#robotics Logs

Aug 27 2015

01:08 theBear holy balls ! surely the channel isn't THAT quiet.. are we important enough that some script kiddie is actually "doing" the channel ? cos i just scrolled (quite a) bit (indeed) and there ar a suspiciously large number of these join/excess moisture messages
01:19 mrdata theBear, same IP
01:19 mrdata each time
01:20 mrdata almost
01:52 theBear mrdata, mmm, didn't notice, past a night or two back (stupid client only has time not date) it was much diffred... i suspect they're all harvested nicks too.... recognized several including capitalization
03:51 MisterX anyone know what the formula is called? when you need to find out how much resistance you need to add in order to get the voltage level you want
03:55 veverak MisterX: I use "led calculators"
03:55 veverak :)
03:55 MisterX hehe
03:56 MisterX could it be ohms law? if r=v/i, then that meen the entire circuit needs to have 4.2 ohms?
03:56 MisterX oh
03:56 MisterX 11.1v/2.6a
06:58 deshipu http://www.theonion.com/article/scientists-confident-artificially-intelligent-mach-51170
08:36 rue_school theBear, its been quiet
08:36 rue_school I get rid of join/part messages so that I can always see the real content thats occured in a channel
08:37 rue_school MisterX,
08:38 rue_school R = (Vsupply - Vled) / Iled
08:38 rue_school leds need to be set to a particlar current
08:38 rue_school I usually use a bit under 5ma
08:38 rue_school I usually use 5V
08:38 rue_school I usually neglect the voltage drop of the led
08:39 rue_school R = (5 - 0)/.005 = 1000
08:39 rue_school so, lets say you have an led that you want to drive 300mA to
08:40 rue_school and you have a 12V supply, and the datasheet for the led says it drops 2V
08:40 rue_school R = (12-2)/0.3 = 33.33 ohms
08:41 rue_school lets say you have a 5 volt supply and a led you want to run 30mA thru
08:41 rue_school and the led drops 1.5V
08:42 rue_school R = (5-1.5)/.03 = calc "(5-1.5)/.03"
08:42 rue_school (5-1.5)/.03 -->> 116.667 = 116.67 ohms
08:42 rue_school now lets say you have a flourescent bulb that you have a 1000V supply for, it needs 900mA and drops 300V
08:43 rue_school R = (1000-300)/0.9 = 777.78 ohms
08:44 rue_school now, you have to be carefull of the power dissipation of that resistor,
08:44 rue_school P = I * V, for the resistor, this is the current thru it and the voltage across it
08:45 rue_school so, for the first case 1000 ohms with 5 volts across it and 5mA thru it
08:45 rue_school P = 5 * .005 = 0.025 watts
08:45 rue_school most of the resistors everyone uses are 1/4W, so .025 is not a problem
08:46 rue_school in the second example,
08:46 robopal leave it as an exercise for the reader
08:46 rue_school P = 10 * 0.3 = 3 watts,
08:47 rue_school so a 1/4W resisstor will go up in smoke
08:47 rue_school robopal, your right, I'm not making this enguaging
08:47 rue_school so, using that information, calculate the resistance and miniminum resistor wattage for the following:
08:48 rue_school 15V supply 50mA led, V drop
08:48 rue_school ^^ sorry, 1.4V drop ; 24V supply, 10mA led, 1.4V drop
08:49 rue_school 13.5V supply, 5mA, 1.4V drop
08:49 rue_school 3.3V supply, 20mA led, 2V drop
08:50 rue_school 7.2V supply, 5mA led, 2V drop
08:50 rue_school 5V supply, 10mA led, 1.5V drop
08:50 rue_school 250V supply, 5mA led, 1.2V drop
08:51 rue_school 90V supply, 10mA, 1.4V drop
08:52 MisterX hang on a sec, (the resistance you need to add)= ((input volt) - (consumption volt)) / (consumption Ampere)?
08:52 rue_school yup
08:52 MisterX aha Thank you =)
08:53 rue_school Answers: 272R 0.68W
08:53 MisterX i was wondering, most Lipo batteries comes with lots of extra wires, what are they for? diagnostics?
08:54 rue_school 2420R, .061w
08:54 rue_school MisterX, balancing
08:54 rue_school see if you can get the answer to #3
08:55 MisterX is that consumtion volt as milli or normal?
08:56 rue_school mA is a milliamp 1/1000 amps
08:56 MisterX millivolt x milliamp? or volt x milliamp?
08:56 rue_school 65 ohms, .026w
08:56 rue_school try the numbers, see what yo uget
08:57 MisterX goo idea =)
08:57 rue_school 1040 ohms, .026w
08:58 rue_school 350R, .035w
08:58 rue_school 49760 ohms, 1.24w
08:59 rue_school 8860 ohms, 0.886w
09:00 MisterX hmm the last one would be (90-1.4) / 10 = 89.86 Ohm?
09:00 rue_school 10ma is 10/1000
09:01 MisterX aha
09:01 rue_school can you get the right number?
09:02 MisterX 90-1.4 / 0.01 = 8860?
09:02 rue_school correct, make sure you put brackets around the subtraction
09:02 MisterX awsome =)
09:02 rue_school otherwise the division will happen first and the answer will be wrong
09:02 MisterX roger that
09:02 rue_school so, tell me the required wattage
09:02 MisterX 0.01 x 1.4?
09:03 rue_school specifically, if a .25w resistor will work
09:03 rue_school (90-1.4) * 0.01
09:03 rue_school (the voltage across the resistor) * (current thru resistor)
09:04 MisterX across the resistor? does that meen what's left?
09:05 MisterX nvm.. think i understood =)
09:06 rue_school its the (supply voltage - voltage drop across led = voltage across resistor) * current thru resistor (same as current thru led)
09:06 rue_school so, for each of the 8 questions above, tell me if a 1/4w resistor is ok
09:08 MisterX wouldn't be enough for any of them?
09:08 rue_school wrong answer ;)
09:08 rue_school whats 1/4w ?
09:08 MisterX 0.25w
09:09 MisterX oh
09:10 MisterX when we speak of watts now, we mean this is the energy it draws?
09:10 rue_school this is the energy that the resistor most lose in heat
09:12 rue_school if your running on battery, you want the number low
09:12 rue_school here is a question for you,
09:13 rue_school supply 13.5V, two 1.4V leds in series, at 5mA
09:13 rue_school in series the voltages add
09:13 rue_school (of the leds)
09:13 rue_school bye!
09:14 MisterX 2140 ohm?
09:15 MisterX hmm
09:15 MisterX 0.05W?
09:15 MisterX what's too low?
09:18 MisterX rue_school thank you very much btw, for clearifying! =)
09:42 theBear rue_school, yeah, but we talking a few thousand in a few days here, everyone excess flooded out a moment later :)
09:43 theBear and all different nicks :)
11:28 MisterX is this gps worth 35 dollars? http://www.digitalimpuls.no/PC-komponenter/Hovedkort/Raspberry-Pi/Raspberry-Pi/MICROSTACK-GPS-ADD-ON-BOARD-L80-GPS-Compatible-with-Raspberry-Pi-2-B-A-B-A135116-p0000120762
11:29 SpeedEvil MisterX: 'no'
11:30 SpeedEvil http://ava.upuaut.net/store/index.php?route=product/category&path=59_60
11:30 SpeedEvil oh - I misread as 85
11:30 SpeedEvil nvm
11:30 SpeedEvil 35 it's a bit overpriced
11:31 MisterX hmm k
11:31 SpeedEvil If you're able to put it together yourself
11:31 SpeedEvil but not too bad
11:33 MisterX cool, i'll just go for that one =) need to pay 25% taxes + security clearance if i order from outsdie the country
11:33 MisterX outside*
11:34 MisterX kinda silly in my opinion.
11:34 SpeedEvil I misread it as 85, so my initial comments were based on that
11:36 MisterX it says the gps has radio links for telemetry
11:37 MisterX does that mean it can recieve and transmitt information with the buildtin antennas?
11:46 deshipu so, I have this robot, https://cdn.hackaday.io/images/6228831440691950345.jpg
11:46 deshipu and I'm trying to make the light blue grippers work
11:46 deshipu with that servo in the middle
11:47 deshipu anybody has suggestions for a mechanism that would let me both close and open them?
13:38 MisterX a normal gps one would connect to a raspberry pi, how precise are they? meters or centimeters?
13:39 Snert__ with or without the NSA decalibrating it's use for civilians?
13:39 Snert__ they throw it off on purpose.
13:39 Snert__ or did, at one point, anyways.
13:40 MisterX hmm let's hope they don't anymore xD
13:40 MisterX deshipu light blue grippers? the ones connected by copper wires?
13:40 Snert__ ... and I'd say 1 meter - and I've actually seen a return-to-home quad copter return to within 1 foot. Repeatable.
13:41 MisterX k, cool.. won't use it to liftoff then xD
13:41 Snert__ I was pretty impressed.
13:42 MisterX altimeters, are they precise?
13:42 MisterX down to centi/milli?
13:42 MisterX or are we better off using lasers for measuring distance to gground when below 10 meters
13:42 MisterX ?
14:08 LoRez meh
14:18 Snert__ sometimes just trying it out gives the best answer.
14:19 Snert__ if cheap is not accurate enuff then do a laser gig.
15:39 theBear lasers are a bit fast and short in wave for measuring distances
15:39 theBear at least with slower micros
15:42 theBear Snert__, yeah, i heard a few years back that the "consumer gps devices must add a random 1-10meter value to all readings) or whatever it was (yeah, wasn't any scrambles, the "map program" was legally obliged in non-mil units... but this still only means 1meter accuracy assuming you can ALWAYS see several sats and are properly sunced to begin with... also i dunno, maybe noone does, what kinda drift/error they DO have, just c'cos you got min, err,
15:42 theBear max ?-1meter tolarences in your idea of the absolute gps/your pos, doesn't mean that it k now what you or your other hand does...
15:43 theBear actually, memory wants me to change the first "quote" there to, errr, woops sorry, sigh, another reminder that i still don't know where my sexy custom half/n/half blk/white case got too a ffwe months ago :(
15:43 Snert__ I also heard that they may have nixed that because the military has moved on to something better.
15:44 Snert__ they're launching secret satellites all the time anyways.
15:44 Snert__ but who can trust anything they say.
15:44 Snert__ they're spooks!
15:45 theBear also cos of generally wanting to do better, it's standard practice teh last few years, maybe decade, to integrate at least gyro AND acceloromeeters/grav/whatve you got with any gps data if you want ANY idea of start?
15:47 Snert__ Yes I think the military is way way ahead of us peons.
15:47 Snert__ we get the dregs.
16:06 theBear i dunno man, anything from a $20 to a $2000 mobile or tablet, noname ornot these days, is trivial to get accurate within maybe 5 or 10 cms "finish" (open loop journey and home, building term, use it to boast in relation to how you maybe put a picture rail around a room, each section positioned from measuring the last, if they still line up acceptably at the end you finihsed nicely :)
16:08 theBear point being, how effin good do you want, and why would mil bother going better, they can do at least wat i just said on each man/vehicle/whatever, and rapidly are, and mil are into anything that makes them more sneaky or anonymous, like avoiding rf either way :)
16:09 Snert__ they wanna shoot that sidewinder strait up yo ass.
16:09 Snert__ with zero chance is that missile not hitting you
16:10 Snert__ missiles are expensive.
16:16 theBear i stopped wanting to live long long ago, mix that with some apathy, apparently being indestructible by mortal men or traditional methods, and having been quite convinced my time was over a few seconds down the line, well, after the last one sidewinders mean nothing to me :-)
16:17 theBear also, EVERYONE hates y ou guys, and thinks i'm awesome and just talk a lotta shit sometimes... it's be a scorched earth mad scenario lobbing a friggin cherry bomb my way <grin.
16:17 theBear but i ain't worried
18:11 sector_0 anyone have any idea how this works?
18:11 sector_0 https://vimeo.com/111027288
18:13 theBear you click it, you see a webpage <grin>
18:13 theBear unless you got my machien :(
18:14 sector_0 it's basically an arm connected to another motor that has a rotating plate
18:14 sector_0 I'm interested in knowing the mechanics
18:17 theBear that's more or less how i liek to think of myself <grin> gimme a second, i'm err, taming a shrew
18:18 Snert__ 2 x-y stepper motors doing x-y co-ordinates.
18:19 sector_0 there's indication that the system uses polar coordinates but if that's the case the swinging arm would create an arc instead of a straight line which is required in the polar coordinate system
18:20 sector_0 how do they get this to create straight lines?
18:20 sector_0 discrete steps?
18:28 Snert__ x .... then y....increment both same amount ...increment both same amount .... = diagonal straight line.
18:29 Snert__ everything is discrete steps....just minute enough so as to appear smooth
18:40 sector_0 that's my thought exactly
18:44 Snert__ stppers can do 200 steps per revolution, and more. depending on the quality of the stepper
18:44 Snert__ and then if you belt drive that it gets smoother even.
18:45 Snert__ and no gear backlash either.
18:45 Snert__ which helps with repeatability.
18:52 rue_school theBear, they still havn't/wont repaired you eh?
18:57 theBear well, err, nup, but there's small victories, like almost xactly a year back, they stopped the ghost pain that had crept into my suddenly quite floppy numb and uselss lower leg and knee, an de
18:57 theBear dammit, just stretching/bending in the chair and headbutted half my tea outta the cup and onto the desk :(
18:57 theBear anyway, they replaced that ghostey pain with a much smaller area of numbness, and springloaded my foot, like a disco robot :)
18:58 Snert__ why, you're a candidate for DARPANET
18:58 theBear also got a not unimpressive scar in the middle of my back, and know what it's like to float on a sea of both morphine AND ketamine and muscle relaxery anti infllams all up a magic arm hole
18:58 theBear i used to be a fidonet member and node
18:59 Snert__ I remember those fidonet days
18:59 Snert__ v.42bis!
18:59 theBear something about frontdoor pausing just made a bbs feel professional, like it was more than some lonley pc iin a corner somewhere
19:07 rue_school damn dude
19:07 rue_school you have a nerve problem dont ya?
19:07 rue_school I cant remmeber who has what
19:15 theBear bunch of em <grin> ... roots from malformed/not-awesome lower disceyand vertey bits, and a should-be-not-rib (youknow down the back you got little not-ribs lower than ribs) had formed a comfy little "joint" by rubbing hard into my assbone which forces the rest of it to grind faster etc etc, but last year (solid 6+ months since i quit work on docs advice, literally so i could rest my back at home and have no work/resp. ,) it went WRONG... now my left
19:15 theBear leg doesnt do or feel 90% of the bits/movements below the knee, and i really need my stick to make it round the local supermakee
21:40 rue_school damnit
21:41 rue_school are they trying to treat you at all or just helping you down?
22:06 theBear well, i've still got some stuff on the list and this years "special order" govt extra-free-doc/med covered things, if i could get a few days without a injured foot or a horrible flu etc, i'd go a couple blocks over the road and signup for my inital 4 rounds of hydrotherapy at the fancy pimming swool there... more like old-people-exercise/in-water-umm, taichi? that thing chinese ladies do in sync at 5am in parks and places like that :) which in
22:06 theBear theory should help just get some weird muscles bigger to avoid what little can be avoided naturally, got a few foot-dude ones 'cos something about walking with my kinda club-foot tortures my big toes, to the point where a trip to the supermarket/grocery on a bad day gets me fairy stepping by the time i reach my front door again, and then SERIOUSLY planning/putting off things just so i don't gotta get up from a chair/couch/wherever i land, cos it
22:06 theBear effings hurts on my feets and merrrr (that one is kinda on my mind, since yesterday or so for whatever reasons, no use keeping track...) and of course anothr free 6rounder with my old buddy patrick the shrinker... can't remember, he's either from the nice side of boston or, naaah, i'm sure he came from right up near your place
22:07 theBear BUT, lets just say aside from them and me going thru these standard kinda motions, mri and doctor/govt-fit-to-work?-doc even reports are starting to use more and more terms like degenerative and forseeable future and other not awesome sounding things
22:24 rue_school so if I ever work out how to cut a head off and attach it to a robot body your game to go first?
22:26 rue_school glad to have known you in your hayday
22:28 theBear actually, i've been seriously (when tech is a LITTLE better of course,) thinking how awesome it'd be to have something sorted for that stupid effing droopy foot,,, i mentioned that during a quick late-night "poorneighbors" forget-relatively recent dying foot smoke-alarm fanning/move-quick last week i took about half the skin off my big toe with a super-stub kinda deal, didn't i ? maaan, NOT COOL
22:29 rue_school can it feel or just not move?>
22:31 rue_school so, somewhere below L5 or S1
22:37 theBear last slip that triggered the surgery/paralysis was l4/5 forcing down the inside (vs previous/normal outside "harmless" "slips" heh, such a misleading term, more like blowouts on those big rubber donut things in big truck suspension and getting all up in the l3/l4 zone, even to my colourblind non doctor eyes, the mri just before surgery was fucking damning... no wonder everything was freaking out and numb and ghost-all-kindsa-things from the knee
22:37 theBear down (went to er after a short nap on the couch waking up to a feeling like some kinda mythical enchanted fire-sword jammed thru my kneecap, was wallowing and flopping around the flat like a fish outta water using all my concentration and effort just to make a fonecall for a lift and find a fone charger and i dunno, spareshirt, oh and a handfull of pills from my pill drawer cos i wasn't gonna remember even my dailies to tell 'em when i arrived :(