#robotics Logs

Jan 11 2013

00:00 Ademan )
00:35 Triffid_Hunter Ademan: http://sound.westhost.com/articles/external-psu.htm#kil
00:36 Triffid_Hunter Ademan: I have some laptop PSUs here with which I can actually measure 120vAC between the DC barrel and safety earth.. anything I connect to them feels very strange when you run your finger over the case- feels similar to what happens when you put two fridge magnets back to back and draw them across each other
00:37 Triffid_Hunter so I'm always pretty careful when using those!
00:46 RifRaf Triffid_Hunter would you like a motor driver?
00:47 rue_bed it should be 1500V isolation
00:47 Triffid_Hunter RifRaf: I already got one, see http://github.com/triffid/ESC
00:47 Triffid_Hunter rue_bed: yeah sure, the caps are mains rated and all that jazz so there's no direct short.. problem is the capacitors themselves hold enough energy to destroy cmos inputs
00:48 RifRaf wow, can i try some of your code in my arduino?
00:48 RifRaf rue_bed you want one?
00:59 RifRaf Triffid_Hunter seems my eagle cannot see your files, too old, are you making any complete units to sell?
01:03 Triffid_Hunter RifRaf: considering it
01:03 RifRaf cool
01:03 Triffid_Hunter RifRaf: that code is written for an atmega328p, should work fine on your arduino :)
01:03 Triffid_Hunter not sure what the IDE might think of it though
01:03 RifRaf i think i have heaps of those hip4082 chips if thats what you are using
01:04 Triffid_Hunter they're awesome
01:04 Triffid_Hunter esp with 10u bootstrap capacitors which is what I used on my first prototype
01:04 Triffid_Hunter ended up stripping the gearbox in my R/C after a few weeks
01:04 RifRaf have dug out many atmel boards today, got several i want to get working
01:05 RifRaf what kind of rc cars do you use?
01:05 Triffid_Hunter RifRaf: https://picasaweb.google.com/lh/photo/Q6cjAftoBdGhgy1Gl4iuydMTjNZETYmyPJy0liipFm0
01:06 RifRaf woah, is that it, some very small chips
01:06 Triffid_Hunter yep
01:06 Triffid_Hunter that's the whole thing. mosfets are good to over 15A with no heatsinks
01:06 RifRaf my eyes have gone now but thank goodness for magnifiers, i reckon i can still do it
01:07 RifRaf the rats ate my hot air tube on the rework station though
01:07 Triffid_Hunter I find my magnifier gives too much distortion, I hand solder without and only use it for inspection afterwards
01:07 Triffid_Hunter :(
01:07 RifRaf have you ever seen that plastic tube material for sale?
01:08 RifRaf thats obviously rather heat proof, but tasty
01:09 Triffid_Hunter hm, not sure.. what is it, some sort of fibreglass-impregnated silicone?
01:09 RifRaf dunno, is very soft like silicon so must be
01:11 Triffid_Hunter RifRaf: the headers are serial, SPI and the servo input goes to timer1 input capture
01:11 Triffid_Hunter I reckon could hook an encoder to either the spi or serial pins and make a high current servo controller from it
01:12 Triffid_Hunter it has full current feedback from the h-bridge via ADC as well as hard overcurrent using the analog comparator
01:13 Triffid_Hunter it runs very nicely if you're curious, was in the process of disabling the drag brake when the gearbox stripped
01:14 RifRaf am hearing you but have not dabbled in motors drivers for too long and am rusty, its sounds sick though
01:46 RifRaf yay plugged in this motor driver and it does something by itself, seems i knew how to program something at some point, just backwards and forwards with a break between
01:49 Triffid_Hunter RifRaf: yeah is awesome, makes me want another channel on my remote so I can switch between coast, drag brake and locked antiphase drive modes
01:53 RifRaf must be an awesome car, this is the driver i am trying to work out now, have found a scematic for it since you reminded me about eagle http://rifraf.dyndns.org/images/motordriver.jpg
02:00 RifRaf seems i put a jumper on to disable the power to the max232 for some reason, but without the jumper nothing gets 5v at all, made jumper permanent, so thats one fault fixed, don't remember if these ever got used
02:10 Triffid_Hunter RifRaf: got the car for $100 from dick smith like 15 yrs ago, the electronics were shit and got chucked fairly soon
02:12 Triffid_Hunter already stripped one gearbox a while back.. annoying part is, I open it up and nothing is visibly damaged at all
02:15 RifRaf ah yes, had a few of them, and broke them all, and you can't get parts for them
02:16 RifRaf have some 1/10 electric parts here if you could use em, pretty sure one car just needs some electronics
02:19 Triffid_Hunter oh that would be neat, have been looking for a rolling chassis since I already have all the electronics I need
02:19 Triffid_Hunter if I could work out which part of this gearbox was damaged, I'd simply print or buy a replacement
02:19 Triffid_Hunter but everything in it looks perfectly ok
02:20 Triffid_Hunter can't drift or powerslide anymore, just makes the characteristic nasty crunching sound of gear teeth slipping
02:21 Triffid_Hunter got a "TowardPro" MG996R servo in the front-end, those things are crazy strong
02:21 Triffid_Hunter rated 10kg.cm torque :O
02:21 Triffid_Hunter steering arms on this car are so loose though that it hardly matters
02:21 RifRaf ok cool, will see what i have, was too good to chuck out but i know there would be useful stuff for a hobbiest
02:22 Triffid_Hunter has a good 20 degrees of play at the wheels :/
02:22 Triffid_Hunter which is enough that it can't drive in a straight line without randomly diving off to the side every time it hits a bump
02:23 Triffid_Hunter gotta work the code in the ESC a bit more too, set it so when I drop the throttle it goes into cruise mode, but brings in the drag brake if I bring it back to 0
02:24 Triffid_Hunter cruise is 1 / Hi-Z on the PWM side of the H, drag brake is 1/0, locked antiphase is similar to drag but it reverses the motor on the supply instead of shorting it
02:33 RifRaf Triffid_Hunter http://rifraf.dyndns.org/images/cars.jpg , you can have them if you like, the one with wheels has working steering and 4wd , shocks and stuff are all ok
02:34 Jak_o_Shadows I foolishly took apart some old RC cars that i didn't have the space to store anymore
02:34 RifRaf even has super bright green headlights for night
02:35 Triffid_Hunter RifRaf: done, how shall I send $ for postage?
02:38 RifRaf well i was gonna be up that way soon but could also post, have this huge semi working inverter i was gonna see if you want as well but its too big to post, was just gonna chuck it out cause i don't have the skills to repair it
02:40 Triffid_Hunter what sort of inverter?
02:40 RifRaf 4000w 12V to 240
02:40 RifRaf 8000 peak
02:41 RifRaf it runs things upto a few hundred watts but the buzzer runs continuously as if there is a fault
02:42 RifRaf will take a photo
02:43 Triffid_Hunter wtf 8kw is like 666A, what sort of input terminals does it have?
02:43 RifRaf big
02:43 Triffid_Hunter that's a ludicrous amount of power to draw from 12v
02:43 RifRaf hopefully in the pic, just gonna get it onto server, brb
02:46 RifRaf need to put an ftp server on me android so i can upload images rather than all this usb stuff
02:47 Triffid_Hunter I generally install dropbear on my androids, then use poor man's scp
02:47 RifRaf http://rifraf.dyndns.org/images/inverter.jpg
02:48 RifRaf ok will check it out shortly
02:48 RifRaf is good having a webserver on though, is just a bit limited
02:49 RifRaf all i did was open the invertor and look, and all looked ok
02:50 Triffid_Hunter woah looks epic
02:51 RifRaf yeah has like 100 good IRF hexfets in it
02:51 Triffid_Hunter yea bring that up when you're coming this way
02:54 RifRaf irf3205
02:55 Triffid_Hunter 8mR is pretty good
03:05 RifRaf yep am sure they could be repurposed in motor drivers etc, have enough irf1404 still to last
03:05 Triffid_Hunter I used IRLB8743 on my ESC, those are fantastic
03:05 Triffid_Hunter just recently discovered AOT240L which are jaw-dropping if you're into that sort of thing.. can carry 10A with only 3v on the gate
03:05 Triffid_Hunter and no heatsink
03:06 RifRaf i looked at the hip chips, mine are all hip4081 not hip4082, is there a big difference?
03:08 RifRaf it sickened me a big to go through all me component boxes today, there is no way they will all get used but picked out a stack of stuff that am gonna try get working to do with robotics
03:10 Triffid_Hunter RifRaf: not sure, didn't check 4081 vs 4082
03:12 Triffid_Hunter RifRaf: looks like 4081 has programmable on-time for high and low side, whereas 4082 has a single programmable dead time
03:13 Triffid_Hunter RifRaf: ah, also, HIP4082 has weaker fet drive to reduce EMI, doesn't have charge pump instead relies on bootstrapping
03:14 Triffid_Hunter so hip4081 would probably be even better but the hip4082 works nicely
03:14 Triffid_Hunter RifRaf: if you have time when you come up, we can hook up the car and I'll show you how well this li'l ESC runs :)
03:15 RifRaf ok cool, good to know its still usefull, i don't recall using any fancy features with it anyway
03:15 Triffid_Hunter RifRaf: ever played with IGBTs?
03:16 RifRaf will make sure i have some time, nope not that i recall anyway, have heard the name
03:16 Triffid_Hunter IGBT is basically a complementary pair except the input transistor is a fet
03:17 Triffid_Hunter all on one piece of silicon, they're better than mosfets when I^2.R > Vds*I, ie when you're shooting past 50-100A
03:18 Triffid_Hunter also they do crazy high voltages, have seen IGBTs rated 1200v, 1200A
03:18 Triffid_Hunter as you can probably imagine, gate drive even at 100A is pretty critical to get right, am wondering if there's any specific difference between driving an IGBT gate and a mosfet gate that we need to be aware of
03:19 Triffid_Hunter they're also generally better than mosfets even in the 5-50A range when the voltage is high, 400v+
03:20 RifRaf wow i though fet ratings were crazy
03:33 Tom_itx http://www2.electronicproducts.com/Step_motor_controller_programmed_via_SPI-article-ICDJH04_StMicro_L6482_Feb2013-html.aspx
05:59 MaoIsAcat hi!
05:59 MaoIsAcat Whats the meaning of 4-7 / 8" x 0.8" for a wheel?
07:20 Tom_itx odd but 4 7/8" diameter .8 wide
19:33 euomorf says hello citizens of the w
21:32 shuggans Hello all - Can anyone help a total noob (me) with my first robotics project? - Just need a bit of guidance. Have a MAX232 board + a L298N board. Need help hooking them together... :S
21:32 GuShH shuggans: download their datasheets
21:33 GuShH read them.
21:33 GuShH that's all you need
21:33 shuggans Bought them off of ebay - one is a total japanese board with only japanese info
21:33 shuggans the other came with nothing + no markings
21:33 GuShH reverse it
21:33 GuShH otherwise jokes on you
21:33 shuggans Im a software guy - First delve into this lvel of hardware.
21:34 GuShH start from the ICs by reading their datasheets and see where each trace goes to
21:34 GuShH so pin 1 see what it does, then find it on the board, see where it goes.
21:34 GuShH iterate until you've drawn the schematic.
21:34 GuShH shuggans: chances are the boards are based off of some app note anyway
21:35 GuShH anyway gotta go... good luck
21:35 GuShH software, I hope it's not java or .net.
21:35 shuggans what is vcc?
21:36 GuShH that would correspond to the positive voltage supply
21:36 GuShH You've got a lot to read!
21:37 shuggans Im confused..
21:37 shuggans There is a +5, a GND and a vcc
21:37 GuShH VCC actually stands for voltage at common collector
21:38 GuShH shuggans: you'd have to provide pictures or schematics otherwise it would be an endless guessing game.
21:39 GuShH it could be you are reading the result of a confused amateur designer or just a brainfart on the silkscreen, maybe it requires two supplies, maybe it doesn't... can't tell from what you've said so far.
21:40 shuggans http://ezoneda.en.alibaba.com/product/585578140-213323747/_original_chip_L298N_font_b_motor_b_font_driven_plate_stepping_font_b_motor_b_font_robot_car_font_b_dc_b_font_font_b_motor_b_font_.html
21:40 shuggans It's the green board on that page
21:41 GuShH shuggans: vcc in this case is the power for the load, the 5v is what powers the board itself
21:41 shuggans so battery + to the +5v, battery - to the vcc?
21:41 GuShH so maybe your load requires 12v, that would be vcc
21:42 GuShH the schematic shows a linear regulator with 5v output also...
21:42 GuShH if it's populated, you only need to provide VCC and GND
21:42 shuggans no +5v?
21:43 GuShH as per the schematic, no.
21:43 GuShH but what exactly is populated on your board, I don't know.
21:44 shuggans http://www.ebay.com/itm/150786681292?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 - is on the
21:44 GuShH see if the trace that goes to the 5v terminal also goes to one of the pins on the tiny device in the center of the board.
21:44 RifRaf do you have the small black chip in the center of the board?
21:44 ShH slaps Ri
21:45 GuShH shuggans: if you find a device and you want to know what it does, download it's datasheet.
21:45 shuggans which board?
21:45 GuShH if the device in the middle of the board reads 7805 or similar, that's your linear reg.
21:45 GuShH the motor driver.
21:45 GuShH ok I'm out, good luck.
21:46 shuggans yes
21:46 GuShH tell Mr. chum yang to die.
21:46 GuShH shuggans: ok so you don't need to provide 5v
21:46 RifRaf then vcc will be the voltage your motors want
21:46 GuShH that's just there as a breakout
21:46 GuShH so you can obtain 5v off the board, for other things.
21:46 shuggans 78M05
21:47 GuShH yes.
21:47 RifRaf yep thats the regulator
21:47 GuShH look at the schematic and you'll see
21:47 GuShH S1 toggles 5+
21:47 GuShH VCC goes to IN of 78M05
21:47 GuShH the design is quite poor, prone to oscillations...
21:47 GuShH no discharge diode either, hence why mr yang should die.
21:48 shuggans lol
21:48 shuggans this is a cheapy for me to learn
21:48 shuggans Im going to buy a sabertooth 2x60 for final project
21:48 GuShH whatever that is.
21:48 shuggans jsut want to get a basic working model: I dont mind burning up this $5 board. Id hate to burn the $200 board
21:48 GuShH I suggest you roll your own from scratch, certainly a learnign experience
21:48 GuShH using things is just meh.
21:49 GuShH 200... I should start designing that kind of crap
21:49 shuggans Takes simplified or packetized serial and drives 2 dc motors up to 60 amps
21:49 shuggans http://www.dimensionengineering.com/products/sabertooth2x60
21:50 GuShH you just want to look out for the input level, keep it within range
21:50 shuggans BUT I want to figure this cheapo board out first.
21:50 GuShH shuggans: way too expensive for what it is.
21:50 shuggans I was goign to try and build one: but can't find schematics for what I need
21:50 shuggans Ive never build componenets before.
21:51 ShH 's eyebrow ra
21:51 shuggans so designing is out of my league for the moment
21:51 GuShH and will remain so if you keep being a consumer
21:51 GuShH anyway, that's just too expensive.
21:52 shuggans I woul;d prefer to build a board with that sabertooth's functionality. I jsut have NO idea where to start.
21:52 GuShH shame on them
21:52 GuShH shuggans: h-bridge is the keyword here.
21:52 Tom_itx http://openbookproject.net/electricCircuits/
21:52 GuShH mosfet is the second keyword
21:52 Tom_itx read those
21:53 GuShH the rest is up to you
21:53 shuggans Is there any way to control the board I have now with the rs232 board?
21:53 RifRaf rs232 is just for communication
21:54 RifRaf you will need a controller of some sort to provide the signals
21:54 shuggans yes
21:54 shuggans I have worte a client server application
21:54 shuggans server on the robot... client controller on the "drivers" pc
21:54 shuggans can use kb/mouse or xbox 360 controlelr
21:55 shuggans Have it ready... rs232 board shows receiving signals
21:55 RifRaf sounds cool
21:55 shuggans I jsut dont know what signals I need to send to the com port or how to hook that driver board to the rs232 board
21:56 shuggans it IS cool... has a login system and everything. But its just a sofgtware bot atm... My brother build a tank and gave me the task of "bringing it to life".
21:56 RifRaf you need to look at the L298 datasheet to see what signals it wants, off hand i cannot remember
21:56 shuggans SO im learning as I go... I dont know this deep level of hardware though.
21:58 RifRaf seems likes it a stepper motor driver
22:00 shuggans Whats a stepper motor vs a dc motor?
22:01 RifRaf they both use DC but a stepper has more coils and gets moved in steps rather than just spinning
22:02 shuggans so... possible with the rs232 board I have to control 2 motors through that board I have?
22:02 shuggans motors out of an old playstation 2 controller
22:02 RifRaf maybe the driver does either 1 stepper motor or 2 normal dc motors so you should be ok
22:03 RifRaf how many wires on the motor?
22:04 shuggans 2
22:04 shuggans each motor has 2 (these are the vibration motors out of an old controller)
22:05 RifRaf yep normal dc then, have a read of this, the logic will apply to your driver still http://www.canakit.com/Media/Manuals/UK1122.pdf
22:06 shuggans So what would I connect on that rs232 board to the driver board?
22:07 RifRaf won't work that way
22:07 shuggans what do you mean?
22:07 RifRaf you'll need a controller between the rs232 and the driver, to provide the signals
22:08 RifRaf the controller interperets the rs232 signals and converts them to highs and lows to make the driver do its thing
22:08 shuggans I have PC with server application >> MAX232 Board >> Motor Driver Board >> Motors
22:08 RifRaf yep and you are missing the microcontroller as i said
22:09 RifRaf your motor driver is just a dumb motor driver, it does not have a controller on it
22:09 shuggans Okay - so that sabertooth does then?
22:09 RifRaf dunno
22:09 RifRaf the ones i made do
22:09 shuggans Says it accepts simplified/packetized serial modes
22:10 shuggans S im assuming yes?
22:10 RifRaf well there should be an RX and TX on the board then, connect to that
22:11 shuggans No no no... dont have THAT board yet. bought this as a cheapy to get this all working on before I spent the $ for the good board
22:11 shuggans but this one doesnt have what I need I guess...
22:12 RifRaf if there is no rx/tx then you cannot hook up your rs232 to it, simple as that
22:13 shuggans How much did your motor drivers cost to make?
22:13 shuggans with the rx/tx?
22:13 RifRaf buy yourself an arduino and you have the missing piece, or learn microcontrollers from scrath which might not be worth it for a single project
22:14 RifRaf shuggans from $2 to $200, but the big ones are like 280A or something crazy
22:14 shuggans the final project will run 2 electric wheel chair motors
22:14 MjrTom sounds like youve done some pretty nice work so far shuggans
22:14 RifRaf well not $200, would have got the part for 3 for that
22:15 RifRaf yeah i use those kind of motors, my robot is a bit overweight
22:15 shuggans These are from Pride... dotn say amps or anything. WHat would be a safe assumption
22:16 shuggans MjrTom: Thanks... Im pretty excited about ti
22:16 shuggans it*
22:16 MjrTom yeah I bet - keep going
22:17 shuggans Im trying... just hung up on the hardware peice. Hard to find a starting point. I found the sabertooth board online + that Id need a board off of the serial port with a MAX232 chip... so I bought one... and bought this cheapy motor driver to test with instead of spending $200 on the brand name board right off the gate.
22:19 shuggans RifRaf: ANy experience with Pride motors?
22:19 RifRaf nope
22:19 shuggans 60 Amps should be sufficient for a motor driver right?
22:20 shuggans for wheel chair motors?
22:20 RifRaf yep
22:20 shuggans sweet. So you think I could beuiiold one for less than $200?
22:20 shuggans build*
22:20 RifRaf well going up a hill with with 2 people on it might draw more
22:20 RifRaf all depends on the load
22:21 shuggans lol. Were building a WiFi controleld tank. no one on it.
22:21 shuggans brother built tracks etc.
22:21 RifRaf depends how big the tank is
22:22 shuggans about 2 1/2 ft x 3 1/2 ft
22:22 shuggans he's using steel tubing for the frame.
22:22 shuggans estimates with the batteries it will be 400 - 500 lbs
22:23 shuggans I think that's a stretch though.
22:23 RifRaf yep, well you need to find out the stall current of the motors you use, and biuld 50% bigger than that
22:23 RifRaf well that big, see if the oscm project is still going, those drivers would handle it, have some here
22:24 RifRaf 500lbs is alot of robot when out of control :)
22:25 shuggans ONLY info I can find on the motors is: MOTOR, E675, 85°, 5.44"LG HANDLE, RIGHT, C-1210-008, (ELECTROCRAFT: 675-050-957)
22:25 shuggans other is the left obviously. but I've spent hours scouring google... can't find anything on them spec wise.
22:27 RifRaf this driver will power just about any motor http://www.robotpower.com/products/osmc_info.html but still needs a comtroller which you can find on same site
22:28 RifRaf gotta get ready to go fishing
22:28 shuggans thanks for your help
22:28 shuggans I appreciate it
22:28 shuggans this will power a single motor?
22:29 RifRaf yeah just for 1, but if you are making a 500lb tank i would recomend drivers more that size
23:27 shuggans Can I build a motor driver with this chip: PIC16F628A ?
23:27 shuggans Can I build a motor driver with this chip: PIC16F628A ?