#qi-hardware IRC log for Tuesday, 2018-01-30

wpwrakpaul: a bit of soldering goes a long way with that kind of things :)04:47
DocScrutinizer05diarything: a mechanical switch has two properties limiting the current it can cope with: the R_on resistance formed by the contact points and leads, which is in the range of milliohms and must not cause a significant warming of the switch. The second factor is electric arcing when opening the switch which will cause immediate destruction when the switch can't stop it. Usually a switch can handle significantly more current while 11:45
DocScrutinizer05closed than when/during opening it. The ratio however is usually undefined, I'd not assume more than factor 10 or max factor 2011:45
DocScrutinizer055/80 sounds like factor 15 and thus makes sense to me11:47
erichvk_DC vs AC11:47
DocScrutinizer0516* sorry11:47
DocScrutinizer05DC vs AC is *somewhat* related but not factor 2011:48
DocScrutinizer055/80 might be voltage rating DC/AC11:49
DocScrutinizer05to stop/extinguish the arc, the current and thus the voltage must drop under a certain amount for a certain time11:50
DocScrutinizer05if that 5/80 rating is actually not explicitly Ampere, it probably means voltage needs to drop below 5V for that switch to extinguish arc, and for a 80V 50Hz sine wave the duration the voltage is below 5V around zero crossing is long enough to achieve same effect11:52
DocScrutinizer05to make long story short and correct my blabla of above: the current rating of a mech switch is determined by R_on while the arcing determines the max *voltage* (which obviously differs between AC and DC, for the reasons I just explained)11:57
DocScrutinizer05you can't use a miniature switch rated at a few ampere to run a load across it that eats dozens of ampere. You might want to add a MOSFET, some of those can handle up to a 1000A in an incredibly small formfactor12:01
DocScrutinizer05I still fail to understand completely the >>reset bms for lipo battery by disconecting battery cus my lipo charger does not like having the main battery wire being disconnected. it refuses to charge the battery but the bms needs to be charged to reset!<< description12:08
DocScrutinizer05diarything: https://www.digikey.com/products/en/discrete-semiconductor-products/transistors-fets-mosfets-single/278?k=&pkeyword=&pv608=1442&pv608=2225&pv608=2288&pv608=2401&pv608=1931&pv608=1560&pv608=2947&pv608=2476&pv608=3152&pv608=2683&pv608=3334&pv608=2173&pv608=1154&pv608=2613&pv608=2282&pv608=3251&pv608=3847&pv608=1407&pv608=3739&pv608=2257&pv608=1903&pv608=1478&pv608=2062&pv608=3846&pv608=2092&pv608=1152&pv608=3811&pv608=2931&12:28
DocScrutinizer05ohdamn, sorry12:28
DocScrutinizer05diarything: arbitrary example http://www.vishay.com/docs/62995/sum70040e.pdf ~10*10mm, (w/o leads) 5mm high. smaller packs exist too for other types12:43
DocScrutinizer05diarything: http://www.ti.com/lit/ds/symlink/csd18563q5a.pdf https://www.digikey.com/product-detail/en/texas-instruments/CSD18563Q5A/296-36511-1-ND/4311727   5.7 m©, 60 V SON 5 mm × 6 mm NexFETTM12:46
DocScrutinizer05max 100A,  15A when soldered to a 1 square inch of 2oz copper pad12:48
DocScrutinizer05diarything: anyway please make sure this isn't a XY problem12:56
diarything5/80 was amps15:59
diarythingthis is the bms https://www.aliexpress.com/item/4S-80A-li-ion-14-8V-18650-BMS-PCM-4s-battery-protection-board-bms-pcm-4s/32757402439.html16:04
diarythingthansk for the info btw16:04
diarythingi found this switch that i have, which has a num/numAmp rating SDS 3 P ALPS 5A/80A 250v~16:04
diarythingexample one https://www.aliexpress.com/item/2-x-Power-Push-Switch-KDC-A04-250V-5A-80A-with-Frame-Solder-Legs/32262230749.html16:05
diarythingive come to the conclusion that ya these 5/80A switches are not suitable for the current :)16:05
diarythingits a 300wh batt, so at 80A its not going to last long ;)16:09
diarythingi guess with a mosfet, there would be a constant little bit of current being eaten up :/16:13
diarythingunless i use it as a on switch instead of a disconnect switch but then the coulomb counter wont work if its not constantly connected and powered up to the batt.16:15
diarythingusing a mosfet for the on switch16:15
diarythinghmm i think i need to remind me self a bit more about mosfets again16:16
diarythingcurrently ive ended up using a screw down banana like post but without the socket for the banna plug. thing and a wire with a err tag, flat metal thing on the end. its compact, can take the current and with no load, i can faily safely disconnect batt and reset bms16:32
paul_boddiewpwrak: I might try the aluminium foil solution for the serial console given my level of soldering expertise.17:16
wpwrakpaul_boddie: meh, this is really easy to solder. maybe time for you to move up one level :)17:28
paul_boddieI live in a country where you cannot readily buy flux as far as I have found, unless you want plumbing quantities.17:29
paul_boddieSo the simple approach might be good enough. I only need it to see if my kernel is booting (or why it isn't).17:30
wpwrak(no flux) you moved to the roman empire ? :)17:31
paul_boddieWell, the Romans did have genuine plumbing. :-)17:34
paul_boddieAny progress on any of your projects recently? World domination within reach, perhaps?17:34
erichvk__Pliny discussed the importance of lead/tin ratios for effective soldering in 79AD17:35
wpwrakif you dig deep enough, you'll probably find a detailed discussion of the virtues of lead-free solder somewhere in the works of Empedocles :)17:38
wpwrakpaul: and not much progress on anelok at the moment. i have some ideas for enabling it to also act as cryptocoin wallet and i've researched new components for that, but haven't designed a new prototype for that yet.17:40
wpwrakthere is this lovely microcontroller by ingenic: http://www.ingenic.com/en/?product/id/9.html17:40
wpwrak1 GHz MIPS, 32 MB or 64 MB RAM, and costs less than the critters i have in anelok at the moment ;)17:41
paul_boddieAh, the X1000. I think they even make the programming manual available, too.17:42
paul_boddieBut where are these things available? Not that I'm a buyer or have the expertise to make boards.17:44
wpwrakyou have to buy directly from ingenic. moq 110. the X1000 (32 MB) is USD 3.0 and the X1000E (64 MB) is USD 3.8.17:59
wpwrak(programming manual) haven't seen that one yet for the X1000. but they have a kernel they seem to update pretty regularly. so that's at least something.18:00
paul_boddieMaybe only the XBurst MXU stuff as a manual for the X1000. I was thinking of the M100/M200 and others.18:07
paul_boddieThey got better at releasing the manuals. The MIPS CI20 may have helped get the JZ4780 manual out and the ball rolling.18:15
wpwrakyes, the others have nearly complete manuals. the only thing i haven't found anywhere is the signed/encrypted boot. so getting that out of ingenic is still on my to do list.18:15
wpwrakah, and another part i'd like but haven't been able to source yet is a finger print sensor. ideally, it would also be able to act as slider. kill two birds with one stone :) but you can either get sensors without specs from aliexpress, or get ignored by the manufacturers.18:17
wpwrakand DIY projects with fingerprint sensors all seem to use monstrous modules, generations behind today's technology18:18
paul_boddieI have to say that having messed around with PIC32MX, such Ingenic stuff seems more interesting.18:19
paul_boddieAlthough not as "maker-friendly" due to the packaging. But at least it has a MMU, I presume, unlike all the mainstream ARM/MIPS microcontrollers.18:20
wpwrak(x1000) you can also get a module. that one should be pretty easy to solder and adds wlan and bluetooth. http://www.ingenic.com/en/?newton/id/12.html18:21
paul_boddieI hadn't really looked at their boards, but they seem quite decent!18:26
wpwrakbut my main DIY project these days is building a proper lighting system for my apartment. that's been pending for many years, because i didn't feel to comfortable working with mains voltage. but it turns out that much of the LED technology operates at 12 V. problem solved :)18:26
wpwrakso the idea is to use 1 m rails with a bunch of LEDs inside (13-18 W/m), then add a 802.15.4-based controller to each. hook up the whole thing to 12 V, et voila, a nice modular solution.18:29
wpwrakfirst i tried to build something with an off-the shelf controller, but a) that one is for controlling a lot of leds, making the thing non-modular, and b) the MCU in there is quite poor (a 8051 clone). it works, though. so i won't have to sit in the dark until i get around to making that modular system :)18:32
paul_boddieSounds a bit too hi-tech for me! But I agree about the MCU.18:34
wpwrak(high-tech) naw, the modular controller is actually quite simple: an ATSAMR21E16A (ARM + 802.15.4 transceiver), three FETs, and a voltage regulator. shouldn't take more than a weekend to get that to work.18:38
wpwrakand maybe make a nice remote control the next weekend :) jog wheel + OLED + CR2032 + ATSAMR21E16A, with the first three parts already exhaustively researched for anelok.18:39
erichvk__would the 802.15-4 aspect give neighbours insights into your habits?18:45
erichvk__we have a 48V battery bank here. Plan is din rail mounted relays controlling light fixtures on a star topology. No phantom loads when off. Switch plates are also on a star topology.18:47
paul_boddieI think the ATSAM stuff may be the future for Microchip. Apparently, their MIPS product evolution stalled somewhat.18:47
erichvk__some of the "smart home" setups like c-bus use ~.4W per switch plate, multiplied by usual number of switch plates in house equals energy consumption of a refrigerator, before the lights are even turned on..18:50
wpwrakerichvk__: well, it can observe most of my lighting habits without too much difficulty from the street :)18:50
erichvk__ah, that other part of  the EM spectrum18:50
wpwrakbut if i was really paranoid, i could create periodic idle traffic so you couldn't tell when i'm sending commands. but, meh :)18:51
erichvk__curtains provide tempest hardening I guess18:51
wpwrak(btw, the main reason for wanting to go modular is that my living room really needs two banks of light sources, some 6 m apart. and coordinating them can only benefit from having a bit of intelligence in the controllers.)18:56
erichvk__fair enough18:58
paul_boddiewpwrak: So, did you get one of those X1000 boards?22:05
wpwraknot yet. i sent them a purchase order a few weeks ago but they never responded. so i'll have to try again.22:30
wpwraksadly, there's no ali-key :)22:31
paul_boddieDo you still do much with the Ben or similar hardware?22:50
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