mandate of measuring up to both Confucianism and Western standards and not meeting them was/is seen as unacceptable.
Same for sexual stuff, where there in the Edo time period Japanese people were fine being naked, bathing in the streets, etc. When the "black ship" came in, they had the benefit of seeing India and China "colonized" / getting taken over for a number of reasons ("they're savages", we want their resources, etc), so the Japanese people united together away from feudal lord system to both defend themselves and appeal to Western sensitivities (think full covering for women timeframe) so as not to be seen as savages. However a lot of those things (just simple touch included) were still needed societally, so they got pushed to the background. Massage parlours, simple "imitated nurse" room things, as well as lots of pornography made and enjoyed in private.
“The best thing to do is avoid getting sunburned in the first place,” says Dr. Tsai. “Use sun-protective clothing; apply a thick layer of broad-spectrum sunscreen with at least SPF 30 every two hours; and stay in the shade.”
Got pretty lobster-y from hiking Mt. Fuji this time around. I need to balance staying cool though too. Maybe a white breathable tunic or something.
Got a package from cnlohr, gives confidence in package.
- Tape over seal. Annoying to open priority mail box though
- Fragile connections are taped to cardboard backing plate
- Static resistant packing material
Multiplexing cameras requires OV5640, as OV2640 doesn't break out FREX pin. However if you're able to mount iPatch to eyes than you only need outward facing camera (hopefully) and can do cheapter OV7670 (less resolution, less features, etc)
Connector is .5mm 24pin FPC. Can do connection on top or bottom of connector, cool! TODO: Confirm that one connector is on top and another on backside of PCB, as camera modules look all the same direction
- Not happening on this board...as it requires flipping all the signal wires. On the real board, buy swapped camera modules and swap sides? not sure.
- Can
Power mostly copied from ESP32-CAM board.
- 2.8V: MD5128_C919702
- 1.2V: MD5112
There's a fully integrated chip form! Only ESP32 (and not S3), but don't require external flash, PSRAM, crystal, etc. No USB though. $5. ESP32-PICO series, newest is V3-02
There are great videos now, Phil's Lab, etc. Notes from Ben Hencke and myself:
- 50 ohm trace out to where your antenna is
- How not to ruin your antenna: https://hackmd.io/oaFVCqXNSZO_LdZHaAnW_g?view
- Dropout's guide to antenna tuning: https://colinkarpfinger.com/blog/2010/the-dropouts-guide-to-antenna-design/
- https://lcantennas.com/a-complete-guide-for-pcb-2-4g-antenna-design/
- Interesting a monopole antenna is design to not radiate up/down. While that works best form factor wise for roller coaster project, might not be best in practice.
- Tune antenna and CLC thing with VNA. There are good cheap $150 ones. MiniVNA I think (up to 5Ghz). But cheaper $50 2.4Ghz might be ok for ESP32. https://www.youtube.com/watch?v=6hdV0Ze3Fmg
- Another good seeming video: https://www.youtube.com/watch?v=HAaWwZ73ygM
I got a fomu from Tim Ansell, cool! He had some nice notes on using bit corruption to detect capacitive touch digitally:
- bit.ly/goog-analog
- Other talks: bit.ly/open-pipe-talk, bit.ly/goog-fpga-22q3
I remember watching a video on bluespec compiler. Is it really good? https://github.com/B-Lang-org/bsc
From this discussion on ch32v003fun from Larry: https://discord.com/channels/665433554787893289/1080242396736000100/1171491001014165555. "I use 2 diodes to effectively create a "wire-OR" between the battery and a GPIO output."
The reason you need diodes is because the microcontroller power is off. Normally it can handle it if power is on and it's sleeping.
Sometimes it makes sense! One less item on the BOM, but it's usually replaced by another item (a mosfet). Downside is you can't outsource the work (uc or peripherals have to stay on)
JLCPCB basic part for n-fet is
Can detect between normal lithium ion battery and LIC based on voltage rise. Also can detect C of LIC automatically too, but can't do lithium ion mah detection since it's a chemical operation (stays at 3.6V for too long)
https://www.microfarad.de/li-charger/
ME2188 and TPS61040DBVR
Buck boost: TPS63* series?
Current limiting on above regulators: https://www.ti.com/lit/an/slva419d/slva419d.pdf (Different Methods to Drive LEDs Using TPS63xxx BuckBoost Converters)
Can use microcontroller too!
Need a 2.5V reference and shunt resistors on high side of n-fet. Still working out I2R/I2T calculation.
I think in the end it's way easier to just use lithium ion capacitors / lithium ion "battery" capacitor if you can sacrifice the slight hit to current, especially now that they are very cost-competitive with supercaps.
TPS63020, 3A!
LSM6DSTR-C. $.70, plus Adafruit Arduino support. Awesome!
The trinamic chips provide all the features I want (silent, automatic dynamic current limiting) and a one-wire uart interface to set it all. Easy, and for only $1 more. Done!
Just in case you want to save $1, here is a circuit I painstakingly put together for the DRV8834. Untested though.
Great cheat sheet: https://www.albertosavoia.com/uploads/1/4/0/9/14099067/pretotyping_quick_reference_for_stanford_ms_e_277.pdf. Only one portion of the book, but a significant portion.
Hold down SW to get to this menu:
Uses modbus, which while there isn't an exact manual, maybe I can create one based on this: https://github.com/joeyda3rd/modbus-power-supply#further-reading or this: https://github.com/kanflo/opendps
Great conversation with Helen while at Dorkbot PDX meetup at Crowd Supply.
Inventions have many different appropriate scales. CS rejects 90% of their project submissions! They focus on hardware, which requires a really different mindset than software! It's real atoms, etc.
You sorta-cold emailed 15 people and none of them got back to you? That's normal! :)
Cheap new good one is apparently CH32V003? and siblings
There is also the cheap STC8 series? Knockoff of STM. https://www.eevblog.com/forum/microcontrollers/stm8s-versus-ch32v003-price-war/msg5169255/?PHPSESSID=9agi2bod1d786sq06n0qjg1m3c#msg5169255
There is also PY32 which is a price-wise competitor with CH32V series, but support doesn't nearly seem to be there.
Safety strap / easy way to turn off? Don't really need it...
Lightweight. 60 pounds is probably ok, sure beats 150.
4. Blood flow (as mentioned by some previous answers): when standing, the heart is not strong enough to pump blood from the ankles / feet / calves back up, so there is a pool of stale blood that accumulates. Without that fresh blood to deliver oxygen, nutrients, and remove toxins, your muscles will feel uncomfortable. Also from #1, you are forcing your muscles to do a lot of work, while simultaneously not giving them what they need. Overworked + underfed = unhappy muscles. When you walk, the increased activity of your muscles keep the blood flowing up to your heart and back, giving the muscles in your extremeties fresh blood, and keeping them happier. Gavin Bradley, the director of Active Working, a group whose focus is to reduce the amount of time people spend sedentary, says that “Metabolism slows down 90 percent after 30 minutes of sitting. The enzymes that move the bad fat from your arteries to your muscles, where it can get burned off, slow down. The muscles in your lower body are turned off. And after two hours, good cholesterol drops 20 percent.”
- This seems directionally right to me (similar experiences for sitting for a long time). Want to verify though.
Long-term bad effects of walking all the time. Might be better to use a lower stress machine, like a elliptical.
The projects I am creating frequently require boost converters, which can create a lot of ripple in voltage. Not sure why they don't do a great job of filtering it!
Anyways, I'm trying to fix it. This "capacitance multiplier" looks to be a sort of simple and elegant circuit. EEVBlog does a good job of explaining it: https://www.youtube.com/watch?v=wopmEyZKnYo
Photos, pretty straightforward.
Gmail, saved on drive. Download via takeout using zip.
Quirky but works.
- Open containing folder on Windowsthen you can click on the mbox file.
- Search using CTRL + F, then be sure to do checkbox of "Find all occurrences". Defaults to jumping to first one and showing normal messages after that.
Need to figure out the dumb setting we want to do still. Don't care about color, amount filled (it has a run-out sensor), ???. But might have a button and light for configuring material (ABS and ... flex?).
Arduino ds2433 implementation with onewire: https://github.com/meawoppl/eepromTool-ds2433
- Put a sticker on the back so you can find the github
https://electronics.stackexchange.com/questions/62092/1-wire-and-the-resistor
Eventually unnecessary GUI: https://github.com/slaytonrnd/CartridgeWriter
https://github.com/bvanheu/stratatools#automation-with-a-raspberry-pi A helper script is available if you wish to automatically rewrite cartridges using a Raspberry Pi. The script will set the manufacturing date to 'today'. It will also randomize the serial number and set the current material qty to the initial material quantity.
Original ledgerwood video: https://www.youtube.com/watch?v=M94D-Pot6c8
- Use prodigy in above software for Dimension 1200es
- Use d-limonene and old support material for better adhesion??
Use latest firmware. I just tried this. It works, with one caveat. You can no longer put in 99,999 or whatever, you have to put in 56.3 for initial quantity (which is the default I believe). Works with the newest firmware as of today. Upgraded from firmware version 7.xx to 10.xx. Updated through GrabCAD print. Hope you see this/already figured it out. Good luck! https://www.reddit.com/r/3Dprinting/comments/a4nzzw/stratasys_dimension_1200es_firmware_update_safe/
Spent about an hour or two … or three on it.
Might prefer RGB LED ones. They are pretty affordable ($20) for 200 LEDs sort of arranged like Christmas Lights. Good enough with current ones though.
Can run them off of DC, just need to connect them together every N lights, depending on desired brightness and voltage. I think that works, but it’d be good to test with simulator, not sure how voltage drops and wiring actually works.
The lights disappear very quickly after Christmas Day!
I think I like white wiring with warm white color best. If they are just $8-10 for an LED strip that runs off of 12V, that’s pretty awesome. Next time when you get the urge
Otherwise your current strand works well and you have a good number of replacement bulbs. Be diligent about replacing them right away. Wait until next year, should
Make reminder to buy on day after christmas?
My current thought is to just take it slow and stay for several weeks if possible, ideally in off season. Much cheaper per day, much less stressful, etc.
Really great breakdown of a simulation and consequences of fast pass by Defunctland: https://youtu.be/9yjZpBq1XBE?t=3403
Safi Bahcall book, nice. Talks about separating the scientists from the more process-oriented military style of production, de-risk. Need both, so you have to keep them separate but yet together.
Interesting story about the enigma machine and Germany. Despite popular accounts, cracking the code did not turn the war. And the Germans were intercepting allied transmissions too! https://youtu.be/JvSAhGsCRWk?t=1620
Long-time discussion on this.
Chad and sharon podcast link: https://subspla.sh/bfv6zs9. "God's Hand and the Pharaoh's heart".
One of John Piper's sermons on Romans 9 and pharaoh. https://www.desiringgod.org/messages/the-hardening-of-pharaoh-and-the-hope-of-the-world
Calvinism vs armenianism is the complete predestination vs free will debate. However, the Bible describes both. A contradiction of sorts. And it's one thing for God to foreknow your future decisions, but another to not allow you to change, as in Pharaoh's case or Canaanites
- Another term is reprobation.
https://engineering.stackexchange.com/questions/7736/schematic-diagrams-for-mechanical-systems
Keeping the file here for safekeeping. A nice original paper documenting the different design tradeoffs and how they got to their design.
Current design uses inductive power transmission instead of probably unreliable slip rings, and IR leds instead of wireless for data transmission.
A Low-Cost Laser Distance Sensor.pdf
Dim non-dimmable LED lights with a safety capacitor...somehow. https://www.youtube.com/watch?v=JH68wBXO5j0
- From Tony Fadell's book "Build"
The inventor sees just the invention, but in practice the customer has to go through the whole onboarding process. And will stumble along the way!
Headlight blocker potential prior art that itself has prior art: https://patents.google.com/patent/US20200290439A1/en?q=vehicle+glare+blocking+camera&oq=vehicle+glare+blocking+camera
See here for some old notes: https://nolanhergert.github.io/notes_old/home/random3.html#carbonation
Current thought is to have:
- Cheap 2L keg with lid. Silicone hose connected to diffuser going to bottom of keg. Output from bottom (coldest), and fill on the top (warmest).
- Optionally add a pump to continue mixing it internally? Or something more violent. Nah, we need to chill the incoming water.
Great source for the physics of the thing: https://web.archive.org/web/20050307180456/https://www.truetex.com/carbonation.htm
- Recommends using pre-frozen ice in the bottle, then break and fill with water. Then carbonate. Keeps it cold
- Physics of various commercial carbonation methods.
- Turn off gas, then shake some more to reduce the head pressure and use up the gas. Need to purge my lines at the beginning too.
- In the words of one person (can't find), diffuser doesn't replace the need for shaking, since the bubbles last so short. It probably reduces the shaking required by 2X (my guess).
- Can't really put a keg in the kitchen area currently, so connecting it to that water line is out of the question. Darn. So that leaves:
- Expensive refrigerator + water line tap somewhere else (nah)
- Refilling beverages manually and storing in fridge. With an optional dispenser if you have a large keg thing, but don't need it currently.
Why is a float switch needed? Do you need to maintain a minimum head space? In the above model, the CO2 is coming from the bottom using a diffuser...
- You need the water at a higher pressure than the CO2 in order for it to enter the chamber. But you need CO2 to go in as well (assume it stays always on). So the water needs to shut off for things to work properly. Float valve is one passive way, but requires the container to be upright. Another is to use a solenoid, which allows you to use it upright or on its side.
- I think the solenoid would work. Keep a constant CO2 headspace, but refill water 1:1 from output. So switch on dispenser causes solenoid on output and water input to open and close CO2 input (so we keep water as 1:1). Need to not have leaking. Hmmm...
Need to use secure DNS too. Chrome is enabling it by default now, except for managed IT laptops. :(
Hacker news thread: https://news.ycombinator.com/item?id=32035054, specifically the section talking about Eric Lander and OCW. Original article is good too.
- Currently watching through: https://ocw.mit.edu/courses/7-016-introductory-biology-fall-2018/
Why do we need them again?
- Not hiking near other people or cell service AND
- Get into an accident and need help AND
- Be conscious still (99%? of situations)
- Unconscious (1%?)
- Need tracking turned on (extra $20/month on inreach, more for others) and someone to watch it.
Garmin Inreach has monthly cancellable subscription for $15. Provides unlimited preset messages with gps coordinates, and allows two way comms for a small fee or something. Seems like a good deal to me! https://hikingguy.com/hiking-gear/in-depth-garmin-inreach-explorer-review/
- A nice thing about the mini is that you don't need a phone to be working to enter or receive messages back and forth
Bivy is another one
Multiple use cases
- playing outside, twisting a lot wears out rubber quickly I think. Needs to have fairly deep tread to not slip in wet weather and last a while.
- rubber, even thick, isn't good enough for running in gorge. (Think the original rubber only sandal things). Need impact distributor that works for tough running impacts.
How long do chacos "last"?
Still might be worthwhile to order retread tread from Eugene?? If find good long lasting sole material. But don't have yet.
Otherwise, even $20 a year for shoes is pretty affordable.
Just try re-soling old sandals using trailer or motorcycle tire (no radial tires, they have steel belts)? Why bother??? It's cool :) $20. Maybe I don't even want the sponge bottom on my current sandals!
- Trailer tire, $20 new. https://www.discounttire.com/buy-tires/carlisle-sport-trail
- Nice video on cutting them easily using razor blade. https://www.youtube.com/watch?v=lGT5RCMMeQw
- Re-soling advice: https://www.youtube.com/watch?v=QTsLv3Kc_xE
Can get big chunks of rubber by getting an old tractor or forklift tire. Can replace missing chunk in car ramp potentially!
- Video here: https://www.youtube.com/watch?v=0genMTQKdIE
Agressively sipe the inside sole of the tire sandal for better grip in water/mud?
- can make cutting / siping tool by bending razor blade. https://youtu.be/0genMTQKdIE?t=338
- Or simply just bend it around! https://youtu.be/oGuoMmY7pnc?t=261
The details....You have to grind or sand the old rubber sole flat so that you have a lot of contact for the sole/cement...better results in the end. I used my bench grinder to remove any of the remaining tread and it took about 5min per shoe. Use a marker to trace the outline of the shoe on the new tread. It is better to leave a bit extra vs cutting directly on the line to allow for the curving of your shoe...sandles will not matter.
Do not use ShoeGoo if you have access to the contact cement as the contact stuff is much stronger. You will also need about 5-8 clamps to squeeze the sole to the shoe, more is better and I used a 4"x10" piece of wood between the clamps and the sole to help even out the clamping pressure. I used a small block of woo on the inside of the shoe for the heal area and it worked well. I did one shoe at a time and let each shoe sit for two days before removing the clamps. It is worth your time to go slow and get a good bond.
The end result is good adhesion with no gaps and the soles work and do the job...new shoes for $10.
Probably will not be able to pull out the steel belt, it's just too much and seems pretty hard. Might be worth a try with a free tire though? https://www.idmsvcs.com/2vmod/suspension/wheels/tires/beadairleak/PICT5932.jpg
Feel tough, except a slight tough rub on the edges of the straps was annoying. On the brown ones, there is a bit more flex and softness on the edges. Returning
Feel tough and likely longer lasting than Decathlon sandals.
- However, the things that stick up on the back sides are easy to step on, unlike the Decathlon pair.
- Feel more sweaty than Decathlon on bottom of foot, since it's not foam
Luna Sandals Origen 2.0 https://lunasandals.com/products/origen-2-0
- Want to try the lace style vs. NH100 style
- Seems less likely to smell when gets wet, since there's less surface area to mold. And can clean a little easier.
- Might be able to grip better than NH100.
- Worth $100 to try out I think. And can easily retread them later technically.
Mono gordo, or bedrock cairn 3D? Can try bedrock in downtown REI.
Ibrahim
He probably should make his own PCB, do it modularly, design a case, etc.
Put sensor in middle by making a hole and wrapping around it?
Run in negative direction once passing through using an h bridge?
-
https://www.youtube.com/watch?v=fKEaDhDTciQ (canadian guys)
- But interestingly even the canadian guys end up switching to a coil gun in later episodes. I wonder why? Limited power. https://youtu.be/qXXYkxCSiUY?t=66
- Has spreadsheet and more explanation: https://www.youtube.com/watch?v=Zm_oZZZBLj8
- Great scott: https://www.youtube.com/watch?v=PMU9TQUDhow
- PCB design! Electronoobs: https://www.youtube.com/watch?v=id90kjYh-Qw
- More explanation and optimization, magnets?: https://www.youtube.com/watch?v=g2p4P36VtQE
I use T-Clock. Here's the format:
h:nn "WW"Wu.wi\n yyyy-mm-dd
Might need to change Wu to Wi. Different one year to the next.
ElevenClock works good.
WW%W.%w %#m/%#d %#I:%M %p
Monkey bars FTW? Probably easiest to obtain RP. However, can get it through individual performance to top bar or by lifting two others to 2nd bar. Interesting.
If have time to do a shooter, can simplify by gathering balls on ground and shoving over to station. Easier loading mechanism. Although intake and shooting isn't that bad.
- More of theory: https://www.youtube.com/watch?v=rLwOkAJqImo. 254, emphasizes latency of vision relative to other sensors, but might not be a problem with the limelight.
Why is height best?
- Area / width isn't great from off angles, ok makes sense.
- How much resolution can you get from height though? Probably enough.
Will is saying that ramsete includes friction while turning inside its effective track width figure.
Haha, this website has nearly the same thing for apple pie and mulling spice.
Thankfully, while mulling spices is out at Winco, I can buy the bulk ingredients by hand.
4 tablespoons ground cinnamon
1 1/2 teaspoons ground nutmeg
1/2 teaspoon ground allspice
1 teaspoon ground ginger
1 1/2 teaspoons ground cardamom
<organic orange peel (or just zest? not sure), use potato peeler?>
Dry the <fresh> ginger and orange peel overnight, then put them all in coffee (spice) grinder
For 3D printers or for neighborhood nighttime pests Think security cameras with logging but hopefully smarter.
- https://github.com/ccrisan/motioneyeos/wiki
- Another solution is to stream to a local computer that runs all the time and scans for motion at the appropriate times
- IP Camera Pro, runs on android and lets you set rules and send emails
Probably want a raspberry pi for it?
Maybe want to combine / go along with octoprint and spaghetti detection / remote monitoring for 3d printer?
If your credit card or identity is stolen or you need a company to take action, it's subtle but useful to act like a professional lawyer. Kalzemeus
https://www.kalzumeus.com/2017/09/09/identity-theft-credit-reports/
Ohh, man...does anyone else want to do one of these .if someone is feeling artsy and creative and wanting to design a badge, I can help out with the design and electronics! https://hackaday.com/2019/09/19/pictorial-guide-to-the-unofficial-electronic-badges-of-def-con-27/
Diffuses LEDs (I think side lit or maybe backwards lit, not sure) with hot glue on back and substrate. https://youtu.be/rE-X1XRsXYE?t=109
- Hackaday on that one: https://hackaday.io/project/165320/components
- His defcon talk: https://www.youtube.com/watch?v=Sbkvza8cKQE
Effects of Printing Parameters on the Fatigue Behaviour of 3D-Printed ABS under Dynamic Thermo-Mechanical Loa ....
Want larger nozzle size and larger layer thickness, interesting.
But this other paper shows it as pretty similar strength, but not strain.
https://www.sculpteo.com/blog/2014/05/14/right-plastic-production-method-part-3/
I have philosophical notes elsewhere
Seems to be allowed, ish. As long as it's COTS and not reprogrammable, which it basically is to the students.
<RE13> Light Sources - Functional and/or decorative light sources (including LEDs) are allowed with the
following constraints:
a. Focused or directed light sources (for example: lasers and mirrors) are not allowed except for the REV
Robotics 2m Distance sensor (REV-31-1505).
b. Light-source control by compatible ports on the REV Expansion Hub or REV Control Hub is allowed.
c. Commercial Off the Shelf (COTS) interface modules (without user programmable microprocessors) are
allowed between the light source and the components listed in <RE13>b.
d. The only approved power sources for lights are as follows:
i. Internal (as supplied by the Commercial Off the Shelf manufacturer) battery pack or battery
holder.
34 | FIRST® Tech Challenge Game Manual Part 1 – Traditional Events
Revision 1.3: 12/1/2021
ii. REV Expansion Hub or REV Control Hub Motor-control ports, XT30 ports, 5V auxiliary power
ports, and I2C sensor ports.
Need band 66 for T-Mobile. I thought I wrote down these notes before...
For Geico safe driving app, reasons I wanted a different phone:
- No need to drain current phone (although might not be an issue)
- Can make recordings / calls while driving. But hmm...maybe I shouldn't be doing that in the first place!
- Don't have to mark trip as passenger of another car. Pretty easy to do though.
Maybe don't need one after all.
I've found cheap earbuds from monoprice + ear muffs work quite well. Just need to tweak the equalizer a bit sometimes, which is hard to do if your laptop doesn't support it?!
- You can install equalizers for Windows and Android. See bottom of this article: https://www.soundguys.com/how-to-equalize-fine-tune-your-listening-experience-16410/
However, it's nice to not have buds in your ear all day, and it's nice to have bluetooth. So thinking about a pair of headphones to try out. I like the Q30 because:
- I tried a bunch at Best Buy. Could tell equalizer differences, but not any real fidelity differences (although most were muffled, probably from overuse at the store?) 90% were comfortable, it's just some were 5X the price of others!
- Seems less chinsy
- Has app, allows equalizer customization
- Good reviews on things, including ANC.
- Only $80. Just get at Best Buy so it's local and easy to return.
- Just try one and return it if not liking it much.
Great mic. Over usb it's 44.1Khz, but on bluetooth it's limited to 16Khz >.<. Also if your USB C cable is at all loose, then a little bump can sever your headset call. Haha. >.<
After trying two expensive (induction + pressure) and cheap (3 zone or 1 zone heating) rice cookers from Zojirushi and Cuckoo along with a standard Hamilton Beach rice cooker, I've found a few things out:
- Measuring matters. Rice cup ~ 3/4 cup. I wasn't hardly measuring the water before, and it's probably important to get the right final texture of rice. Not too mushy.
- My original rice cooker worked the same as the others with proper measurement.
- "The best way to cook rice is all about the right ratio": https://www.youtube.com/watch?v=JOOSikanIlI. 1:1 ratio plus 1/4 to 1/2 cup for evaporation.
- There was a slight al dente with the fancier cookers with sushi rice, but:
- I couldn't replicate it with black rice
- I feel like with a little less water or time on the other cookers I could emulate the same thing.
- A thin pan mattered only when using the warm function. The one with heater on the bottom tended to make the bottom crispy on warm, but it might've just been because the thermostat was too high too.
It's a little annoying to only get two buttons (white rice / brown rice) on a normal rice cooker, but I can just set a timer too. If need more knobs, would recommend a cuckoo one.
Serious Eats article on rice cookers
MICOM = microcontroller
Why are there 3-4 different cuckoo cookers with the same features (pressure and induction) and same price point?!
Is 3 heating zones (bottom, sides, top) effectively the same as induction?
Buy a few used and return the ones you don't like!
I might like the more expensive pot style? (better nonstick surface)
One commenter said just pre-soaking the rice resulted in similar results with his normal cooker.
- How to wash rice by Zojirushi on YouTube. Quite in depth! https://www.youtube.com/watch?v=3k9ItS0QVTc
Jae's first reaction to pressure cooker version was "tasted like you had less water", the slight chewiness was a bug not a feature to him. However, I like it, which means I might be able to emulate it by just having a little less water so it stops cooking sooner.
https://www.youtube.com/watch?v=JOOSikanIlI
- 1:1 for rice, generally, but add 1/4 to 1/2 cup for evaporation.
- What about cooking time or temperature? Why let sit for 10-15 minutes afterwards?
http://www.wastenotfoodtaxi.org/volunteer.html over by Westview high school.
Fidelity Charitable is probably the cheapest way to do Donor-Advised Fund.
- Hesitant to do it, because Liberty High Robotics and Century Band probably aren't in GuideStar or whatever.
- Maybe give Fidelity Charitable a call?
- Be sure to take notes on basis.
However, why not just give double out of income this year? Cash flow...
- If doing this route, just use new credit card.
Trim edges without re-encoding.
ffmpeg -i in.mp4 -ss [start] -to [endtime] -c copy out.mp4
Audio with Moto G6 and headset works well, but audio is a bit noisy/crackly still.
Youtubers use Tascam and Marantz handheld recorders, but I've gotten great results (very low noise) with my dad's red usb capture box.
- Should be at least 60F for low bubbles and good cure. (bring it inside)
- Best debubbling with pressure pot. Can make with Harbor Freight paint pot
Stuff from the Shenzhen market (with a little bit of bargaining) is 1/2 off the Aliexpress price usually: https://shift.newco.co/2016/10/13/what-50-buys-you-at-huaqiangbei-the-worlds-most-fascinating-electronic-market/
The Hall sensor will outlast in an application where the switching events number in the millions. However, a simple static discharge will destroy it at once.
Specifically gaffers tape is nice.
Trying out P-665W Shurtape ($25/roll) (less pro looking) and Pro Gaff gaffers tape ($20/roll).
Duct tape is sticky for a while, but isn't great for the long term. Leaves residue and degrades fairly quickly.
https://hackaday.com/2017/04/27/stealing-cars-for-20-bucks/
What are some good people games?
https://www.mindblastgames.com/wits
("v neck belly shirt" from college)
https://drawphone.tannerkrewson.com/ is one online version of it.
- 120 seconds is good
- Max rounds
- Let player pick first word (really sentence)
A good intro: https://www.thegamegal.com/2011/06/18/paper-telephone/
- You want a detailed but interesting scene to start with. Just a word is boring
- Now everyone receives a paper with just a drawing visible, and everyone writes the sentence that presumably could have led to that picture (usually with some humor thrown in). For example, Bob, given the above picture, might write this sentence underneath: “Once there was a family of tree huggers.” Then everyone folds over their paper so only the last sentence is visible and passes the paper to the right.
Technically a trivia game, but quite well done, fun, and interactive.
Pictionary game online
3 random interesting facts about a few people. Then others guess who they correspond to? Forget how it was done exactly.
It's really only for life coaching stuff. But it was interesting. https://cameronfreeman.com/personal/confessions-cult-leader-lifestream-seminar-experience/confessions-cult-leader-day-lifestream-basic-seminar-5/
https://cameronfreeman.com/personal/confessions-cult-leader-lifestream-seminar-experience/
Want to:
- Know better what technical people are looking for in a presentation.
- Get honest immediate feedback on my presentation quality, determine how important it is to fix, and improve if necessary.
- Find out what I don't know! Tiffany seems to have some opinions on this.
Don't want to:
- Say lots about nothing that matters.
- Spend endless hours on improving the last 10% of speaking ability. I don't value it that much.
https://toastmasters.fandom.com/wiki/Table_Topics_Ideas
Describe modern inventions (and how people typically use them) to someone from long ago. Selfie stick, iphone, traffic light, I like objects that don't just solve problems that didn't exist 500 years ago, but solve problems caused by inventions that didn't exist 500 years ago. For example:
Traffic light Football helmet Bowling pin Selfie stick Lawnmower Outlet cover Exercise ball Cat tower DVD
Made to stick / memorable practice ideas
Had a great conversation with someone from Axiom electronics on this.
Current idea: Use a peltier cooler with a water block on both sides of it to have a hot and cold chamber. Then place the device in alternating cold and hot side with a robot, immersed in moving liquid. Maybe with basic conformal coating. Liquid will cool the device fastest. Use car coolant (-38C and 120C) as the medium, which allows wide temperature range without freezing.
- Will a peltier cooler go to higher temperature gradient? No, not normally. But you can stack them? Read into more.
- Potentially useful kit with clamps for both sides: JUULASEN DC12V Thermoelectric Electronic Peltier CPU Auxiliary Water Cooler Aluminum Refrigeration PC Chiller Kit
- "The temperature is not a problem as much as pumping power. Peltier devices can be stacked to pump on each other and get one side down to cryogenic temperatures with a triple stack (each smaller than the other). Each diode (they are a semiconductor diode) can reach as much as 40-50 degrees difference in temperature if there is little actual heat being pumped. One 2 inch cell will easily make ice from the air but 2 gallons will practically never freeze even with perfect insulation in a reasonable amount of time."
Cheaper/easier idea: Just do ice water and sous vide controlled water chambers.
Want thermal cycling (freezing?), salt fog (salt won't evaporate normally). Thinking of just having a module in the freezer.
Aquarium atomizer ultrasonic. $10 with tricky driver circuit. Nice.
Don't need fast cycling, but why not.
- Fan to the inside that cools the air
- Aluminum cpu liquid cooler heat exchanger to outside of container? Only turn on when need to cool it off and water is liquid. That'll be really fast. Can use atomizer too.
Have wider container and place styrofoam or something in there as a platform for electronics and limit the amount of water needed.
Nice paper: https://backend.orbit.dtu.dk/ws/portalfiles/portal/100370544/Corrosion_in_electronics.pdf
- Several different types of corrosion.
- Metals have different inherent "voltages" to them. Adding a conductor to water allows them to conduct and do electrolysis over time, amongst other stuff.
I'm not selling a submodule. I'm selling an entire thing. However, I don't need to test for intentional radiation since I'm using an ESP8266. Might need to test unintentional radiation though.
- However if used on a vehicle, then ok?
- More on testing from Hackaday: https://hackaday.com/2016/09/19/preparing-your-product-for-the-fcc/
- Checking out EMC For Product Designers
It's here somewhere. USB frequency spectrum analyzer. Would like to try it out and see if the led strips and stuff emit any FCC-annoying radiation. https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf
I think since the helmet project is exclusively on a vehicle, we're ok. However, should still look into it so it's not annoying.
(a) A digital device utilized exclusively in any transportation vehicle including motor vehicles and aircraft.
More information from Sparkfun: https://www.sparkfun.com/tutorials/398
Do I want a pneumatic foot switch, or a 12V or 120V electronic one that might wear out sooner, but allows for easy future automation of other projects (controlled by microcontroller).
Easier to swap where the pedal goes, right?
h:nn "WW"Wu.wi\n yyyy-mm-dd
A common cry is that when the government prints money or bails out companies (TARP https://en.wikipedia.org/wiki/Troubled_Asset_Relief_Program) is that the American people in general pay when hedge funds and whatnot still get their bonuses. Except... most Americans (50%) pay only 3% of the income taxes, and the top 1% pay 40% of it! Hmm...something smells fishy here. I might be wrong still though.
Scary sharp system. YouTube video I saw before: https://www.youtube.com/watch?v=eom0qu5YO94
$50 all in. Uses float glass.
Can test for salinity using multimeter. Or just have test plastics.
With a light amount of NaCl:
- Floats: HDPE (milk jugs), polypropylene (PP, yogurt container)
- Sinks: Styrene (clear packaging material, think Harbor Freight), PETG (3D printing material)
- Red Pocket (Verizon) is $2.50 / month, but limited calling minutes. https://www.ebay.com/itm/133196831828
- Moto E5 in Portland looks good, has case and screen protector. Call on Friday?
- If not, go with E6 in vancouver.
- Alcatel Go Flip 3 (has latest band 71). $50 new though, but maybe breaks easily?
- There's a tougher phone, Sonim XP3
https://www.comparecellular.com/coverage-maps/verizon-wireless-coverage-map/
- Then sub-select on the map itself to see other providers
Voicemail setup, just enter your phone number in the voicemail field instead of *86? https://help.ting.com/hc/en-us/community/posts/115009509208-Voice-mail-The-feature-code-is-not-valid-
Pin is their address #
SMBC comic. https://www.smbc-comics.com/comic/science-fictions
Share about our team, what we are doing.
Let them ask questions.
- Always have more material for the advanced folks. Don't want to make the job look basic (it isn't!)
- Leave time at the end for questions.
- No C++ for ipmctl.
- Null at end of string
https://replit.com/@nolanhergert/InterviewQs#main.c
Just talk about tradeoffs between linked lists and arrays? As a latency question
-
How do they think about clean and well-tested code? Do they think about edge cases?
-
Find the bugs in this code. Kind of like Kelly's question of string reversal I guess?
-
Can you describe a challenge you ran into with one of your projects? How did you overcome it?
-
What is const, what is static, etc.
Want to get good dispersion of light (can't see the light source) with a minimal of opaqueness/transmission.
There's plenty of sheets (Optix comes to mind, "white" HDPE sheets, etc) that seem to work well. But I'm preparing to do a roto-cast maybe and need the epoxy or plastic to have the pigment inside.
I think they need to be really small...
- Mica powder
- Microspheres, at least the ones made by Fasco
- Milk jugs (too transparent)
- White pigment drops / titanium dioxide. Working on getting the source from the Portland CNC group
- Really small microspheres, single-digit micron apparently. So...dust! How would I get the small ones out from the big ones efficiently? Static electricity?
- Slightly better to have non-spherical particles, but whatever. http://www.tech-p.com/english/product/development/biconvex.html
Need to mix it all evenly as well.
FYI, I did some more research into light diffusion. Looking at the MSDS, the pigment drops you are using are mostly titanium dioxide + rubbing alcohol. The mica powders end up being too large of particle size for me. I was able to confirm that I can buy a 4 oz container of titanium dioxide from the art store for $6-8 and get the same effect.
But, based on this video (https://youtu.be/-3qGltHW018?t=173), there's an even more advanced material, microspheres. But it requires the really small kind, single-digit micron, not the generic kind that doesn't get down that small (that I already bought). I finally found some suppliers that didn't have a crazy price for them on Alibaba (https://www.alibaba.com/product-detail/PMMA-light-diffusing-agent-PMMA-microsphere_62392420945.html). Haven't yet purchased them since it's probably a $50 minimum for just a sample, but I can let you know if I ever pull the trigger or pick some up. YouTube PyraSied Xtreme Acrylic Versato® Light Diffusers 2018 - PyraSied Xtreme Acrylic | www.pyras...
Kenneth fritzToday at 11:26 AM I looked into this a bit, I even looked at glass beads used for light reflectors but my understanding was the surface texture was so critical that putting them in resin would negate a lot of qualities I wanted Id be up for putting some money to split an order of some experimental stuff nhergertToday at 1:18 PM You bring up a good question, why are microspheres ideal when at a larger size they are retroreflective? I assume they are retroreflective when they are small too. Maybe that is the ideal property, I just don't understand why yet.
Surface texture meaning perfectly smooth? Resin shouldn't change that. Maybe they are a similar refractive index to resin so they just look clear and light doesn't behave differently. Need to be spheres exposed to air or something.
This looks like a good article outlining various important points. https://www.ledsmagazine.com/leds-ssl-design/article/16695585/plastic-light-diffusion-systems-match-led-lighting-needs-part-2-magazine
- larger relative RI (they say reflective index, but I think they mean refractive index) means better diffusion
- Ideal particle size is 2-3 um
- Still doesn't explain why spherical shape though. Some counter-examples:
- Bi-convex lenses are better apparently: http://www.tech-p.com/english/product/development/biconvex.html
- Making a specialized lens with holography (no clue how) is probably an even better result: https://www.luminitco.com/products/light-shaping-diffusers
I kinda like the look/feel of this one better. https://squidfunk.github.io/mkdocs-material/getting-started/
Apparently supports Github pages too?
Root issue is tartar buildup. Main folks recommend a treatment of vinegar.
Put cleaning solution into a glass jar or ziploc bag (plastic jar is not quite as effective, is able to move), fully fill up the bin with clean water, and use various cleaners. For really persistent stuff, a guy recommends gasoline. https://www.youtube.com/watch?v=jeBB-J0fOp4
You want as many people to get vaccines as possible (or isolate) so that those who vaccines aren't effective have a much lower chance of getting the disease. Therefore anti-vaccination folks put more people at risk. https://www.vaccines.gov/basics/work/protection