#robotics Logs

Mar 25 2014

17:24 GargantuaSauce well i got my hexapod all up and running again last night after a minor catestrophic failure a couple weeks ago
17:24 GargantuaSauce and i'm probably gonna etch my very first pcb tomorrow
17:33 Toneloc GargantuaSauce- how catestrophic was it ?
17:33 GargantuaSauce http://xn--d-bga.su/deadservo.jpg
17:34 Toneloc GargantuaSauce- first pcb- excellent ! I done the toner transfer but never had the acid to etch yet !
17:34 Toneloc I intend to try brick cleaner and peroxide
17:34 GargantuaSauce i have ferric chloride but it's kinda scary
17:34 GargantuaSauce yeah i want to try hcl /h2o2
17:35 Toneloc oh yeah-that's catestrophic
17:35 Toneloc !
17:35 Toneloc what was that? A mosfet?
17:35 Toneloc and yes, ferric chloride looks scary to me too
17:39 robopal GargantuaSauce, how did this happen??
17:39 GargantuaSauce dangling pointer
17:49 Toneloc GargantuaSauce-as in a laser pointer ?
17:49 Toneloc GargantuaSauce-as in a laser pointer ?
17:49 Toneloc GargantuaSauce-as in a laser pointer ?
17:49 GargantuaSauce no, as in a pointer in c to memory that was not valid
17:50 Toneloc sorryfolks, didn't scroll down and couldn't figure out why it wasn't showing !lol
17:50 Toneloc GargantuaSauce-oh, and what did that make it do that caused this?
17:51 Toneloc send out some signal at too high of a duty cycle or just turn on the device at the wrong time?
17:52 GargantuaSauce i think the mcu sent out a super short pulse as a result
17:52 GargantuaSauce and the servo interpreted that as "push as hard as we can into the endstop"
17:52 GargantuaSauce --->6A later, magic smoke
17:53 Toneloc oh, that's pretty nasty- I have never came across that before- neither do I want to
17:53 Toneloc but I don't reallt deal with electro-mechanical stuff
17:53 Toneloc but anytime I ever did- things like this do happen
17:53 Toneloc *really
17:54 GargantuaSauce bugs affecting physical systems is kind of scary
17:54 Toneloc GargantuaSauce- welcome to Toyota !
17:54 GargantuaSauce heh
17:54 Toneloc :)
17:55 Toneloc "The best built bugs in the world"
19:11 rue_more still on about your smoked servo?
19:11 GargantuaSauce well it's over and dealt with, but it's something i will probably never stop still being on about
19:12 GargantuaSauce because it's the first thing i own that has been melted by a software bug
21:27 rue_more not completely a software bug, the servo should have overload protection
21:29 GargantuaSauce well it counts as a servo firmware bug also
21:32 rue_more you didn't read my servo page did you
21:32 rue_more THEY DONT AHVE FIRMWARE
21:32 rue_more :) I'm gonna return my kingston SSD to them in a 5.25" diskette box
21:33 rue_more GUESS WHICH ONES STILL WORK!?
21:34 GargantuaSauce this one is definitely not analog
21:40 rue_more ah
21:40 rue_more so when the pulses stop it holds its position?
21:40 GargantuaSauce yep
21:40 GargantuaSauce yet they couldn't stick a damn if in there
21:40 GargantuaSauce to check the bounds of the pulse width
22:01 rue_shop2 I dont think you gap the core of a forward converter, ... do you?
22:02 GargantuaSauce gap?
22:05 rue_shop2 yea
22:05 rue_shop2 core gapping
22:05 rue_shop2 significantly increases the energy storage of the core
22:05 rue_shop2 in the right operating modes
22:05 GargantuaSauce isnt that just using an air core
22:05 GargantuaSauce gapping seems like odd terminology
22:06 rue_shop2 no
22:06 rue_shop2 if you take apart a TV flyback coil, you will find there is a cap in the middle of the core under the windings
22:06 rue_shop2 as with any flyback core technically
22:07 GargantuaSauce it increases the saturation current at the cost of inductance, right?
22:07 rue_shop2 hmm, been too long, I think it increases inductance
22:07 rue_shop2 I should read the book I wrote again
22:08 GargantuaSauce anyway every smps i have seen whose topology i have verified to be forward has had a solid core i believe
22:09 rue_shop2 almost all PC supplies are pushpull
22:09 GargantuaSauce yeah not talking about those
22:10 GargantuaSauce one was in a laser printer and another a weird kiosk terminal thing
22:10 GargantuaSauce so full disclosure, grand sample size of 2
22:10 rue_shop2 :)
22:11 rue_shop2 I came up with the MOST AWESOME finger joint
22:13 rue_shop2 there will be better joints out there, but this is my best cable driven one yet
22:14 GargantuaSauce i wanna see
22:37 rue_shop2 I'll shoot it later
22:37 rue_shop2 I'm gonna go eat and sleep
22:37 rue_shop2 tommorow will be a nightmare day
22:37 GargantuaSauce we're getting a blizzard tomorrow
23:56 MrCurious as a going away present from my job, the last 3 days there will be highlighted by asbestos abatement in teh building
23:56 MrCurious would have rather had a box of chocolates