Electrical Engineering

Skyler

00:29

@Asmyldof so basically it just lies to you all day every day?

Asmyldof

@Skyler It involves firehoses and high pressure pumps

Skyler

now im picturing you sucking in a birthday cake through a vacuum and spitting it out a hose

Nick Alexeev

02:00

@Asmyldof Now many containers?

Shalvenay

02:18

hey there @NickAlexeev

Peter K

04:23

Go home AVX, you are drunk.

Their "1210" SMT tantalum is actually 138 thou by 110 thou typical

I would call that a 1411, not a 1210. Anyway, that just royally screwed me on a huge board order and I had to vent.

Asmyldof

05:11

@NickAlexeev I suspect 2 full pallets

@PeterK On the one End Tantalums are notorious for their liberal sizing. On the other hand 1210 is one of those packages that, granted be it more often in width, regularly is flexible with exact sizes for no reason I know of.

Bartek Banachewicz

07:23

@Asmyldof woop. I bought a PSU.

Asmyldof

10:01

@BartekBanachewicz That's not whoop. Now it'll be much harder to bamboozle you into buying a fancy one

Which one?

Bartek Banachewicz

10:45

@Asmyldof Korad ka3005p. It's kinda fancy when you think about it.

PlasmaHH

only for rather crude definitions of fancy...

Bartek Banachewicz

kinda

I've concluded that I have too many things to possibly extend my workshop with to get just a PSU for the whole budget

like a new multimeter at some point

PlasmaHH

which reminds me of that I still wanted to buy and test that cheapo meter dave talked about...

Bartek Banachewicz

I was reading through this post and comments and one said that, lemme

> It’s a pity thermal imaging cameras are so expensive – it’d be really good to have one looking at a circuit as it’s powered up.

I actually found a meter with such a camera recently, now I know what that was for

@Asmyldof also I might still free you from other lab equipment you might not need ;)

PlasmaHH

be careful, he wants money or favours in exchange for that

Bartek Banachewicz

10:55

@PlasmaHH money is fine

PlasmaHH

you have somet hat you dont need? ^^

Bartek Banachewicz

@PlasmaHH sort of.

PlasmaHH

11:10

let me compile you a list of things and where to send it to...

Bartek Banachewicz

lol

@PlasmaHH it's just that I have a pool of imaginary money (earned on the internet) that I spend on random stuff

since it's earned on top of my wage my SO doesn't mind myself buying the strangest things with it :)

PlasmaHH

imaginary money? so you buy imaginary stuff with it?

Bartek Banachewicz

@PlasmaHH e.g. games

Bartek Banachewicz

11:36

@PlasmaHH and now I'm watching a "how to find a $50 scope on ebay" vid which also counts as imaginary :D

KyranF

Anyone able to recommend a PCI card that does Profibus for a Windows PC and has a nice and straightforward C++ API?

PlasmaHH

windows 98?

KyranF

lol no, Windows 7 Pro

Asmyldof

@KyranF Can't say that I do, no

KyranF

What about one that has a shitty API, like the SERCOS CIFX cards by Hilscher?

Asmyldof

11:51

@KyranF National Instruments if you have the money

KyranF

the CIFX cards by hilcher are about US$1k, and support profibus, but the main cost is SERCOS III I think. I'm hoping to find something around $500 that just handles profibus to PLC

Bartek Banachewicz

damn I've been reading about scopes and now I want one

it seems that living my life without one has been a waste

and wow seems they really dropped in price

PlasmaHH

not much, in the last couple of years there has appeared a low price market that didn't exist before

a good one still costs as much as years before, its just that for much less money you get a usable one.

Asmyldof

12:11

Might have a 500MHz turn of the century Agilent "left over" if I can reset it and calibrate properly * cough *

PlasmaHH

defective 500mhz scopes sell on ebay here for about the same price whether they are functional or broken :(

Asmyldof

@PlasmaHH That's why I tried to win the broken one in the US

Still spensive though

Because Agilent

PlasmaHH

and shipping

Asmyldof

But, I'm hopeful I can double it in value

Well, this is the 400kg lot of stuff, so the one 18kg Agilent wasn't going to be adding much cost

PlasmaHH

ah ok

Asmyldof

12:20

Which is why I pre-bid on the 500MHz, the 1GHz and the 1.5GHz one, hoping to win one of the GHz and the MHz as backup and then none of the auctions pop-corned and I won them all

1GHz has been sold pre-emptively

Well, not guaranteed sold, but likely they'll have it

Keeping the 1.5GHz one

So probably going to have the 500MHz to either keep if the offers aren't high enough (who doesn't want 8 channels of Agilent in his lab?!), or sell (because, who really needs more than 4 channels of Agilent!?)

Giskard42

Hey, when you guys are troubleshooting a system, do you take notes constantly, or just load it all into headspace?

PlasmaHH

depends

Asmyldof

@Giskard42 Depends. At the office there's so much hassle and interruption that I write even the tiniest thing down. Home lab I'm always alone and can follow a plan to the letter, so all the Scope images will also be in accurate order and I can always type the report weeks later without missing a detail

Bartek Banachewicz

@Asmyldof lol

@PlasmaHH yeah that's what I meant. I've been looking at one of those newer Sigilent ones and it's kinda cool that it doubles as a bus analyzer

they brag I2C, SPI, UART, serial...

I suppose I'd use that much more than super high frequency stuff, but then again I have no idea what I mean

PlasmaHH

most seem to have it, and in most it doesnt seem to work that well...

e.g. in my rigol its next to unsuable

Bartek Banachewicz

12:32

hmpfh

I've looked at Saleae before, but they seem to be kinda expensive for what they offer

it's just much less versatile than a scope

oh shit they also accept paypal

PlasmaHH

Just make an excel sheet, one row for each feature you can think about that might be useful to you and enter stuff for every candidate scope to get an overview

also think about features like a bandpass filter in the math functions ^^

Bartek Banachewicz

@PlasmaHH well right now I'm thinking that scopes are mostly for analog stuff and digital probes are for digital stuff

this is a huge generalization obviously since they overlap to quite some extent

PlasmaHH

I would say that the best thing is to buy a scope for analogue and salae for digital stuff if you don't want to buy a big mso from agilent or so

Bartek Banachewicz

@PlasmaHH IOW, both :D

PlasmaHH

If I had some spare mmoney I would probably try out if a tektronix mdo is useful

Bartek Banachewicz

12:44

it's a pity Saleae charges $40 for shipping

but then again

Bartek Banachewicz

12:58

~~oh hey I found a shop that ships bus pirates for free~~

well then

oh ugh no

Asmyldof

13:14

@BartekBanachewicz get a fake salaeaeae from aliexpress

They work with the freely available sealaalalaaalaa software

Paid $29 including shipping for two of the simplest way back when

Or some such

Giskard42

13:41

@Asmyldof I think salamieae said they're going to lock down their software soon

Won't work with off-brands

@BartekBanachewicz I think you're going to be pretty disappointed with anything less than a DS1054Z

I had an off-brand Atten scope for a few years and the difference is pretty substantial for like $100

The salamiaeaes are semi-useful, but I haven't found them more useful than a bus pirate and a good Rigol analog scope

Bartek Banachewicz

13:57

@Asmyldof mm

they seem to be going for around $8

Asmyldof

14:11

@Giskard42 I have the sabbellabbedingdongs just to leave at customer sites. And I always keep installers of the last two versions of any software I use, so no worries

Eggi

Hi there,

I am searching for a vertical RJ45 connector for a 1000Base-T application, like this one:
http://www.mouser.com/ds/2/706/fastjack-vertical-gigabit-520346.pdf
Circuit E, where all 4 center taps are seperated and with 0.01µF or 0.1µF connected to ground.
But this one is rather expensive. An additional transformer stage is not necessary.
Can you help me here?
I've seen a few from Wuerth Electronics but horizontal, are the vertical ones the rare ones?

Bartek Banachewicz

@Asmyldof why would you leave them anywhere?

anyway, I just bought a $5 clone. We'll see how useful it is in a month

Asmyldof

But I do use them myself, also @BartekBanachewicz, because they can record MANY more points than a Rigol and that's extremely useful for statistics

Giskard42

@BartekBanachewicz Often embed them into test equipment as acquisition boards

Bartek Banachewicz

well if the chinese clone is good enough then I'll just need a scope without all those fancy decoding features

@Giskard42 oh I see

Asmyldof

14:13

@BartekBanachewicz When you're a Freelancer and you leave a driver board you know works and it doesn't work with whatever a customer has made, you leave them some tools and say in a more friendly manner "figure it out, or pay me to"

Bartek Banachewicz

oh okay

Asmyldof

99/100 times in my case it turns out I'm fully to their spec, but their spec isn't correctly written, or they actually didn't design to their own spec

Which is very much not a me-problem

Giskard42

@BartekBanachewicz Seriously, DS1054Z. It's worth it.

Bartek Banachewicz

@Giskard42 €400, huh.

Asmyldof

@Giskard42 Only when you need it for what you want to figure out

Bartek Banachewicz

14:18

why would I need 4 channels?

Giskard42

@Asmyldof Wut

Asmyldof

I worked the first 3 years of getting paid as a freelancer with a good and calibrated Fluke, second hand and a 20MHz analogue scope

Giskard42

@BartekBanachewicz You don't, but rigol doesn't make a 2 channel

Asmyldof

Perfectly fine

Giskard42

Yeah, but how much did that run you?

Bartek Banachewicz

14:19

yeah I've figured that the PSU is the most important part to get actually

Giskard42

I bought my 25mhz atten for $250

Asmyldof

The 20MHz scope I found in a dumpster? I found it in a dumpster

2

Giskard42

@BartekBanachewicz I'd scour ebay for the psu

Bartek Banachewicz

so that's what I ordered. I could use a new multimeter, a new soldering station, stuff

@Giskard42 that's ordered already. I went for the Korad.

Giskard42

Ah, good man

Asmyldof

14:19

Second hand low-end Fluke back then was 80 euros or so

But one of those Fluke 17 ones from China is, what 110 now?

Bartek Banachewicz

choosing multimeters is just a nightmare for a beginner btw

Giskard42

Okay, I guess I'm wrong, I thought digital scopes were more expensive

guess I'm behind the times

Bartek Banachewicz

well if you get rid of USB then it's sorta ok

the functionality overlap between all of those is also pretty confusing

PlasmaHH

chosing anything is just tedious if you follow the excel sheet approach, nothing more

Asmyldof

@Giskard42 What I'm saying is you do not need digital when you're starting. That's right nonsense

Bartek Banachewicz

14:21

@PlasmaHH that requires you to know what you want

Giskard42

@BartekBanachewicz You can get GDM-8251 bench multimeters really cheap on ebay right now, there was a big liquidation

PlasmaHH

@BartekBanachewicz you better make your mind up about that then

Bartek Banachewicz

@Giskard42 oooh, shiny. That's a sexy looking meter alright.

Asmyldof

Any old analogue anyone is doing away with that works or that you can probably fix will do for the first year to even decade

Giskard42

@Asmyldof Maaaan, whaat?

PlasmaHH

14:22

@Giskard42 oh nice, 180 bucks and 220 bucks shipping... yeah

Bartek Banachewicz

@PlasmaHH I found one for 275+20 so far

Giskard42

Snagged mine for like $150 +20

Bartek Banachewicz

oh there you go 190+35

is that thing really more convenient than a "handheld" one?

I suppose being heavy and not moving around could be a feature

Giskard42

@BartekBanachewicz Hella precise, really high resolution, and RS-232

Asmyldof

@BartekBanachewicz Depends on what you feel is convenient and what you expect to be doing in the next X months

PlasmaHH

14:24

@BartekBanachewicz customs and taxes included?

Bartek Banachewicz

@PlasmaHH hmpfh. That's a bit random here.

PlasmaHH

I have never found something in the US that is worth it on ebay...

Bartek Banachewicz

@Asmyldof so far I'd like a one that beeps

PlasmaHH

usually the shipping prices are ricioulous

Bartek Banachewicz

mine doesn't beep in the continuity mode

Giskard42

14:26

This does, but the latency is atrocious

It's about a half-second on continuity mode before it beeps

PlasmaHH

lets all buy daves meter then ^^

Bartek Banachewicz

@Giskard42 interesting, so it would seem that this one isn't that great after all :)

Giskard42

Oh yeah, eevblog.com/product/bm235-multimeter

@BartekBanachewicz It's not perfect

PlasmaHH

@Giskard42 a huge amount of the "slow" continuity mode meters I found are only that because they have shitty probes. my cheap 3 buck ebay probes work much better than those that came with my agilent meter

Asmyldof

@PlasmaHH Don't need to have 2 Keysights and 8 Flukes

PlasmaHH

14:32

@Asmyldof I mean the one he might one day sell

Asmyldof

@PlasmaHH Ah yes, got myself some genuinely golden probes off China

@PlasmaHH I'm not that confident in the actual down under the hood quality of it all, if I may be so blunt

PlasmaHH

It would be intresting to see, since feature wise it has some noticeable things (15V diode mode, low burden voltage) but I would not be so sure if the software side of things is ok, and the long term stability...

Asmyldof

@PlasmaHH He's still a bit... clunky in his path of assumptions and inferences in that really low noise or really high stability, I'd want to see the boards before I told anyone to go out and buy at the price driven by the claimed specs

PlasmaHH

@Asmyldof yeah, I often hope its just his wanting to be quick on camera and that when he sits down with enough time he gets it right. But what I think will happen is that many people will take that one apart and do suggestions of all kinds so that either the 1st revision can be "hacked" to be better, or the 2nd revision will be useful

Asmyldof

@PlasmaHH He is not doing that just for the camera

PlasmaHH

14:46

@Asmyldof I mean he seems to want to get everything in one take and rushes through the stuff. I hope he takes more time off camera. If he rushes through the stuff in that same way off camera, then well... have you ever had a look at any of his products?

Asmyldof

@PlasmaHH I have not. But I mean he does it in all his videos where he starts with assumption A, works through process B, gets to assumption C, which invalidates assumption A, and then goes through Process D on basis of assumption C, etc

Well, not all his videos

But the ones where he is fixing or designing something

PlasmaHH

Yeah, when he is fixing stuff he reminds me of some coworkers I had that had degrees in physics or chemistry or something like that and never really learned structured debugging and jumped from here to there without collecting data first and only then drawing conclusions

Asmyldof

Or keeping an overview of the information gathered when making assumptions or decisions

And if you do that in such videos, you do that with everything

PlasmaHH

hm, maybe. I find it at times difficult to explain my approaches to people, I should do my own youtube channel to figure out if I would be the same on videos ^^

Asmyldof

:-)

PlasmaHH

14:58

The comment section would be fun, people screaming all over the things that I get wrong

Giskard42

@Asmyldof Have you ever encountered a problem in which a SAM4S will enable the clock, waits for the rc oscillator to start, switches to the RC oscillator, but then hangs waiting for the clock source to start?

Asmyldof

@Giskard42 Not on SAM4S no, there's an erratum which can cause something similar if you use the accurate RC into the PLL, but that only applies to the M0+ devices

Not related to M3 or M4 types at all

Giskard42

Huh. It's definitely a hardware problem, because one board revision prior works fine with the same code.

So weird

PlasmaHH

switch chips?

Giskard42

@PlasmaHH You mean I might have a bad batch of chips or something?

I've tested like five new boards and they all have the same problem

PlasmaHH

15:06

@Giskard42 who knows? at least you can rule them out that way.

Asmyldof

@Giskard42 It's not unheard of in lower price assembly houses that reflow profiles are "guesstimated" rather than controlled

PlasmaHH

which package do you use? qfp or bga?

Giskard42

QFP

PlasmaHH

that shouldnt be too hard then to switch the chips, just for having it ruled out

Giskard42

Will do, brb

Nope

PlasmaHH

15:21

sot he new chip works fine on the old board (and/or vv?)

Giskard42

Old chip works fine on the old board, old chip doesn't start on the new board

PlasmaHH

good point to start from there.

I guess I would start at square 0 and check every pin for what its doing and what is the difference.

gnd vs. floating etc.

actually measure it

Giskard42

Yeah, probably a good idea.

PlasmaHH

stability of the power rails and stuff like that

thing is, like you might have goofed up somewhere and a pin is not conneted to where you thought it is

have seen that with quite a few gnd pins that went nowhere

anyways, have to catch a train to go home

Giskard42

@PlasmaHH Okay, thanks for the help

And asmyldof

Giskard42

15:39

they aren't even different boards

this is doing my gorram head in

They're the SAME revision

The Photon

16:21

@Giskard42 Some other part has the wrong PN installed, maybe.

Giskard42

@ThePhoton ...It's a good idea, but A. I've checked the BOM, nothing's been changed, and B.

There's nothing I can think of that could possibly have this effect

The only external component involved is a watch crystal, but if I remove it on the old boards I get a totally different response to what I'm seeing

The Photon

@Giskard42 Don't check the BOM, check the actual boards. Assembly shops do make mistakes. The machine might drop a part and they pick the wrong one up to replace it (because you didn't budget them spares to allow for this kind of loss). I've also seen distributors (well-known ones) ship mis-labeled parts.

@Giskard42 Wrong value R or C in your RC circuit...or cracked capacitor.

Giskard42

@ThePhoton It's an internal rc

in the chip

I'm powering just the chip, bypassing other components

Putting 3.3v on the rail

All that's in there is decoupling and the watch crystal

I've replaced the watch crystal

The Photon

@Giskard42 mmm

@Giskard42 No floating reset/NMI/JTAG pins?

Giskard42

16:46

@ThePhoton Nope, I'm stepping through

(with JTAG)

loads code fine

just halts on wait_for_osc()

PlasmaHH

19:07

@Giskard42 any idea if the pll successfully goes to 12mhz or if its still trying or so?

Giskard42

@PlasmaHH It just constantly waits for the pll to come up

I've filed a support ticket with atmel-cum-microchip, guess we'll see if they have any insight

PlasmaHH

does the datasheet contain details about how the pll functions exactly? you might be able to assert a few conditions

PlasmaHH

19:33

start with the cleanliness of the pll voltage ;)

Bartek Banachewicz

19:58

welp, I incorporated the regulator into my test circuit, and sure enough it draws steady 5mA

but it's cool, I have my own dual voltage setup with the tiny running at 3V3 and the transistor fed straight from the power battery

at the same time I've discovered that the MCU on the damaged board is actually perfectly functional, so it must be something else that fried

I've actually emailed the manufacturer and asked for the schematic, but I don't hope for much

I could theoretically perform the tests with the power LED now but I think I might want to wait for the PSU

with some luck it should actually ship tomorrow

PlasmaHH

and arrive in 6 weeks

Bartek Banachewicz

oh by "ship" I actually meant arrive, it's sent locally

and I ordered it to work which is in the middle of the city and a guaranteed pickup

anyway, I should probably (finally!) order stuff for PCBs as well

PlasmaHH

20:14

hm, in the 80s, have there been diodes (zeners possibly?) that use some body material that can either rust (brownish) or corrode (whitish)? I have on this corroded board a component that has a diode symbol under it but doesnt look like a diode at all

EwokNightmares

20:50

I'm confused. I programmed a microconroller to communicate over USB as a CDC device and then am listening to it on a hyper terminal. The code is not able to handle inputs yet, so if I right click into the terminal with my mouse, my CDC device will receive the click codes and decide to transmit an entire function from my code in plain text, even formatted in my style from the programming IDE.

I'm confused how this could even exist in the code and how it is transmitted in plain text to my terminal. Only thing I can guess is that somehow the compiler didn't compile the function but instead packed it into the machine code as plain text. Anyone ever see this before?

I also connected the USB code to the stdio printf

not sure how it could get into the printf buffer either

Bartek Banachewicz

@EwokNightmares have you perhaps copied your source before?

Try doing Paste in some text editor.

EwokNightmares

yes that was it haha

thank you

That's a big relief and makes me feel silly lol

Bartek Banachewicz

happens to the best of us :)

EwokNightmares

:40121628 I thought the terminal was transmitting the ASCII combinations of windows to represent mouse clicks

Bartek Banachewicz

21:14

hm I think I'll do some analog measurements today as well, since I got the output stage more or less ready

user228700

22:24

Hello, everyone :-) I was wondering if any one of you has the time to help me with an incredibly dumb question about electric power that has gone unanswered inside my mind for years now.

Giskard42

@Kaumudi.H Shoot!

Asmyldof

* kills @Giskard42 *

user228700

Oh, thanks! Right, well, I am learning (for the umpteenth time) about electric power and have come across, of course, problems regarding the calculation of energy in kilo Watt hours.

user228700

My question is this: how is it that simply multiplying kW by h gives me kWh?

Giskard42

Energy flow over time multiplied by time gives you energy

If I understand your question :>

user228700

22:28

Yes, right, however, 1 kW of power signifies that 1000 Joules are being generated/consumed in one second, no?

Giskard42

Yup

user228700

1 second. How does it work, then, when we simply multiply this by h?

Giskard42

Ah, I see

user228700

Yes? :-)

Giskard42

One sec, just trying to work this out myself :>

user228700

22:30

:-P Sure.

Giskard42

Okay, just wanted to check weather my understanding was correct

user228700

Wokay.

Giskard42

One "kilowatt hour" is just the amount of energy that corresponds to 1 kilowatt/second for 3600 seconds

if that's a slightly better phrasing

user228700

Oh, crap, one second.

Giskard42

I find it very helpful to play around with WolframAlpha's conversion system

It does this kind of dimensional conversion very well

IE. wolframalpha.com/input/?i=1+kilowatt+second*3600

user228700

22:35

I'm back! Sorry about that. Oh, WolframAlpha, hmm.

user228700

@Giskard42 Where does this number 3600 disappear to when we simply multiply by h to get kWh? O_O

Giskard42

@Kaumudi.H h=3600

I think.

user228700

Hmm, under this definition, does this make sense:

user228700

To me, it doesn't :-/ That conversion unit, 3600 is nowhere to be found!

user228700

22:41

This is what I found in another source:

user228700

So...

Giskard42

I fell into the same trap as you, I think

user228700

:-(

user228700

I'm sorry, lol.

Giskard42

22:44

Ah, I think I got it

There are zero dimensions of time in 3.12kw

not /s not /h.

It's just instantaneous power draw.

So when we multiply it by hours, that's our unit of time

not seconds

user228700

@Giskard42 Huh, how is that?

Asmyldof

kWh has unit equivalency to Joules

W = J/s

kWh = kW * h = 1000W * 3600s = 3600000J

Giskard42

@Asmyldof Dammit, now you've confused me even more

Anna K.

Hi, can all Karnaugh map simplifications be expressed as boolean algebra simplifications?

user228700

Ah, right, I think I understand. While converting W to kWh by multiplying by the number of hours for which the equipment in question consumed/generated $x$ kWs, the unit of kWh remains Joules $\times$ 1 hr/1 sec.

user228700

22:52

Is that correct?

user228700

I'm not particularly bothered about this unit when multiplying this number by, say, the cost of 1 kWh of electricity to pay my bills is all, yes?

Giskard42

Mainly for my own understanding:

1kw is 1 joule/second

1kw/s is 1 joule/s/s

1kw/h is 3.6x10^6 joules

user228700

@Giskard42 Shouldn't that be 1 $kW\times h$?

Giskard42

@Kaumudi.H AAh, yes

I'm an idiot

1kw/h is joules /s/s

user228700

@Giskard42 As am I, don't worry :-P

user228700

23:00

In any case, thanks, y'all! :-)

Transcript for

Electrical Engineering