#robotics Logs

Apr 13 2013

01:35 Jak_o_Shadows motor drivers. Should look at that
01:38 Triffid_Hunter printers usually just use a ULN2803 or similar
01:39 rue_house no, 4 wire motors are popular and they come with current regulated drivers
01:41 Triffid_Hunter must be new, all the printers I've taken apart had 5-wire motors and uln2803 or discrete equivalent to drive them
01:42 rue_house oh
01:45 Jak_o_Shadows these are 4wire motors. Mitsumi M35SP-7T http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&ved=0CGYQFjAI&url=http%3A%2F%2Fvinvin.dyndns.org%2Fprojects%2FM35SP-7T.pdf&ei=0vtoUZPSC4iRiQfb4oDQBw&usg=AFQjCNENz-2FuiAQHsh7eY1B3nWriouskg&sig2=wh7eCKyH_HNRZTuS3TJZfg&bvm=bv.45175338,d.aGc , MITSUMI M42SP-6TG http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CFEQFjAD&url=http%3A%2F%2Fwww
01:45 Jak_o_Shadows
02:40 rue_house power went out gnight
11:21 fooman2011 Hello guys, I'm very very noob. I have a little robot. I want that it came back to its charge beacon. How to detect the position and the distance between the bot and the beacon ? This must work even trough the walls... I'm mean IR are for low distance...what technology should I use ?
11:24 fooman2011 Guys ?
11:28 fooman2011 ?
11:32 fooman2011 Anyone here ?
11:41 zap0 yes, didn't you read the topic?
17:53 rue_shop2 yaya I glued the cloth back to the cieling of my truck!
17:57 rue_house er, yay
17:57 rue_house even
17:57 rue_house ok 5 min rest
18:13 Tom_itx with what?
18:13 Tom_itx mine was starting to come loose before i got rid of it
19:28 Jak_o_Shadows Triffid_Hunter: Did you have a circuit that uses a hip 4082? If you did, could you relink itplease?
20:00 Jak_o_Shadows Tom_itx: Is your site down?
20:07 Tom_itx umm
20:07 Tom_itx i dunno
20:07 m_itx l
20:08 Tom_itx lemme go fix it
20:08 Tom_itx brb
20:08 Jak_o_Shadows Cool. Thanks
20:12 Tom_itx should be nice n quick now
20:14 Jak_o_Shadows thanks, tworking now
20:40 Triffid_Hunter Jak_o_Shadows: http://triffid-hunter.no-ip.info/esc_sch.png
20:41 Triffid_Hunter Jak_o_Shadows: the hip4082 is set up so you hook [AB]HI to simple GPIO then run your PWM on [AB]LI
21:11 Jak_o_Shadows Thanks
21:12 Jak_o_Shadows How necessary is the overcurrent sense?
21:15 Triffid_Hunter Jak_o_Shadows: if your motor's stall current is within the mosfet's capabilities given your supply's max voltage you can skip it
21:15 Jak_o_Shadows Ok cool, I can check that.
21:15 Triffid_Hunter Jak_o_Shadows: P=I^2.R, Rds(on) increases by up to 2.25x as the mosfet heats up and the TO-220 package can dissipate 2 watts without a heatsink
21:16 Jak_o_Shadows Oh, i'm definitely heatsinking. They're coming a little late in arriving, but I will be using some.
21:17 Triffid_Hunter Jak_o_Shadows: so those IRLB8743 I use should be good to about 19A without heatsinks
21:18 Jak_o_Shadows I have some irf640s, I'm not anticipating more than 10A stall current. (It may be just 6A)
21:20 Triffid_Hunter Jak_o_Shadows: yikes, 180mOhm Rds(on)! those are dreadful
21:20 Triffid_Hunter Jak_o_Shadows: maximum 2A without a heatsink
21:21 Jak_o_Shadows Definitely using a heatsink. May even use an old 80mm 12V computer fan for some more cooling.
21:22 Jak_o_Shadows I got those because the drill came with one, so it must vaguely work, and I have a spare in case I blow one.
21:32 Triffid_Hunter Jak_o_Shadows: if you go shopping for new ones, the most interesting value in the datasheet is Rds(on)
21:32 Triffid_Hunter ignore Id(max), that figure is fairly useless
21:33 jesseg Howdy folks!
21:33 Triffid_Hunter hey
21:33 jesseg How's it going Triffid_Hunter ?
21:35 Triffid_Hunter good, actually have some sunshine here today
21:35 jesseg I'm really interested in these DIY drones style IMUs or spark fun units. Having not saved up the pennies for long enough to get one of my own I'm sort of curious to hear from somebody who has
21:35 jesseg sun-what? oh be quiet! it's raining here! :-)
21:35 jesseg Actually the sun did shine for a little while here between rain storms
21:36 Triffid_Hunter it's been raining here for like 4 months
21:36 jesseg what state? Washington (Western) here -- so I guess I can expect a fair amount of washing.
21:36 Triffid_Hunter nsw Australia :P
21:36 jesseg oh ha!
21:37 jesseg well it looks like there's not very many folks in my timezone here
21:38 Jak_o_Shadows Lots of australians on the internet actually
21:38 Jak_o_Shadows More than I would have suspected
21:38 Jak_o_Shadows either that, or our timezone is whacked in regards to the most populus areas
21:39 jesseg with all those kangaroos to carry data packets in their packet pouches it's no surprise to me
21:41 Jak_o_Shadows BTW Triffid_Hunter, why the resistors before the gate of the mosfets? The example in the thing doesn't have them.
21:42 Triffid_Hunter Jak_o_Shadows: because the gate looks like a ~2nF capacitor. the pcb trace has some inductance. when you have an inductor and a capacitor in series, you have a resonator
21:42 Triffid_Hunter Jak_o_Shadows: when your mosfet's gate voltage is ringing with RF, they tend to melt down
21:42 Jak_o_Shadows Which is bad. Gotcha.
21:42 Triffid_Hunter the resistor is there solely to bleed energy from the LC resonator and stop the gate from ringing
21:43 Triffid_Hunter Jak_o_Shadows: value is typically 10-22nF
21:43 Triffid_Hunter sorry, ohms
21:43 Jak_o_Shadows Yeah, that's no problem, and easy enough to do
21:43 Triffid_Hunter resistor should be as close to the mosfet gate as practical
21:43 Jak_o_Shadows Thanks
21:44 Triffid_Hunter Jak_o_Shadows: http://triffid-hunter.no-ip.info/esc_brd.png <-- can see here that some are actually placed under the mosfets
21:45 Jak_o_Shadows I'm planning on using a scrap of protoboard (the one with the metal strips, not just the holes)
21:51 Jak_o_Shadows !thisone
21:51 Jak_o_Shadows !thislog
21:51 Jak_o_Shadows tobbor noooooo
22:08 rue_mohr it wasn't a diode that went in the ups, it was a surge arrestor
22:12 Tom_itx kindof ironic
22:12 Tom_itx they're supposed to protect
22:14 rue_mohr I dont know where I'm gona find a replacement
22:15 Tom_itx pull one from a surge protector