Electrical Engineering

Anindo Ghosh

4:05 AM

Shhhhhh!

angelatlarge

@AnindoGhosh Hi

Anindo Ghosh

@angelatlarge Hiya

angelatlarge

@AnindoGhosh Did you get your circuit done?

Anindo Ghosh

@angelatlarge Awaiting feedback and suggestions. Also I might redesign part of it by replacing the N-MOSFET IRLML2502 with the N and P MOSFET pair Si4562DY. That way, the N will be the switch, the P will be reverse protection. Any thoughts on that?

@angelatlarge See Figure 5 in this note.

@angelatlarge Plus, I have to figure out what parts will need decoupling caps. I'm not sure yet, haven't thought about that part sufficiently.

angelatlarge

4:21 AM

@AnindoGhosh Don't know enough about that to have an opinion

Anindo Ghosh

@angelatlarge No worries. What about the capacitors? Any ideas what parts should have a cap on them? Meanwhile I'm revisiting the design with the dual-MOSFET package, this time I'll label for public consumption, so slightly bigger text :-D

angelatlarge

@AnindoGhosh I don't think slightly is going to cut it. I mean a magnifying glass is preferred to a microscope, but still

@AnindoGhosh I am the guy that always forgets decoupling caps.

Anindo Ghosh

@angelatlarge Yeah yeah yeah :-) I get it. I honestly never planned to mail that one out... My final client friendly version usually is massively reader-friendly.

angelatlarge

4:46 AM

@AnindoGhosh All is quiet again...

Anindo Ghosh

@angelatlarge Yeah, terribly boring place during my daytime, this chat.

... and hello, @rawbrawb :-)

rawbrawb

@AnindoGhosh good timing hey? Boring = me

Anindo Ghosh

@rawbrawb Not saying you can't be boring if you set your mind to it...

OK someone tell me why the heck every optocoupler is in a huge package? Essentially a DIP with the pins gull-winged into SMD form. Aren't there any tiny optos?

rawbrawb

@AnindoGhosh voltage withstand, distance is the only solution in some cases.

Anindo Ghosh

@rawbrawb Well, there are HV MOSFETs in insanely tiny packages.

rawbrawb

4:51 AM

@AnindoGhosh but are they safety rated?

Anindo Ghosh

@rawbrawb So how about non safety rated, lower isolation voltage ones? The best I can find are 1.27 mm pitch SOP-4 from Vishay, and those are 5 times the price of the DIP-SMD crossovers.

rawbrawb

@AnindoGhosh yes, but are they NON safety rated?

;) it worked before so I thought I'd try an variant.

Anindo Ghosh

@rawbrawb Like I care about safety rating in non-industrial settings. If a hobbyist manages to put a few kV onto a breadboard, they have bigger problems :-)

rawbrawb

@AnindoGhosh just make your own out of TP rolls and stop whingeing

Anindo Ghosh

@rawbrawb Hey wait a sec, that's actually giving me an idea. What's to prevent me from using a sideways-facing IRLED and IRDiode at 0603 size, putting them face to face, and potting the lot? Heck, maybe even 0402.

rawbrawb

4:57 AM

putting? potting! ahhhhh I got an @AnindoGhosh spelling/type ...

Anindo Ghosh

Yep, there are side-facing IREDs and PIN diodes. 0402 for the LED, check. 1210 for the diode, ugh!

rawbrawb

@AnindoGhosh well if you use the right type of clear epoxy (clear in the IR too - don't forget) you don't need to maintain the airgap (just don't get bubbles in there)

Anindo Ghosh

@rawbrawb I love spell-check when it un-corrects stuff.

rawbrawb

@AnindoGhosh Uuuum yeah, yeah I KNOW exactly what you mean!

;)

Anindo Ghosh

@rawbrawb I'm going to think about this later today. Added it to my "to-think-on-throne" list

rawbrawb

5:00 AM

@AnindoGhosh TMI

@AnindoGhosh I did this once in the past with acrylic light pipes when I couldn't get a high enough withstand voltage. But that was a 35 KV testing system.

The Photon

@rawbrawb Not only you need a big enough gap between the two sides of the leadframe inside the part, you also need the pins far enough apart to maintain creeepage distance on the pcb tracks connected to it.

rawbrawb

@ThePhoton Oh great. @AnindoGhosh calls me boring and you call me a creep ....

The Photon

Also, the optoisolator business isn't really looking for innovative applications, AFAIK. The optoisolator guys I know talk a lot about high reliability specs (MIL, aviation, automotive, ...). Not so much about, "wouldn't it be nice to have a part that can break a ground loop but doesn't need to maintain a safety barrier."

rawbrawb

@ThePhoton That reminds me of those cool little couplers that ADI has come out with for exactly that! But being ADI they're probably $50 a piece.

The Photon

@rawbrawb Even $5 is pretty steep compared to a basic optocoupler, I suspect.

angelatlarge

5:15 AM

Wow, I didn't know you can bitbang serial. But I guess that's exactly what software serial does. neat-o.

The Photon

@rawbrawb, I think this question might be for you:

0

Q: Amp measures board twist (unfortunately!)

Well, this is a toughie -- though fairly simple. Does anyone have experience with board twist affecting your circuit? We have a board design that is supposed to measure a loadcell. We have finally tracked a system accuracy fault down to the amp IC. When we twist the board, the amp IC changes ...

amplifier

Question is basically, can physical stress increase the offset voltage of an AD623?

rawbrawb

@ThePhoton yep I saw that.

Anindo Ghosh

5:38 AM

@ThePhoton Yeah, the optos I'm looking at are all under 10 cents each in 100 quantity. Going by that, pure low voltage isolation should be possible for far less and far smaller, I would think.

@ThePhoton What are the odds the R7 is changing value on stress?

jippie

good morning

Anindo Ghosh

@ThePhoton Though the question states that they've taken R7 off the board to check, somehow I am not convinced most resistor types will not change value when stressed.

@jippie Hiya @jippie

angelatlarge

@jippie Hello

Stacey Anne

how would one test the resistor stress individually in the manner described on long leads? They're tiny

Anindo Ghosh

@StaceyAnne Since the question states they took the resistor off onto wires, I'm assuming it isn't SMD

rawbrawb

5:44 AM

@AnindoGhosh I have seen this before on some high altitude eqt.

Anindo Ghosh

@rawbrawb If I go by that, then I'd be looking at using a flex PCB for the problem portion.

rawbrawb

@AnindoGhosh I'd agree with you. Although metal film (given they are typically spiral etched) should be OK but then you'd never use that with an In-Amp like that.

@AnindoGhosh Through Hole also is good, of J-LEad SMD. LCC not good.

Anindo Ghosh

@rawbrawb Also, given it's a bog-standard, boring and not super-sensitive inAmp, I'm surprised no similar report is showing up elsewhere on my cursory search. Leads me to suspect the problem is specific to their board, not a behavioral pattern for that IC.

user61389

@angelatlarge nah, I'll upvote you again instead, how sounds that?

rawbrawb

@AnindoGhosh it could be the board design, but it doesn't surprise me.

Anindo Ghosh

5:50 AM

@rawbrawb Another idea: They're inadvertently coupling something inductively across layers... Flex the board, the coupling changes. Not sure that applies to the DC signal case, though

jippie

did you see my Rc/Re msg on messenger @AnindoGhosh?

Anindo Ghosh

@rawbrawb I once saw a board that would reset every time a truck dumped rocks into a nearby huge hole in the ground, that was used as a holding area for a rock crusher. They never did figure out why that was happening, I just suggested flex PCB, and they were happy with results.

rawbrawb

@AnindoGhosh The reaction of Si effective mass to stress is a large-ish signal ( I use it in some MEMS designs). BUt it's worth mentioning, seems like a serious problem.

Anindo Ghosh

@jippie Last I saw on messenger was the explanation for the various parts which I typed out, and no response from you. One sec let me see.

@jippie What is Rc/Re by the way? And no, last communication with you on the messenger was me saying "Any other mistakes or any easy add on bits?"

rawbrawb

Ok all, I'm out ... have a great [daily interval period name here]

angelatlarge

5:59 AM

@jippie Nice answer.

@CamilStaps Sorry, were you talking to me? Missed that.

user61389

@angelatlarge no problem, about your SO answer

angelatlarge

@jippie You see me whorin'... You're hatin'... Patrolling.. you're tryin to catch me postin' turdies, postin' turdies, postin' turdies.

user61389

You mentioned me somewhere this night, but I slept already

angelatlarge

@CamilStaps Yeah, I saw shocked, that answer got upvoted

I was using the "leaving messages through the chat" trick

jippie

@AnindoGhosh Rc and Re seem a bit low for the current that is required.

Anindo Ghosh

6:08 AM

@rawbrawb Bye!

user61389

It is a good answer, but I'm afraid most SO people don't want to read all those letters without code

jippie

@angelatlarge ?

angelatlarge

@jippie Feelin' dirty. Was thinking of a song.

@CamilStaps We'll see. I just posted my own question that could qualify for the Moby Dick badge

@jippie What's your favorite HV programmer project out there?

Anindo Ghosh

@jippie How so? at 20 Volts, 1260 Ohms = 15.8 mA, right? And if only Re is considered (for initial Gate charging), that's a momentary 32 mA, still not too bad.

And that's a worst-case when input is 20 Volts, I'm considering clamping via Zener at 18 Volts.

jippie

@AnindoGhosh 330+330=660, where does the 1260 come from?

user61389

6:12 AM

@angelatlarge linky?

jippie

@angelatlarge the one I posted the other day

Anindo Ghosh

@jippie Ohhh damn, good catch!

angelatlarge

1

Q: bound service versus started service on Android and how to do both

I am asking a vexed question that has been (partially, to my mind) addressed here and here. Let's say like in many examples we want to create a music application, using (say) a single activity and a service. We want the service to persist when the Activity is stopped or destroyed. This kind of li...

java android service binding

Anindo Ghosh

@jippie For some reason I was thinking 630, which isn't even a valid value.

angelatlarge

@jippie You posted one the other day?

jippie

6:13 AM

@angelatlarge rickety.us/2010/03/arduino-avr-high-voltage-serial-programmer

user61389

@angelatlarge thanks - I just got an upvote on the question as well :o

Anindo Ghosh

@angelatlarge What's a moby dick badge?

angelatlarge

@AnindoGhosh Awarded to any question written as if the author is paid by the word. May be awarded multiple times.

@CamilStaps That was me: I forgot to do that before

user61389

@angelatlarge Oh, thanks

angelatlarge

Not that I want to say that I'll upvote all your guys posts regardless. I love ya all and everything, but I don't automatically upvote

And I expect the same from y'all. Except when I am begging. Which might be all the time.

Anindo Ghosh

6:17 AM

@angelatlarge I automatically upvote when I see an answer I would have written. Also when I see a great answer to a poor question.

user61389

Hey @jippie remember that compiler bug when I was working on ethernet? It really was a compiler bug. ;)

angelatlarge

@AnindoGhosh That's not "automatically". That's just "upvote"

Anindo Ghosh

@angelatlarge Hmm. You have a point.

angelatlarge

BTW, Anindo, is this a good time to beg^H^H^Hsuggest that you weigh in on my battery question too?

Anindo Ghosh

My absolute favorite answers are the "decoded" ones, where the person answering manages to divine what the underlying issue is, from a question that seems all foggy or improbable at first glance. +1 for the engineering experience I see on such answers.

@angelatlarge I already told you all I could, didn't I? If you want to self-answer, I'd be happy to either suggest edits, or upvote if it's good.

@angelatlarge I'm very stressed by being unable to figure out how to make an irregular-outline pad in Proteus.

angelatlarge

6:21 AM

@AnindoGhosh Ah, sorry, I didn't get that. I thought at the end of our discussion you said that you'd return to answering questions. OK, I can write an answer, no problem.

abdullah kahraman

Morning!

user61389

@abdullahkahraman morning!

abdullah kahraman

Anybody into Python?

angelatlarge

@abdullahkahraman Hallo

@abdullahkahraman I've written a few scripts...

jippie

@abdullahkahraman you are the one taking the looniversity course, so we should ask you the difficult questions

abdullah kahraman

6:33 AM

@angelatlarge Did you do any user interface?

angelatlarge

@abdullahkahraman Nope

abdullah kahraman

@jippie That course is starting from bottom edge and going really slooow, lol..

It is Rice University.. My friend asked me; "I thought rice means pirinç". Pirinç is the turkish of rice, the legume..

I told him it is a state name in USA

Anindo Ghosh

@abdullahkahraman Rice is not a state. Rice Uni is in Houston, in Texas state.

abdullah kahraman

@AnindoGhosh Oh :)

Ouch

Anindo Ghosh

@abdullahkahraman Named after William something Rice, person's name.

abdullah kahraman

6:39 AM

@AnindoGhosh hmm

Oh, my dictionary told me that it is a city in Minnesota, I understood it as a state lol

I sometimes don't understand myself, there is always Wikipedia..

Anindo Ghosh

@abdullahkahraman Wikipedia to the rescue, it is William Marsh Rice. I wonder if there is a breed of rice called Marsh Rice, that would be interesting.

abdullah kahraman

@AnindoGhosh lol, picture is cool:

William Marsh Rice

William Marsh Rice (March 14, 1816 – September 23, 1900) was an American businessman who bequeathed his fortune to found Rice University in Houston, Texas. Biography Rice was born in Springfield, Massachusetts, the third of ten children of David and Patty (née Hall) Rice. His first job was as a grocery store clerk in Springfield, at the age of 15. By age 22, he had purchased the store from its owner. In 1838, Rice traveled to Texas in search of new business opportunities. Unfortunately, all the merchandise from his store was lost at sea, and Rice was forced to start anew in Houston as a ...

Anindo Ghosh

@abdullahkahraman Yeah, looks like someone we know.

abdullah kahraman

lol ;)

Anindo Ghosh

Strange... "all the merchandise from his store was lost at sea". For going from Springfield MA to Houston TX, why would one need a sea voyage?

abdullah kahraman

6:44 AM

lol, a very very very strange programming class:

@jippie You there?

@AnindoGhosh sort of

@jippie OK so here's the thing on that collector current bit: If I wanted a max collector current of up to 50 mA if Re is shorted, and a max collector current of 30 mA if Re is not shorted, with a voltage of 18 Volts, what would I be using for my resistors? I'm managing to confuse myself now.

@jippie 390 Ohms on the Rc, and 220 on Re would work, right?

abdullah kahraman

@AnindoGhosh Is this some kind of joke between you two now, guys.. :/

Anindo Ghosh

@abdullahkahraman No, my brain is shorted, because of some problems with SMT footprints.

abdullah kahraman

6:49 AM

@AnindoGhosh Smoke..

angelatlarge

@jippie So all the HV programmers are for fuses only?

jippie

@angelatlarge no don't think so

@AnindoGhosh why is Re shorted?

abdullah kahraman

@AnindoGhosh 360 ohms and 240 ohms will work

Anindo Ghosh

@jippie Wait, I don't need to allow 30 mA once the Gate is charged. So I could use anything for Re such that the voltage divider does not go higher than around 9 Volts. Hence, 390, 390

abdullah kahraman

@jippie Maybe there is a cap?

Anindo Ghosh

6:51 AM

@jippie Because at the beginning of gate charging, the gate to source looks like a short due to gate capacitance.

@abdullahkahraman Dude, you've got potential! You picked that up without even having context! Well done!

@abdullahkahraman Smoke?

abdullah kahraman

@AnindoGhosh Nah, I picked it up wrong.. I thought this was an audio amp with a transistor

@AnindoGhosh Your brain was shorted?

Anindo Ghosh

@abdullahkahraman Brain still overloaded. Too many parallel threads.

angelatlarge

@AnindoGhosh His potential is about 3.3V

jippie

@AnindoGhosh I still think the currents are rather high, but then again, I have no idea about the transistor's gate capacitance.

angelatlarge

@jippie: Fuses only, I think

Anindo Ghosh

6:54 AM

@abdullahkahraman 360 and 240 Ohms are not standard values, one tries to move up to the next higher (or next lower depending on context) E12 resistor value.

abdullah kahraman

@AnindoGhosh :'(

jippie

@AnindoGhosh what would be 5 tau for the designed combination?

abdullah kahraman

ecee.colorado.edu/~mcclurel/resistorsandcaps.pdf

jippie

what is the formula again for current, capacity and time?

Anindo Ghosh

@jippie See, normal operating current need not be high, but gate charging current needs to be as high as possible, to switch the FET fast. Problem is, if I put Re too high (which I can do) then the voltage divider will go higher than 10 volts which is the absmax for gate on that FET. But... I'm missing something obvious again, shows my mind needs a holiday.

jippie

6:57 AM

@AnindoGhosh no you won't go higher than 10 volts because you have a zener there.

Anindo Ghosh

@jippie Even of the voltage divider goes too high, the Zener I added at the gate will clamp it at 10 Volts. Or 9 Volts or whatever Zener I use.

@jippie Yes exactly. Hmm so I can bring down normal operating current to much less. What's a good minimum for stability, would you say?

@abdullahkahraman Those are E24 values, more expensive than E12 (small difference, but matters for production)

jippie

say voltage = 10V; C(gs) = 1n; I = 20mA => t = 1e-9*10/.02 = 0.5us

abdullah kahraman

@AnindoGhosh Hmm

jippie

@AnindoGhosh to go from 0 to 10V

Anindo Ghosh

@abdullahkahraman E12 is the yellow column in this page: logwell.com/tech/components/resistor_values.html

abdullah kahraman

7:01 AM

Eeew what is wrong with E6?

jippie

I personally would start with a current around 5mA or so.

Anindo Ghosh

@jippie 0.5 microsecond rise time = roughly 1 microsecond cycle time = max frequency for PWM etc is 1 MHz.

abdullah kahraman

There was also E3! 50% tolerance, wow!

jippie

I did neglect quite a few factors of course (including a V(th))

Anyways

Anindo Ghosh

@abdullahkahraman Yeah, that's when you use a line drawn on paper with a graphite pencil, for creating a resistor. There's a video about it out there, by some MIT folks I think.

jippie

7:03 AM

I have a question for you guys, not sure if it will survive when I post it as a question:

My cat likes to chew on IGBT's, how can I make her stop this habit. arduino cattiny

abdullah kahraman

@AnindoGhosh Wow!

Anindo Ghosh

@jippie Hmm, hold on a sec. There are two phases: During gate charging, we need max current, sure. After that, just need some current through c-e to hold the voltage up high at the gate. So 5 mA holding current sounds OK?

abdullah kahraman

@jippie How did you do those tags!

Anindo Ghosh

@jippie That should be tagged cattiny and destructive-testing.

jippie

@AnindoGhosh a parallel cap for Rc for the quick charging?

Anindo Ghosh

7:05 AM

@jippie Maybe destructive-Tasting

@jippie That's an idea - that's how some MOSFET drivers work internally.

jippie

@AnindoGhosh she also likes pin headers and small signal diodes. I bet she likes any component lying on my desk.

Anindo Ghosh

@jippie Brilliant. Thanks.

abdullah kahraman

@jippie Good idea..

jippie

yes you may upvote me now

or solve my CATtiny problem

/me is out for now

abdullah kahraman

@jippie bye..

Anindo Ghosh

7:07 AM

@jippie You'll definitely get 4 upvotes on deserving answers today :-)

@jippie so 3.3 k for Re and 390 Ohms || a cap for Rc.

Very nice, I think that'll work well.

angelatlarge

@jippie: Found one that actually can program, I think

der-hammer.info/hvprog/index_en.htm#hardware

user61389

Guys.. any idea why I get a syntax error on line 1, #include <p18f4620.h>?

abdullah kahraman

@AnindoGhosh What is that for? An IGBT?

angelatlarge

@CamilStaps Because p18f4620.h is FU?

user61389

@angelatlarge yeah saw that coming :)

Anindo Ghosh

7:21 AM

@CamilStaps Depending on what error and which compiler, it might be an error within the included file not in your source file.

angelatlarge

That's what he said!

user61389

@AnindoGhosh hmm, but it isn't my file and I used it before

Anindo Ghosh

@angelatlarge Yeah, didn't see the message till I had posted mine.

abdullah kahraman

@CamilStaps What is your compiler?

user61389

No custom error message unfortunately, just syntax error

user61389

7:22 AM

@abdullahkahraman C18

Anindo Ghosh

@CamilStaps Check include paths, or use "xyz.h" instead of <> and put a copy in the source folder, to check.

angelatlarge

@CamilStaps and you think that p18f4620.h s fine?

abdullah kahraman

@CamilStaps Is there anything wrong with line 2?

angelatlarge

Also a good point

user61389

@AnindoGhosh already did, doesn't help

user61389

7:23 AM

@angelatlarge I used it before without problems

abdullah kahraman

@CamilStaps Any new updates on the compiler?

user61389

@abdullahkahraman nope, even not when I add an empty line. Also, there aren't weird non-visible characters on line 1/2, I checked

Anindo Ghosh

@CamilStaps Copy-paste the contents of the H file into the source, in place of the H file include line.

user61389

@AnindoGhosh good idea

user61389

@abdullahkahraman nothing relevant

angelatlarge

7:24 AM

@CamilStaps Maybe you typed a character in there and saved it by mistake?

user61389

@angelatlarge not likely, the other program still compiles

user61389

@AnindoGhosh okay, copying the H file into the main.c works. Can you tell what the problem is then?

angelatlarge

@CamilStaps Ah, OK.

Anindo Ghosh

@CamilStaps Yup, your include path variables are screwed.

angelatlarge

Did you try #include "picdung.h" ?

user61389

7:26 AM

I'll fiddle a bit with the directive and paths and so

Anindo Ghosh

@angelatlarge Naughty! How many beers down?

angelatlarge

@AnindoGhosh Sorry. Did you try #include "picfoo.h" ?

Anindo Ghosh

@angelatlarge :-)

abdullah kahraman

@CamilStaps Why don't you move to XC compilers? I think support for C18 will be finished soon.

PeterJ

Hi all! Quick random poll, on the following question I think Kurt's answer is good because the components are different to the schematic. But who makes the resistors in the bottom two photos out as 2.2M and who makes then out as 3.3M?

5

Q: Why does my 555 stop oscillating under load?

I've got a 555-timer circuit. When I examine the output-pin on an oscilloscope, I get a nice square wave. I want to turn an LED on and off, so I've attached an LED and resistor to the output pin (see image, below). However, the LED stays on. When I examine the output pin again, I find a solid s...

led 555

Anindo Ghosh

7:28 AM

@abdullahkahraman Or maybe he'll upgrade to a non-PIC platform :-D

abdullah kahraman

@AnindoGhosh Grr!

user61389

@abdullahkahraman yeah, Uli told me before as well, but I haven't searched before

user61389

Would XC be compatible with old C18 programs?

user61389

@AnindoGhosh that's no upgrade.

Anindo Ghosh

@PeterJ I see 3.3M

Orange-Orange-Green

angelatlarge

7:30 AM

@PeterJ That's very hard to say...

Anindo Ghosh

@angelatlarge He's polling, not looking for definitive responses :-)

abdullah kahraman

@CamilStaps I think they have some good info on migration

jippie

@CamilStaps remove the question mark

user61389

@abdullahkahraman okay, I'll use that for future projects then

angelatlarge

@PeterJ If you made me choose, I'd say orange, I guess

user61389

7:31 AM

@jippie :)

angelatlarge

If I answer that question correctly, can I have his scope?

Anindo Ghosh

@PeterJ Also, compare the color of the bands with the color of the red strip on the breadboard. Resistor reds should appear darker red than the breadboard's band, not lighter. That gives me orange, despite any Auto White Balance issues with the camera.

angelatlarge

y'all can have the rep

abdullah kahraman

Check this first: toledo-bend.com/colorblind/Ishihara.asp

angelatlarge

@AnindoGhosh I was comparing it with breadboard strips and wire colors too

user61389

7:32 AM

Hmm, when I put a new line before all code it works... Ideas?

Anindo Ghosh

@CamilStaps Because it's a pic?

angelatlarge

@CamilStaps Note how it wasn't me who said it.

user61389

Note how everyone hates PIC :(

Anindo Ghosh

@abdullahkahraman Yup, checked, I am not colorblind. Fortunately for me, as my other life (photography) involves massive amounts of color discerning.

jippie

@PeterJ 3M3, isn't that a bit high for a 555 circuit with a tantalium cap?

angelatlarge

7:34 AM

@CamilStaps You mean if your file starts with a newline, before #include?

user61389

@angelatlarge yep - in the header there were comments, so that works as well

angelatlarge

@CamilStaps Is that file getting concatenated with something?

PeterJ

@AnindoGhosh, I see them as 2.2M. I did have a test at school that showed 'pretty average' results on colour blindness. @abdullahkahraman Thanks for that link just about to take a look now. @jippie I had a quick look at that earlier and one app note said it was OK at 12V (but personally I'd use lower).

user61389

@angelatlarge not that I know of, it's the main file, it's the only one I compile

abdullah kahraman

@AnindoGhosh My dad is colourblind. He was not accepting it for a long while, then I thought maybe there are some online tests out there. Uncle Google pointed me to the right direction and we made the test. He accepts now :)

Anindo Ghosh

7:36 AM

@abdullahkahraman Some very large percentage of human males are colorblind. It's pretty commonplace.

angelatlarge

@CamilStaps Are you having PC/Un*x issues? CR/LF business?

abdullah kahraman

@AnindoGhosh Wow, really?

angelatlarge

@abdullahkahraman In think at least 10%, right?

For the common red/green kind

Not total

Anindo Ghosh

@abdullahkahraman Random fact: That is the reason certain hand-assembly industrial jobs which require color identification, preferentially employ women.

user61389

@angelatlarge I'm using \r\n as line breaks, can try to change, however, I've never used C18 in a unix environment - nope, \n doesn't work either

jippie

7:36 AM

@PeterJ I'd say he has a tantalum cap on his breadboard, no way it is 4n7

angelatlarge

@CamilStaps No, if everything else works fine. I guess at this point, I'd try recreating your main file, and typing in the #include, then pasting everything else afterwards.

user61389

@angelatlarge Hm, okay, weird :)

angelatlarge

@CamilStaps I am thinking "stray weird character in a file, like ASCII 255"?

Anindo Ghosh

@abdullahkahraman And here's an interesting fact in the opposite direction: For jobs where exposure to ultrasonic frequencies is expected, men are preferred over women, because women on average are more sensitive to the low ultrasonic range than men, and at a point they begin to suffer nausea and other adverse effects.

abdullah kahraman

What do you guys see in this picture:

angelatlarge

7:39 AM

I see nothing

user61389

@angelatlarge when I look with Notepad++ and display all (also non-printable) characters, I only see \r, \n and \t

jippie

@abdullahkahraman pink noise

user61389

@abdullahkahraman 56

PeterJ

@jippie, I agree, looks like one ceramic and one tantalum.

abdullah kahraman

@CamilStaps Correct

user61389

7:39 AM

@abdullahkahraman do I get the washing machine?

Anindo Ghosh

@abdullahkahraman I see a patterned bathroom tile, with the tile number (56) crayoned onto it.

angelatlarge

Yeah, if I tilt my laptop screen back I can see purple 56 too

abdullah kahraman

I see 5 and 6 is a little bit blurred

angelatlarge

@CamilStaps You can have the washing machine. I want the scope

abdullah kahraman

@CamilStaps @AnindoGhosh Is it very apparent?

jippie

7:41 AM

@PeterJ ceramic one is on the control voltage pin (if memory serves me right)

PeterJ

@abdullahkahraman, I see 56 above too. On that link the only one I couldn't spot at all was the bottom left, and read another as 66 not 56. Probably much like the school test where they said I was just a bit borderline on some colours.

Anindo Ghosh

@abdullahkahraman It's pretty apparent, yes.

user61389

@abdullahkahraman wasn't there something with better visible when young? I don't remember. But yeah, I didn't have to look very long

user61389

@angelatlarge new file from scratch doesn't work either. I'll just make up some comment block then :)

abdullah kahraman

@AnindoGhosh @CamilStaps I meant "very different and distinguishable from background" by apparent :)

user61389

7:42 AM

@abdullahkahraman me too

jippie

@abdullahkahraman what are you diagnosing us for?

angelatlarge

@CamilStaps Weird. I give up.

Anindo Ghosh

@abdullahkahraman Not *very different and distinguishable", no, but instantly apparent.

abdullah kahraman

@jippie I can see the number, but I was not able to see 6 very good at first glance..

jippie

@abdullahkahraman the smarter you are, the more noise you see?

abdullah kahraman

7:44 AM

@jippie No, I am damn colourblind on that short-wavelength pigment! I cannot see that easily, like @AnindoGhosh or @CamilStaps did..

Anindo Ghosh

@abdullahkahraman Do you wear glasses?

abdullah kahraman

I don't get it, I can see everything on Ishihara Test

user61389

@abdullahkahraman we have supernatural powers.

abdullah kahraman

@AnindoGhosh I am wearing contact-lenses now

Anindo Ghosh

@abdullahkahraman Because here's another interesting trick: A good quality (highly transmittive) pair of polarized glasses can help many partly colorblind people distinguish color variation better.

jippie

7:53 AM

/me is out to work

abdullah kahraman

@AnindoGhosh A platform to learn digital electronics for students:

►

user61389

@jippie bye!

Anindo Ghosh

@abdullahkahraman Used to crash a lot when I last tried it.

@jippie Have a great day!

PeterJ

I normally don't struggle with resistors in front of me, but sometimes struggle with the blue background on many 1% resistors if the lighting isn't so good. My habit of double-checking with a meter paid off a while back because it's the first time I've ever seen it but I bought a pack that were colour coded as something like 180R but had a resistance of almost exactly 47K or a standard value.

abdullah kahraman

@AnindoGhosh Oh, so you know about it?

Anindo Ghosh

8:01 AM

@PeterJ I once found resistors with 5 bands + gold instead of 3 + silver, that too in a tiny 1/8 watt size. Those were a pain to decipher. Also, a bold green body color, creating further color confusion.

@abdullahkahraman Yes, I still probably have it installed on one of the PCs.

abdullah kahraman

8:16 AM

I think I have a lot on the syntax and basics on Python.. Do you guys think that I should start user interface?

No python guys here?

user61389

@abdullahkahraman try SO :P

abdullah kahraman

@CamilStaps Nah, I have a fear to ask question there, unless I think that my question will be great..

I am confused now, which one to choose, GTK or Qt

user61389

@abdullahkahraman I feel the same, but sorry, can't help you

abdullah kahraman

@CamilStaps No problem.. Thanks :)

abdullah kahraman

8:37 AM

►

user61389

@abdullahkahraman nice :)

abdullah kahraman

@CamilStaps I really liked him :)

PeterJ

@abdullahkahraman, I'm not a Python person but looking on SO at a similar question it appears it's not all that clear cut:

44

A: What should I choose: GTK+ or Qt?

As you seem to primarily target Linux, then the choice mostly depends on the programming language you want to use. If you code in C, then obviously go for GTK+ If you code in C++, go for Qt, otherwise you will need Gtkmm (a C++ wrapper over GTK+) If you code in Python, both GTK+ and Qt have bi...

abdullah kahraman

@PeterJ Yeah, that's why I was very confused..

user61389

@abdullahkahraman girlfriend is a waste of time, sweet

abdullah kahraman

8:46 AM

@CamilStaps lol, and he is pretty consistent on that :)

PeterJ

@abdullahkahraman, I guess if you want my two cents worth I've seen Qt a bit more on embedded platforms used as examples etc, so that might be better to learn in case you want to use C++ down the track. I've never done much with it (just modded some existing code) but I think it adds a bit more of a framework than GTK.

abdullah kahraman

@PeterJ I want to go with Python.

user61389

@abdullahkahraman ultimate goal to work at apple, that's a shame

abdullah kahraman

I think Qt has some licence issues.

@CamilStaps Well, he is a software guy and he is young..

user61389

@abdullahkahraman yeah okay

abdullah kahraman

8:49 AM

@PeterJ Also, they say that GTK looks nicer and I think the same.

@PeterJ But, documentation for GTK is very poor and documentation for Qt is great they say..

The project I want to do is with a Raspberry Pi.

PeterJ

@abdullahkahraman, I wasn't suggesting to use C++ for the moment, just it doesn't sound like for Python it doesn't make much difference either way so it might be a better skill to have down the track. But yeah there are pros / cons like the above so it's really hard to know.

abdullah kahraman

The Raspberry Pi with a 15" LCD screen that has a touch panel on it, is going to be the "user interface" of a PLC.

It is going to communicate with the PLC and do some input/output from/to the user.

Like showing the temperature, speed or setting them etc.

@PeterJ So, it is not much I am going to do.. But I want to consider the future, too.. As you said about Python/C++. I also think that Python will have much down the track.

Also, a good decision point for me is that they say GTK is more fast and efficient than Qt.

It is important for me, in this application.

Hakonbogen

Anyone know of websites that sell reflective IR sensors ?

PeterJ

@Hakonbogen, I'm no expert in the area but what sort of distance / objects are you looking to detect?

Hakonbogen

very small minimum range 1mm to 1cm max

small objects about the size 5mm x 10 mm

PeterJ

9:01 AM

@Hakonbogen, a good thing to search for is infrared proximity, for example at Digikey digikey.com/product-search/…

Many products should handle that distance / size easily, just wanted to make sure you weren't expecting 100 meters or anything ;-)

abdullah kahraman

@Hakonbogen Here you go: taydaelectronics.com/sensors-transducer/optical-sensor.html

Hakonbogen

I don't need the distance, only to sense if an object is present or not.

user61389

9:15 AM

0

Q: Suspcicious pointer conversion warning

I'm compiling my C code using Microchip's C18 compiler. I'm getting a warning [2054] suspicious pointer conversion on this line: puts(ENC_ReadRegister(ENC_MAADR1)); ENC_ReadRegister is an unsigned char (unsigned char), ENC_MAADR1 is an unsigned char. What does this warning mean and how can I...

c pointers warnings compiler-warnings c18

abdullah kahraman

I don't know why, but I choose GTK...

I guess I have a little bit "fanboyism"

Hakonbogen

gtk?

abdullah kahraman

GTK+

GTK+ (GIMP Toolkit) is a cross-platform widget toolkit for creating graphical user interfaces. It is licensed under the terms of the GNU LGPL, allowing both free and proprietary software to use it. It is one of the most popular toolkits for the X Window System, along with Qt. The name GTK+ originates from GTK; the plus was added to distinguish an enhanced version. It was originally created for the GNU Image Manipulation Program (GIMP), a free software raster graphics editor, in 1997 by Spencer Kimball and Peter Mattis, members of eXperimental Computing Facility (XCF) at the University o...

@Hakonbogen It is a GUI kit.

Hakonbogen

Ah

PeterJ

@CamilStaps, just gave your question an upvote, and downvote to the second answer ignore that one lol

user61389

9:22 AM

@PeterJ yeah even I understand that's not a good idea :P

PeterJ

@CamilStaps, does C18 have putchar? That'll go to stdout and not need the file parameter.

user61389

@PeterJ no, I said it in a now removed comment, that's why he changed to putc

Anindo Ghosh

9:40 AM

@Hakonbogen I get mine from eBay, look for TCRT5000

user61389

9:54 AM

So I'm using MPLAB and added all source files to my project, but when I build the project, all files are compiled. How can I prevent the IDE from doing that?

Hakonbogen

10:37 AM

thanks @AnindoGhosh i bought that one, and wrote a new question on the site :-)

Basically about how to read its data sheet

Basically you get downvoted if you mention Arduino and beginner on the site :-/

Anindo Ghosh

@Hakonbogen Yes, this is unfortunately true, though the moderators and some of us who actually care about newbies are trying to change that mind-set.

@Hakonbogen OK, as I'm very distracted by some design I'm doing, I don't have the patience to write a well-formulated answer... and I don't like posting half-baked answers. So I'll give you a briefing on chat, and you can either take it and run with it, or use it to answer your own question if you like, I don't mind. Is that OK?

... or you can just ignore me, and I'll get back to what I was doing ;-)

Hakonbogen

Thanks @AnindoGhosh, its good to hear. If you don't have time, its no problem. I just ordered the part so i will take some time before i get it anyway

If you have time some other day its better to save the energy till then :-)

Anindo Ghosh

@Hakonbogen OK, for this specific part, it consists of two semiconductor devices, which for the purposes of schematic design, you can treat as separate entities. If you want a single composite part within your schematic software, use an Optocoupler such as PC817, assuming TCRT5000 is not listed in your schematic software's libraries.

@Hakonbogen The LED is one component: It's a standard Infrared LED, read up on its forward voltage and normal operating current in the datasheet. Also read the "Absolute maximum" values, just to know what you should NEVER subject any given component to.

So I'm not going to open the datasheet now, but let's say the forward voltage is 1.3 Volts, normal current is 50 mA, and absmax current is 100 mA.

Hakonbogen

yes

Anindo Ghosh

10:53 AM

@Hakonbogen Now, if your supply voltage rail is at 5 Volts, the surplus voltage after catering to the LED's forward voltage is Vcc - Vf = 5 - 1.3 = 3.7 Volts. You need to get rid of that voltage, and you need to regulate the current through the LED. We can use a resistor for this. For 50 mA current to develop 3.7 Volts across a resistor, V = I x R, hence R = V / I = 3.7 / 0.05 = 74 Ohms. So use a 75 Ohm resistor, or the next higher value you can buy. That'll take care of driving the LED.

Hakonbogen

Ah, didn't think of that i needed that

Anindo Ghosh

Got all that? Then we can move to the optotransistor part.

Hakonbogen

Yes

saved it

Transcript for