Some ideas:
starting from experience
That does work better, I think!
That would be funny, although I think it may have been closed down and converted to some other purpose. It was a vast concrete sarcophagus of a building. No windows or proper heating. Weird cardboard dividers for walls, so all classrooms could hear all nearby classrooms. Bizarre skywells on the upper floors with no cages or guard rails.
It was really a building suitable for any purpose except a school :D
Haha, yeah...
I did the classic overachiever route and finished my thesis pretty fast, focused on a specific career. Then still ended up with a shitty full-time job, so took on three more jobs and started a nonprofit. All that still got me exactly nowhere. I was ridiculously stressed. One time I didn't sleep for 3 days and had to check in to the hospital.
Hopefully this offers some comfort. The things you consider mistakes, are the things I wish I had done. Even spending more time with my parents. So perhaps nothing is so serious :)
My "nuclear option" was immigration. I sold everything and (just barely) got a business license in the developing world. I'm basically Ozymandias from watchmen, but less fit and I don't own tights. Also none of my friends are blue. Splicing genes and splitting atoms, I will admit to though.
Anyway the point is, what matters is what happens next. I don't recommend immigrating to the developing world (it's acutely distressing), but it's surprising how much we can influence the outcomes of our lives if we radically commit to a course of action. If the exact details of your course of action aren't optimal (or even borderline insane), I think that's OK, it's being radically committed to improving your future that matters. The context isn't exactly irrelevant, but I think it's secondary.
So no need to stress. Better to spend that energy doing. Anything reasonable will do. Start a side hustle, learn programming, design websites, learn to do taxes for yourself and others. Degrees are OK but I don't value them any more personally. Get used to starting at square one over and over -- it's a good habit and you will eventually know how to do many things. People who can do many things are rare and valuable.
Not exactly! I just sort of take finely chopped apples (for pectin), onions, mango, and dried raisins or dried apricots. Then I boil, adding (a little) vinegar over time until it looks like chunky jam. Then I flavor it with soup stock and cinnamon to taste. Some nutmeg too, if you like. Finally I adjust acidity and sweetness with more vinegar or some sugar -- but that's usually not necessary if I add things in slowly.
If it's too acidic, boil it longer, adding a little water if it gets dry. Vinegar (acetic acid) is a gas and will evaporate out slowly this way.
Mix frequently.
I save them up all year, and come Christmas / Lunar New Year, I bake cookies then hand out jars filled with cookies to coworkers and neighbors.
It turns out that my wife and I consume exactly enough jam in a year to balance out the jar egress for the maximum number of social connections we can sustain.
If I have a spare, I might make mango chutney. It doesn't need to be vacuum sealed if you just make one jar and eat it reasonably soon.
I suppose you could engineer them to be solar garden lights too. There ought to be enough room for the panel on top of the lid, a battery and circuit on the underside, and then you hang an LED in there.
Just another day running a business in the developing world, haha. You win some, you lose some :)
The only videos that YouTube manages to convince me to watch are by clickspring. So satisfying to watch metal being machined, and much to learn too.
Yup, I do the same -- although my remote desktop is just SSH, so even truly ancient stuff is completely fine. I've been looking at getting a portable terminal as an alternative to even a laptop, which is a bit of a pain to lug around if I'm on vacation.
This technique failed disastrously one time though. A billing dispute between the person renting me office space and the building owner meant my AI workstation got seized for a year once. That was a real pain -- I never expected to see it again. Thankfully it did return to my possession. Eventually.
I've always thought that learning the native language of a developing country would be a huge asset. Very few people do so, and outsourcing has a huge cost differential, so it opens up unusual career moves to capture that growth.
Hilariously, 12 year old me suggested this on the "what 3rd language would you like to learn" form in high school and somehow got in trouble for it. I guess they thought I was joking. Perhaps the joke was on them though, I immigrated to Vietnam and own a (small) tech company now.
Free computer operating systems are great these days.
I regularly spend hours designing electronics to be cheaper. Not worse -- just cheaper. Electronic components sometimes vary in price by two orders of magnitude for the same performance, so it's worth cramming datasheets in your head as a professional or hobbyist.
For tools, I've found good midrange Chinese brands, and stuck to them. I could never afford things like Tektronix and so on.
I don't strictly require clothing to be cheap, but I do require it to be fungible -- this works out similarly though. When I find something that's good value for money and looks good, I buy a bunch and rotate them. That way I don't have to think about what to wear, and it always looks decent.
I also prefer cheap laptops. I don't need a supercomputer to work. When I do need a supercomputer, I rent one from google cloud for a few dollars an hour.
Disclaimer: this is not specifically for a commercial product, but various things I design sometimes get commercialized. I mention this so that you may decide whether you want to weigh in. If it's commercialized, I will probably make very little money but a bunch of university students may get a neat STEM program in the countryside :D
That out of the way, I've designed some boards for a Wi-Fi controlled robot with mechanum wheels. So 4 independent motor drivers, one for each wheel, allow omnidirectional motion. It's built around a Pi Pico W, 4 SOIC-8 9110S motor drivers, and some buck/boost converters to give the system a 5V and 12V line. It's very basic, mostly made to be cheap. Here's a photo:
Right now it just receives UDP communications (a little app written in Godot) and activates the motors in different combinations -- very "hello world". I'm planning to add some autonomy to move around pre-generated maps, solve mazes, and so on.
I have foolishly used 2-pin JST connectors for the motors, so using motors with rotary encoders would be a pain without ordering new boards. I'll probably fix that in a later board revision or just hack it in. Also the routing is sloppy and there's no ground plane. It works well enough for development and testing though :D
What I'm thinking about right now, is how to let the robot position itself in a room effectively and cheaply. I was thinking of adding either a full LiDAR or building a limited LiDAR out of a servo motor and two cheap laser ToF sensors -- e.g. one pointed forward, the other back, and I can sweep it 90 degrees. Since the LiDAR does not need to be fast or continuously sweep, I am leaning toward the latter approach.
Then the processing is handled remotely -- a server requests that the robot do a LiDAR sweep, the robot sends a minimal point cloud back to the server, which estimates the robot's current location and sends back some instructions to move in a direction for some distance -- probably this is where the lack of rotary encoders is going to hurt, but for now I'm planning on just pointing the forward laser ToF sensor towards a target and give the instruction "turn or move forward at static speed X until the sensor reads Y", which should be pretty easy for the MCU To handle.
I'm planning to control multiple robots from the same server. The robots don't need to be super fast.
What I'm currently wondering is whether my approach really needs rotary encoders in practice -- I've heard that mechanum wheels have high enough mechanical slippage that they end up inaccurate, and designers often add another set of unpowered wheels for position tracking anyway. I don't want to add more wheels in this way though.
On the other hand, it would probably be easier to tell the MCU to "move forward X rotary encoder pulses at a velocity defined by Y pulses per second, and then check position and correct at a lower speed" than to use a pure LiDAR approach (e.g. even if rotary encoders don't give me accurate position, on small time scales, they give me good feedback to control speed). I could possibly even send a fairly complex series of instructions in one go, making the communications efficient enough to eliminate a local server and control a ton of robots from a cloud VPS or whatever.
Anyone have some experience with encoders + mechanum wheels that can offer a few tips my way? At this stage the project doesn't have clear engineering goals and this is mostly an academic exercise. I've read that using a rigid chassis and minimizing the need for lateral motion can reduce slippage, reading through a few papers didn't get me any numerical indication of what to expect.
You those software projects that have no defined scope, budget, or timeline? Yet somehow land on your desk?
For those times, I built a Lemmy bot that does an I Ching divination (https://en.wikibooks.org/wiki/I_Ching) using a hardware random number generator.
It doesn't help, but it makes me feel better.
If it would make you feel better too, you can use it too by sending a DM to @kong_ming@voltage.vn.
The message can't be length zero. You should not consider the messaging secure :D
It also may break, bug out, catch on fire, get unplugged, or get overloaded with requests. If none of those things happen, you'll get a response in a couple of minutes.
It's also literally build from scrap, and is sitting precariously on the edge of my desk in Vietnam. Still, it's the state-of-the-art in software consulting!
So I wanted to design a children's toy, where the electronics could last 100 years (ignoring mechanical abuse). I figured some people here might be interested.
I settled on a CR2032-powered night light, using an attiny10 microcontroller, where the flash is rated for 100 years unless you're writing to it (which I am not). I did some pretty heavy power optimization. The firmware is hand-optimized assembly.
When you turn it upside-down, a tilt switch toggles an LED @ 3mA via a pretty intense debouncing routine.
A watchdog timer has it auto power off in 30 minutes.
When off, it consumes less than 1 uA. So it has about 25 years of standby time, although the battery is only rated for 10 years (it is replaceable though).
If a child uses it every day, then the battery should last about 4.5 months.
I made custom boards for it -- I kept is simple with few components as possible (resistor is for scale):
I kept assembly simple. A better design would snap right in to the pins of the CR2032 holder, but that's an addition I'll make another day. I also should have added one more ground pad to solder to, but forgot. Still, an OK result I think.
I used some spay-on lacquer to protect the traces a bit after assembly.
What I've done is take a large 2n3055 BJT NPN power transistor, and decap it (it is a large metal-can type). Then I carefully removed any coating from the exposed silicon (it typically has a dab of silicone potting compound on it).
Then, I had a weak alpha source at ~5MeV lying around the lab from previous work. This was inserted into the can with the beam facing downward towards the exposed silicon, and the can reattached and made lightproof.
Then I threw together the circuit shown here using the modified transistor (the base is left floating). What I expected to happen was that at TP1 (relative to GND), with my scope AC-coupled, I should see small voltage spikes followed by a decay. This is caused by alpha particles impacting the silicon and knocking loose enough electrons to permit some current flow.
However, I just see... more or less nothing, maybe some electrical noise from fluorescent lamps in the room next door. Certainly not the spike+decay curve I've seen with other detectors.
Did I make a wrong assumption somewhere? It's been a while since I worked with discrete transistors much, and I feel like I am missing something silly.
Or is this more or less right, and I should maybe question whether my alpha source is still good? Or whether the signal strength is in a voltage domain I can even clearly see without amplification? Or maybe I should suspect that a thin passivating glass layer is added to big BJTs these days, enough to block the alpha?
The source is past expiry, but not by that much. I'm mostly interested in characterizing and documenting the detector as an academic exercise.
I'm sure someone was complying maliciously here, but I'm not sure who.
Everything in the store was on 'sale'. What they do is mark up the price, then discount it back to the normal price. For every single item in the store. So there are hundreds of these little printed standee signs everywhere next to each little thing.
Looks like management forgot to define a markup+discount to an item, and a programmer and/or sales staff just abided by the ridiculous 'everything must be on (fake) sale' directive.
This is sometimes my example for 'why paying attention to documentation is important'. I didn't take the photo myself, a colleague sent it to me years back.
I only occasionally see that here in Asia. It exists, but I feel like it's much less. I immigrated here maybe 12 years ago from the West. The overall level of violence is much lower than I grew up with (even in Canada).
Most young people I know consider handling guns more of a chore. In Vietnam, learning to disassemble, clean, maintain, and reassemble an AK-47 is a mandatory class. My wife got top score :)
Anyway, we stumbled on a great way to make guns uncool, I think. Personal possession is illegal here except for shotguns, it's for some very specific scenario that I don't exactly recall. I knew of some remote workplaces with one, in case of wild animals. We get some, but not many, illegal firearms.