#robotics Logs

Mar 20 2013

00:11 rue_house yes, but you still seem to want to find a way to code just with a gui :)
00:11 Rif never
00:11 Rif i alway code in notepad
00:11 rue_house hah, I'm sure you use a java ide
00:14 Rif only for hardware setup
00:16 Rif it just works, so why make life any harder
00:21 Rif anyway rue_house, -50 to +50 amp, ac or dc, $13, 1 part, with a voltage ready for your adc
00:22 rue_house dude, I ahve 18 channels
00:22 rue_house no
00:22 rue_house I'm using the $0.10 .01R resistors I bought off ebay
00:24 Rif ok then
00:25 Rif the other ammeter i made, i get different adc readings as soon as i increase the load, so is all wrong with differing amounts of leds, normal?
00:25 rue_house hu?
00:27 GuShH hu!
00:33 Rif hrm, ok not normal, will check again when i get home
00:45 theBear but erm, different load = different current
00:47 GuShH theBear: ?
00:52 theBear before you got hee
00:52 theBear here
00:53 GuShH I wonder if a slipper clutch is what I think it is
01:33 RifRaf ok so a current sence resistor should not care if i am drawing 1amp from 3 leds or 1a from 20 leds?
01:40 GuShH RifRaf: did you solve your dc offset problem
01:40 GuShH you went offline
01:40 GuShH RifRaf: the shunt doesn't "care" what the load is
01:41 GuShH the voltage drop is proportional to the current
01:41 RifRaf well am gonna resolder and make better closer connections to see if that helps
01:41 GuShH a voltage divider is formed with the load
01:41 GuShH RifRaf: again, did you solve your 0-2.5v issue
01:41 RifRaf it happened after changing some wires and adding a plug
01:42 RifRaf no, i am gonna just use the adc vref of 5V
01:42 GuShH I made a draft with a couple opamps but you went offline
01:42 RifRaf and have 2.5V as 0
01:42 GuShH that halves your resolution
01:42 RifRaf oh damb, well in that case i'll take a look, i did look at op amp circiuts
01:42 GuShH differential amplifier
01:42 RifRaf but they talk of very small offsets, not like 2.5V
01:43 GuShH I'll post my draft, it's not stable under 2.5v input, I didn't care to build a proper circuit it's just to show you the idea
01:43 GuShH you were looking at output offset
01:43 GuShH different thing.
01:43 GuShH (offset required due to discrepancies in the opamps
01:43 GuShH ie to obtain 0.0 out for example
01:44 RifRaf ok so it is possible, again i am worried that the closer the 2.5V gets to 0V that i will have the same issues due to single supply, so maybe better to just use 5V vref
01:44 GuShH 324 goes to 0v
01:44 RifRaf gush, i was not worried about negative current, so will not be reading less than 2.5V
01:44 GuShH dont worry about heresay, worry about observed issues
01:44 RifRaf yes most of my issues are observed ones
01:45 RifRaf from making and trying circuits
01:46 GuShH where the hell is it
01:52 GuShH RifRaf: something like this http://gushh.net/tmp/rifraf_diffamp1.png not sure how it would behave with no negative rail when it gets close to 2.5v input, maybe it'll latch up... can't test right now
01:52 RifRaf yep that was my other worry
01:52 GuShH maybe there's a simpler way, the other opamp is just acting as a follower for the divider
01:53 GuShH R7 is just there because I'm a 324 legacy idiot
01:53 RifRaf lm324 you reckon?
01:53 GuShH yeah
01:53 RifRaf ok will breadboard one up later, trying to work out how to make this servo bracket useful
01:56 RifRaf GuShH, so that circiut will drop 2.5V from the input, or 2V
01:56 GuShH 2.5
01:56 GuShH or 2
01:57 RifRaf ok cool, so i could still use up to + 27A
01:57 GuShH 2
01:57 RifRaf and have adc vref at 1.1V
01:57 GuShH you can play around with the dividers
01:57 GuShH don't know if it'll latch up at < 2.5v input
01:57 GuShH I'm sure there are simpler topologies
01:57 RifRaf 2 limits things a bit more, but still workable, so 2.5V in = 0.5V out
01:58 RifRaf < 2.5V would be negative current , and not gonna be using that
01:58 GuShH just get a negative rail boosted from the mcu as a controller
01:58 GuShH and be happy
01:58 GuShH pwm
01:58 RifRaf or the max232 idea?
01:59 GuShH you may want to have a hard enable set to OFF while it settles
01:59 GuShH so you don't get current spikes during startup
02:00 RifRaf i got some of these http://www.ebay.com.au/itm/F03711-1-set-Robot-servo-spare-parts-Metal-U-holder-round-servo-mount-Bracket-/261122127397#vi-content
02:00 RifRaf well not those ones, i paid 1.50 per set
02:01 RifRaf i don't get what the smaller u bracket is for
02:01 RifRaf i hooked the bigger one up fine, machine a standoff for other side of servo and superglued it to servo, that seems usefull
02:02 GuShH pan-tilt
02:02 GuShH http://www.sparkfun.com/images/tutorials/PanTiltFaceDetection/PanTilt-1L.jpg
02:02 GuShH ew sparkfun, bad google, bad.
02:02 RifRaf hrm, i wanted to try make me robot arm stronger with them
02:03 GuShH maybe it's two rejects from two different pan-tilt sets? :p
02:03 RifRaf those are 9g servos,
02:03 GuShH same principle
02:03 GuShH you don't need more than 9g to pan-tilt a webcam, for instance.
02:03 GuShH they have plenty torque to wobble it around
02:04 GuShH I forgot if the weigh was 9 grams with cable or without
02:04 RifRaf without
02:05 RifRaf no good for me dslr camera though
02:05 RifRaf will try with the mg996
02:07 RifRaf ok back to current sensor, i have lots of pantilt setups with plexiglass brackets already
02:07 RifRaf i think this nanoduino is bad since i resoldered the usb connector back on
02:07 GuShH meh plexi is heavy
02:07 RifRaf lcd displays garbage and does not work 39 times out of 40
02:08 GuShH easy to bend, but heavy.
02:08 RifRaf when powered up
02:08 GuShH see if the lcd connections are fine?
02:08 RifRaf yes, is fine for the gripper but not as good for the arm bones
02:09 RifRaf yeah have resoldered and tryed lots, i have to keep replugging it in for a minute or so and suddenly it works ok
02:09 RifRaf resoldering and changing all connects now
02:09 RifRaf also my distance sensor keeps freezing up when i move it or change the distance it senses abruptly
02:10 RifRaf is all very annoying
02:15 RifRaf btw, my corruption on lcd is the same each time eg, D533C B then bunch of gibberish
02:15 GuShH could be the data pins are not making good contact
02:16 GuShH or any of the control pins
02:16 RifRaf yep, gonna replace everything
02:16 RifRaf when it does start, like now, is fine till i disconnect battery
02:20 RifRaf gonna get rid of breadboard, maybe its too used
02:30 GuShH theBear: yet another hobby I wasn't aware of http://www.youtube.com/watch?v=Xp-KGgE_BiA
02:31 GuShH fucking yankees
02:31 ShH shakes
02:32 RifRaf yeah they get those pretty strong
02:33 RifRaf GuShH, a mate showed me this site at work today, is a bit different http://www.thisiswhyimbroke.com/
02:33 RifRaf look for the mech warrior
02:36 RifRaf http://www.thisiswhyimbroke.com/diesel-powered-mechwarrior
02:36 Hukka Oh my...
02:36 RifRaf surely they are not really trying to sell that
02:37 Hukka That site is like a siren call
02:37 Hukka Ah, that's the Kuratas
02:37 Hukka I'm not psychopatic enough to drive it
02:37 Hukka With it's smile activated weaponry etc
02:38 RifRaf they galling gun operates by smiling
02:38 RifRaf gattling* , yeah
02:38 GuShH heheheh
02:38 GuShH theBear: http://www.thisiswhyimbroke.com/workaholics-bear-coat
02:44 GuShH Yes! http://www.thisiswhyimbroke.com/beer-ammo-bandolier
02:46 Hukka That site does have lot's of interesting DIY ideas too
02:46 Hukka Like that Triforce lamp
02:48 GuShH do they resell? a lot of prices are 3x to 4x the real value
02:48 GuShH compared to actual buy-it-now I've seen out there
02:51 RifRaf not sure, but at least great for ideas, theres definatly more than a thing or 2 i want
02:51 RifRaf still going through the list
02:51 Hukka How many pages do they have?
02:52 RifRaf dunno yet, the first page is long enough
02:52 Hukka I'm on third
02:52 RifRaf they reckon it would take 23 hours if you looked at one item a minute, read that somewhere today
02:53 RifRaf so around 1400 items i guess
02:54 Hukka Some of that stuff I've already made
02:54 Hukka Like the paracord bracelet
02:54 Hukka Well... I made it a keyfob
02:55 RifRaf heh i've made one of them too, used paracord for lots
02:56 Hukka Glow in the dark duct tape
02:56 Hukka !
03:13 Hukka Ok, 8 pages
03:14 RifRaf lol, good to know, didn't make it too the second yet, far too distracting, had to start soldering this stuff
03:21 RifRaf omg i think i have been not driving the nanoduino board correctly, have been feeding it 5v the whole time into the Vin pin
03:22 RifRaf looks like that goes into a reg, shoulda been using the 5V on the other side , maybe thats part of the problems
03:25 RifRaf so i don't even need a voltage regulator then, just use onboard one, which i never saw before, will check under microscope
04:25 RifRaf wow :/ same lcd issues with different nanoduino board and resolded different connectors
04:26 RifRaf must be the lcd
04:35 GuShH RifRaf: or the operator
04:35 ShH
04:35 RifRaf oh so very true
04:35 GuShH lol
04:35 RifRaf now i am thinking its my code
04:35 RifRaf shock horror
04:36 GuShH failcode
04:36 RifRaf am gonna try some basic lcd example now
04:36 RifRaf new project, just lcd, and use example code
04:41 RifRaf ok test code works after pressing reset, but still garbage when plugging in
04:42 RifRaf checked lcd datasheet, is connected fine, voltages are good
04:42 RifRaf but only 4x20 i have
04:43 RifRaf a 4x40 is only other 4 line and thats too big
04:43 RifRaf but could put lots of info on it maybe
04:48 RifRaf hrm i need a pcb now, for an opamp, npn, and a few diodes a premade should do, can't say i've seen any spare around here though
04:54 RifRaf heh this 40x4line lcd is crusty and the wiring is shocking, will redo and test, had it in a pc case for years
06:01 RifRaf dammit 40x4 lcd is not standard, uses 2 x HD44780 chips
06:02 RifRaf guess i will try 16x2 now and try make data fit, but got 5.30am work start so not right now
07:22 ShH idly takes theBear's p
09:10 rue_house rif, coulda told ya that
09:10 jennie hi rue_house
09:10 rue_house hi
09:10 jennie garfield ?
11:53 thinkanish hi
14:32 SorcererX what would be the simplest way to convert 12V DC to 24V DC, if I only need say.. max 50 mA?
14:47 jumijoze TSR 1-24120 :)
14:47 jumijoze from tracopower
14:48 jumijoze sorry wrong type
14:52 SorcererX yeah, that would give me 12V from 24V :)
14:58 SorcererX hmm, I found something that would provide 24V from 5V, I can work with that I guess :)
14:58 SorcererX LMR62421XMF
19:23 rue_house SorcererX,
19:23 rue_house I have a circuit if you want
19:23 rue_house its small
19:24 rue_house http://eds.dyndns.org/~ircjunk/robots/mowerbot/dscn9634.jpg
19:24 rue_house well not tiny
19:27 rue_house hmm dont know where the schematic went
19:28 rue_house its a balanced 7414 osc driving two transistors against a EMI filter thats wired as a center tapped inductor, with the two legs having a diode off them to catch the extra 12V
19:31 yahweh Rue is home from work it seems
19:32 Tom_itx not for long it seems
19:33 yahweh Curses , you'll Rue the day you didn't Rue all day.
19:35 rue_house I hae to go back to work
19:35 yahweh D:
19:35 Tom_itx +v or +t ?
19:35 rue_house :) v
19:36 rue_house I have to go install a 70V speaker
19:37 Tom_itx they can't do without it until tomorrow?
19:41 rue_house nope
19:54 yahweh What's it for Rue?
19:55 rue_house a PA speaker
19:55 yahweh huh
19:56 rue_house have to have it for the opening I think
19:56 yahweh I guess that makes more sense then a desperate need for a sweet home theatre setup.
23:46 rue_house yea, that tv, hmmm
23:46 rue_house I was told I might be abel to find a bare bulb off ebay cheap