Would the power be measured in kilowatt-hours?

like 2 hours ago

.... no

You could, but it makes no sense

:/

@NickAlexeev all yours, hardly keeping my eyes open

:-P

@MaryStar I posted it already ^^

@MaryStar Do you know how to translate dB into a ratio between two powers?

@skillpatrol [Kilowatt-hour] is a unit of energy, not power.

If not, look up decibels on Wikipedia

@MaryStar 2nd, do you know how many kilometers is 400 m?

@skillpatrol Oh... I didn't see that... (I cannot delete it anymore :/ )

@NickAlexeev right, that makes sense now :)

@ThePhoton It is 400/1000=4/10=0.4, right?

@ThePhoton Not really... Could yo give me some hints how we can do this?

@MaryStar OK, so you have 0.4 km. And the attenuation is 4.5 dB/km. So what's the total attenuation in dB?

Yes. Now you need to convert 1.8 dB into a ratio between two power levels. Since this is attenuation, it will be the ratio between input power and output power.

The definition of dB is that the value in dB is 10 * log10 ( P1/P0 ). So you need to reverse that definition to get the ratio from the dB value.

Then you have the input power, and the ratio between input and output power. So you can find the output power.

killowatt-hours per second?

> To exclude the possibility of damage to the gate oxide layer by an electrostatic charge building up on the high resistance gate electrode, the leads of the device have been short circuited by a clip. The clip has been arranged so that it need not be removed until the device has been mounted in the equipment or circuit.

morning

@Asmyldof why is the matrix one all mixed up? I mean the numbers 0 ~ 10.

Don't know which one would be the better one. There is a lot of info :-p

Probably like the matrix best, but the content seems to be different for all three options too. Is that deliberate or just as an example?

@crasic Shall I tell you about the physiology of suffocation by N2? Or, do you know the scary stories already?

@NickAlexeev I used to work in an academic setting, I've seen more dewars on their sides than I would prefer

but in seriousness we have an O2 sensor

the venting is startling when soldering 0402!

@crasic Nitrogen atmosphere doesn't trigger a natural suffocation warning. From what I was told, human respiration system fires a warning when it can't get rid of blood CO2. This happens in CO2-rich atmosphere, but not in pure N2 atmosphere.

So, in pure N2 atmosphere, an unlucky person simply collapses because of the lack of O2. And that happens without a warning or an urge to run away.

Yes, but nitrogen is not harmful, if the O2 level stays at 20% you will be fine

we have an O2 as in Oxygen meter in the lab

@crasic There's a reason why the meter and alarm are there. Don't neglect them.

Thank you for the reminder, precautions are followed and I have worked with it before

Ideally we would pull it off into atmosphere container, but we need the pressure

@Asmyldof I found where the unaccounted 2.5mA was going. It turned out that I wasn't actually powering down the USB peripheral.

@jippie this is as is. Different contents is because it's three different kits. The jumbled contents is to avoid problems if pieces from one fall into the other. Front label mentions lengths and colours, back label mentions bin planning and diameters.

@NickAlexeev Hah! What do I win?

:-P

@Asmyldof color?

@jippie Colour

:-P

why write the color in black if you have color print ;o)

for readability

geeen kermis van maken hoor.

I tried, but yellow green and white don't work

I have to get to work, to my home office ...

... wait.

Waiting

@Asmyldof my home office, not yours

You said to wait...

No idea for what

But I'm waiting

@Asmyldof you have to tell me your sioux story later on, I thought it was interesting how you mentioned that name more or less out of the blue.

but now I'm heading for my corporate laptop

@Asmyldof I would put a , behind White ...

about the qr codes, I dont know how you have your site set up and all, but you might want to have the uris product specific. but not to the actual shop uri where you can buy it (that isn't there anyways) but to some redirect string (like tinyurls) so that you can then change the redirect to your shop item even when the shop gets reorganized. that way such qr codes are not invalid after you restructure your shop

not sure if for the single colour only colour: black or colours: black would be best

thats it for now, cant find anything else that would prevent me from printing it

Am I asking too many questions here: electronics.stackexchange.com/questions/178363/… ?

@PlasmaHH the QR code is actually a "trick". If you link a QR code to the product, people will be super happy about getting the direct link. But they already own your kit, so what will that be selling? If they in stead get sent to your shop, they're almost there and the QR did something useful (so complaining is unlikely), but they land on a nice page that will, at that time, be having all kinds of promotions, not necessarily the kit they already bought

Anyway, what was my thought, already sent it to the printers

I did have one with ?AHS8601_K etc, but then I thought ^^

@Asmyldof useful marketing reasoning. moot to discuss it further when they are already printing, but in that case maybe a page "you like our colour kit? here we have some other nice options for you that you might like too:" would be even better, marketing wise...

Fair point.

Next product

:-)

Already happy I asked for your input a couple times before, was very helpful

@Christoph You're not nescesarily asking too many things, you're asking a lot of information from a lot of fields. I could answer you about 95% as I have been running projects similar for higher power applications, but not many people can and when I saw your question and right now I'm way too busy to spend an hour answering everything

I can tell you though, that the original Q/A research post by Russel is flawed in a couple of important assumtions

you mean this one electronics.stackexchange.com/a/169656/18496 ?

anyway, as you don't have sufficient time now I'll just wait a bit longer. Maybe someone is thinking about it already

@Christoph no, this one: electronics.stackexchange.com/questions/71056/…

ah, I really didn't notice that so many of the links I included lead to his questions/answers

he also answered his own question there

twice

I just know about that one, because I have become across it before and to be honest I'm not a fan of people using batteries making such assumptions about a chemical process and I sort of think he should have known better

@Christoph if there's no answer saturday morning EU time (or tonight late US time) remind me, possibly I'll have the energy to write all the answers I can give then

@Asmyldof thanks for that offer! I might add something to the question today, though (in the next 2 or 3 hours) because I'm thinking about different "topologies", i.e. which part of the overall circuit is supplied by which voltage regulator. I think getting that right is crucial.

That would otherwise be a part of my answer, most liekly

likely*

I'm not well known for my short answers here

I hope there will be a common demoniator

logging into chat is a pita...

same here, I always click back and forth between different SE sites until suddenly things start working

I found just today that first logging into stackoverflow.com seems to work best

caps lock, cruise control of the cool

I have no idea what you lot are on about

But then I have it linked to my google account and I use chrome, so that might fix some issues...

there was a popup with a new question in all caps

can I use an analog switch to select between current sensing resistors in front of a high-side current sensing amp?

you mean to chose between shunts?

yes

well, if the relative resistance of your mux is low and it can handle the amps...

maybe we are having a misunderstanding here...I have two loads, each with its own fixed shunt. So I want to switch between the shunts of two loads, not between two shunts for the same load

so the mux wouldn't have to handle the current

Maybe today is a good day to sell my old mobile airco. It still works, but I never really use it other than as a dust collector.

ah that, so yeah, thats possible too, but you have to check the isolation between the channels in the datasheet if they match for your intended measurement accuracy

@jippie I take it if it has free express delivery

@PlasmaHH like the transformer, right?

yep

@PlasmaHH which parameter would that be? I'm a mechanical engineer, this is far from obvious to me

@Christoph its not always called the same I think, I would need to have an actual datasheet to have a look

let's assume it's an ADG409 powered from 12V, the shunts are at about 12V and 4V common mode, each 0.1Ohm, and the currents are 15mA at the 12V shunt and 40 mA at the 4V shunt. They will have a voltage drop of 1.5 mV and 4 mV, respectively.

datasheet: analog.com/media/en/technical-documentation/data-sheets/…

look for the leakage current table and if you are happy with that

you can also just test it by building the thing, not connecting the second shunt but select it and see how it behaves

I'm not getting the idea behind that (apart from "see if it works"). What would the leakage current do? It's a current from the supply to the output, right? The current sense amp has a very high input impedance, so a small leakage current could build up a high voltage at the amp's inputs. Or is that line of thought totally wrong?

ah...do I have to relate that to the current sense amp's input leakage current to see how much error the analog switch's leakage would cause?

@Christoph leaking from supply to output could simply be calculated as an offset, but leaking from one input that is off to the output might be a big deal. imagine 10nA leaking there, and the current for your measurement is 23nA ... quite some difference that can not be calibrated out because it changes with what is available on the input. it might be 10nA vs. 20nA or it might be 1nA vs. 1mA who knows...

"the current for your measurement is 23 nA" - is that the current through the shunt?

if you had two amplifiers before the mux that also have output enable pins, then you could get rid of that problem easier, but maybe its not necessary because the voltage change induced by the leakage current is far below your desired accuracy anyways

@Christoph no, that is the current through the mux

in this case the mux leakage is 50 nA max, and the current sense amp's input leakage is 50 nA typical (2000 nA max). So big deal

well, its your design so your numbers and your call... I havent done much with muxes lately so I cant say if there is maybe a better mux or if amplifying the signal before it reaches the mux is a better thing to do

I considered using a mux because a high-side current sense amp can be rather expensive. If I wanted to amplifiy the signal before it goes into the mux I'd have a high common mode voltage at those amplifiers' inputs again. It's not the number of outputs that I want to keep down, but the number of amplifiers

but I see that the good muxes aren't cheap either

do you have the parts available? you could just hack your thing together, measure on one channel, and vary current on the other channel and see what happens...

no I don't have parts available

@all I'm back-ish

:-D

If I missed anything relevant let me know

we destroyed and reconstructed the universe, but nothing else

and I'm still a noob

hopefully with more questions than before

tons

mission accomplished

the entropy of education

yeah, frustrating, isn't it?

not at all, the other way round would be. imagine the day you have no more questions to ask

I'd start gaining rep by writing answers

I would ask why would I have to imagine, but that's a question and that would induce a paradoxical oscillation

:-)

greetings from goedel

the other day we were compiling a list of stuff that professors liked... he said "anything not on your list"

:-)

@Christoph what's the status of the LiFePO4 related questions in particular?

well, I have not updated the question because I'm really struggling to come up with something that actually improves the question instead of simply broadening it. First of all I need several power supplies running off the solar cell and/or the battery, and I can imagine several different topologies for that.

for example: I need a battery charger IC. That can be microcontroller or something off the shelf. If I program an mcu, it needs its own regulator that runs off the solar cell, say 3.3V switching (mcp1603?). The mcu would then control another regulator that charges the battery. I now have three supplies: 3.3V, charger regulator, and the battery. I can use all of these to supply the actual application circuit, and that seems to be tricky

including all these sketchy design considerations in the question wouldn't help anyone

Fair dues

hm, is it weird if you take off yoru headphones to test if the tone you hear comes from them or your head?

Well, one thing you need to consider/wonder at is your total point of optimum efficiency

With that I mean: You can go and make stuff infinitely well engineered, but if you then link them such that you put it all in the crapper, don't waste too much energy on your designs

@PlasmaHH Not really. I usually put them on for that reason though

But, for the voices, not tones

And not to test, but to drown them out

I hate it when they give comments about the music you have on

Otherwise, exactly the same

but today it must be too hot for any of them

@Christoph What you need to consider in your design before and after each decision with systems like these is: Where will my power flow, and what's the effect of saving 5% on efficiency at point A, B, C, D, etc

If you optimise section one, which then drives you to make very bad choices for the next part, you're shooting in your foot or elsewhere

@PlasmaHH Mine usually only complain about what I say or hear in a non-music way

@Christoph so, for example, if you have Solar --> Battery --> Application, that can be very valid, especially if your application always runs at night time

But if you have Solar, an MCU, a battery and an application that only works when the minimum amount of sun is present, it's much more sensible to have:

If your application uses very little, these choices are of no consequence

IF you then have an MCU turned on at all times, you can start muxing the power paths to all other devices through that

In a design like that you assume your battery is always powered

Because if it isn't that's a big issue, and then when the sun appears it will charge soon enough

Regarding the chemistry, with LiFePO4, for relatively low maintenance you are spot on, and smaller cells of a default size are quite affordable.

One thing, for example, that Russel had completely wrong in his comparison is the fact that LiFePO4 has the same chemical reactions at over-charge as LiIon, it doesn't. It hardly outgasses, it takes more to Lithium plate an electrode and they create no highly flammable gasses on hard shorts, so the risk of explosion is 1/100th of that of LiIon

Not to mention the better thermal performance

One thing you do want to keep an eye on is charging below freezing

That's still very bad for LiFePO

Using, unless in very harsh weather, is not really a problem, but you may want to make sure you only allow charging, through a MOST on your MCU, if the battery can be assumed to be at least 1 or 2 degrees C

That's the most important lesson I can help you avoid

Aaaaan

wall of text

Now I have to go into the next meeting.

@Asmyldof I chose LiFePo for better performance at low temperatures, and when my charger is sufficiently smart (that's why I'm considering rolling my own), charging can be done when the temperature is right.

@PlasmaHH I like that wall, though

@Christoph The only thing you have to feasibly do in normal livable conditions is keep an eye on when you allow charging. I'd still consider a cell-protector PCB, just because it is easy and as it is analogue it reacts to faults immediately rather than on a timed basis between sleeps

Off to meet people I have met before anyway

Home time!

Njooooommmmm

Hmm my hands small of factory fresh silicone wire

<3 ordering from factory direct :-D

evening EU fellows

and morning Americas ones

I am woozy

and I need some usb isolation adapter

piece of gum?

what3 kind of isolation

I only have i2c and spi gum left, no usb gum

I am melting...

Yup

gooblyboobly florp

That's the level I'm operating at right now

I am now staring for 5 minutes at my desk trying to remember what I wanted to do

6

@PlasmaHH Pretend you're in the USA and take the day off ;)

although you're probably already off from work

that I am, but what does taking a day off have to do with the US?

If anything, I thought days off were not done there :-P

Flooooooorrrrppppp

I knew a cute girl called Floor once

Probably weird to all you English speaking people, though

^^ this is how my mind works at 32 degrees

Deal with it

Anybody need silicone wire?

Or a solar panel?

@Asmyldof Seriously?

...

I'm always seriously, you guys

Silicone wire smells funny

So, my living room smells funny now

@ThePhoton what kind of lasery toys do you work with?

@Asmyldof details?

sun --> panel --> poweerrrrr

:-P

...

I'm RFQ'ing Chinese panels to go with the batteries

m

^.^

chinese

If it's made of silicon and has a peak output at its rated value, I crap not a give who made it

I want just a single panel, a small'ish one to experiment with

Already have those. Well...

2V 200mA

:-P

@jippie I have a 20x20mm one ...

small = 2V 200mA

Also Chinese, so apparently you don't want them

small'ish = 50Wp or thereabouts

:-P

Yeah, but you don't want them

Cus Chinese

Mono or poly?

I like blue color

colour* you're not an American

@Asmyldof It is lead on old iron which is better :-p

I'd probably like mono best.

although maybe for dutch weather poly is better

Rated is rated. Mono is more expensive but smaller per Wp

Diff between Mono and Poly in low light conditions is not that great

@Asmyldof am I confused with amorf maybe

Temp, never noticed much of a difference either

Yeah, I'm not buying a 40Wp amorphous

I can't afford to ship that

Or the pole you need to keep it up in the air

@Asmyldof I never really understood why nobody uses water cooling under their panels.

@Asmyldof are they so large, really?

Because it's a hassle

Amorphous has great low light performance but abominable power per m2

@Asmyldof yeah I was confused then.

Mono and poly is just the efficiency per m2 in order of 15 to 20%

I think the Mono 40W panel is 4.2kg including frame and glass, Poly is 4.5kg

bit larger

and in size?

Asked for shipping of both, to see if the diffs in weight and size make up for the diff in price per watt

50×50 ish?

Different, but can't remember

maybe 50×60

I think 60x50 for mono

65x60 for poly?

can't recall

Too hot for storing facts

I have a fan in my storage cabinet.

I have a fan here, not helping

temperature is stable around 28 degrees at the disks

I should probably hook up those parabolic Papsts on the windows all night

?

drunk kid below my window ... throwing up

Little noise, but full cycle of all the air in my house in about a minute or three if I put two on a window in the living room and two on a window in the kitchen

Fun

noisy*

I don't know how it is with your room/house, but my walls are the problem. They're hot.

Yes...

If I cool the air, within a couple minutes it heats up again.

So if you blow 20degree midnight air along them they cool...

The largest wall is facing west

FANS!

Wooooosssshh

....

I have those fun fans that do 12k rpm.

but they're small, 60mm square

and they sound like a jet engine

they are speed controlled, they don't stop for a kids finger or a pencil

Anyways, I can't really open my windows too far, because my cats will crawl out

ebmpapst.com/en/products/compact-fans/diagonal-compact-fans/…

Something a tiny bit like that

But of an older generation and somewhat better performance

And PWM or Temp flow control

Constant speed from 32V to 72V based on input signal or internal thermal sensor

And somewhat more noise

And more power in

:-)

@Asmyldof these are the kind: if you have to ask for the price, then you can't afford them ?

If you buy them new

:-)

I also have their tiny brothers, I think 20W

I'm off to bed.

They might be more suited to my purpose

Enjoy

I have a box full of 48V 300mA SMPS's, I have no clue what to do with them ...

just too little power for your fans

anyways

night

@jippie might cut it for the smaller ones if I can get them to power up at 33%

And then kick in the regulation at peak power of the supplies

:-)

@Asmyldof 48V @ 0.38A

amazon.co.uk/B00H0GRBPY/dp/…

good heavens, I'm rich

haha

Legacy power can sometimes be rewarding to stock

I dremel'd one open the other day, just to have a look if I can adjust the output voltage

I hope LiFePO and solar will become legacy soon.. I'll be rich too

I Dremel'd 80€ worth brand new power supply :-s

You can.

don't look at ebay, they're only 8€ there

Half the voltage will only be 1.3 times the current probably, though

haha

Everything is only € 8 on eBay

No, my Heineken Millennium 3L bottle was 10€

I have to sell them for 50€ to the english bloke

anyways, I'm hitting the shower

and then to bed

night

Good luck

:-)

wtf ... people setting off fireworks? wtf do we have to do with id4?

arrest them all.