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esaj last won the day on July 12

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About esaj

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  1. Interesting New Inventions

    Here's an interesting old invention: HZ-1 Aerocycle In 1954 the U.S Army decided that walking into battle is for poor commie suckers, and that U.S infantryman should have the privilege of flying into the frontline, thus traversing minefields, rivers etc with ease. The HZ-1 Aerocycle was the horrifying response to this bizarre request from the Army. This combination of a helicopter and a pogo-stick guaranteed amputation when one realizes the pilot stood about three inches above the totally exposed rotor blades. Engine control was provided through a motorbike-style handgrip, and movement was controlled by the pilot’s leaning movement. Imagine trying to control a helicopter like a Segway, but without any digital stabilization or fly-by-wire systems, because it’s the 1950s. The U.S Army Transportation Museum stated, “it’s determined that the craft was much more difficult to fly than had been expected.” Well, no shit. In addition, the two rotors would smash into each other at high speeds, rendering the HZ-1 useless even in the hands of highly trained pilots. The program was cancelled in 1957. Morons responsible for coming up with this idea of a lethal hoverboard were given slaps to the face. From "A few of the shittiest aircraft designs throughout history" : https://imgur.com/gallery/KKHtD
  2. There's a schematic there, just a matter of getting the parts & building the circuit Ok, slight modifications (changing some values) for the higher voltage is necessary. A friend with some electronics knowledge, local hacklab or similar could likely help you make one if you really want it, and the components aren't even expensive, the most expensive parts are the 100W LEDs, but even those aren't much if you order from Aliexpress/eBay/Amazon. "Gray market" 100W LEDs might be slightly off-spec/overrated by the power, but it's not like they have to burn for a long while at a time, so even if they're lower wattage they likely would still work for the intended purpose. I did consider building one of the choppers, but never got around to it (have the parts though). Would be kinda hard to test, as I don't have a power supply that could go into high enough voltages. Anybody got an adjustable 100+V/few hundred watt 19" rack-mount PSU for sale?
  3. How much do you spend to maintain your Addiction?

    Close, but I bet @EUC Extreme goes beyond that, both in amount of wheels per year and cost... I don't remember if he has posted the amounts in the forums or just mentioned them in private message, so I won't disclose them, but suffice to say that he had plotted down more than that already back in 2015 or maybe early 2016 and at least had quite a collection of wheels & equipment... Not that it's a race, and I couldn't afford to drop 13k into wheels
  4. KS16S overvoltage and vibrations?

    That sucks, luckily never had any issues with the S myself (so far, knock on wood)... If they find out what's causing it, I'd be curious to know.
  5. M Super V2

    I don't think MSuper V2 works with iPhone (at all), but could be wrong... MSuper V2 uses the older Bluetooth 2 protocol/chips, whereas the newer wheels use Bluetooth 4 ("LE" or Low Energy), and I'm not sure if (at least newer) iPhones allow connecting to BT 2.0 devices at all. At least the LE protocol stack is completely different from what was used with BT 2.
  6. How much do you spend to maintain your Addiction?

    In the ballpark of 4500+€ (roughly $5400) for 4 wheels + spare/custom parts, accessories and safety gear, but about 1/4th of that went into a failed custom-battery project... What can I say, it's an expensive country, and at the time I wasn't aware of 1RadWerkstatt's existence. Almost all of my trips are just recreational, sometimes in the summer I actually wish I didn't have remote work so I'd have a good reason to go riding to work and back I don't want to calculate the cost per kilometer, because that would be just depressing The "funny" thing is that I didn't even have a working wheel last summer (2016 I mean), and this summer we (again) had pretty lousy weather. Getting kinda cold to ride again, but I did go pick up some packages and then came back the "scenic route" today, wearing long johns & thin gloves under the wrist protectors, +8 Celsius, dark and slight rain outside
  7. 3D Printer

    Kapton might work, also some people apply glue (from a glue-stick, not liquid)... Based on other people's experiences, the PEI-sheet should work pretty well, and be much less of a hassle, as all the maintenance it should require is wipe down with IPA to get rid of fingerprints or other crap on the surface. Fine so far, just the first couple of weeks have been pretty demanding, I wasn't expecting that we have to decide on a project so soon and get the design underway that fast. The actual lectures so far have been mostly about general IoT-stuff, so not that interesting for me, but at least I've gotten to pester the teachers with stupid questions about hardware. And ordered parts on the school's tab worth almost the equivalent of what I'm paying for the course The actual project we (hastily) decided upon might be a bit "too much", but we'll see. At least it should be theoretically possible, but there are certain parts that I don't know for sure until I get the components and can make measurements, namely IR-distance measurement between robots for group behavior, while there are lots and lots of IR-distance -sensors, they all work differently than what we had in mind. We're actually measuring the IR-light between one robot lighting an IR-led and the other one measuring the intensity and knowing the direction from where it came (using multiple sensors around the robot chassis perimeter), and which robot was sending it (the sending & receiving of IR-light between robots is synchronized over separate radio-communication, so they take "turns" in lighting up and reading the intensity), they can form a (crude) understanding of their relative placement to each other, and act as a group. Mostly the problems come down to how much power we need to use for the light to carry far enough, as we're using wide-angle lenses (cost & building issues, can't line tens of LED/photodiode or phototransistor -pairs per robot) and the signal might be too weak or get lost in ambient IR-"noise" over further distance. If it's unreadable less than a half a meter away, we might have to come up with a new plan.
  8. 3D Printer

    Just took a quick photo, but there's really not much to see: The whole thing's encased with plexiglass & an Ikea-table sitting on top of a rotating "pedestal", and the spool sits on top of the casing, feeding through a teflon-tube on the "ceiling". I still haven't figured where to place it in the end, right now it's just filling up the guest bedroom along with my wheels and other stuff... hope that no-one's going to come visit anytime soon Blue painter's tape is used for adhesion for now, I've got a PEI-sheet ( http://reprap.org/wiki/PEI_build_surface ) coming, hopefully that will make working with ABS more easier. There's a heated bed there, but even with that, so far anything I've tried with ABS has failed, usually the base layer doesn't stick and/or the print starts to warp. Not that I've had much time to try things since the first weekend, since I've been pretty swamped with work & school stuff since... A picture of the few prints I made on the first weekend: The smaller ones are earrings, the larger part is a servo-arm. All are made with PLA.
  9. 3D Printer

    Oh yeah, I actually got a 3d-printer... about 20 hours after posting my message on this thread. I pestered my cousin about his experience with his printer, and ended up owning it the next day It's a typical RepRap Prusa -clone, with some additions made later on (like extra fan at the extruder, motor heatsink, some parts to make it more sturdier and housing for the entire thing to keep temperature more even etc). Or more like, was made the new owner, he first asked me if I'd be interested in buying it, and then before I even had said yes or no, he said "either way, I'm bringing it over now". So, now I have a 3D-printer, although I haven't had much time to play around with it since I got it. Getting good quality prints has so far been a bit of a hit and miss, sometimes they come out ok, sometimes everything goes to hell, usually from the very start... ABS seems a lot harder to get right than PLA, also got a spool of PETT, but haven't even tried with it yet. Already got the nozzle so jammed once that I had to take the extruder apart to clean it.
  10. Has anybody Heard of this?

    I'm always a bit sceptical when it comes to claiming "big numbers", but the batteries could actually be pouch-LiPos instead of cylindrical cells (like 18650's or others), that would make it possible to drop the weight (no metal casings) and size (no "empty" space between cells) of the packs, and they can give out far higher sustained amps and take fast charging better (way above 1C), apparently due to much lower internal resistance vs. cylindrical cells. Downside is that they're also far more dangerous than cylindrical cells Vee/EUC Extreme has been using LiPo-pouches in his custom wheels for a couple of years, and showed his chargers pumping several kilowatts into them during charging This video is over 2 years old (June 2015, charging 370Wh packs at half power, 30A per 8S pack): Well, you probably won't get much out of the video as it's in Finnish... as for the battery output, suffice to say that his custom packs have had enough power to vaporize mosfet legs in the past
  11. Headache

    Just a heads up, I'm (still) not dead, just haven't had much time... last few weeks have taken their toll, I've got a shiny new project at work (on top of earlier ones), and started the embedded course at the uni of applied sciences. Unfortunately, the start of the course has been a bit rocky, as we were required to come up with a project plan on the first week, and make up component lists by the end of second week (at least if we want the school to pay for some of the components), and with the new work project, I ended up doing 52-hour workweek on the first week to get things rolling, and then reading through datasheets, taking best guesses at schedules and how stuff should work, designing hardware (first time I've had to deal with calculations of designing a switching power supply, btw), picking components and writing parts of a report detailing the course project for the rest of the time, sleeping a few hours per night. It's probably too ambitious (kinda like swarm robotics, with 5 robots to build from scratch) and my project partner really isn't that experienced with electronics or programming (but otherwise well versed in natural sciences, I'm sure he could walk over me in maths and physics anytime and seems to catch up on things fast ). So, lately I've mostly been either working at work stuff or the course project or sleeping. Throw in a couple of days on the weekends where I wasn't able to do much anything but lay on the couch and stare at the ceiling Last night I slept 15 hours straight just to catch up on my sleep deprivation (2.5 hours on the night prior, the course lectures are during early Friday mornings and I head to the office straight from there for a full work day afterwards, it's been like that for the past 2-3 weeks), and it's likely going to continue on the same route for a while still. But I guess the "worst" is over now, as there aren't any that tight deadlines at least for a while. I'm so far behind on following what's been going on at the forums, that I'll likely never catch up with everything, as I still have lots of unread posts going back to something like early August, if not older. We'd "need" a newsletter that sums up bigger stuff, but I doubt anyone's willing to do that, I have no idea what's going in Gotway / KS / Ninebot -space, just glimpsed that Austin Marhold has announced a new wheel, which I guess is the current big thing...
  12. Power beeps while power breaking

    There's some interesting background info on plugging-type here (if the wheels actually use battery power for braking, my best guess is that plugging would be used): https://electronics.stackexchange.com/questions/264252/non-regenerative-braking-on-a-pmsm-bldc-motor For those who don't want to read it: basically it says that (at least in most cases) the majority of the energy is burned off as heat in the motor windings.
  13. Power beeps while power breaking

    At least mostly the braking seems to be the regenerative kind, and the 80% power alarm could be triggered by high current flowing in reverse (based simply on the assumption that the 80% power warning works only by measuring the amount of current flowing, not the direction). There are other types of braking, like dynamic/rheostatic (causing the current produced by the motor back-EMF to flow through some resistance, which might be resistors or the low-side mosfets partially conducting), but I doubt that is used in the wheels as there are no large braking resistors and the mosfets would likely overheat. So-called "plugging" type braking uses the battery (or other power source) by reversing it over the motor (so kind of like trying to run it in reverse), which maybe could be used in (some) wheels. The problem with that one is that it heats up the motor windings a lot, as that's where the power of the motor back-EMF + power applied from the battery/power source is wasted and could even melt/burn them if applied for a bit longer while. So far, I don't think anyone has shown any conclusive proof that wheels do have plugging-type braking, I think the assumption is mostly based on some app logs, where it at least sometimes seems that the speed is dropping while the current is actually running from battery to motor. But that could also just be a misconclusion, like actually riding up a hill, where the motor is using power, but the speed drops because not enough torque to keep constant speed/accelerate is provided... it's all guesswork The manufacturers/firmware programmers probably know, but I doubt they're willing to share their code or intimate details about the motor drives.
  14. Aw Man I Hate Youtube.

    I've played around with the idea of building one of these, but this thing is on a danger-level of its own:
  15. 3D Printer

    I've slowly warmed up to the idea of a 3D-printer, but it's really hard to tell what's good and what's not, as there's a gazillion of those nowadays (most are Prusa i3-clones though, at least I think). So far I've dismissed the deltas, as I somehow doubt they stay in "tune" for a long time and might require lots of tweaking, but could be wrong. One interesting piece I saw was Flsun Cube, not that expensive at around 300€ (with free shipping from Europe): https://www.aliexpress.com/item/Flsun-Cube-3d-Printer-Metal-Frame-Large-Printing-Size-Diy-3-D-Printer-Kit-Auto-leveling/32825217668.html Compared to most, the working area is pretty large (260*260*350mm) and it uses two motors to move the bed up and down, not the print head. Unfortunately, although the "cube" is made from aluminum extrusions, the frame's not entirely made from metal (the motors are attached with plastic parts ) Thoughts? Or should I look further into the Prusa-clones or delta-builds? I'm thinking single extruder, I guess either bowden or direct is ok, sturdy metal frame, at least something like 150x150x150mm working area, preferably more, automatic leveling, and heated bed for about 300€ max. Oh, and shipping from within EU, usually the shipping + customs + VAT makes the direct from China -options too costly in the end. There are some models with aluminum extrusion-frame, like this one (I think this clones yet another one, the name had something spider-like in it), but the bed mechanism doesn't look too sturdy to my eye (I'd prefer it would have shafts on both sides instead): Yet another one was a Prusa-clone with metal frame, the bed mechanism looks better, but the frame's not made from aluminum extrusions, looks like few mm steel sheets or something, not sure how sturdy that is in the end: The picture's of a dual extruder, but there's single extruder -model also. Might be that my budget is too low for anything really worthwhile...