#robotics Logs

Sep 10 2014

12:22 deshipu http://letsmakerobots.com/files/userpics/u22498/IMG_20140910_183730.jpg
12:22 deshipu sixpack :D
12:24 GargantuaSauce lol
12:24 GargantuaSauce my pcbs came! woo
12:28 deshipu they are very nice once you clean off the paper: http://letsmakerobots.com/files/userpics/u22498/IMG_20140910_183812.jpg
12:29 deshipu transparent would be better, but can't have everything
12:35 deshipu GargantuaSauce: do they work?
12:35 GargantuaSauce well i have some assembly to do before that can be answered!
12:35 GargantuaSauce they look really good though
12:47 deshipu :)
13:08 GargantuaSauce http://imgur.com/a/dRhv1
14:03 deshipu GargantuaSauce: a little bit off-center
14:03 GargantuaSauce yeah the soldermask is offset by about 0.05mm i think
14:04 GargantuaSauce maybe closer to 100 microns i dunno
14:04 deshipu the photo on the bottom looks like an eclipse of the sun
14:04 GargantuaSauce oh yeah the drills are a little bit more offset, that's to be expected
14:06 deshipu I took a shoot at making a board for my robot in diptrace, but it misses half the components I need -- I tried to find different components that use the same package, but it's still a pain
14:07 GargantuaSauce that's a .5mm via, just for scale
14:07 GargantuaSauce yeah i had to make a couple custom patterns for the headers, it's a pain indeed
14:07 deshipu why don't manufacturers publish their component data in a form that can be easily imported into those libraries?
14:08 GargantuaSauce many do, it's usually eagle or altium though
14:09 deshipu doesn't matter as long as it's a single open and documented format
14:10 GargantuaSauce lol
14:10 GargantuaSauce you are a funny guy!
14:13 Hyratel what's the Sauceborad do?
14:17 GargantuaSauce it's gonna be the mcu platform for a few different projects
14:17 Hyratel glorified MCU breakout? mega2560?
14:18 GargantuaSauce stm32f103vc
14:18 Hyratel not familiar with ST's stuff
14:19 GargantuaSauce one of their earlier models, cm3, 100 pin tqfp, quarter megabyte of flash, 48kB sram
14:20 GargantuaSauce i broke out one spi, 2 uarts, 2 i2cs, bunch of timers
14:20 GargantuaSauce usb
14:23 GargantuaSauce first two projects to use it will be a radio transceiver for the pc and UAV controller
16:10 deshipu rue_mohr2: show me your board!
19:28 rue_mohr2 ah , yes
19:29 adam789654123 rumor
19:29 GargantuaSauce the led, she flashes
20:16 rue_mohr2 deshipu, ...
20:17 rue_mohr2 posting...
20:18 rue_mohr2 http://ruemohr.org/~ircjunk/robots/arm8/p1060720.jpg
20:19 rue_mohr2 see the dirty trick I pulled?
20:19 rgantuaSauce squ
20:20 rue_mohr2 maybe that one could be trimmed up a bit better
20:20 GargantuaSauce oh the sideways header?
20:20 rue_mohr2 yea
20:20 GargantuaSauce ive considered doing that but decided it was a bit too risky
20:20 rue_mohr2 the control pin is tacked to the board }:)
20:20 rue_mohr2 the other two are bussed for power
20:20 GargantuaSauce very easy for not very much force to twist one pin off the board and short the power
20:21 rue_mohr2 (I doubled up the #22 ribon wire)
20:22 rue_mohr2 adam789654123, ?
20:22 adam789654123 its a silly joke
20:23 adam789654123 a play or your tag
20:23 rue_mohr2 well you pronounced it right :)
20:23 adam789654123 :)
20:23 adam789654123 whacha up to?
20:23 rue_mohr2 about 5 foot 5
20:23 adam789654123 5'11"
20:24 GargantuaSauce jeez you guys are short
20:24 rue_mohr2 I'm thinking about working on the 12' mecha, but in the process I'm falling asleep
20:24 GargantuaSauce i love falling asleep thinking hard about something
20:24 GargantuaSauce makes for a very smooth transition to unconsciousness...and i dont really stop thinking
20:25 GargantuaSauce great way to wake up with solutions
20:25 GargantuaSauce anyway my [suggestion|demand] is that you pound some tea and work on buddy III
20:26 rue_mohr2 I have to work tommorow, so I cant
20:26 rue_mohr2 (no tea!)
20:26 GargantuaSauce it's only 8 there!
20:26 adam789654123 GargantuaSauce: that works to a point
20:26 adam789654123 GargantuaSauce: sometimes it helps to stop thingking about something
20:26 adam789654123 GargantuaSauce: COMPLETELY
20:26 GargantuaSauce yeah that is true
20:26 rue_mohr2 I'm pondering how to deal with the overload situation
20:26 adam789654123 GargantuaSauce: it can be hard to do though
20:26 adam789654123 GargantuaSauce: especially when you are deep into ti
20:26 adam789654123 it
20:27 rue_mohr2 I put a 1uF cap on the op-amp input, and I dont think it helped
20:27 rue_mohr2 in the process of power-draw testing, I opened a scratched trace on the baord
20:27 rue_mohr2 ( pfff )
20:27 GargantuaSauce put it in parallel with the feedback resistor
20:27 rue_mohr2 solder bridged it..
20:27 adam789654123 luckily, im learning a new programing language, and basically feeling stimulated
20:27 GargantuaSauce so that it makes a low pass filter
20:27 rue_mohr2 I was wondering that
20:28 rue_mohr2 I think from - input to ground actually makes it worse
20:28 adam789654123 no real problem i have to solve but understand the concepts in the book
20:28 adam789654123 and writing simple programs
20:28 rue_mohr2 as the output would spike trying to normalize the input
20:29 adam789654123 unfortunately, I dont understand about op-amp
20:29 rue_mohr2 an op-amp is simple
20:29 rue_mohr2 it tries to make the votlages on its inputs the same
20:29 adam789654123 oh
20:29 adam789654123 so its like a voltage source
20:29 adam789654123 ?
20:30 adam789654123 uhhh
20:30 adam789654123 a stable voltage source
20:30 rue_mohr2 if the votlage on the - input is higher than the + it will decrease the output votlage
20:30 rue_mohr2 if I didn't get that backwards
20:30 adam789654123 ill think about that
20:30 GargantuaSauce http://www.electronics-tutorials.ws/filter/fil90.gif
20:30 rue_mohr2 the + votlage basically sets the 0 level
20:31 GargantuaSauce what i said only works for an inverting amp which i assume is not what you're using for current measurement
20:31 GargantuaSauce so do this
20:31 rue_mohr2 the resistance from the source to input is made different from the output to input feedback
20:31 adam789654123 the day i learn to read these schematics i will have made some real progress
20:32 rue_mohr2 if you use 1k and 10k, then 1V of source needs 10V at the output to counteract it
20:32 adam789654123 i can follow things around
20:32 rue_mohr2 thats your amplification
20:32 adam789654123 i just cant see the big picure
20:32 adam789654123 how it all flows together
20:32 rue_mohr2 it can be constrewn into all sorts of things
20:32 adam789654123 over the whole circuit
20:33 rue_mohr2 I sample the votlage over a 0.1R resistor, and amplify it such that 2A is 0V and -2A is 5V
20:33 rue_mohr2 0A is 2.5V
20:34 adam789654123 these schematics look more incredible now then ever
20:34 adam789654123 i just have no idea how to organize the infomation
20:34 rue_mohr2 oh just a sec
20:34 GargantuaSauce alright i should finish asembling this board
20:34 GargantuaSauce pics in a half hour or so
20:34 rue_mohr2 http://ruemohr.org/~ircjunk/tutorials/elex/schematic.jpg
20:34 rue_mohr2 ^^^ do your schematics like that *always*
20:35 GargantuaSauce is that a P-type or N-type doodad
20:35 rue_mohr2 if you put a negitive rail on the top, you will be slaughtered
20:35 rue_mohr2 if you put a positive rail on the bottom, ditto
20:35 rue_mohr2 if your circuit output is on the left, dead again
20:35 adam789654123 i see the positive and negative are set up like rails on a digital circuit
20:36 rue_mohr2 if your circuit input is on the right, another X-|
20:36 rue_mohr2 yea
20:36 rue_mohr2 always do that
20:36 rue_mohr2 electrons FLOW FROM + TO -, NOMATTER WHAT ANYONE EVER SAYS. GOT IT!!!?!?!
20:37 adam789654123 :/
20:37 rue_mohr2 holes can flow whichever way they damn well please cause I work with electricity, not holetricity
20:37 adam789654123 im make such a point to see it from - to +
20:37 adam789654123 the concept of holes flowing is useful in semiconductors though, no?
20:38 rue_mohr2 if its in votlage follower mode, thing could be NPN
20:38 adam789654123 ok ........
20:38 adam789654123 *-?,*?
20:38 rue_mohr2 I squished a fly and then felt bad, but then thought "there are lots of those tho" but really, there are lots of humans too
20:39 adam789654123 i try to throw insects outside
20:39 adam789654123 its not always eays though
20:40 adam789654123 there is a design with a funnel and a flashlight that can catch flies alive
20:41 adam789654123 its actually really cool
20:41 adam789654123 and really simple
20:41 rue_mohr2 mabye you could use an arc lamp
20:43 rue_mohr2 http://www.ebay.ca/itm/FA821-DC-Boost-Step-Up-Converter-3-3-5Vdc-to-12Vdc-100mA-Assembled-Kit-/321208175144
20:44 rue_mohr2 EMI? I dont know what you mean! where could that be comming from!?
21:44 fluffywolf yay! my car finally has power steering hoses.
21:46 fluffywolf I gave up trying to find any ready-made solution, or even any lines from other cars that could somehow be used... so got adapter fittings for the pump and gearbox to AN/JIC, then built standard hydraulic hoses.
21:54 GargantuaSauce http://imgur.com/a/d2d1L
21:54 GargantuaSauce do forgive the super sloppy assembly. first time doing smd
21:54 GargantuaSauce 0603s are annoying
21:55 fluffywolf that has nothing to do with either power steering or dildos.
21:55 fluffywolf I've given up on SMT... my paws aren't steady enough.
21:55 Tom_itx sure they are
21:56 GargantuaSauce the tqfp100 was a bitch to get aligned right
21:57 armyofevilrobots The tqfp is hard enough, but BGA is basically out of reach for manual work.
21:58 fluffywolf I thought people liked toaster oven bga?
21:58 armyofevilrobots Perhaps, but it's beyond most of us mere mortals. Even a toaster oven BGA requires perfect alignment.
22:00 armyofevilrobots I can barely get an MLF to work right, never mind a BGA package.
22:00 myofevilrobots whinin
22:00 armyofevilrobots although dead-bug MLF isn't too bad.
22:00 armyofevilrobots if you have a loupe and some teeny-tiny magnet wire.
22:01 uffywolf prefers MILFs to MLF
22:01 armyofevilrobots In unrelated news: Sawstop cartridge works. Although now I need a new sawstop cartridge.
22:01 myofevilrobots counts fin
22:02 armyofevilrobots it actually hit a piece of metal on a jig that was a bit too close to flush with the cut, not any fingers.
22:02 fluffywolf sawstop? that the one where they slam something into the blade, causing it to rotate downwards, but costing lots of money every time?
22:02 fluffywolf the one with all the demo videos using hot dogs?
22:04 fluffywolf I'll probably add a stop to my new cnc mill... of the big red mushroom switch variety. I thought a while ago about adding one to my current mill, but decided it wasn't large enough to justify one. (sherline)
22:10 fluffywolf if I remember how those work, you'll need a new blade to go with the new cartridge... and possibly a new spindle.
22:20 Hyratel fluffywolf, yeah
22:21 Hyratel it uses the inertia of the blade to yank it down
22:21 Hyratel it's a good idea, but what happens when you go to cut plastic sheet and it trips wrongly
22:24 fluffywolf plastic?
22:24 fluffywolf aluminum sheet is a far bigger problem. :)
22:29 armyofevilrobots fluffywolf: Yep. $200 mistake :(
22:29 armyofevilrobots you can disable the stop for metals or conductive (ie: salty) wood, but you have to know in advance. It doesn't trip on plastic, just conductive materials. It's a capacitance sensor.
22:31 fluffywolf they need a two-stage version that actuates a normal friction brake, then if a few ms later the conductivity keeps increasing, then the mangle-everything brake.
22:31 fluffywolf less cost at the expense of deeper minor cuts.