Electrical Engineering

rawbrawb

00:12

@ThePhoton you have a nice phone! Who says you've bought into the shallow bay area life style with your iPhone

The Photon

00:40

@rawbrawb I love how 2-3, 5-6 and 9-0 are on rocker switches instead of an individual switch for each number!

Gotta get outta here!

icarus74

03:54

Hello friends

rawbrawb

04:09

@icarus74 hey

Stacey Anne

hello!

rawbrawb

@StaceyAnne greetsings

Stacey Anne

woo only 6 hours of work today

rawbrawb

@StaceyAnne is that too many or not enough?

Stacey Anne

I've been working 9 hours a day this week, so 6 is a nice break :)

Mikhail

04:24

Do you guys know how to use a parallel port?

rawbrawb

@StaceyAnne and it's friday for you too.

@Mikhail in what sense, you mean program it?

Mikhail

Yeah I can't seem to get it to output a voltage

0

Q: How do I get a voltage on a PCIe Parallel Port?

I'm trying to use a PCIe Parallel port from C++. (http://www.amazon.com/StarTech-com-Express-Profile-Parallel-PEX1PLP/dp/B004G7O2AC) I can't seem to change the status of any of the registeres and my voltometer and LEDs don't change. I am using inpout32.dll on a Windows 7 x64 bit machine. I thin...

rawbrawb

@Mikhail can't really help you. It's been years since I had to do that and I've also hear d that the recent windows OS's don't allow direct writes to the parallels ports (but I may be misremembering this) in the same way that I would have done it before.

Mikhail

@rawbrawb hopefully somebody can, this stuff is driving me up a wall!

rawbrawb

@Mikhail I remember someone telling me taht the protected mode stuff gets in the way.

@Mikhail here is something I found ...

vbforums.com/…

that's the best I can do .. sorry.

Rick_2047

04:40

hello all

help me decide what to do guys

I can choose between one of two projects

making an active analog filter with 20dB gain and 100kHz bandwidth using LM385s or I can learn dsPIC33f controller and make a lock - in amplifier

I have only 5 days I guess

I am not sure of the feasibility of these projects in this time frame as I have not really used any of them before

jippie

05:21

good morning

Rick_2047

@jippie good morning

jippie

@Rick_2047 haven't seen you around for a couple days

Rick_2047

yeah

have been busy

jippie

how can anything be more important than us?

Rick_2047

05:37

you know, life

i hate microchip i hate microchip i hate microchip

i am going to register ihatemicrochip.com

jippie

05:50

@Rick_2047 what's up?

Rick_2047

there is no simple documentation they put out which will enable one to learn there things

I should not be reading 334 page document just to flip a bit

@jippie they just bombard us with so much of info that one is blinded by it

jippie

? on PIC's you mean?

Rick_2047

yeah

on dsPICS

jippie

what makes a pic a dspic?

Rick_2047

it has an aditional part called a MAC

helps in digital signal processing

jippie

06:05

m.

Rick_2047

06:41

microship people just do not understand the meaning of "simple"

or "beginner"

jippie

@all? and @Kortuk? I can't get the formatting right on this answer:

0

A: AVR - How to program an AVR chip in Linux

I don't have the time for a full explanation, but I can give you cookbook-style the commands I use on my Linux box to program AVRs: Preparations I started to create a directory in which all my ATtiny projects find a home: mkdir ~/attiny: cd ~/attiny For each project I create a dedicated subfo...

Anindo Ghosh

@Rick_2047 Neither project seems feasible from a standing start, in the 5 day time frame. Your choice would depend on what expertise you can tap locally, especially people with the experience, tools and equipment to help you.

@icarus74 Enjoyed my photos?

jippie

The makefile won't show as 'code'

Rick_2047

@AnindoGhosh the problem here is experience, this is new for everyone

jippie

ah I managed to fix it by putting <pre> and </pre> tags around it, but I am still not sure why the normal way of indenting doesn't work

Stacey Anne

06:52

I fixed it

or at least submitted a fix

jippie

@StaceyAnne ?

what was your fix?

Stacey Anne

It seems to not like going from bullets to code. I added "This is the makefile" in normal text as a header and that worked

Anindo Ghosh

@StaceyAnne Approved it.

jippie

:) me too

thnx @StaceyAnne

/me is stepping into the shower now.

Stacey Anne

very interesting to note that when you look at the edit history, it renders the bullets-then-code absolutely fine

Anindo Ghosh

06:57

OK, I definitely deserve a bunch of votes for my efforts to advance the state of the art in ultrasonic sensing (see the photos and read the descriptions towards the end):

1

A: Collimating a sonar beam

Coincidentally, I happen to be playing with almost precisely what the question refers to, since yesterday. My distance sensor unit boasts a 25 degree angle, but I faced the same problems with my bucket of water. My solution may not be an engineering marvel, and there will likely be some reaction...

jippie

@AnindoGhosh You didn't vote for my AVR answer either

Anindo Ghosh

@jippie Lies! I'm the only one who did, that too only after Stacey made it readable. She deserves 5 of those rep points.

jippie

humhumhum

Stacey Anne

there, both of you got some love from me

Anindo Ghosh

@StaceyAnne Thanks :-)

I'm still amused at posting experiment photos taken in my bathroom!

icarus74

07:11

@AnindoGhosh Absolutely. Wish I could give multiple up votes for that.

Anindo Ghosh

@icarus74 I was about to step out for a meeting, which would have taken all day - but it got cancelled, so I came back home and took those photos for you :-)

icarus74

Lucky for me

BTW, anyone here can point me to the basics of "3 point calibration" ? Is this a curve-fitting thing ?

Anuj Kaithwas

hey guys, is there any limit to the size of hard disk that we can attach to a motherboard in a computer? say, a limit of 160gb? and does it goes the same way in terms of RAM? and if so, why?

icarus74

The chatter here, got me to @jippie 's answer on the AVR prog on Linux question. Love the answer and really liked the clean formatting (thanks @StaceyAnne). I am glad that I didn't leave the comment on the question, pointing to be moved to SO !! Sometimes it's better not to play the smartass.

@AnujKaithwas How about a long answer ? Check this out: hardwaresecrets.com/article/482

There are several factors at play there, starting with the interface type (IDE, SCSI, SAS...), firmware on mobo, the HDD itself (access rate).

Folks over at Superuser, might be able to give more pointers.

jippie

07:27

@icarus74 some questions justify existing on more than one stack, unfortunately SE hasn't implemented a mechanism for that.

user61389

@AnujKaithwas you'd get a better response at Super User

user61389

(Morning all!)

icarus74

Morning @Camil

jippie

@CamilStaps are you in student time zone today? 9:30AM!?

Anuj Kaithwas

thank you @CamilStaps @icarus74

user61389

07:29

@jippie haha :)

Anindo Ghosh

People, please flag as spam on this question: electronics.stackexchange.com/q/66167/14004

PeterJ

Just did, their '*' website doesn't work anyway ;-)

user61389

Ah, removed :( that was quick

icarus74

Done.

user61389

Let's make radiofrequency a synonym of rf: electronics.stackexchange.com/tags/rf/synonyms

PeterJ

07:40

"You do not have the required score on this tag to vote for this tag synonym"

icarus74

@CamilStaps camel-case world ? why not "radio-frequency" ?

user61389

@PeterJ hmpf - the thresholds are really high, I had to have some score to suggest it as well, like you wouldn't know what RF and radiofrequency without some score

icarus74

bump...

26 mins ago, by icarus74

BTW, anyone here can point me to the basics of "3 point calibration" ? Is this a curve-fitting thing ?

jippie

/me is out

user61389

@icarus74 yeah, that would be possible too, but they're still synonyms. I like radiofrequency (or radio-frequency) better than rf, but I'm not going to retag all the rf questions.

user61389

07:43

@jippie bye!

Anindo Ghosh

@jippie Bye!

@CamilStaps Just get a few more people to upvote the synonym. I already did. ALso, how do I know if I have enough points on that particular tag, for upvoting?

user61389

This: "Users with a total answer score (total upvotes minus total downvotes) of 5 or more on the tag, can vote for tag synonyms." + this: electronics.stackexchange.com/users/14004/…

Anindo Ghosh

@CamilStaps Ahh... So I can't vote, my tag score for RF is 3, is that correct?

@CamilStaps No wait, it's 9, on 3 answers.

@Kortuk / @W5VO Please check on this user: electronics.stackexchange.com/users/22803/user22803

Stacey Anne

08:51

does anyone here know if it's safe to cat a device in linux?

Rick_2047

09:06

@StaceyAnne you will get a lot of garbage, may freeze the terminal

@StaceyAnne you can use the less command "cat <device>|less"

but this may freeze too

user61389

@Rick_2047 @StaceyAnne if that's the only problem, you can use tail, which only displays the last 10 lines

Stacey Anne

I've been using cat to view debugging data over the serial connection

so I know it's serial, but my pc freezes whenever I restart my board

I'm trying to figure out if that's expected bahavior or not

Rick_2047

why are you using cat for serial anyway?

there are good serial programs available for linux command line, any specific reason?

Stacey Anne

honestly just didn't know what other options there are? i've always used cat before and it's been fine

user61389

@StaceyAnne I'm using putty on Windows and that works fine. They have something for Unix as well, I believe

PeterJ

09:25

@StaceyAnne, if your whole PC locks up not just the terminal window (assuming you're using a distro with a GUI) I doubt cat has a lot to do with it. Does the PC still freeze even if you're not viewing the debug output using cat?

Stacey Anne

@PeterJ, The entire pc freezes to the point where it needs a hard reset. It only freezes when I'm viewing output data with cat

I'm not used to linux freezing on me, it's a bit concering

PeterJ

@StaceyAnne, odd - cat only runs in user land and a while ago for other reasons I checked the source and it doesn't do any odd low level things. Maybe try PuTTY for a start as @CamilStaps suggested for comparison.

Stacey Anne

@PeterJ, I was running it as root :/ would that make a difference?

PeterJ

@StaceyAnne, I'm not the world's biggest Linux kernel guru but not for any reason I can think of. But I guess for comparison it might be worth creating a new standard user account, give it access to the device if necessary and see if it does make a difference. Is it a hardware serial port or a USB to serial converter? I'm just thinking it sounds more like a kernel level driver problem of some sort.

Stacey Anne

09:42

It's a USB serial device

you're right, it might be a kernel driver problem - that makes sense. It seems like the driver is freaking out when I reset the board

PeterJ

If you have one handy or can borrow one I'd certainly try a different manufacturer's one. Some of drivers can vary a bit in quality, maybe you're just sending a bit of random junk and/or toggling some flow control lines it doesn't like when the reboot happens.

Rick_2047

10:35

hey if the datasheet says "oscillator runs at nominal speed of 7.4Mhz what does that mean?

PeterJ

@Rick_2047, it just means it's designed to run at about 7.4MHz but could be elsewhere, maybe likely to vary a fair bit with temperature and maybe something not accurate enough that the manufacturer is willing to specify exact specifications because it varies among parts. I guess it's something with an RC oscillator?

Rick_2047

no, its the dsPIC internal oscillator

PeterJ

That probably is an RC oscillator, although not sure. But in general it's a way of saying if one part is 7MHz and the next is 8MHz don't complain. Normally though they will specify the minimum / maximum speed somewhere so you know if at worst case if it'll be fast enough for a particular application.

Rick_2047

okey

better not use it though

I have an on board 8MHz crystal

I am going to document my learning experience

should make a tumblr blog for this

PeterJ

Not sure about the dsPIC in particular, but most micros have about a 2-5% tolerance on the internal oscillator. So nothing wrong with them for many things, but a crystal is of course much more accurate.

Rick_2047

10:49

@PeterJ yeah, have been using Atmel ATmega internal oscillators for 90% of my projects

most of my projects are not that sensitive to timing errors

going to write this blog in first person as its not going to be that general anyways. But I hope this becomes helpful for people another guy somewhere else who is struggling with the same things

Rick_2047

11:26

wrote some things on my blog. anyone wants to review?

learndspic.tumblr.com

PeterJ

"perhaps the most easiest" -> "perhaps the easiest"

Rick_2047

@PeterJ thanks, corrected that

Rick_2047

11:46

changed the blog to blogger

tumblr wasn't working well for me

learndspic.blogspot.in

abdullah kahraman

12:50

Hi!

Stacey Anne

hi @abdullahkahraman

Toby Lawrence

yo

oi, well that's bad

domain I use for electronics-related development had bad DNS server records

so I had been wondering my I hadn't been getting any e-mail

well.. now I have my answer :<

Polynomial

13:58

Anyone familiar with the USB protocol? Trying to find out if the clock sync is used to set the timings for the rest of the message.

and also trying to work out how a timing signal is agreed upon, e.g. could a USB 2.0 device run at a significantly lower speed than normal.

abdullah kahraman

@Polynomial @Kortuk @Kortuk @Kortuk

Toby Lawrence

@Polynominal: at low/full, a pull-up on either the D- or D+ line indicates the speed

for high speed, it "chirps" the line

it starts out as full-speed, with d+ pulled high

once the host resets the data lines

it pulls the d- line high as well

which tells the host "i'm a high-speed device"

3.0... no idea

Anindo Ghosh

14:16

chirp chirp

Toby Lawrence

that shit is cray cray

David Kessner

Morning all.

Anindo Ghosh

Morning :-)

abdullah kahraman

Morning

user61389

Hello!

Toby Lawrence

14:21

y0

so, I made the plunge (again)

ordered prototype boards AND a stencil for my data logger

solder paste

sample orders galore

Polynomial

@TobyLawrence that determines which protocol is being used, e.g. USB 2.0 or USB 1.1

Toby Lawrence

right

Polynomial

but not necessarily the speed, since clock sync is used for that

Toby Lawrence

and both of them have a speed

well, see, now you're stating facts

when you explicitly asked whether or not something was in fact true

so what is it? are you not sure or are you? :)

Polynomial

they have a max speed which is dictated by the protocol. the actual speed is variable, but I'm not sure how the variation is achieved. the clock sync is almost certainly used to fine-tune the timings and prevent any phase issues, but I don't know to what extent it can be exploited in terms of speed reduction.

Rick_2047

14:29

@AnindoGhosh in which time zone are you?

Polynomial

USB 2.0 keyboards can definitely transmit and receive at significantly lower speeds than the 480Mbps maximum.

Toby Lawrence

@Polynomial: the clock rate is fixed, with margins

Polynomial

@TobyLawrence hmm. so what allows the reduction in transmission speeds? for example, my USB flash stick certainly doesn't achieve 480Mbps reads or writes.

Toby Lawrence

if you send 1 megabyte of data in a single second, over USB 2.0, your throughput is 8Mbps

but USB 2.0 still could send faster

that's not throttling, it's just low utilization

also, there's overhead

Polynomial

so it's a burst instead of a trickle?

Toby Lawrence

14:32

the 480Mbps rate of USB 2.0, for example, is the theoretical maximum based on the signaling rate

@Polynomial: right. take gigabit ethernet for example

Polynomial

also, does that not mean that USB transceiver devices run at 480MHz? seems unusually high.

Toby Lawrence

you wouldn't say that your connection between computer and switch/router is only 100Mbps because your hard drive can't transfer any faster

it just means you're only using 100Mbps of that 1000Mbps theoretical

@Polynomial: yes, it does mean that

Polynomial

hmm

Toby Lawrence

sorry, it runs lower

IIRC

Polynomial

how is that possible? surely to get the differential signal to transmit 480Mbps they need 480Msps, therefore 480MHz?

Toby Lawrence

14:35

I'm probably confusing myself at this point

the signaling runs at 480MHz in the case of USB 2.0

Anindo Ghosh

14:58

@Rick_2047 Mumbai, so India timezone.

Rick_2047

@AnindoGhosh then how come that was goodmorning?

Anindo Ghosh

@Rick_2047 Oh I was echoing David. I gave up trying to keep track of people's timezones, and my own, a couple of decades ago.

Rick_2047

@AnindoGhosh i hope I get that problem sometime

W5VO

@TobyLawrence Right - the signalling runs at 480MHz, but there's probably only a SerDes at that frequency. Also, the actual data rate is lower because the signalling is a variant of NRZ - not every bit conveys data. This doesn't get it down that far, but you might need to transmit 10 bits for every 8 bits of data.

Toby Lawrence

oh, right

I meant literally in terms of what's going over the wire

W5VO

15:08

also, if there's anything else on the bus, then that will take chunks out of your transfer rate

Toby Lawrence

right

rawbrawb

15:28

salutations !

Anindo Ghosh

grEEtz

rawbrawb

@AnindoGhosh how goes the many projects that you have going?

Anindo Ghosh

@rawbrawb Mixed bag as always. Sent off some boards for fabbing today, which is a milestone. Or at least an inch-stone.

rawbrawb

@AnindoGhosh this is using the hated SW?

Anindo Ghosh

@rawbrawb Nahh, a friend offered to take my files and convert them to the hated software, also re-check them after that. So I dodged that bullet.

rawbrawb

15:35

@AnindoGhosh How many times have you in your career had to learn "yet another way" of doing the same thing but differently?

Anindo Ghosh

@rawbrawb Oh, pretty much every other week in the last two decades. That's fine. What is not fine is a schematic capture / PCB layout tool where you enter stuff into a spreadsheet. If I wanted to do that, I'd be using Excel for it, at least I'm proficient at that.

rawbrawb

@AnindoGhosh I lost count a long time ago. It's the cost of doing business I guess, the thing that pesters me is that most of the different ways don't seem to be any better. Some of the best SW tools I've used have been developed in house ...

@AnindoGhosh the spreadsheet can be handy in some cases.

W5VO

@AnindoGhosh How do you feel about the Arduino.SE decision?

Anindo Ghosh

@rawbrawb I agree - I absolutely love the timing diagrams thing with Excel.

@W5VO Blatant prejudice. Close-down decision in 9 days, and a mention of the decision having been done 4 days before that.

The Photon

@Polynomial I'm pretty sure the speeds for USB are fixed (depending on which standard). Probably with tolerance measured in ppm. If you have multiple devices on the bus, you wouldn't want one device to hog up the bus for a long time sending a packet at 100 kbps or something. Also, designing a narrow band clock-recovery circuit is easier and will have lower noise than a wide band clock recovery circuit.

W5VO

15:42

@AnindoGhosh I'm sorry you feel that way

If it makes you feel any better, we (the mods) didn't have any input on the decision

Anindo Ghosh

@W5VO The numbers speak for themselves. Even with the slow-down in the last few days, the private beta stats are way ahead of many other proposals that went through to live. An excuse of "high standards" to set unrealistic requirements is just ... shoddy.

@W5VO I appreciate knowing that.

rawbrawb

@W5VO Boy, you guys get it from both sides, don't you? - You don't have to (shouldn't) answer that.

Polynomial

@ThePhoton Interesting.

rawbrawb

@ThePhoton I concur, it's likely the little chirp at the beginning sets the timing for the length of the packet. of course the error accumulates but the packets are short enough that it can get the reads done by then. next packet, new timing, Isochronous

The Photon

@rawbrawb I'd guess that the clock recovery circuit continues to use incoming edges to maintain lock --- but it needs the chirp at the beginning to get into lock before real data starts arriving. (On the other hand, if you've actually designed CDRs, feel free to correct me)

rawbrawb

15:54

@ThePhoton I agree (and yes I have - but not USB) but it's NRZI data so you don't get continuous energy at the main frequency, at the lower frequencies you could easily do this w/o a PLL. You know the PLL will be drifty simply because it can lock in so quickly.

Quick question - bash command to remove a directory and all it's structures recursively is > rm -R XXXX whereas >rmdir -r XXXX requires empty directories. Right? I have a bunch of crud in a directory holding a job open (file space is gone).

Anindo Ghosh

@rawbrawb rm -rf

W5VO

the -f is to not ask for confirmation (just do it)

rawbrawb

there is a difference between -R and -r right?

Anindo Ghosh

@rawbrawb Not to my knowledge. The man pages used to say -r or -R with no distinction in the explanation.

rawbrawb

@AnindoGhosh thanks, not often I need to tickle these servers and my bash is rusty, but mainly I can't mess up ....

Anindo Ghosh

16:07

@rawbrawb yw. Not been in bash for a long time myself, but rm is a unix command from when the people who created the Bourne Again SHell were probably in their nappies. ;-)

Toby Lawrence

rm -rf is recursive delete

forced

doesn't matter what's in the directories below

it all goes

rawbrawb

well it's all going .... ;) can hear the drives spooling. Thanks

Toby Lawrence

haha

rawbrawb

16:29

Wow, I guess I was remiss, ~1 TB of temp files ...

Nick Halden

@rawbrawb 1TB?

damn what the hell were you doing?

rawbrawb

@NickHalden simulations ...

rawbrawb

16:42

@AnindoGhosh love the toilet pictures ... great answer!

Anindo Ghosh

@rawbrawb Now the Internet will forever know that Anindo posted toilet pictures. Thanks!

rawbrawb

@AnindoGhosh just doing my part to ensure an ever broader audience for you ...

Anindo Ghosh

@rawbrawb That statement could be taken so many ways :-)

angelatlarge

Hallo from sunny Boston :)

rawbrawb

@AnindoGhosh I'd hoped you'd realize that.

user61389

16:49

@angelatlarge which one? Hi :)

Anindo Ghosh

@angelatlarge Hi Bunny Soston.

rawbrawb

@angelatlarge hello

angelatlarge

Everyone here has gone mad

Toby Lawrence

I'm in MA as well

over in Waltham, right next to Watertown

Anindo Ghosh

@angelatlarge Not true. For some of us it comes preinstalled.

angelatlarge

16:58

@AnindoGhosh +1

Stacey Anne

17:12

good morning everyone

rawbrawb

@angelatlarge I see what you mean

@StaceyAnne good morning!

icarus74

Just got off CNN... man, some serious action happening there, with the lockdown and all ! Folks in the vicinity, stay safe.

Stacey Anne

@icarus74, what's happening?

Toby Lawrence

@StaceyAnne manhunt for the 2nd suspect in the Boston Marathon bombings

Kortuk

@StaceyAnne capturing one of the bombers probably!

icarus74

17:15

I meant Boston.

Toby Lawrence

they have the town they're conducting the manhunt in locked down, amongnst other surrounding towns

public transit and flights are suspended as well

Stacey Anne

I followed that on CNN the first day, and then our CNN channel disappeared for some reason

hectic

Toby Lawrence

instructing citizens to stay indoors

icarus74

Actually it's all over BBC as well... and quite frankly, BBC's video feed quality is about a decade ahead of CNN's (no offence). At least on my TV set.

rawbrawb

@StaceyAnne One of the bombers is dead the second (his brother) is on the run, they killed a MIT police officer last night. car chase, bombs thrown, rumoured one of the bomber ran over the over. general mayhem...

Stacey Anne

17:18

wow,

Anindo Ghosh

@rawbrawb Ran over the other perp? "How am I supposed to cook my rice, without my pressure cooker? Die!!!"

angelatlarge

@rawbrawb Yeah, I am not sure about that last sentence either.

rawbrawb

@angelatlarge I'm just reporting what I read ...

angelatlarge

@rawbrawb Are you reading Chechen newsfeeds?

@rawbrawb "rumoured one of the bomber ran over the over"?

icarus74

Apart from the "one bomber ran over the other", rest everything is there on news.

rawbrawb

17:29

@angelatlarge we're talking about the same thing.

@angelatlarge I'll see if I can find the link

angelatlarge

@rawbrawb Ah.. the second over is supposed to be other?

The Photon

@icarus74 PAL/NTSC issue?

icarus74

ha ha ... or the royal scissors ! (oops, I didn't say that)

rawbrawb

@angelatlarge yep

@angelatlarge as usual there is conflicting reports ...

@angelatlarge here is one link that mentions it. news.nationalpost.com/2013/04/19/…

just below first map ...

angelatlarge

@rawbrawb That 7-11 has nothing to do with MIT campus, and not particularly near. Conclusion: not inclined to trust.

rawbrawb

17:35

@angelatlarge that probably safe MO for ALL reports at this time.

angelatlarge

@rawbrawb Yeah, that's probably right, actually.

icarus74

same page, on the police radio timeline, at 12:48, the description says the 1st suspect was shot, and mentions nothing of being run over ! anyhow, it's mayhem, and these things are hardly ever completely black-n-white.

angelatlarge

Can someone explain to me why this answer is grayed out:

-3

A: I2C level shifting

Yes, you have done things on your schematic that are horribly wrong. To properly level shift your voltage levels, see I2C slave address not acknowledged (sometimes) The MAX3373E IC is used for level shifting. Please note that, pull up resistors are shown on the SDA & SCK lines. However, when usin...

Is it because it is -3?

user61389

@angelatlarge Yep.

angelatlarge

@CamilStaps Is this documented somewhere?

user61389

17:42

7

Q: Why is the text of this answer gray?

Why is the text-color of this answer gray instead of black? I don't see what's special about it - except for the fact that it is an exact duplicate of another answer to the same question.

discussion color formatting

angelatlarge

@CamilStaps Cool, thanks.

user61389

@angelatlarge I can't find any authoritative reference, but this will do ;)

Nick Halden

@AnindoGhosh WHERE?!

Anindo Ghosh

@NickHalden Hmm, your enthusiasm about my toilet is a bit... worrying. :-)

rawbrawb

9

A: Collimating a sonar beam

Coincidentally, I happen to be playing with almost precisely what the question refers to, since yesterday. My distance sensor unit boasts a 25 degree angle, but I faced the same problems with my bucket of water. My solution may not be an engineering marvel, and there will likely be some reaction...

icarus74

17:57

Didn't get an answer earlier, so trying my luck again -- Is "3-point calibration" explained somewhere ? Didn't have much luck on google.

rawbrawb

@icarus74 did you post a question?

icarus74

A question on chat, so far... earlier today.

rawbrawb

@icarus74 linky?

@icarus74 are you really in Kathmandu?

icarus74

11 hours ago, by icarus74

BTW, anyone here can point me to the basics of "3 point calibration" ? Is this a curve-fitting thing ?

rawbrawb

@icarus74 Oh, I'd hoped it to be more detailed .... ;)

icarus74

18:04

@rawbrawb was! now in Pokhara. More beautiful, less peaceful :)

rawbrawb

in short it is curve fitting. It's best if you understand the basic relationship or trends that the variables follow. Else you have to make some assumptions .

@icarus74 wow, this chat truly is multinational! awesome

icarus74

:)

The reference to 3-point calibration came via one of the comment on Anindo's answers to this old question (also asked by your's truly).

rawbrawb

@icarus74 you're close to Annapurna, right?

@icarus74 what is the problem? there are many ways to do it.

icarus74

Yes. Have you visited or planning a vist ?

Anindo Ghosh

@icarus74 Pokhara! I've been there.

jippie

18:10

good morning @all

icarus74

@Anindo, when was this ?

rawbrawb

@icarus74 I used to do a fair amount of mountaineering and the Himalaya was always an attraction. Sadly I've never been!

Anindo Ghosh

@icarus74 Around 1990, maybe 91.

@rawbrawb You must!

rawbrawb

@AnindoGhosh yes I must

icarus74

Wow, that's like a long time ago @Anindo. I moved here rather recently (little more than 2 months), but I am told that even 7-8 years back, the town was an order of magnitude smaller. Hard to beat the view you get here.

@rawbrawb excellent, then this is the place to be. strangely, I am a fish out of water here... not much of a mountaineer. Prefer the fossil-fuel drinking mules to go uphill, and that's about as far as I go.

Anindo Ghosh

18:18

@icarus74 Yes, it was. That was when I spent several months hiking through Ladakh, Leh, and Nepal.

icarus74

We have lot of 'mooners coming in over here from India, and of course, also other parts of the world. However, they usually stick to Kathmandu.

rawbrawb

@AnindoGhosh damn! that's awesome, I'm jealous, but in a good way!

@icarus74 can you describe your system that you're trying to model? that's always the best way to curve fit. If not you can do a least squares fit to a quadratic system.

Anindo Ghosh

@icarus74 I was not married then :-)

@rawbrawb Want to hear more? I once spent 2 months at a Serai (like an Ashram, but also allow overnight stay to travelers) in Ladakh where I had only stopped for a night halt - The guru at the Serai and I got chatting, and we continued debating a million subjects for the next couple of months.

rawbrawb

@AnindoGhosh I love it! so the nitpickiness was fostered by a Monk? from Jesuit to Lama - you never stood a chance .... ;)

Anindo Ghosh

@rawbrawb And then there was the time I hitchhiked on trucks from Chennai on the East coast, to Goa on the West coast, with just a backpack. Even rode on the roof of trucks, ate at *Dhaba*s (roadside open restaurants favored by truckers, usually with a few outdoor cots for a nap), it was pretty crazy.

rawbrawb

18:29

@AnindoGhosh sounds pretty attractive a lot of times.

Anindo Ghosh

@rawbrawb Pretty amazing monk that man was. My first conversation with him was around my being an atheist, hence a bit awkward being in an Ashram. He said "I'm an atheist too, that doesn't prevent anyone from being spiritually well grounded". And then it began.

rawbrawb

@AnindoGhosh Very wise man (men) ...

Anindo Ghosh

@rawbrawb And very knowledgeable too.

user61389

What is the difference between the MPLAB IDE and MPLAB X?

user61389

Ah, never mind :)

rawbrawb

18:47

well all, take care. signing off ...

Anindo Ghosh

@rawbrawb Take care :-)

jippie

I'm confused with the Thévinin question too.

1

Q: Thevenin Equivalent Circuit

QUESTION: I'm having a hard time figuring up what the Thevenin Voltage is along with Thevenin Resistance for this circuit below. I'm also confused on what I'm suppose to do when there is a current source thrown in or multiple sources of any kind thrown in. Do I convert them all to voltage sourc...

circuit-analysis thevenin

What was the trick again to solve this?

I can remove the current source, calculate R(th) = 2k2 // 5k6 = 1k6

U(th) = 16V × 5.6 / (2.2 + 5.6) = 11.5V

But then?

The trick is superposition?

I keep getting a different number from the simulation :-s

hmmzzz made a rounding error -:s

was right all along

I thought I was loosing it

(more than I already had)

well thanks @all for your help

Nick Halden

19:13

@jippie anytime man

that's what we're here for

Wow I got 9 pts for this answer: electronics.stackexchange.com/a/66147/4159

er, 90 pts

Toby Lawrence

woo, design assigned to panel and stencil cut and shipped out

exciting

Nick Halden

@TobyLawrence wooooop wooooooooooooooooooooop

is that for sapphire?

Toby Lawrence

yah

it's my rev A

I had to do some component swaps because of availability

and my last proto I made changes to the board before I sent out for the stencil

so they were essentially useless

except for testing fitment in the enclosure

so now everything is under version control :)

Nick Halden

19:29

@TobyLawrence respeKt

alright i gotta roll for a bit guys

Toby Lawrence

cya

Anindo Ghosh

19:47

@NickHalden 100 now

Anindo Ghosh

19:58

Could someone ID a package name for me please? It's the SMD gullwing (non wide) version of the PC817, Image 2 on Page 2 of that datasheet.

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