Electrical Engineering - 2013-04-21 (page 2 of 2)

« first day (906 days earlier) ← previous day next day → last day (4031 days later) »

user61389

12:01 PM

@PeterJ it does say things like replying to ARP request on the serial communication, but it keeps getting the requests, so I'm going to check that out! Thanks!

12:19 PM

@CamilStaps, ignore what I said above about ARP not mattering for static IP, of course it does I had the previous DNS / WINS thing stuck in my mind and didn't re-read properly.

refresh my comment @CamilStaps

user61389

@jippie I know, I've been using it for those purposes :)

user61389

Testing only, of course, to make things more secure, that kind of things

Yeah Wireshark is a good idea to see what happens on the PC end (plus what it received)

user61389

Hmm, I'm getting the ARP request Who has 192.168.0.1? Tell 192.192.192.192 - the sender MAC address is 00:00:00_00:00:00. Like the ENC isn't initialized, could that be the problem?

12:37 PM

@CamilStaps Sounds like it, after a quick look at the datsheet that's the default. I'm heading off soon but it might be worth reading back some registers you're setting to see if they change.

user61389

@PeterJ will do, going to take a deep dive into those libs.. Thanks a lot for your help! Really, really helpful :)

Realize that before you can have IP traffic (layer 3), you need to establish a 'connection' on layer 2. Layer two is all about MAC addresses. If the MAC address in your packets is wrong, the NIC (network Interface Card) will drop the packet.

@CamilStaps so what is happening with ARP is trying to figure out the MAC address that goes with a given IP address

user61389

@jippie so ARP is to go from layer 2 to layer 3?

it is the rosetta stone

user61389

@jippie I know the stone, but what do you mean with it in this context?

12:41 PM

if your device spits out packets with MAC 00:00:... then probably nothing will happen. Not sure if that is a broadcast addres. I thought ff:ff:..... was broadcast.

the arp table translates between layer two and layer 3

on you pc type on a command line arp -a

or arp /a

you'll get a table of all IP vs. MAC addresses it is aware of

user61389

Ah, (yeah ff:ff.. is broadcast), that table is useful. For now, it only displays the WLAN router

also the 192.192.192.192 address is wrong, the PC will send responses to that over its wlan interface

user61389

Okay, I'm going to check on the writing of the MAC and IP addresses to the chip

it appears as if your device doesn't have a mac address set

Here is an example of a typical ARP handshake:
14:48:37.233443 ARP, Request who-has 192.168.0.130 tell 192.168.0.1, length 46
14:48:37.233458 ARP, Reply 192.168.0.130 is-at 00:27:0e:03:f1:0e, length 28

(not sure if handshake is the proper terminology here)

user61389

Out of curiosity, are these the layers you were talking about?

12:54 PM

@CamilStaps somewhat

the layers come from the OSI-model

The Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar communication functions are grouped into logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next low...

and the typical implementation for a TCP/IP stack fits for about 70 or 80 percent.

user61389

@jippie Ah so. Interesting, will read that later

nevertheless most people conveniently forget about the remaining 20 or 30 percent.

the cable = layer 0 (unofficial layer, the medium)

ethernet = layer 1

mac = layer 2

IP = layer 3

TCP and UDP = layer 4

HTTP = layer 5

user61389

What about ICMP? In my sample file NETWORK_USE_ICMP is set to false, because it's only required for pinging?

and the idea behind all this is that local layer 1 talks to the remote layer 1 and is unaware of all the other layers

same for 2<=> 2, etc.

ICMP != TCP or UDP

user61389

Looks like a nice setup

12:59 PM

I believe ICMP is on layer 3

icmp echo request = ping

icmp reply = 'pong'

ping - pong

user61389

Okay - I'll just leave that alone for now then, I'm already in way over my head :)

the layers of the various protocols are on wikipedia, usually in a table on the left of the article

icmp is commonly the first and simplest tool for network debugging

user61389

Yeah, I always ping google to see if I have a connection. No idea what it does, but it works :)

user61389

ICMP is on layer 3, indeed

user61389

But what I don't get - how can the ARP mechanism ask for "telling 192.192.192.192" if layer 3 isn't set up yet?

user61389

1:09 PM

Ah never mind, it is because of the static IP, isn't it?

arp is one of the protocols that doen't entirely fit the OSI model

your device is sending that 192.192.... address. You PC will never answer to the request, or at least not on the wired interface.

user61389

@jippie no, but I can't find where it gets the 192 from - @PeterJ said it was a default, but I can't find it in the ENC28J60 datasheet

@CamilStaps, still here for a sec but it's here ww1.microchip.com/downloads/en/devicedoc/39662b.pdf

user61389

@PeterJ oh I thought you left already - I have the datasheet, but can't find the default - 192 nor C0

@CamilStaps, page 14 shows the reset values

user61389

1:20 PM

@PeterJ at what register should I look? I don't see c0 anywhere

(or 16 in the PDF)

MAADR - I'll double-check but assume it's the MAC address of the adapter not the end client

user61389

@PeterJ yeah, it is, so that sets the MAC to 00:00:00_00:00:00 by default, but not 192.192.192.192 for the IP, right? Did I misunderstood you before?

@CamilStaps Sorry looks like I'm wrong, that looks like a multicast receive address

user61389

@PeterJ no problem of course - so you don't know where the 192 comes from?

user61389

I have to go for a while now - talk to you later, thanks all!

1:28 PM

@CamilStaps, not off hand, but it does look like that is a MAC address register after alll, do a search of on the PDF of MAADR1. I'm about to head of soon as well catch soon.

user61389

@PeterJ yeah, that's MAC - bye!

2:17 PM

Why is this closed as off-topic ? I would think its NC or NARQ or TL but certainly not off-topic

-7

Q: What are the ways I can use to check for presence of metal things?

I thought about sonar, light and metal detection. But I need a solution that is fail proof and cheap. I am using arduino. I need to detect the presence of a large object, think of a car or a fridge for instance. The detector will be on the ground. The detectable object will be around 60-70cm a...

arduino range-detector

user61389

@AshRj I would've found NARQ better indeed, but voted off topic because it's also off topic, off topic already had 2 votes, and I just wanted to get it closed soon. In my opinion, it's off topic because it's a shopping question: "Does any one know what should I go for to have the best precision with the best price?"

@AshRj don't know, i think it is a good question. I also don't understand all the downvotes

@CamilStaps Shopping questions are usually marked NC or in some cases TL. I dont think they should be closed as OT to the best of my knowledge.

I mean 7! downvotes, that must be an intensively poor question.

user61389

@AshRj shopping questions are in the list of off topic things in the faq

2:24 PM

@CamilStaps Also, close votes are counted cumulatively. The close reason with max votes gets marked as the actual close reason

@AshRj I usually barely worry about the exact reason. Closed is closed. I think it is an interesing question, but 5 people think not. (actually 7)

@CamilStaps Ok. I usually go with NC or NARQ

user61389

@AshRj yeah, but it doesn't get closed with 4 OT and 1 NC, right? I wanted it to get closed soon, so I voted on OT because it already had votes and I would be able to reason for OT.

@jippie Sure. But, generally, accurate close reasons do help others who might come across it.

user61389

It really looks like someone who's in way over his head to me

2:26 PM

@CamilStaps I am not sure, but I think it would. 5 close votes is the requirement for closing, irrespective of reason IIRC.

@AshRj I mean after the q was closed. When voting to close it is important.

if someone is way in over his head, is that a good reason to deny him an answer?

user61389

@AshRj yeah, that's what it looks like on the relevant privilege page. I should've voted for NARQ then.

@CamilStaps "I'm not going to tell you because you won't understand anyway"?

user61389

@jippie no, but, yeah, that. I was wondering how many use it would have for the OP to get really good answers. That wasn't my reason to close, by the way. But it would be the reason for me not to answer. To explain everything he'd want to know would take some time, or at least that's what it looks like to me

@jippie The question doesnt make complete sense to me. He wants to detect large objects like a car or a fridge. What would he be building that would need to detect cars and fridges ?

2:31 PM

@AshRj If I'm curious like that, I usually leave a comment and most of the time it gets explained, often adding more information for the solution.

@AshRj you could of course edit the question an vote for reopening :)

user61389

After the update, I think he just wants to detect cars over asphalt. The word 'fridge' doesn't make sense, it must have been inserted accidentally by some higher power. Perhaps there was a problem with the internet connection, so that random bits were transmitted.

@jippie Does this edit make sense ? I tried to improve it, not sure if it makes things any better.

electronics.stackexchange.com/review/suggested-edits/16303

user61389

@AshRj I approved it. It's nice that you ask for specific requirements.

2:46 PM

definitely better

user61389

Okay, I also voted for reopening. Since the question is now also about accurateness, there are requirements now => not NARQ, and it isn't merely about shopping anymore => on topic

show it some upvote love ;o)

user61389

Well okay, to undo the downvotes :)

I forgot the about the title. Could you @jippie or @CamilStaps edit that?

@AshRj @CamilStaps is after the editing badge

user61389

2:52 PM

@AshRj done - I also removed the spaces before the question marks, why is it that so many people do that? As far as I know that isn't a rule in any language, but I'm probably mistake?

@CamilStaps I didnt know that there was a rule about not having spaces until I started posting on SO. Its one of the things nobody really mentions (at least none of my English teachers did) :)

@CamilStaps you forgot an n right there

user61389

@AshRj but is it like a rule / generally used in your own language?

user61389

@jippie saw that too late :(

you forgot to edit out the [closed] part from the title

2:57 PM

@CamilStaps If you mean my first language Hindi, then yes, spaces are used before punctuation marks.

user61389

@AshRj ah, cool, that explains!

user61389

3:09 PM

@PeterJ @jippie okay, got the MAC address working now - turned out to be a compiler bug (or that's what it very much looks like)

@CamilStaps sure, blame it all on the compiler

user61389

:)

3:34 PM

Any idea how much current a single fan notebook cooler takes ? Specifically this one.

depends on the fan

@AshRj I have fans that vary from 150mA max to 3.5A max, all conveniently 60x60mm sized

@AshRj It is attached to USB so < 500mA

@jippie I was looking for something more accurate. I was thinking of using a hub with the USB port. Wanted to see how many things I could plug in safely.

I can add more accuracy: > 0mA

:-p

user61389

@AshRj try it out! :D

@AshRj if it does not register as a USB2 device, then < 100mA

3:41 PM

@jippie Does that always hold ?

@AshRj it should

@hhh Dont be sorry.

@Kortuk Worth reopening ?

@AshRj meh, still not great, but user put some time into improving.

3:57 PM

@Kortuk The OP lacks knowledge of what he is asking. I dont think that should mean the question should be closed.

@jippie Personally I suspect the downvotes are largely "Not my area of interest, so let's downvote him"

@AnindoGhosh agree

@CamilStaps Does it strike you that you're rather young to begin emulating Olin's attitude of intolerance?

3

@AshRj Agreed. After all, in another situation, I've often heard the homily that "Questions are answered not for the OP but for the rest of the world that might have the same problem". I wonder why that doesn't apply when a question appears that isn't interesting to habitual downvoters.

@AnindoGhosh True that. But, the question does still have some issues. His desired application isnt clear (at least to me), for starters.

@AshRj Fair enough. That's where one either solves for a general case: Detect big objects (incidentally they're metallic) passing through a particular location, or if such a general solution is inconceivable not just by you, but by others who may have better understanding of the subject area, then Ask the OP for further clarification.

From the hosepipe / pressure sensor comments, and others, clearly there are possible solutions to the general case. So I understand neither the downvoting nor the closing votes, other than as "Not my kind of problem, so I won't let anyone else make a few points either". Overstating to make a point, of course.

4:12 PM

@AnindoGhosh Yes, one of the reasons why I brought it up :)

@AshRj It's well brought up, even one question like this saved, improves the newbie friendliness some people claim this site has anyway.

@jippie I think my answer is better than yours :-)

0

A: MOSFET or Transistor for using as switch for audio signals

Assumption: Audio signal is a +4 dBU line level signal DC-biased to not go into negative region. Audio source has a low output impedance. Assumed signal voltage, as per above: Vsignal = 1.737 Volts peak + 1.8 Volts DC bias The STP16NF06L N-channel MOSFET can be used as a voltage controlled ...

@Kortuk I have investigated bionic things a bit further: the voltage measurements are about 1E3 smaller than my multimeter can measure -- so I need to amplify things a lot, analog op-amp or digital amplifier for this?

.
"The electrical source is the muscle membrane potential of about –90 mV.[3] Measured EMG potentials range between less than 50 μV and up to 20 to 30 mV, depending on the muscle under observation." http://en.wikipedia.org/wiki/Electromyography

user61389

@AnindoGhosh I wouldn't call this intolerance. I voted to close for a valid reason, after the edit I voted to reopen. I prefer not to answer such a question, but I won't leave comments about that, as Olin tends to do. I also prefer not to answer questions about dangerous stuff - I sometimes leave a comment with a tip to do stuff safe, but won't write an answer to point out letter per letter what's wrong with the question.

4:30 PM

@CamilStaps "I just wanted to get it closed soon" sounds like either (a) No, you can't tolerate such a question being existent, it offends your sensibilities, or (b) Since you don't see yourself answering it, you cannot imagine someone else could be capable of or interested in answering it.

@CamilStaps I call that intolerance. You can call it anything you like.

@hhh For that magnitude of signal, I would consider a device like this one for initial experiments, before getting into building one of one's own.

@hhh There are other such ultra low voltage amplifiers out there, off the shelf. Building one yourself would involve a fair amount of bias tuning, experiments with resistive noise, signal contamination and so on: Which is cool if building such an amplifier is your primary goal, rather than figuring out the bionic measurement concepts.

@AnindoGhosh how easily do they break up? I have tested op amps with much higher range and it is easy to break them...

user61389

@AnindoGhosh I won't close a question because I don't intend to answer it, that's ridiculous. However, it seemed clear to me that that question had to get closed for either NARQ or OT. I thought it would take 5 votes for a specific reason to close, so I chose OT, as there were already 2 votes. That's what I meant with "I just wanted to get it closed soon", that I chose OT instead of NARQ for having two more votes there already.

@hhh Please explain what you mean. Any device designed for a signal voltage in microvolts, will quite likely be destroyed by an input one or more orders of magnitude higher than the design maximum.

@CamilStaps I'll take that at face value, it isn't an issue as long as you also vote to reopen questions with equal alacrity - I certainly try to balance my views on open v/s close, preferring to err on the side of tolerance.

Suppose my house is not well grounded. Can static electricity easily destroy such op-amps?

I think if I get this kind of op-maps I need to ground all kind of electronics to my ground (fortunately, it is possible :D

@hhh Yes, super-sensitive instrumentation requires careful grounding. That's a given.

user61389

4:44 PM

@AnindoGhosh I hope I do, at least I'm trying.

@hhh However that has little to do with your house grounding: All that must be ensured is that any signals are referenced to the same ground, within your work equipment.

Fun times at EE.chat. Hallo all.

user61389

@angelatlarge hallo!

@CamilStaps That's good then :-) I'll withdraw my views on incipient ohhhlinitis

user61389

@AnindoGhosh I'm not sure what that is, but thanks :)

4:47 PM

@AnindoGhosh I thought one was supposed to mellow with age, not harden.

user61389

@angelatlarge in that case I feel sorry for Olin's parents

@angelatlarge We have at least one living example to the contrary. Maybe two, I'm not getting any mellower with age.

@AnindoGhosh for this kind of super-sensitive electronics, things such as Antistatic mat and grounding with copper wire to ground needed -- other things?

@angelatlarge I was probably way more diplomatic at 30 than at 42. However, I am a lot more tolerant of ignorance / newbie-ness now.

Speaking of examples to the contrary, where is Mr. T? I need him for my badge!

user61389

4:50 PM

@angelatlarge , stop. I don't want to star all your messages.

@hhh Honestly, there are others in this chat room way way more expert than I am, in the area of high-sensitivity instrumentation. My work is typically at the other extreme, with industrial-grade noise and horribly high ESD / EMI floors.

@hhh I was just doing a quick scan, don't have much time but I have to jump in here NEVER connect with a copper wire unless you want to get dead. always have a 1 Mohm resistor to ground. You just need dissipation NOT shorting.

@angelatlarge If you're using your circuit to interface to a multimeter, you should be able to design it to be relatively safe from static. multimeter means low bandwidth required. But I won't discourage you from using proper ESD precautions if you're working on any electronics with the cover off.

user61389

1

A: What's the use of a decoupling capacitor near a reservoir capacitor?

When two or more decoupling capacitor of different value are used in parallel, is necessary consider the parallele resonance that occours between the two network. Clayton Paul described this phenomena. If we consider a parallel couple of capacitors C1, C2, with different value and i.e. C1>>C2 wit...

@rawbrawb The mat itself usually has the 1-10 MegOhm resistor included.

user61389

4:57 PM

So I cannot just randomly add capacitors to reduce noise? (@AnindoGhosh)

@ThePhoton Are you sure that was meant for me, or am I missing something?

@ThePhoton Usually yes, but the reasoning and KNOWLedge of WHY is what I am worried about.

@ThePhoton Granted, I did just wake up, and haven't had my coffee yet.

@CamilStaps Why me? :-) I randomly add everything everywhere anyway.

@CamilStaps Are you sure that was meant for me, or am I missing something? (thanks, @angelatlarge)

user61389

@AnindoGhosh like comments? ;)

4:59 PM

@rawbrawb I could not understand this "always have a 1 Mohm resistor to ground. You just need dissipation NOT shorting." -- is there some picture how to do this correctly?

@CamilStaps Well, I loved the very step-by-step explanation. And incidentally, no, just randomly adding capacitors isn't optimal for noise reduction. Besides, some forms of noise are not going to go away, they'll actually increase. For instance, check your nearest electrolytic capacitor on a scope, it makes a nifty RF antenna :-D

@hhh Good, you replied. What is important is that you never short yourself. THat is just dangerous. You just need to know that you don't need to short yourself to be ESD safe. even high resistances will dissipate charge nicely.

@angelatlarge Should have been @hhh

user61389

@AnindoGhosh okay, good to know - I can now safely upvote this answer :) (that cap, for a moment I worried about my scope)

@ThePhoton Got it

5:03 PM

@hhh As @ThePhoton mentioned most ESD mats have 1 MOhm built in. and proper ESD straps will have 1 MOhm to ground. So if you make a home build ESD wrist strap make sure there is 1 MOhm in series.

and just to bother @AnindoGhosh

@hhh To put it a somewhat different way, you need to be sure you don't build up a charge, relative to the electronics you're working on. The usual way to do it is to connect yourself to "ground" via a 1 MOhm resistor. Usually the resistor is included in a wrist or heel strap that you wear.

Gotta run ...

But if you're designing an amplifier, you need to be sure it's protected when it's hooked up to whatever you're going to hook it up to, not just while you're working on it.

@AnindoGhosh I'm trying to reproduce your capacitor experiment, but how many kW radiostation do I need exactly and at what distance?

@ThePhoton It's going to be hooked up to human victims :-)

@rawbrawb Ha! Ha!

5:09 PM

awww man =(

@AnindoGhosh So it would be a good idea to design in esd protection instead of just wear a wrist strap while you're working on it.

my AVR on Linux answer fell prey to an anonymous downvote =(

@jippie Oh, even a CCFL lamp in the vicinity will induce a nice signal on a capacitor. The higher the DC resistance of the cap is, the more visible the signal will be on your scope. Check the DC resistance of the cap first.

@jippie He's probably talking about radial-lead caps, not so much SMT.

@ThePhoton Agreed.

5:10 PM

Axial are probably even better, but I haven't seen one of those in a while.

@ThePhoton Yup. SMT automatically has less "antenna size", but I doubt @jippie is friendly with SMT caps.

http://electronics.stackexchange.com/questions/66145/avr-how-to-program-an-avr-chip-in-linux/66147#66147

Who wants to upvote to rectify the situation???? xP

@NickHalden I don't know what situation you refer to, but that answer already had my upvote.

@AnindoGhosh Thanks! I just recently got a -10 from that answer... dont know why =/

@ThePhoton I have this kind of wrap ebay.com/itm/… but I have never understood where to put the alligator clip

(whitish blue wrap, I have this wrap and a wrap without the alligator clip, I usually wear two wraps -- and avoid the alligator clip because not understanding it)

5:12 PM

@ThePhoton I notice axials in use only in some DIY type audio amps these days. I haven't been able to elicit a technical justification for them, the DIY folks just say "It makes the sound better", which is a load.

@NickHalden Someone removed their upvote, perhaps?

@AnindoGhosh Or downvoted =/

@NickHalden No, I just looked at vote detail (10k+ feature I think) and it's a (+9), not a (+10 -1)

@NickHalden And now it is a (+10).

@hhh I'm back. So you were just wearing jewellery then .... You connect to the mat (if you have one) or the chassis of what you are working on.

@hhh You can clip the aligator to anything connected to ground of your circuit...Somewhere on your circuit board, or to the case of some equipment (oscilloscope or whatever) that is grounded, or to the button on your ESD mat, if you have one.

@AnindoGhosh oh, interesting... so somebody removed an upvote that has previously been given. I wonder why?

5:17 PM

Usually the alligator is connected to the cord by a banana plug. You can remove the alligator and use the banana plug to connect to circuit ground.

The one you linked, there is 1 MegOhm embedded in the clasp of the strap (unless its a totally bogus product).

@NickHalden Dude you can't sweat it too much. there are certain people around here who down vote if you disagree with them. call it drive by down voting if you will. Often the correct answer doesn't get the most votes or even accepted.

@ThePhoton I only have radials, but maybe an insensitive scope? @AnindoGhosh

@NickHalden there is also the corollary in that there sometimes lots of votes given for inane answers. @AnindoGhosh gets lots of those .... ;)

@NickHalden I agree my answer should have much higer votes than yours

@jippie volume weighted?

5:22 PM

@jippie Try with a tantalum or a mica cap, maybe? Though I find that micas don't seem to exhibit the antenna effect.

@jippie -1 for vi

i bet i stated 'your favorite editor'

@angelatlarge and we don't have notepad.exe on linux

@jippie No, but you do have scite and sublime

thus?

@jippie Unless they haven't discovered X windows in Holland yet.

5:25 PM

ever done sys admin on a bare bone headless unix server?

@jippie I have, but that's not what the poster's question is about

you'll learn to appreciate the power of vi and vim

@angelatlarge everyone in unison now .... "he doesn't live in holland"

@rawbrawb ROTFL

@rawbrawb He doesn't? Why are the cats Dutch then?

5:26 PM

@angelatlarge I do it all the time, so I am pretty familiar with it

@angelatlarge please don't ask, please ....

@angelatlarge Just like not all Britons live in England, not all Dutch people live in Holland.

@jippie Much and often, in my younger days. Headless DEC VAX VMS boxes too.

vms != unix

There was a funny video linked some weeks ago.

5:27 PM

@jippie Sure, but (and this doesn't actually apply to your post), the argument being pursued is something like: sometimes you need to use toggle switches to input your program into a VAX, therefore, I don't use visual editors.

actually linux != unix either, but it is unix'like more than vms is

@ThePhoton Most Bretons don't live in England in fact :)

@angelatlarge briton the people, breton the people, or breton the cracker?

@jippie No, I added that for timeline context :-) I've paid my dues on Solaris, Irix, BSD, FreeBSD, and when Linux happened, I just stopped. I don't like design by committee.

@angelatlarge That is why I said Britons, not Bretons. But even not all Britons in the UK are in England.

5:28 PM

you can use a visual vi (gvim), there is even a version that doesn't have command/edit mode and just edit mode.

@rawbrawb I have good friends in Brighton

@rawbrawb Who're you calling a cracker?

I bought this mat but I don't know whether it has a resistor, any way to check it?

http://www.ebay.com/itm/370564096073?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

@CamilStaps OMH, I am seeing the "Upvote me, I am lonely ad." I thought it didn't make the cut.

cgpgrey.com/blog/the-difference-between-holland-the-netherlands

5:30 PM

@angelatlarge LOL, BTW Holland is the name of two regions of the Nederlands. Like calling the US "Carolina", there is NC and SC but neither apply to the country.

@rawbrawb Wasn't there a nice youtube video on that?

@angelatlarge damn there's some serious echoing going one here

@rawbrawb We do this all the time. Nothing new. "Soviet Union" was routinely called Russia, and so on. It is called "metaphorical extention" I believe, and I stand by it.

@angelatlarge cgpgrey.com/blog/the-difference-between-holland-the-netherlands

@rawbrawb I think even something like "He is sooooo big" (to mean his... part is big) is an example of the same thing. So I refuse to be corrected.

5:33 PM

@angelatlarge Nah, that's just 'merican for "I'll call you want I want to call you and you'll like it"

@ThePhoton Sorry, didn't follow that first link, thank you

@angelatlarge persistent isn't he?

@rawbrawb That amounts to the claim that it doesn't happen in other languages/cultures. Fortunately this is a falsifiable prediction.

@hhh It should have the resistor. But it would be nice to have a datasheet that says for sure it does.

@rawbrawb He needed to get that through my thick skull

5:34 PM

@angelatlarge I said persistnet isn't he ? ...

@rawbrawb NICE!!!

@angelatlarge I should have used teh reply button the first time

@ThePhoton Oh, well, that's for the excuse. I'll take it.... YOU DIDN'T USE THE REPLY BUTTON, DAMMIT!

@angelatlarge There has got to be a law (like godwins law) that states something like " when one party invokes the falsify-able criterion".

@rawbrawb (that was brilliant. Still ROFL. thank you. My beer belly exercize for the day)

@rawbrawb Hmmm... is that just intellectual/pretentious version of Godwin's law? But there are so many other good candidates.

5:38 PM

@rawbrawb We call Zhongguo "China", why not call the Netherlands "Holland"?

@angelatlarge true, how true. I know lets call it O...'s law

@rawbrawb I believe it is called simply "falsifiability", sir. Is there such a thing as falsifiable criterion? (sips wine, turns page of Margins of Philosophy)

@angelatlarge no there isn't neither is the a falsifiability criterion either. It's only one writer who used that term and tech nerds seem to have stuck to it.

@ThePhoton Koln = Cologne, Munchen = Munich, aw what ever

@angelatlarge don't you mean Quaffs? not sips.

@rawbrawb I am not talking about mispronunciations.

@rawbrawb Swirls and spits?

@angelatlarge I'll just leave that one for people from Holland.

6:02 PM

Hi everyone - anyone have a moment to answer a question regarding battery charging?

1 hour later…

7:06 PM

@AnindoGhosh Are you around?

7:19 PM

@AshRj He was not originally very clear on what he was doing, that is why it is closed, until it can be made more clear.

@AnindoGhosh Look at the first revision.

user image

Is there some way to model this on software?

each part-by-part like with Simulink

user image

I found a guy using this kind of software to model robotic project, can you detect what is the software?

Matlab's stateflow?

I wish I could understand Spanish, source of the picture is this video: youtube.com/watch?v=gkc6P0saDrA&NR=1&feature=endscreen

7:38 PM

@angelatlarge Now I am

@Kortuk Fair point, now that I did.

@AnindoGhosh You seem to know something about batteries. Is mAh rating a good estimate of battery capacity?

@angelatlarge Insufficient data for a definitive answer. mAh varies by load and temperature, so it's a good first estimate, but no further without the graphs in the datasheet.

@hhh There are several circuit simulators around, if that is what you mean. Look for SPICE, PSPICE, LTSPICE, and a horde of others. Also, some of the EDA software do simulation, e.g. Proteus

@AnindoGhosh I am on OS X, which one best?

(I have Windows virtualized)

@hhh Sorry, (a) I'm pretty out of touch with Mac OS versions of the last decade, and (b) There's no "best", or the others would not exist, and (c) You can run Windows stuff in a Windows virtual box.

Yes but which one would you recommend of the softwares?

7:45 PM

I've seen these motors that look like donuts: hole in the center, and the outer part of the donus spins around the inner part. Is there a name for such a beast?

good morning

good afternoon :)

@hhh I just recommended all of them, actually. Individual preferences will vary depending on what is important to you, simplicity and ease of use, availability of ready simulation models for lots of different ICs, precision and speed of simulation, pretty colors, or a large community to discuss problems with. Sorry, but this really isn't answerable, is it? :-)

@angelatlarge "Motor" :-)

@angelatlarge image link?

@AnindoGhosh I don't have one. Motor where the center is permanently mounted, and the outer part spins.

8:05 PM

In an el-cheapo smps, what happens here at 305 seconds after power up (Uin=12V, Uout=5V Iout=100mA)

user image

let me see if I can find the type number of the little psu

@AnindoGhosh Maybe "shafless motor"? "Outer rotor motor"?

user image

LM2596 based

@angelatlarge Is it a toroidal motor? google.com/…

Coreless motor? I can't visualize what motor you mean, so just guessing.

8:22 PM

@SimpleCoder Maybe. Can't find enough clear images descriptions to be sure.

@AnindoGhosh No, not that.

The thing I have in mind has stator in the center, and the rotor is the outer part.

So the outer part of the motor spins around a fixed center.

As opposed to regular motor where there is a centered rotor, usually with a shaft coming out of it, and it is the centered rotor that spins, while the outer part is stationary.

8:55 PM

@angelatlarge those motors accelerate insanely fast, because the rotor is very light.

@jippie What are they called, do you know?

aren't they called insanely fast accelerating motors?

I believe "buitenankermotor" in dutch

@angelatlarge I see 'outrunner' as translation

@jippie That sounds like a nautical term. Which makes sense for Dutch.

The term outrunner refers to a type of brushless motor primarily used in electrically propelled, radio-controlled model aircraft. This type of motor spins its outer shell around its windings, much like motors found in ordinary CD-ROM computer drives. In fact, CD-ROM motors are frequently rewound into brushless outrunner motors for small park flyer aircraft. Parts to aid in converting CD-ROM motors to aircraft use are commercially available. Outrunners spin much slower than their inrunner counterparts with their more traditional layout (though still considerably faster than ferrite moto...

@angelatlarge 'outrunner' sounds hobby electronics

And @jippie wins the prize.

Though not for speed accuracy: from wiki: "Outrunners spin much slower than their inrunner counterparts with their more traditional layout"

Although the wiki article makes me believe that there might be a more general term still... "This type of motor spins its outer shell around its windings, much like motors found in ordinary CD-ROM computer drives."

9:02 PM

@angelatlarge I have seen servo motors that have the stator in the middle and on the outside. Then the rotor is a thin cylindrical shell that rotates in between them. Professional ones have an insane small air gap.

@angelatlarge as I mentioned, it sounds like hobby electronics

a bit like a kooiankermotor but with the insides of the rotor emptied so it can be filled with stator.

Squirrel-cage rotor

A squirrel-cage rotor is the rotating part used in the most common form of AC induction motor. An electric motor with a squirrel-cage rotor is termed a squirrel-cage motor. Structure In overall shape, it is a cylinder mounted on a shaft. Internally it contains longitudinal conductive bars (usually made of aluminum or copper) set into grooves and connected at both ends by shorting rings forming a cage-like shape. The name is derived from the similarity between this rings-and-bars winding and a squirrel cage. The solid core of the rotor is built with stacks of electrical steel laminat...

user image

@angelatlarge bit like that but with stator and rotor swapped

9:27 PM

@angelatlarge speed != acceleration

but I think we are talking about slightly different motors

2 hours later…

11:32 PM

@jippie You still around?

« first day (906 days earlier) ← previous day next day → last day (4031 days later) »

Transcript for

Apr '1321

Electrical Engineering

A place to talk with friends from the EE community about vacuu...

join this room
about this room

00:00

06:00

12:00

18:00

all times are UTC

site design / logo © 2024 Stack Exchange Inc; legal

mobile