#robotics Logs

Dec 27 2011

01:10 rue_house 25mA
01:11 rue_house hmm
01:11 rue_house easier to make a sourcing or sinking op-amp supply for that...
01:11 rue_house I suppose at that point either is easy
01:11 rue_house sensors is 100 to 200 ohms
01:12 rue_house I can use the 2.5V to my advantage
01:12 rue_house so I want 2.5 to 5V out, so I dont have to invert the calculation
01:12 theBear so long as it isn't drunk... it's wrong to take advantage of things when they are drunk :)
01:12 rue_house meaning
01:12 rue_house hmm
01:13 rue_house sourcing current supply
01:14 rue_house no this screws up where I put my feedback resistor
01:14 rue_house unless
01:14 rue_house I use the rtd to ..
01:14 rue_house so the ... is the ...
01:15 rue_house if the sensor always has the same voltage, and I use the op-amp error to work out what the value is
01:16 rue_house oh I just went in a complete circle, congrads rue
01:18 rue_house voltage needed to provide the same amount of current as the... ARG
02:45 rue_house I can find no op-amps that go all the way to vcc
02:45 rue_house so, in for a foot, in for a torso
03:39 rue_house damn these op-amps
03:39 rue_house if its not a problem wiht the output voltage swing, its a problem with the input voltage swing
03:40 rue_house nowonder none of my op-amp circuits never worked
05:45 Kingsy can someone offer some advice as to why I am getting this error --> http://pastie.org/3078946
05:46 Kingsy basically I am new to robotics and I am just trying to understand the programming process.. i.e how you upload your program
05:52 Tobias| My first thought is that you may not have access to /dev/ttyACM0 without root
05:52 Tobias| but beyond that I have absolutely no suggestions/insight
05:53 Kingsy if you sudo the command you get the same result
06:00 KongfuPanda hello robotics people ! :D
06:02 Kingsy lol this is like a joke.. it doesnt even tell you what the leds on the AVR even mean
06:04 Kingsy hehe there is solid light which means "error" and it says "you can debug this using this utility" but its an .exe what if your on linux???
06:07 KongfuPanda Kingsy, AVR studio 5?
06:08 Kingsy KongfuPanda: see I was hoping to get talking to someone about this.. I don't really know what I am doing, I am just trying to get started.
06:09 Kingsy at the moment, I have a pololu avr connected to a 3pi robot, I am trying to get a blinking led on the avr but I am getting an error http://pastie.org/3078946 when I try to use avrdude to run the program
06:09 KongfuPanda oh, well, I'm a complete noob in Robotics, but I got AVR studio 5 to work on WIndows 7 64bit, with WInAVR compiler, Webbot library (specific to my AXON 2 controller) and a cross -platform java bootloader (also specific to my controller)
06:09 Kingsy KongfuPanda: the avr also has a solid red light on it.. and according to the manual this means "programming" error but the only app to debug this is a windows app
06:09 Kingsy ah
06:10 Kingsy man I just need a 15 minute conversation with someone that has done this before
06:10 KongfuPanda there are probably people here who know about this stuff.. U need to wait untill they wake up
06:11 dunz0r Kingsy: Sure you're using the correct ttyACM-device?
06:11 KongfuPanda Kingsy, but it's AVR studio 4 or 5 ? or is it win avr that you are using?
06:11 KongfuPanda maybe it's something else
06:11 Kingsy dunz0r: yeah, I edited "makefile" and used "ttyACM0"
06:11 dunz0r Kingsy: Sure it's not ttyACM1? Iirc the pololu-programmer creates two ttyACM-devices.
06:12 Kingsy dunz0r: it does, why does it do that? and how do you know which to use?
06:12 Kingsy dunz0r: this tutorial --> http://www.pololu.com/docs/0J36/4.b <-- which is what I am following said to use ACM0 thats all
06:12 dunz0r Kingsy: Don't know. Try with the other one :)
06:12 Kingsy okie dokie
06:13 KongfuPanda http://www.avrfreaks.net/index.php?name=PNphpBB2&file=printview&t=96764&start=0
06:13 dunz0r Kingsy: Also... sure your 3pi has an Atmega168? I'm probably mistaken, but some models have an Atmega328p instead of an 168. Check what yours says.
06:14 KongfuPanda http://www.nerdkits.com/forum/thread/1415/
06:14 KongfuPanda http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=73102
06:14 nz0r ordered some robot parts to
06:14 Kingsy dunz0r: now it says avrdude: stk500_2_ReceiveMessage(): timeout
06:14 KongfuPanda http://www.dontronics-shop.com/avr-isp500.html
06:15 dunz0r Kingsy: Ah. Means it is ttyACM0 after all.
06:15 Kingsy cool ummmm
06:15 KongfuPanda Steffanx, hola !
06:15 Kingsy dunz0r: yeah its a ATmega328p
06:16 Steffanx Ha KongfuPanda !
06:16 dunz0r Kingsy: Then there's your problem :)
06:16 KongfuPanda Kingsy, ask Steffanx, maybe he knows
06:16 dunz0r Kingsy: Since you're telling it is an Atmega168 :)
06:16 Kingsy dunz0r: hang on here, I thought at this point I was just trying to program the avr controller... not the 3pi
06:16 KongfuPanda what is better ATmega328p or ATmega640?
06:17 Kingsy dunz0r: or am I confused? I really just thought I was messing with the avr here
06:17 Steffanx Better.. there is no better KongfuPanda
06:17 dunz0r Kingsy: Are you trying to program an Atmega328p, right now?
06:18 KongfuPanda Steffanx, I got ATmega640 on my little robot :)
06:18 Kingsy dunz0r: I am following this tutorial
06:18 Kingsy http://www.pololu.com/docs/0J36/4.b
06:18 Steffanx It's just peripherals vs more peripherals / ram / flash KongfuPanda
06:18 Kingsy so yeah I think so
06:18 Kingsy so 1 sec I will change that
06:19 dunz0r Kingsy: Then that's your problem. Exchange the values of atmega168 for whatever name the 328p has.
06:19 KongfuPanda Steffanx, also it seems ATmega328p is faster 20 Mhz vs 16 Mhz :(
06:19 Steffanx Ah, true
06:19 KongfuPanda Steffanx, what Mhz did 8086 or something have? like the first processor?
06:20 Steffanx In that case the 328p is probably better
06:20 dunz0r KongfuPanda: Sure you need as much as 20MHz? I mean 16MHz is 16 million operations a second :)
06:20 dunz0r I use 328ps though.
06:20 dunz0r But that's just because that's what I have.
06:21 dunz0r The 328 has more RAM and PROGMEM than the 168 though, iirc.
06:21 KongfuPanda dunz0r, I have ATMega640, which has 16Mhz, I was saying that Kingsy had ATmega328p, and I was wondering which one is better
06:21 Steffanx Not true dunz0r .. 64k vs 32k
06:21 Steffanx nvm :P
06:21 Steffanx You said 168 :P
06:21 Steffanx Oops
06:21 Kingsy hmm just done that.. I got the same error
06:22 Kingsy 1sec I will output what commands I am using
06:22 dunz0r Kingsy: Did you recompile the code for a 328 instead of an 168?
06:22 Kingsy dunz0r: yeah
06:22 Kingsy http://pastie.org/3079097 <-- check it out
06:23 Steffanx Triple check the connections Kingsy
06:23 Steffanx Check the power supply
06:23 Steffanx Check if you have VCC and AVCC connected
06:23 KongfuPanda check that batteries are charged
06:23 Steffanx GND's etc
06:24 KongfuPanda oh man, how many days did I waste trying to program my robot on discharged batteries...
06:24 Steffanx LOL
06:24 dunz0r Kingsy: This looks like something: http://forum.pololu.com/viewtopic.php?t=2122
06:24 dunz0r And make sure you have enough power.
06:24 Kingsy Steffanx: ok can you explain something, what exactly is this code doing? am I programming the 3pi or the avr?
06:24 KongfuPanda :D
06:25 dunz0r Kingsy: There is an AVR, on your 3pi, which you are programming :)
06:25 Kingsy dunz0r: oh, ummm I don't think my 3pi is turned on then
06:25 Steffanx Oh, it's on a board :)
06:25 dunz0r Kingsy: Haha that might be a problem :D
06:25 Kingsy honestly I couldnt find a on/off switch on the 3pi
06:25 Steffanx :S
06:26 Kingsy I put some batteries on it, but it does nothing
06:26 Kingsy lol sorry guys, you all must think I am a dumbass
06:26 dunz0r Kingsy: Checked polarity?
06:26 dunz0r A bit, yes. :)
06:26 KongfuPanda e)_(e <-Kingsy
06:26 KongfuPanda mhahaha
06:26 dunz0r Kingsy: http://www.pololu.com/docs/0J21/4.b
06:27 Kingsy thanks.. looking now
06:27 dunz0r "Next, push the power button (located on the left side of the rear battery pack) to turn on your 3pi"
06:27 KongfuPanda joking
06:27 dunz0r Hey. Everyone does things like this :)
06:27 Steffanx I did it too when i started with AVR's ages ago
06:27 Steffanx Programmer => AVR
06:27 Steffanx No power supply
06:28 Steffanx "Why it doesn't work?!?!?!"
06:28 Kingsy ok doing it now
06:28 dunz0r Anyone have any experience with Lynxmotions "sumo wheels" btw?
06:28 dunz0r I just ordered four
06:29 Kingsy ooook now I have some action
06:29 dunz0r These: http://www.lynxmotion.com/p-112-green-dot-sumo-tire-288d-x-15w-pair.aspx
06:29 KongfuPanda Steffanx, can you explain to me what is he doing? is he using a hardware programmer? or trying to setup AVR studio or something?
06:29 dunz0r Kingsy: Congratulations \o/
06:29 Steffanx No, i missed that part of the conversation KongfuPanda :)
06:29 Kingsy just uploading the program now, see if it works
06:29 Steffanx but i think he does KongfuPanda
06:29 dunz0r KongfuPanda: He's using a pololu programmer, with avrdude as the software on his linux box.
06:30 KongfuPanda Kingsy, what's your battery voltage?
06:30 KongfuPanda dunz0r, i see
06:30 dunz0r I use avrdude too. It's great in combination with avr-gcc and vim.
06:31 Steffanx vim :( :P
06:31 KongfuPanda I use WInAvr and bootloader (no hardware programmer)
06:31 Kingsy well I uploaded the program, it seemed to upload ok but it did nothing
06:32 dunz0r Steffanx: What's wrong with vim?
06:32 Steffanx nvm dunz0r
06:32 Kingsy KongfuPanda: I have no idea
06:32 KongfuPanda Kingsy, are you going to use C++ or C?
06:32 Kingsy C
06:33 Kingsy I think its nearly 10 Volts
06:33 Kingsy I kinda want this to be slowed down a little, things arnt working and I am not sure whats going on
06:34 KongfuPanda Kingsy, anyway, there is this program called Webbotlib and Project designer that can generate for you low -level programming for ATMega328p or whatever. SO that the only thing left for you is to write the actual code in C in AVR studio.
06:34 KongfuPanda Kingsy, I'm trying to generate source files right now for that
06:35 Kingsy YAY I got it working
06:35 Kingsy the first command is to erase the chip
06:36 Kingsy the second uploads the program
06:36 KongfuPanda Kingsy, see if this has anything useful: http://dl.dropbox.com/u/26776513/328p.zip
06:36 Kingsy cool I will check it out
06:36 Kingsy KongfuPanda: but I have a light blinking now! :) which is good
06:37 dunz0r Kingsy: Great! Nice work :)
06:37 KongfuPanda Kingsy, excellent. e)_(e -> ^_^
06:38 KongfuPanda webbot.org.uk/iPoint/37.page
06:38 KongfuPanda that's what I use
06:38 KongfuPanda because I don't want to deal with low-level programming and stuff
06:39 Steffanx Nah KongfuPanda
06:39 KongfuPanda or rather because I don't have time or knowledge
06:39 Steffanx The low-level stuff is the nicest part
06:39 KongfuPanda {@.@}
06:39 KongfuPanda sure, if you don't have homeworks that take you 1 week to do if I spend 7 hours a day doing it
06:40 KongfuPanda +lectures, +projects, +life
06:40 dunz0r Priorities :)
06:40 KongfuPanda I study Physics :( /cry
06:40 ngfuPanda
06:40 dunz0r I usually make time for robot programming/building, otherwise there's no time for it.
06:41 KongfuPanda dunz0r, what do you do?
06:41 dunz0r Write "robots!" in my calendar on about one sunday a month
06:41 KongfuPanda I mean for living
06:41 dunz0r KongfuPanda: I work in IT. Network engineer.
06:41 Steffanx Physics is also low-level KongfuPanda :)
06:41 KongfuPanda student? work?
06:41 KongfuPanda oh nice
06:43 KongfuPanda Steffanx, yeah, it's low level Physics atm :D I'm in my final year of MPhys. Applying for a PhD now. Maybe in material science. I love graphene. Have you heard about it? it's going to replace your silicon and everything . Because the lattice is such that it counteracts the mass of electrons inside, so they behave like relativistic Dirac-Fermions, and basically move much much faster than...
06:43 KongfuPanda ...electrons in Silicon. Almost approaching speed of light in that material.
06:43 KongfuPanda i.e. electrons inside are massless
06:43 Steffanx Yes, i've heard about it
06:44 Steffanx A tech website i visit has an article about it once i a while
06:44 KongfuPanda people who isolated it in 2005 got a Nobel prize in it in 2010. And there's a huge boom of patents everywhere, from transparent screen to chip on graphene
06:45 Steffanx Yeah, didn't that guy just use a pencil and type?
06:45 KongfuPanda it's also the hardest material know to man, because it's Carbon. I.e. chicken-wire structure of carbon atoms
06:45 Steffanx *tape
06:45 Tom_itx i thought diamond was
06:46 Steffanx Which is carbon Tom_itx :)
06:46 KongfuPanda yeah, in every pensil there's graphIte : layers of graphene weakly stuck together. People have known about graphene for ~60 years now. But it was thought to be unstable, since it's 2D, and if it's completely flat , every tiny thermal fluctuation would destroy the lattice. But in fact, it's not completely 2D, it has hills and valleys. Like this: http://www.nanowerk.com/spotlight/id2340.jpg
06:46 KongfuPanda and this is why it's stable
06:47 Tom_itx i talked to a guy the other day that was really into that stuff
06:47 Steffanx Physics like that are too difficult for me KongfuPanda
06:47 Steffanx :)
06:47 Tom_itx he's a scientist and does wafer testing
06:47 Steffanx Sounds like a boring job
06:48 Tom_itx been all over the world
06:48 Tom_itx for ibm, toshiba etc
06:48 Steffanx I need a battery/adapter in a AAA enclosure, does that exist?
06:48 KongfuPanda and two Russian guys working in Manchester university, used "tape method" to isolate a tiny bit of graphene. THey were quite lucky, because graphene is transparent, but not entirely, and after this tape method they accidently found a tiny almost transparent layer of graphene, and did some measurements on it, and were like WTF, this has properties of graphene
06:49 KongfuPanda so graphene is stable
06:49 KongfuPanda and quite strong
06:49 KongfuPanda Tom_itx, I want to do a PhD in graphene
06:50 KongfuPanda in particular, trying to make a solar cell based on graphene
06:50 Steffanx Sounds nice KongfuPanda
06:50 KongfuPanda since it's transparent it's useful as conductor on top of cells. Metal conductors reflect light and so on
06:50 Tom_itx it was interesting talking to the guy but most of it was over my head
06:51 KongfuPanda or there's another PhD project about testing how fast can electrons go in graphene or carbon nanotubes
06:51 Tom_itx he was one of the few that had been in the field long enough he didn't have a Phd but said nowdays it's a requirement
06:51 KongfuPanda Tom_itx, it's because you think it's complicated and your brain refuses to understand it, although it's commong language/knowledge
06:52 KongfuPanda I might make a website of notes on Physics. :D
06:54 KongfuPanda Every year before exams I write "summary notes", because if I don't write it I can't remember it. ANd usually I try to do it very very thoroughly, but only essential bits. (on my tablet pc). And they turned out to be very useful in #physics channel :D some people loved them, and even demanded all of my notes
06:54 KongfuPanda this year I will have to make some on advanced condensed matter
06:55 KongfuPanda but anyway, this is robotics channel :D
06:55 KongfuPanda some of you should make like a website for noobs
06:55 Tom_itx rue has somewhat of one
06:55 KongfuPanda I think that these days people don't have to learn "low level " stuff to progress in many fields
06:56 Tom_itx they should
06:56 KongfuPanda nah
06:56 dunz0r KongfuPanda: This is quite good and beginner friendly http://www.robotroom.com/
06:56 Tom_itx gives you a better understanding of things
06:56 KongfuPanda looks nice dunz0r
06:57 dunz0r Yeah. It's a bit lowlevel as well :)
06:57 dunz0r Just the way it should be :)
06:58 KongfuPanda well, suppose I want to build a robot that can plant stuff on solar cells.
06:58 dunz0r KongfuPanda: You mean it should be powered by solar cells or that it should drive around and put things on solar cells?
06:58 Tom_itx there was a guy in #emc that was working at that level i believe
06:59 Steffanx KongfuPanda you should get me a AAA battery with wires .. i mean a battery without the chemicals inside it :)
06:59 Tom_itx 'nanobotics'
07:02 Steffanx * mean AA
07:03 KongfuPanda dunz0r, it will have a big solar cell on tom, probably on wheel or some other low-energy platform. And probably robotics hand. And it need to be programmed and loaded with seeds, and once it 's charged it will go and plant seeds. Once it's discharged it will wait until it's charged again and continue
07:04 Tom_itx solar cell with supercap
07:05 KongfuPanda Steffanx, yeah, there's a lot of research about that stuff. I heard from one professor that there's a company that is trying to make current go around a superconducting cylinder. In superconductors there's 0 loss of current. So, if somehow you make it loop around, you will get a very powerful permanent magnet. It with some other modifications it can be used as energy storage
07:07 KongfuPanda I think even though we have like lithium batteries and stuff, they are nowhere near the energy capacity that we need
07:08 KongfuPanda it's all still based on chemical processes, I think we will need some other "cleaner" process in the future. Like magnetic storage or something
07:08 Tom_itx it's already stored for us we just have to release it
07:09 Steffanx I actually meant some batteries i can use inside some xmas stuff, with a wire so it's power by 230V KongfuPanda :)
07:09 Tom_itx or move it to a useful container
07:09 KongfuPanda Tom_itx, what do you mean?
07:09 Steffanx For my mother :)
07:09 KongfuPanda you mean like electric shock prank?
07:09 Steffanx Some lights draw 300mA .. too much for 2 AA batteries
07:10 KongfuPanda oh
07:10 KongfuPanda yeah
07:10 Steffanx So I what battery a-like things with wires so i can power them using an adapter :)
07:13 KongfuPanda Steffanx, I had a similar problem with my robot. It needed ~1-2A of peak current , 7V and small weight. I got three Li_ion camera batteries (7.4V each) 1800mAh each. And connected them in series, together with ~5 different capacitors.
07:13 KongfuPanda and they just use standard automatic camera charger
07:14 KongfuPanda I tested their actualy capacitance, and got like 1500 mAh (since I bought them on ebay).
07:14 Steffanx I can find this.. http://www.dealextreme.com/p/translucent-aaa-to-aa-type-battery-converter-cases-4-case-54457 but that's still not really what i'm looking for :(
07:14 KongfuPanda and for some reason those 3 batteries are lighter than 3mAh Li-pO battery
07:15 Tom_itx maybe you got cheated on them
07:15 KongfuPanda Tom_itx, how come?
07:15 Tom_itx i've gotten cheap batteries of supposedly higher capacity that didn't last at all
07:16 KongfuPanda http://www.ebay.co.uk/itm/2X-1800mAh-NB-2L-NB-2LH-BP-2LH-Battery-Canon-Camera-/390323243301
07:16 Steffanx The problem is just .. with 300mA the batteries are empty within a few hours
07:16 Steffanx *few evenings
07:16 KongfuPanda mine have been working for a few months now. I gone bad (before I added the capacitors)
07:16 KongfuPanda 1 gone*
07:17 KongfuPanda Steffanx, yeah, that what I was saying that even with current technology the capacity is still not so good
07:17 KongfuPanda for many applications
07:17 Steffanx Indeed
07:18 Steffanx xmas lights for example :P
07:20 Steffanx With real tiny lightbulbs instead of led's
07:21 KongfuPanda Tom_itx, did you click that link? their weight is 31g. I checked it's ~50g. So 3 batteries weigh ~150g. And have capacity ~ 4500 mAh. Now, lipo batteries say http://www.tresrey-usa.com/racers-edge-7-4v-60c-4000-race-edition-short-lipo-battery/ , 7.4V, 4000mAh weighs 340 g.
07:21 KongfuPanda I don't get it
07:21 KongfuPanda how is it possible..
07:22 Tom_itx they are lying to you
07:23 KongfuPanda yeah, but I checked the capacitance myself , by discharging 1 battery for 4 hours, then integrating it over 5*decay time
07:23 KongfuPanda and got ~1500mAh per battery
07:23 KongfuPanda yeah, not 1800mAh as promised, but still
07:23 Tom_itx they won't live as long either
07:23 KongfuPanda (5*decay time was ~25 hours)
07:24 KongfuPanda sure, but with extra capacitors in parallel to reduce the fluctuations they live reasonably long for the price
07:24 KongfuPanda ($5 per battery)
07:25 Tom_itx there are so many misrepresented batteries on the interweb it's hard to know when you're actually getting what is advertised
07:25 Steffanx Sanyo ftw :)
07:26 KongfuPanda Tom_itx, so to your knowledge there's nothing better than li-po batteries ?
07:27 Tom_itx not that i'm aware of
07:29 KongfuPanda well, maybe I need to test these batteries more thoroughly. Since i was discharging them over a fan :D mhahaha
07:29 KongfuPanda I was told it's non-linear or something
07:30 KongfuPanda anyway, I got this graph: http://dl.dropbox.com/u/26776513/Graph1.pdf
07:30 KongfuPanda x axis is time, y -axis is current
07:31 KongfuPanda I integrated it over 25 hours, but I don't know if it would last that long. It was just an approximation
07:31 KongfuPanda and got 1500 mAh
07:32 Steffanx I think that's even that bad
07:32 Steffanx When they say it's 1800
07:33 KongfuPanda well, they don't except people to test it I guess :D
07:33 KongfuPanda but 1500 is still A LOT
07:33 KongfuPanda and I think it wasn't fully charged actually
07:33 KongfuPanda I just wanted to have a very rough idea
07:33 KongfuPanda if it's like 900 or something
07:34 KongfuPanda I will do this test again, on 3 batteries, But I need to find something that's linear
07:34 KongfuPanda maybe a resistor
07:38 KongfuPanda but it seems too good to be true to me so far
07:38 KongfuPanda lighter and higher capacity that lipo...
07:38 Tom_itx like i said, they're lying to you
07:38 KongfuPanda and easy to charge: just put in the camera charger , wait for light to go from red to green and it's done
07:39 Steffanx There are lots of tests on the www KongfuPanda
07:39 KongfuPanda Tom_itx, if I do the tests, will you change your mind?
07:39 KongfuPanda maybe they put li-po batteries inside?
07:39 KongfuPanda who knows
07:39 Tom_itx my experience is that over time they deteriorate quicker too
07:40 Tom_itx cheap mfg process = cheap inferior product
07:41 Tom_itx i haven't found a replacement battery yet that lasted like an OEM one
07:42 KongfuPanda I see
07:42 KongfuPanda anyway, for my budget robot it's fine :P
07:42 Tom_itx i didn't say you wouldn't get use out of them
07:43 Tom_itx they should tell you exactly what you are getting though
07:43 KongfuPanda true true
07:44 KongfuPanda I have no evidence that they are lying so far
07:44 Steffanx Tom_itx you never watch tellsell do you? :P
08:28 KongfuPanda http://www.youtube.com/watch?v=cpnoYEMMYdk
08:45 Steffanx You like that bullshit KongfuPanda ?
08:45 KongfuPanda Steffanx, haha :D it's funny
08:45 Steffanx if you say so
12:56 KongfuPanda {@.@}
13:01 Steffanx ?
13:01 effanx doesnt recognize that pic
13:02 rue_bed {4,3};
13:02 Steffanx Yes rue_bed
13:03 Steffanx This is your clipboarD?
13:04 rue_bed \/{(/d+),(/d+)/}\
13:04 KongfuPanda how about this one:
13:04 KongfuPanda ( * )( * )
13:04 KongfuPanda \ . /
13:04 rue_bed pff
13:04 KongfuPanda ( V )
13:04 KongfuPanda ta da
13:05 rue_bed keep the ascii art clean eh?
13:05 joink I bit on the pudgy side
13:05 joink eh. A
13:06 KongfuPanda you give me an A, joink? thanks man
13:06 rue_bed ok <-- its a person, the o is the head and the k is all the limbs
13:06 Steffanx OK
13:06 joink space man!
13:06 rue_bed its stewie!
13:06 rue_bed good one
13:06 KongfuPanda e)_(e
13:07 rue_bed U
13:08 rue_bed well, recon I should get up
13:09 Tom_itx you recon?
13:11 KongfuPanda raccoon ?
13:11 Steffanx baboon
15:42 rue_shop hmm I dont have any 1/2" id bearings
15:42 rue_shop the motor will use bushings
15:42 rue_shop so if I cant recover the origional shaft, which is unlikley, then I'm pooched
15:53 rue_shop drat, 1/2" is exactly between everything I have
15:54 Tom_itx damn canadian metrics
16:05 rue_shop even my imperial stuff
16:06 rue_shop I cant replace the motor till I can get some beraings on a 1/2" shaft
16:07 Tom_itx https://www.vxb.com/
16:07 Tom_itx what OD?
16:08 Tom_itx what width?
16:08 Tom_itx http://www.vxb.com/page/bearings/CTGY/1-2inch
16:14 rue_shop it dosn't matter
16:14 rue_shop the origional motor has to have its shat drilled and cut to get it off the cage
16:15 Tom_itx you can't press it off?
16:15 rue_shop if the shaft could stay in tact, I'd remove the field and armature from the motor and fold it down into a bearing set with the shat going out the back, and fit a pulley onto it, drive that with the new motor
16:15 rue_shop no, I cant get it out of the assembly wihtout taking the cage off
16:15 rue_shop and the set scerw that holds the cage on is siezed and stripped
16:16 Tom_itx they have decent cheap bearings
16:16 rue_shop yea, I have other options, just have to find them
16:17 Tom_itx they had my SS washer bearings
16:17 Tom_itx cheaper than local
16:18 Tom_itx i doubt local had SS though
16:18 rue_shop excellent, I dont want to spend the money
16:18 rue_shop or wait for parts
16:18 Tom_itx well you never do
16:18 Tom_itx so why am i not surprised
16:19 rue_shop I weant an asembly, I just havn't thought of where it comes from yet
16:19 rue_shop but I also have another problem the only sprocket I have that fits the motor I want to use has no matching sprocket for a 1/2" shaft
16:20 Tom_itx maybe this birthday you can get a lathe
16:21 rue_shop too late
16:22 rue_shop I just need to find an induction motor witha 1/2" shaft
16:23 rue_shop which I suspect would be about 1/4HP
16:23 rue_shop er 1/8
16:24 rue_shop the brushless motor I have has a shaft that too big
16:24 rue_shop by 5 thou
16:25 Tom_itx 11
16:25 Tom_itx that would be 13mm
16:30 rue_shop the motors I dont want to use direct are .625"
16:30 Tom_itx 5/8
20:08 rue_house damned op-amps
20:09 rue_house if I have a op-amp on a 5V supply, its outputs cant go to 2V within the rails, so I have a whole freaking 1V to work with
20:19 m_itx offers rue_house some leftover
20:21 theBear don't say that, i was gonna try pushing the limits a bit later thismorning
21:32 rue_house I have a problem that should be easy and its giving me trouble
21:32 home hai
21:33 Tom_itx rue_house, the op amp?
21:33 rue_house I have a variable resistor, 100 to 200 ohms, and I want to put it in a voltage divider such that there is a 1V difference in output as the resistor is valied from 100 to 200 ohms
21:34 Tom_itx oh
21:34 rue_house dosn't that sound easy?
21:34 Triffid_Hunter rue_house: with a linear relationship? use a constant current source
21:34 rue_house no, with a 2 resistor voltage divider
21:35 home better..start....hmm..
21:35 Triffid_Hunter rue_house: ah well it won't be linear.. just a simultaneous equation from there I think, two voltages for two resistances, solve for the other resistor in the divider and V+
21:36 rue_house pls, go for it
21:37 Tom_itx 5v ref?
21:37 rue_house yes
21:37 Tom_itx 5v what's the vdrop across 100 and 200 ohm respectively?
21:38 rue_house setup however you want
21:38 rue_house the resistor changing from 100 to 200 ohms shoudl cause a output difference of 1V
21:38 rue_house :/ lost my calculator
21:39 home i lost my soul
21:39 rue_house python
21:39 rue_house erp
21:43 rue_house I'm starting to think its not possable, but I cant prove it
21:43 home everything is not possible :D
21:44 Tom_itx i get 400 and 800 ohms to stay within 1v differential
21:44 rue_house hu?
21:44 rue_house the other resistor has to be fixed
21:44 Tom_itx not sure you can
21:44 Tom_itx i know
21:44 Tom_itx err wait
21:45 rue_house sounds like what I been saying to myself for hours now
21:45 home cool
21:46 Tom_itx try 140 ohm
21:46 Tom_itx 150
21:46 rue_house 5V 140R vout 100-200R gnd?
21:47 Tom_itx 140
21:47 Tom_itx 2-3v range
21:47 Tom_itx you might get it closer if you go for a more midrange voltage between 5 and 0
21:48 Tom_itx well 2.5 is
21:48 home 2.75
21:48 Tom_itx probably about as close as you're gonna get
21:49 Tom_itx yes rue, try that
21:49 Tom_itx and see what you get
21:50 rue_house I get 2.083 to 2.941
21:50 Tom_itx it won't quite be 1v
21:50 rue_house so thats really close
21:50 rue_house how did you come up with that
21:50 Tom_itx wag
21:50 Tom_itx :)
21:50 Tom_itx http://www.electronics2000.co.uk/calc/potential-divider-calculator.php
21:50 Tom_itx stuffed some numbers in that
21:51 rue_house hmm
21:51 Tom_itx the bottom one
21:51 Tom_itx v1 5
21:51 Tom_itx r2 100 and 200
21:51 Tom_itx and tried a 1v variance
21:52 Tom_itx 150 + 133 / 2
21:52 Tom_itx ~141 ohm
22:01 rue_house R1: 141.100067 Vh: 2.931691 Vl: 2.073828 dV: -0.857863
22:01 rue_house R1: 141.200073 Vh: 2.930832 Vl: 2.072968 dV: -0.857864
22:01 rue_house R1: 141.300079 Vh: 2.929973 Vl: 2.072109 dV: -0.857864
22:01 rue_house R1: 141.400085 Vh: 2.929115 Vl: 2.071250 dV: -0.857864
22:01 rue_house R1: 141.500092 Vh: 2.928257 Vl: 2.070393 dV: -0.857864
22:01 rue_house R1: 141.600098 Vh: 2.927400 Vl: 2.069535 dV: -0.857864
22:01 rue_house R1: 141.700104 Vh: 2.926543 Vl: 2.068679 dV: -0.857863
22:07 rue_house well the current there are too high for the sensor, but thats still an interesting problem
22:07 Tom_itx increase the resistance in the divider?
22:13 rue_house wont give you more tho
22:13 Tom_itx no
22:13 rue_house if I wanted .103V I'd use 4550 ohms
22:13 Tom_itx i thought you needed less
22:14 rue_house but I only know cause I had the computer do 200000 calculated runs
22:14 Tom_itx current that is
22:14 rue_house yea, its gonna have to be done with an amp
22:14 rue_house it turned into a bit of an accademic problem
22:15 rue_house I have a transistor amp here that MUST be close to what I want
22:15 rue_house I'm just a little too clumsy with transistor amp circuits
22:16 rue_house and this isn't a standard amp circuit, I deal best with capacitor coupled AC ampliders
22:16 rue_house this has to be DC coupled
22:16 Tom_itx what's this for?
22:17 rue_house this is for a exhaust gas temp sensor for the boiler
22:17 Tom_itx oh
22:17 rue_house no other sensor I have can take the temps
22:17 Tom_itx how hot?
22:17 Tom_itx more than 500c?
22:18 rue_house there are two sensor elements in it, but one is shot, your supposed to make a wien bridge with it
22:18 rue_house no, I think that the max temp is 250c
22:18 Tom_itx pt100 will take that much
22:18 rue_house call it 300 be safe
22:18 Tom_itx or pt1000
22:18 rue_house I have these....
22:18 Tom_itx yeah yeah i know
22:19 rue_house I suppose I could use a working one and put an instermentaion amp it on
22:19 rue_house but I wanted to keep it really simple
22:20 rue_house I'm not used to designing transistor amps around resistances that change
22:27 rue_house idea
22:28 rue_house lots of variable resistors, a freq gen, and a fet , ... and the scope
22:28 rue_house this math is so touchy the results are gonna be useless anyhow
22:29 rue_house problem with my waterproofing scheme
22:30 rue_house I'm gonna need to find tupperware that can take 300c
22:32 Tom_itx how so?
23:53 rue_shop so
23:53 rue_shop temp = (614-(adc-205))/2.36
23:54 rue_shop 614+205-adc
23:54 rue_shop 809-adc
23:54 rue_shop did I do that right?
23:54 rue_shop 819
23:55 rue_shop (819-adc)/2.36
23:57 rue_shop cool!
23:57 rue_shop 1 transistor, 4 resistors, 2 trims, and its done!
23:58 rue_shop I could put it in a shrinkwrap in the cable if I really wanted to
23:59 rue_shop so then, hmm
23:59 rue_shop need to figure out how I built the io bank so I can make a card for this