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Tinker Tuesday for May 13, 2025

This thread is for anyone working on personal projects to share their progress, and hold themselves somewhat accountable to a group of peers.

Post your project, your progress from last week, and what you hope to accomplish this week.

If you want to be pinged with a reminder asking about your project, let me know, and I'll harass you each week until you cancel the service

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So, as mentioned in previous weeks, I've been trying to TRONify my cargo bike and kids' bike helmets the last few weeks and I've never quite appreciated how much of small electronics work is shopping in general and specifically, shopping for plastic pieces of shit. This isn't what I thought I would struggle with. I'm a fairly skilled dev so I thought I would struggle with EE concepts or the dexterity required for soldering or even simply being able to work with a magnifying glass but no, shopping, which I find borderline triggering due to hatred of clutter, is the actual limiting factor for me.

And shopping for an enclosure for housing all of this junk is the challenge. For the bikes themselves I can use standard Hammond plastic enclosures and consumer battery packs, but for bike helmets all of the standard stuff adds way, way too much bulk.

The rough sketch of components I need housed are

  1. ESP32 board, mounted to a perfboard
  2. a boost converter to bring the 3.7v put out by the 18650 cell up to 12v for LED lights
  3. a buck converter to bring 12v down to 5.5 for the ESP32 board
  4. a charging board with USB-C[1]
  5. an SPST(?) switch for physically breaking the connection from the battery to everything else
  6. an N-channel MOSFET for controlling COB LEDs (if I supplement the WS2815s)
  7. a P-channel MOSFET for having the rest of the load shut off if it detects that a USB charger is connected
  8. nylon standoffs for the various boards
  9. a holder/receptacle for the 18650 battery itself

Finding an enclosure that isn't as bulky as shit for this seems impossible, so I'll probably have to 3d print something. Which means I need a 3d printer[2]. From my time being involved with a local Makerspace, my opinion of 3d printers is that they spend most of their time being broken, but I've heard from trusted advisors that that's because my experience has been with 3d printers made by the decadent and pathetic Western concerns and that the Bambu 3d printers from China have changed everything[3]

So... maybe that's my next purchase. Perhaps I can justify the 3d printer as some kind of educational value for the kids.

Does my experience here sound right so far? Small electronics success often hinges on shopping skill?

Notes

  1. I do see combination boost converter/USB chargers for 18650 cells, and that would cut down on complexity/bulk/work, but their amperage is much too low to run LED strips off of so I'm stuck buying individual components for this.

  2. Though I think if I want a really cool looking transparent enclosure so we can see circuit boards and blinken lights I'll need acrylic covers? Which requires getting a laser cutter too? I wonder what educational value for kids these have...

  3. So long as you have no opsec concerns from running proprietary firmware that requires a cloud connection to do anything from a nation state that we might go to war with in the near future. Though I'd be kind of amused to see the worst that can happen.


Switching gears (ha), but to avoid making another post, I'll consolidate into this one.

Aliexpress.com has incredible deals but takes forever, so that stalls my TRON helmet project out.

So, in the meantime, I've gotten to triangle dodge charger skydome in my 3d game (pic attached) that was inspired by binge watching the Fast and the Furious series while feverish. I made some generic cyberspace background while waiting for the right time to take a 360 panorama pic of a skyline in my town.

I fixed the texture banding issue. The camera now follows the car. The car can steer and accelerate. It runs okay on my hardware. So... I guess the next priority is to make a race track and add some collision detection to this bitch? A computer controlled car to drive against? Maybe incorporate some engine revving sounds?

I suppose a true Ride or Die Homies game needs something more inspired than a race track though. Like outrunning a nuclear explosion. Or battling a mechanized raptor.

I should be doing this smart and using Unreal Engine or something, instead of writing a 3d engine from scratch, but I got into computers in the first place because I wanted to write a 3d engine (before getting distracted by the world of Linux and networking), so coming back to this feels like addressing some unresolved spiritual concerns.

On the power side, I'd at least consider 3S LiPo battery pack, running the LEDs from that voltage, and just using one buck converter for ESP32 (which can be a tiny 5 watt one). That's only a nominal "12v", and really a 10ish-12.6 range, so you'll want to double-check the datasheet for your specific LEDs, but it's well within spec for the WS2815s. You can get 3S 18650 chargers cheap (eg here, not endorsed), though premade packs are so widely available (and tend to have much better low-current protection) that it's hard to justify building your own packs unless you need 5+ amp.

While series is generally pretty safe, never use LiPo in parallel until you have a very good familiarity with the technology and necessary safety precautions. Further instruction on that matter not available here.

On the circuit design work, yeah, part control is a Problem. As you get more experience you'll start to collect a bunch of standard parts and design with them around whatever your target is, and only need to order a handful of specialized things, but on the path there you'll end up with literally thousands of bags of stupid little components that are worth fractions of a penny and you'll never use again. And even once you have your 'jellybean' parts together, you'll always need something specific to a given project, or find that your old parts aren't available anymore, yada yada. Breaking projects into modules can help, but then you're juggling them, too.

There are some "MakerSpace Starter Kits" (and a much broader number of order lists) for component-level parts, but as you go from components to prebuilt boards they tend to get a more 'cheap plastic toy rather than tool' problems. There used to be some good lists of common sensor boards for educational uses that I'd cribbed from, but SnapCircuits and Cubelets et all have kinda cut the bottom out from that market; nowadays, you're probably better off just spending a birthday at a Microcenter or on Adafruit.

For 3d printers, yes, for FDM the entry-level ones (eg Ender3s) tend to be glorified junk that will need maintenance within days, if not hours, and owning them is an exercise in modification and repair. This can be a great educational experience, but it's also a lot of ship of thesus for a tool. You can pay a bit more and get a professional- or educator- grade one that can go hundreds of hours without as much work or a lot more and get an industrial-grade one that gets thousands of hours before serious repairs (eg, GenFabCo), but unless you want to Be The 3d Printing Guy, it's hard to justify the cost of either.

For small parts, resin printers are another option. They're still fiddly, because support material is even less of a solved problem, but they don't so much have maintenance schedules so much as they just have parts you replace, and even the absolute cheapo ones (eg Elego) tend to work just as a 'replace screen and bulb every few hundred hours' sorta thing. They don't scale well beyond about six-eight inch size parts, though, and they're very much not things to be used without proper ventilation.

If you're only needing a handful and had little or no interest in 3d printing, seriously consider various fabrication services, or local marker spaces (or some libraries), rather than buying a full 3d printer.

Laser cutters are ... iffy as a value proposition; they're extremely limited in both what they can cut or etch (some woods, acrylic, anodized coatings), and also how (both depth and angle). The big value proposition to a comparable CNC is ease of use and operating costs, but this is a very rough tradeoff. I'm very hesitant to recommend them for any structural component, just because anything capable of cutting deep enough into transparent plastic to make a useful part is going to be ludicrously expensive.

For flexible, light-weight, shaped transparent pieces with little 3d complexity, my go-to has been vacuum-forming. Big ones get surprisingly complicated fast, but for anything under a couple feet square you can get away with stuff you probably have in your house, and the big trouble becomes sourcing the right types of plastic.

I'd also recommend considering Traditional Manufacturing -- just as there's a lot of people 3d printing what could be made with a handsaw in ten seconds, you may well be engineering something that could be sewn together in a good half-hour. If you want something flexible and comfortable for long-term wear, sewing is kinda the way to go. You'll still want some boxes for the batteries and protoboards to provide impact resistance, but it'll give a lot more space to consider multiple small project boxes or such, and those are a lot easier to source.