#garfield Logs

Aug 18 2015

00:01 rue_school Line is : 3.000, 4.000 -> 5.000, 6.000
00:01 rue_school Line is : 7.000, 3.000 -> 9.000, 6.000
00:01 rue_school sl
00:01 rue_school sl
00:01 rue_school A = -2.000000, B = 2.000000, C = 2.000000
00:01 rue_school A = -2.000000, B = 3.000000, C = -15.000000
00:01 rue_school -> 0xbfb7d9c0
00:01 rue_school Intersection: -18.000, -17.000
00:01 rue_school but the intersection is at +18,+17
00:02 zhanx- The bed light thing on hackaday.com, I need to make one
00:03 rue_school didn't see it yet
00:03 zhanx- Turns on under the bed lights when you get up in the night
00:03 rue_school hah
00:04 ^kat^ ow does it know when you get up in the nite?
00:04 zhanx- Pir sensors
00:04 rue_school what did they use as a sensor?
00:04 rue_school ah
00:04 rue_school great minds...
00:04 zhanx- I got a few if them
00:04 zhanx- Of
00:04 zhanx- Wife wants it
00:04 zhanx- Of course she does
00:05 rue_school I better do some homework before the night is over
00:05 rue_school zhanx, would you like to take a detour for a bit and help me test a C function?
00:06 ^kat^ wth, hackaday lost all it's page formatting
00:07 rue_school http://codepad.org/Z5JUG4s8 <-- 2d.h
00:07 zhanx- Rue, I will in the morning ok I fried from the kid today, link me and I will check it
00:07 rue_school http://codepad.org/h1AESstE <-- 2d.c
00:07 rue_school compile with -lm
00:07 rue_school but its all there,
00:07 rue_school need to cross check the output of lineGF_t * line2General(lineGF_t *g1, line_t *this) against known results from wolfram alpha or otherwise
00:07 zhanx- Line 32
00:08 rue_school it compiles, the page cant because it cant to multi=file compiles
00:08 rue_school you need the header file and the c file
00:08 zhanx- K
00:09 rue_school it could be a handy library maybe one day for you :)
00:09 zhanx- True
00:09 zhanx- I am coding a stm32 pi library now
00:09 rue_school I'm working it up to be able to make a cad program with it
00:10 zhanx- Nice I could use it in my robots targeting routine
00:10 rue_school so I'll be adding fn's for things like "parallel line x distance from that line"
00:11 zhanx- I use Inkscape for cad 2d
00:11 rue_school I use librecad
00:11 rue_school but I want a cam program
00:11 rue_school and I need a library that can do cad fn's to a drawing to do it
00:12 zhanx- Quicker for Inkscape to export paths to cut things
00:12 rue_school I might also make a program to generate gear profiles, it turns out the teeth that inkscape generates consist of about 7 lines each
00:12 rue_school I want proper involute gears
00:12 zhanx- That pdf you linked was awesome for that
00:12 rue_school tho I'm making a set using that webpage I was given
00:13 rue_school yea, it told me how to do it, but right now my 2d C library cant do the required operations
00:13 rue_school thats what this line intersection is for
00:14 zhanx- K
00:14 rue_school it is used in the fn that finds the circle solution for 3 points
00:14 rue_school which is used at the bottom of each tooth
00:14 zhanx- Ok udev rules fixed
00:14 rue_school heh
00:14 zhanx- No longer need sudo to upload to my chip
00:15 zhanx- Chinese knockoff had the identification wrong by one number 3749 instead of 3748
00:16 zhanx- Now to make a shell script out the makefile
00:19 rue_school good show
00:19 zhanx- Rue when your ready for ARM let me know
00:19 zhanx- I will send you the makefile etc
00:21 rue_school I have a hammer
00:22 rue_school couldn't develop software for it cause its arm
00:22 zhanx- It's c++
00:22 rue_school couldn't get the whole cross compileing environment set up
00:22 rue_school its got linux on it now
00:22 zhanx- I did today
00:22 rue_school k
00:23 zhanx- Hence why I said it
00:23 zhanx- Took me all dsy
00:23 rue_school http://www.elinux.org/Hammer_Board
00:23 rue_school its been sitting in a box since the guy I bought it for abandoned his project
00:23 rue_school (and didn't pay me)
00:24 zhanx- I am using cortex not the same but might work
00:24 rue_school I have a mostly assembed ethernet board for it
00:25 rue_school wow
00:25 rue_school I just took a school problem that i couldn't get the numbers to come out right this evening when I was exhausted, and they came out right hte first time
00:26 zhanx- Nice
00:26 rue_school same process! I swear!
00:26 rue_school its 2015, COULD WE PLEASE STOP MEASURING POWER IN HORSES!
00:27 zhanx- Nope
00:27 zhanx- Bhp
00:27 rue_school delta motor, 480V,66A...
00:28 zhanx- I will take 6
00:28 rue_school P = 480 * (66/sqrt(3)) * 3
00:29 rue_school 54871.37VA
00:29 rue_school 50hp(37300w) at 90% eff (41444.44w in)
00:30 rue_school find power factor,
00:30 zhanx- No
00:31 rue_school 75.53%
00:31 rue_school the kvar rating of the cap req'd to correct the power factor to 95%
00:34 rue_school 22.37kvar
00:34 rue_school and the answers are...
00:34 rue_school 75.5%
00:34 rue_school 22.3kvar
00:34 rue_school yay!
00:35 rue_school ""
00:36 rue_school a small mill has a load of 300kw on a 600V 3phase service. the line current is 350A. if a 200kw electrically heated kiln is to be added, what will the new power factor be
00:36 rue_school ok
00:36 rue_school so
00:36 rue_school 300kw is 300kw
00:36 ^kat^ same
00:36 rue_school line current is 350A
00:37 rue_school so, just assume delta,
00:37 rue_school the phase current is 350/sqrt(3)
00:37 rue_school (202.073A)
00:37 ^kat^ but the kiln is resistive
00:38 rue_school so thats 121243.557 VA total
00:38 rue_school (havn't added kiln yet)
00:38 rue_school so the var is
00:39 rue_school 40.415%
00:39 rue_school ...
00:39 ^kat^ wow
00:40 rue_school 678.98 var?
00:40 rue_school seems low
00:41 rue_school something broke
00:41 rue_school wait
00:41 rue_school ugh
00:41 rue_school maybe I should start again
00:42 ^kat^ http://hackaday.com/2015/06/03/how-to-build-beautiful-enclosures-from-fr4-aka-pcbs/
00:42 rue_school oh
00:42 rue_school total va is 363731.4
00:43 rue_school so power factor is 82.478%
00:44 rue_school var is 205674.39
00:44 rue_school now add the kiln
00:46 rue_school damnit pressing the wrong button on this calculator cleras everything
00:46 rue_school 22.36 degrees, which is
00:47 rue_school 92.48%
00:47 rue_school and the answer is...
00:47 rue_school I HATE EATING CAUSE NOW MY GUTS HURT AND I CANT DO ANYTHING SLEEPING INCLUSIVE
00:48 rue_school answer is 92.5%
00:48 rue_school yay
00:48 at^ hands rue some gut d
00:48 rue_school maybe 2 more qurestins
00:48 rue_school ""
00:49 rue_school three 16 ohms impedences at a power factor or 80% lagging are connected delta to a 208V 3 phase supply
00:49 ^kat^ ok, "is yes the correct answer to this question?"
00:49 rue_school find the kva, kw, kvar the new line currents if one of the fuses open
00:50 ^kat^ ppeople still connect 208 delta?
00:50 rue_school 16R 208V, so between 2 phases the power is
00:50 ^kat^ reminds me of the guy selling 277v stuff
00:50 rue_school 2704VA
00:51 rue_school *3 =
00:51 rue_school 8112VA total
00:51 rue_school at 80%
00:52 rue_school is 6489.6w
00:52 rue_school and 4867.2var
00:53 rue_school so
00:53 rue_school at 208V, 16R, there is 13A between phases
00:54 rue_school when the fuse blows one line current drops to 0
00:54 rue_school the load drops to 1/2 the va rating
00:55 rue_school so its now 4056VA across 208V
00:55 rue_school is 19.5A
00:55 rue_school and its single phasing so the details dont matter
00:56 rue_school answres are:
00:56 rue_school 8.112kva, 6.49kw, 4.86kvar, 19.5A
00:56 rue_school yay!
00:57 rue_school how many is that, one more?
00:57 rue_school a balnaced delta connected, 240V 3 phase load has a line current of 10A at a power factor of 60% lagging
00:58 rue_school find theimpedence of each load, the total kva total kw, total kvar, the line currents if one fuse blows
00:59 ^kat^ may i suggest a dropped line detector to avoid burned motors?
00:59 rue_school :)
01:00 rue_school they havn't even gone into the fact that motors will keep outputting power dispite the phase loss and suck as much current to keep us as req'd
01:01 ^kat^ ~1975, i was called in to help a guy who replaced a burned motor and couldn't get the new unit up to full speed and was popping fuses like mad
01:01 ^kat^ he'd lost a phase somewhere, the motor was trying as hard as it could
01:01 rue_school my brain lacks a [start of frame] when sending digits to my hand, there is a startup latency and my hand may drop the first 1 or 2 digits of the number being written
01:02 rue_school yup
01:03 rue_school my answers are..
01:03 rue_school 41.566 ohms on each load
01:04 rue_school 4.16kva
01:04 ^kat^ had to explain a few yrs after that, to a guy, why you cannot replace a 3hp repulsion-induction motor with a 3hp cap-start motor,, or even a 10hp sometimes
01:04 rue_school 2.49kw
01:04 rue_school 3.33kvar
01:05 ^kat^ every service call he went out, the 10hp cap start motor was spinning the engine in reverse
01:05 rue_school ooo repulsion induction, I got one of those once
01:05 rue_school man they start good
01:05 rue_school hah!
01:05 at^ nods, impressive be
01:05 rue_school I gave it to my guru who uses it for a compressor to this day
01:06 rue_school and when the fuse blows, 8.66A
01:06 rue_school and the answers are...
01:06 rue_school 41,6R
01:06 rue_school 4.16kva
01:06 rue_school 2.49kw
01:07 ^kat^ the cap start would turn it over the right direction till it got to TDC, then the engine stalled the motor, the motor start winding went out on overheat, the engine compression pushed the motor in revers, where it happily kept on spinning
01:07 rue_school 3.33kvar
01:07 rue_school 8.66A
01:07 rue_school yay!
01:07 rue_school exam is on friday for this stuff
01:07 rue_school maybe I will leave some questions for later
01:07 ^kat^ the R-I motor had simply sucked more amps and torqued the engine over TDC
01:08 rue_school I bet it had much less resistance from the load in reverse :)
01:08 rue_school but if you like, I will leave you with this:
01:08 rue_school ""
01:08 ^kat^ it also had the engine compression to boost it, and 2 engine revolutions to come up to speed
01:09 rue_school three 20R resistors are delta connected to a 480V 3 phase supply, find
01:09 ^kat^ you know some golf cart engines run just as well either direction?
01:09 rue_school the phase current, the line current, the total kw
01:09 rue_school I'v heard of bidir engines, matter a fact, I THINK our ferries use them
01:10 ^kat^ shut off, pull a lever, restart in other direction
01:10 rue_school yea
01:11 rue_school ok, I can do these questions if my mind is in an ok state
01:11 ^kat^ it's after midnite, no wonder my brian is off
01:11 rue_school speaking of, its 10:48 and I should get to bed
01:19 at^ waves gn
01:24 rue_school wait wait, I know the answer, the slopes are backwards
01:28 rue_school haha! I fixed it!
19:35 rue_school ok, I told myself I'd do some homework
21:36 anx embeds code in a gif to see if it w
21:42 rue_school oh oh oh oh, embed a program that prints out the meaning of life, the universe and everything
21:43 zhanx that i would fail at
21:51 rue_school printf("42");
21:51 zhanx that is the answer but the question still remains
21:51 rue_school thats ok, everyone thinks they know what the question is, so they aren't looking for it
22:43 rue_school its amazing how using a library for something new can cause you to have to double its functionality
22:43 rue_school sometimes the little things, turns out I had no fn for the distance between two points