Electrical Engineering

coding_corgi

12:13 AM

@jippie after some googling i found out i needed a -vvvv to slow down my uno, now I got a different error:

avrdude: stk500_cmd(): programmer is out of sync

Working on that now...

Anindo Ghosh

3:53 AM

nice and peaceful today

angelatlarge

@AnindoGhosh Hi Anindo

Anindo Ghosh

Hiya

angelatlarge

@AnindoGhosh We decided to ditch the LiPos for my project. Thank god. Not just AAs.

angelatlarge

4:16 AM

@coding_corgi You really want to watch out for posting on the same topic with new questions: as Kurt notes. People here usually don't like very similar looking questions here. Often it is best to edit a previous question when you have new information.

angelatlarge

4:35 AM

@AnindoGhosh Wow, I really don't understand what is popular on this site.

32

Q: How can anyone use a microcontroller which has only 384 bytes of program memory?

For instance a PIC10F200T Virtually any code you write will be larger than that, unless it is a single purpose chip. Is there any way to load more program memory from external storage or something? I'm just curious, I don't see how this could be very useful... but it must be.

Anindo Ghosh

@angelatlarge Hmm? Insufficient context.

angelatlarge

+32 +56 +30 +11

In one day? Why?

With no less than ten people marking it as a favorite question.

I just don't get it.

Not that there is anything wrong with it....

Anindo Ghosh

@angelatlarge In any given sample set of people the world over, the hardcore technical or pedantic will account for only a minuscule subset, I believe. The vast majority are "outsiders looking in", on EE.SE or anywhere else you look, electronics or otherwise. The votes clearly show what's what.

angelatlarge

@AnindoGhosh Yeah, that was my hypothesis, but how in the world do they find the questions? I mean did they all search for "384 bytes of code" on Google yesterday?

rawbrawb

@angelatlarge here is one that has been around without answer electronics.stackexchange.com/q/59057/11861

and here is a meta discussion in which something almost got voted off the island but we saved it. meta.electronics.stackexchange.com/q/2704/11861

to come up with a few very quickly ...

Anindo Ghosh

4:40 AM

@angelatlarge Some form of Google Zeitgeist should tell us. Most likely, this got reposted to schools and colleges on their internal intranets or newsletters

angelatlarge

@rawbrawb OK, thanks.

Ah, the pleasure of editing without the queue. Has worn off, mostly. Now I am just one of the hamsters in a wheel.

angelatlarge

5:07 AM

Is this spam? I can't tell

0

A: Boost converter to 5V

Do you want a particular chip that you use to build a circuit, or do you want a ready-built circuit? Pololu has a ready-build boost converter based on the NCP1402. The NCP1402 is a fine boost controller for low voltage/current, and the Pololu implementation is decent. http://www.pololu.com/catalo...

0

A: How do I improve efficiency of a boost converter?

Or you could buy a properly implemented ready-made boost converter with > 90% efficiency for under $5. If you make many of these, vendors like Recom or Murata may actually have pre-built modules. If you only need one or a few, Pololu has a nice 5V 200 mA boost converter with 90% efficiency for $4...

Anindo Ghosh

5:24 AM

@angelatlarge No, John is not really bad. Basically he found something that works for him, and every problem is a nail.

angelatlarge

@AnindoGhosh OK. I didn't help matters by (previousely) editing the second question (pushing it to the top of the stack) but the "while it lasts" comment, and the somewhat off-topic answer to the second question began to worry me.

jippie

good morning @all

Anindo Ghosh

@angelatlarge It's like someone else we (unfortunately) know, for whom every question has to be answered with the acronym ESR inserted somewhere.

angelatlarge

@AnindoGhosh Tony?

@jippie Hallo, @jippie. You are a hero.

Anindo Ghosh

@angelatlarge You need to ask?

►

Check the guy at the last row center.

jippie

5:31 AM

@angelatlarge ?

angelatlarge

@AnindoGhosh Yes. I don't read those posts

@jippie You spent like 4 hours trying to fix @coding_corgi's problems, it was very sweet of you, and I just wanted you to know that we all saw that.

jippie

@AnindoGhosh is that you?

Anindo Ghosh

@jippie No, but it could be a certain grumpy person in better times ;-)

jippie

the bearded one? :-)

Anindo Ghosh

@jippie ja

AshRj

5:48 AM

Am I imagining things or did another "answer" to a "question" just cross 50?

Anindo Ghosh

@AshRj it did

AshRj

@AnindoGhosh Thats two in a week now. Unbelievable.

Anindo Ghosh

Both very similar - of interest only to "outsiders looking in"

@AshRj Which might be a good sign of fresh enthusiasts breaking into the previously forbidding EE.SE site.

AshRj

@AnindoGhosh I would rather if people enter this site by asking "real" questions. It might get new users on the site, but it will have a cost later on (if it is indeed new users who are voting/asking these questions)

Anindo Ghosh

@AshRj Maybe or maybe not the ones asking, but I can't imagine the regulars voting up like crazy on those questions, so it has to be newcomers.

angelatlarge

6:01 AM

@AshRj What's the other one?

Anindo Ghosh

@AshRj Also, I would rather know what the world wants asked and answered, than presuming to be the person to rule on what should, or should not, be of mass interest. I'd rather err on the side of humility than arrogance.

@angelatlarge The creating of ICs in backyard.

angelatlarge

@AnindoGhosh Do you have a link?

jippie

A man caught fire last night her in Netherland

he was trying to steal copper from a factory and got electrocuted.

angelatlarge

@jippie Was the copper energized???

jippie

talking about releasing the magic blue smoke ...

Anindo Ghosh

6:05 AM

53

A: How are electronic circuits implanted on to microprocessors?

No big deal really. First you get a pile of silicon. A bucket of ordinary beach sand contains a lifetime supply if you're going to make your own chips. There is lots of silicon on this planet, but it's mostly all so annoyingly bound up with oxygen. You have to break those bonds, discard the n...

AshRj

@AnindoGhosh Both are NARQs. Both are easily search-able. Both are overly broad. Its not about humility/arrogance.

Anindo Ghosh

@AshRj I'm sorry but it is. If the world clearly feels differently from the FAQ, the FAQ is outdated. I refuse to be an uptight arse about it.

@AshRj The votes speak for themselves.

AshRj

@AnindoGhosh Would you have the site filled with more such questions ? Its not just about this one question.

Anindo Ghosh

@jippie Evidently not someone the gene pool will miss terribly.

@AshRj I would have the site filled with a bit more diversity - not just a small set of people playing reputation tennis.

jippie

society in general can do without copper thieves.

Anindo Ghosh

6:09 AM

@AshRj If that means there will be more questions appealing to the non-purist audience, well, good.

jippie

it is quite a problem here

Anindo Ghosh

@jippie Less of a problem if they continue to try stealing the copper while the power is on.

@jippie That's called a Dar-Win

jippie

@AnindoGhosh even powered overhead lines on traintracks dissappear sometimes

that is 1500V(DC)

Anindo Ghosh

@jippie ... and the thieves vaporize sometimes?

jippie

not sure if they've tried the 20kV(AC) High speed lines.

@AnindoGhosh apparently they just catch fire

angelatlarge

6:12 AM

I don't see that question as such a problem. People come here and learn that some stuff is pretty damn difficult. And that was a good way of talking about it.

Anindo Ghosh

@jippie Wait, railway catenary isn't usually copper, is it? Copper is too ductile for the mechanical tension involved, I believe.

AshRj

@jippie Thats has been happening here in Delhi as well.

DMRC lost quite a bit of HVCs on a line.

Anindo Ghosh

@angelatlarge I agree. The "reality check" is a healthy thing if done without insults (or at least insults the newbie will realize are insults).

@AshRj Yeah, in Mumbai I hear of entire sections of track getting stolen in the outskirts.

angelatlarge

@AnindoGhosh I think Olin's answer was quite good: entertaining for the OP and the rest of us. It is a bit insulting, but not in a way the the OP would feel turned off, I would think.

Anindo Ghosh

@angelatlarge Like I said, I'd rather have the mild form of insulting, than some of his prior efforts like "We don't speak the dialect of Gibberish you prefer" etc.

@angelatlarge Although, there were huge factual gaps, as the comments and some other answers allude to.

jippie

6:16 AM

@AshRj @AnindoGhosh the copper is also sometimes stolen when it is still on the reel, before being installed. The problem is that these reels have a very accurate length, they fit exactly between a cerain number of portals.

angelatlarge

@AnindoGhosh I agree 100%. When he channels the disdain into those kinds of posts it an asset to the community.

AshRj

@AnindoGhosh Thats something new o.O Havent heard of complete tracks being stolen ..

Anindo Ghosh

@angelatlarge Spot on!

@AshRj Between Virar and Nalasopara, last week. 400 meters of track. They apparently had the cutting torches and other equipment to cut the rails, move them onto trucks (they're not light), and vanish, all within a couple of hours. Something similar happened in Delhi, where the old pontoon bridge near Appu Ghar got stolen overnight.

AshRj

@AnindoGhosh Yeah. The stolen bridge made for a real funny headline on the morning papers :D

Anindo Ghosh

@AshRj It might well be the same bunch of people: Their operational preparedness, equipment and skill indicate some solid team + management.

abdullah kahraman

6:20 AM

Hi!

angelatlarge

@abdullahkahraman Hello

Anindo Ghosh

@angelatlarge Speaking about assets to the community, I am coming around to the view that those two questions are both massive assets to the community, inasmuch as they open doors to new blood.

AshRj

@AnindoGhosh Come on. Dont underestimate the number of innovative individuals in this country ;) There probably are many groups like that.

Anindo Ghosh

@AshRj Enthusiastic and greedy, sure. That organized? Our country in general couldn't organize itself out of a jute sack.

angelatlarge

@AnindoGhosh We are in agreement here. I think those questions a fine/good/expected/helpful.

Anindo Ghosh

6:23 AM

@angelatlarge That's what I have been trying to say.

AshRj

@AnindoGhosh Two cranes, an earthmover and more than 20 workers were engaged in the illegal act . Possibly. Thats a lot of stuff to get together and transport.

Anindo Ghosh

@AshRj Yup, there's some serious project management going on there.

angelatlarge

6:48 AM

Kaz edited that post like 10 times already.

abdullah kahraman

What are those small resistors for? I always see them in high-speed designs.

This board is salvaged from an old printer :P

Anindo Ghosh

@abdullahkahraman Which small resistors? There are many. Also, resistors are resistors, so is there something specific that strikes you as different?

abdullah kahraman

@AnindoGhosh Yeah, sorry :) The resistor banks I meant.

RA17, RA16, RA12, RA11, RA10 etc.

Anindo Ghosh

@abdullahkahraman Circle them please

PeterJ

@abdullahkahraman, sometimes resistors are placed close to the package to limit the current close to the source, so you don't have high current / fast transition lines running across the board

abdullah kahraman

7:03 AM

@PeterJ Are these the resistors that they call the "termination resistors"?

PeterJ

@abdullahkahraman, no but now I think about it my explanation is probably wrong, if it was straight current limiting the end wouldn't matter much. But I have seen the technique a lot.

Now I think further I think it's more of a filter, taking advantage of the track capacitance but I'm not really sure.

Anindo Ghosh

@abdullahkahraman I'm thinking termination / bus filters.

abdullah kahraman

@AnindoGhosh So, on the working principle, do you think the same with @PeterJ?

Anindo Ghosh

@abdullahkahraman If you mean why they are close to the part: For routing convenience, and for design convenience. Try tracking down random resistors at the other end of tracks on a complex board :-)

abdullah kahraman

7:20 AM

@AnindoGhosh Hmm.. Do you think they are slowing the edges down?

Anindo Ghosh

@abdullahkahraman Unlikely but not impossible.

@abdullahkahraman To slow edges one would need a capacitor for each resistor too.

@abdullahkahraman Well, not really - tracks themselves are capacitors

PeterJ

@abdullahkahraman, I didn't realise I could click above to get above to a larger view. What is on the other side of the vias near the resistor packs?

abdullah kahraman

@AnindoGhosh Just like a MOSFET's gate. If you connect a big resistor, it will turn ON slowly because it have to charge the parasitic capacitance on the gate.

angelatlarge

@AnindoGhosh Did you decide to unearth a bunch of old questions?

Anindo Ghosh

@abdullahkahraman yup yup like I said traces are capacitors

@angelatlarge I edited some Arduino misspellings which had been bothering me for a month or more. There are many more but I'll stick to a handful at a time

jippie

7:33 AM

There seems to be a problem connecting to the server. Please check your internet connection and reload this page.

:(

PeterJ

@jippie, same here so looks like a problem their end

jippie

I believe there was a database migration @SE

abdullah kahraman

@PeterJ Sorry for the delay. I believe they go to the IC on the left. I have circled the vias.

So, these pins of the big IC are connected to the both of the smaller ICs, I guess.

Actually this is one of my old designs. It is completely designed by me. However, I am really having trouble remembering what I did. I guess you should always take notes..

PeterJ

7:53 AM

@abdullahkahraman, maybe you used an autoplace and that's where they ended up by random ;-)

abdullah kahraman

@PeterJ Please, I am a professional. Of course I have used the autoplacer and autorouter.

user61389

8:14 AM

Good morning!

user61389

Anyone familiar with TCP here?

Anindo Ghosh

@CamilStaps yes

user61389

@AnindoGhosh I'm trying to open a socket with my PC/client and an embedded board/server. The client sends a packet with the SYN flag to open the socket, the server replies with SYN+ACK, and then the client sends a SYN again, instead of the ACK that is expected. Could you take a look at the packets to see what's going on?

Anindo Ghosh

@CamilStaps That's more @jippie territory :-)

user61389

Okay, is @jippie still here? :) Anyway, the question is here:

user61389

8:18 AM

0

Q: What's wrong with this TCP reply?

I'm building a server with the ENC28J60 chip and a PIC18F4620. The chip is connected to my PC via ethernet. Currently, I'm trying to set up the TCP connection over which I'll build an HTTP connection later on. I have never worked with TCP before. I'm implementing TCP on the embedded device only,...

tcp client-server packet packets tcpserver

Anindo Ghosh

@CamilStaps If you do a netstat on the server, do you see open sockets?

user61389

How do I do that?

user61389

Ah, from the list of all connections, I see no connection with the server. Is that what you mean?

abdullah kahraman

@CamilStaps Morning!

@CamilStaps I have written the TCP/IP standard, so I think, I am, yes.

user61389

@abdullahkahraman I don't believe you...

abdullah kahraman

8:22 AM

@CamilStaps You will, some day..

user61389

@abdullahkahraman well show me, answer the question :)

abdullah kahraman

@CamilStaps You have a small problem that when you find it, you will say "aah, come on, how could I not see that?!".. It is better you find out, it will be more permanent on your brain.

user61389

@abdullahkahraman oh come on! :P

abdullah kahraman

@CamilStaps Btw, are you going to believe that I have written the TCP/IP standard if I answer your question?

user61389

@abdullahkahraman only if that encourages you to answer the question

abdullah kahraman

8:32 AM

@CamilStaps It would be better if you asked the question in EE.SE. Olin Lathrop, my grumpy uncle, has written a TCP/IP stack in assembly, from scratch!

user61389

@abdullahkahraman really?

abdullah kahraman

@CamilStaps Yeah, he is a bad-ass engineer :)

user61389

I asked almost the same question on Server Fault yesterday, the problem was the acknowledgement, one byte was missing. They told me I should go to SO, so that's what I'm doing now with this new question :)

abdullah kahraman

@CamilStaps He has also written a USB stack, too. embedinc.com/pic/dload.htm

user61389

Anyway, as far as I can see, the acknowledgement number is correct, the sequence number can't really be incorrect as it's random, and the flags are correct too. Would the checksum be the issue? Wireshark has validation disabled for some reason, so I can't see.

abdullah kahraman

8:35 AM

@CamilStaps What are you going to do with it?

user61389

@abdullahkahraman that is... terrible.

user61389

@abdullahkahraman hack the world.

Anindo Ghosh

9:19 AM

@angelatlarge Instead of your 595 8-bit shift registers or your TLC constant current LED drivers, would you consider the STP16CL596? 16 bit shift register with constant current sink, 15-90 mA, up to 25 MHz clock, and as little as $2 on eBay.

@angelatlarge Then there is the Allegro Micro A6276, again 16 bit latching constant current sink driver. I was going through some old project documents from some prototypes, and found these two references which had been in my part search list.

coding_corgi

11:26 AM

@CamilStaps Good choice! :)

user61389

:)

coding_corgi

@CamilStaps Inwhat code did you write your TCP thing in?

user61389

@coding_corgi C - I'm basically porting Jalv2 libraries to C

coding_corgi

@CamilStaps Sort've bad choice, (for me at least), to build something proficient like that I would build it in java...

user61389

@coding_corgi I'm building the embedded side, not the PC-side

coding_corgi

11:32 AM

@CamilStaps Oh, sorry

user61389

@coding_corgi no problem

user61389

The guys on Server Fault were confused about that as well already :) I'll make it more clear in my question.

coding_corgi

@CamilStaps What-cha building a TCP server for?

user61389

@coding_corgi just fun

coding_corgi

@CamilStaps What will it do?

user61389

11:35 AM

@coding_corgi I'll first try to do a 'hello world', then fiddle a bit with POST requests, see if I can enable/disable ports on the chip. Then I have the base working and can I start thinking about a real-world implementation

coding_corgi

@CamilStaps Cool!

user61389

@coding_corgi thanks :)

coding_corgi

Networking is my home, my favorite part of programming

user61389

@coding_corgi really! Then this must be peanuts for you ;)

user61389

You're relatively new on the stack, aren't you? What brought you here?

PeterJ

11:41 AM

@CamilStaps, it's been ages since I've done anything like that but should the sequence number keep incrementing even for the ACK? Or maybe I'm reading it wrong.

user61389

@PeterJ according to this, client sends a sequence number A, server replies with acknowledgement number A+1 and a new random sequence number B, then the client replies with sequence number A+1 and acknowledgement number B+1

PeterJ

@CamilStaps, I must have been thinking of something else, I've only done it with UDP when micros that could do proper TCP were fairly expensive, and I've never do it again ;-)

user61389

@PeterJ haha okay, thanks anyway

PeterJ

@CamilStaps, TCP/IP has quite a few states, as opposed to a system with just one input and output ;)

user61389

@PeterJ quite a few indeed!

PeterJ

11:55 AM

@CamilStaps, sometimes I wonder if questions like the one you just edited are even meant to be serious. Whether homework or a practical problem I don't know how anyone can be expected to answer that in a reasonable way.

user61389

@PeterJ the lookup table?

abdullah kahraman

@CamilStaps Here, you scared him, and he's gone.

user61389

@abdullahkahraman and where've you been, Mr. TCP/IP designer?

abdullah kahraman

@CamilStaps It was my lunch break.

PeterJ

@CamilStaps, yeah, I mean if I was really unsure of something like that at least I'd say it was to convert celcius to farenheit or whatever.

user61389

11:58 AM

@PeterJ I'd as well. I'm writing a general answer now, let's hope he adds more information later on.

user61389

@abdullahkahraman ah, sorry :)

user61389

For an array {..., ..., ...} in C what is the element with index 0? The first or the last?

abdullah kahraman

Cool: smart-prototyping.com/index.php?route=product/…

@CamilStaps The first.

user61389

@abdullahkahraman thanks!

PeterJ

@abdullahkahraman, this could be an interesting answer ;)

user61389

12:04 PM

0

A: Creating a lookup table in a microcontroller using in C

I'll give a general answer since the question lacks information. Suppose you have an char as input and a char as output and you want to create a full lookup table (i.e. every input has an output). You'd need 256 values, as the input can have 256 different values. You can now create a table wit...

user61389

What do you think?

Anindo Ghosh

@abdullahkahraman That's really neat - though I would probably order the 0603 version. Nice find!

PeterJ

@CamilStaps, looks good :-)

user61389

@PeterJ thanks :)

Anindo Ghosh

@CamilStaps I would have said "Here is a Gray Code LUT for example". It's a practical and useful table of values.

user61389

12:07 PM

@AnindoGhosh haha

Anindo Ghosh

@CamilStaps But other than that, I like answers like this, which take a poorly thought through question, and turn it around with a useful answer that others could refer to besides the OP.

@CamilStaps I'm serious - a Gray Code is a pain to formulate in code, always easier to use a LUT.

user61389

:)

abdullah kahraman

@AnindoGhosh Thanks :)

user61389

@AnindoGhosh yes but for 8 values...

Anindo Ghosh

3-bit
000
001
011
010
110
111
101
100

4-bit

0000
0001
0011
0010
0110
0111
0101
0100
1100
1101
1111
1110
1010
1011
1001
1000

@CamilStaps Why not? I just gave you the tables by copying from Wikipedia :-D

user61389

12:10 PM

@AnindoGhosh you type fast! Where did you get that?

Anindo Ghosh

@CamilStaps I type fast all right, I answered your question before you asked it.

user61389

@AnindoGhosh yes it of course depends on the application how many bits you want

Anindo Ghosh

@CamilStaps So go ahead and change the example to something a person could directly use :-)

user61389

@AnindoGhosh done :)

Anindo Ghosh

@CamilStaps Nice, I was just going to suggest changing the array name, and you did it. Since you already had my upvote, you can't get another one. :-)

user61389

12:16 PM

What does the grayscale of a LUT actually determine? Why is your LUT grayer than mine?

user61389

@AnindoGhosh too bad :)

Anindo Ghosh

Fahrenheit conversion is not ideal as a LUT example, because it's straight math.

user61389

@AnindoGhosh but in every table you can find some, far-fetched math, can't you?

Anindo Ghosh

@CamilStaps Basically it's quite an useful sequence, especially for things like rotary encoders - Since each subsequent value differs from the previous by just one bit changing, it is simple to detect either a missed value, or a communication error, with a simplistic approach.

user61389

@AnindoGhosh the hamming code :)

Anindo Ghosh

12:19 PM

@CamilStaps Complicated math is a different issue, but a simple two or three operation math is simply not worth doing a LUT for. Actual calculation provides flexibility for arbitrary precision as desired, LUTs do not.

user61389

@AnindoGhosh ah yes that's true

Anindo Ghosh

@CamilStaps hamming is more complicated, Gray is taught even in beginner level courses, so I felt it was a good example to work with.

user61389

@AnindoGhosh then I must be mistaken, I thought hamming was this (pic), but it appears to be not, reading the wiki

user61389

Anindo Ghosh

@CamilStaps Nope

That's a Gray

user61389

12:24 PM

@AnindoGhosh I got it from the rotary encoder's wiki :)

Anindo Ghosh

@CamilStaps Once upon a time, such encoders were made using what we call "limit switches". Using a Gray Code avoids invalid values due to switch bounce.

user61389

@AnindoGhosh not anymore then? What do they use nowadays?

Anindo Ghosh

@CamilStaps LED + photodiode

user61389

@AnindoGhosh doesn't that draw more current?

Anindo Ghosh

@CamilStaps mechanical switches fail.

user61389

12:34 PM

@AnindoGhosh I'll read that as a yes :)

user61389

Why have your gray codes been flagged?

Anindo Ghosh

@CamilStaps flagged?

user61389

Eh, starred

Anindo Ghosh

@CamilStaps no idea. Maybe to make it seem like I talk in Binary

user61389

Honestly, I wouldn't be surprised if you did ;)

PeterJ

12:37 PM

@CamilStaps, I starred them because it makes the chatroom look cool. Binary is better than English.

user61389

@PeterJ :)

abdullah kahraman

This is crazy, really, crazy!

►

Anindo Ghosh

12:53 PM

@abdullahkahraman Reminds me of this one guy we caught at one of my previous jobs - He was routinely throwing slightly bad computer parts out for recycling, then having the junk man deliver those items to his house. I had a home-grown database system that trend-analyzed hardware failures, the graphs showed a change in slope around a month after this guy had joined the support team - and that's how we caught him :-)

abdullah kahraman

@AnindoGhosh Wow!

@AnindoGhosh What are those group resistors that are on the left of AD9648 analog to digital converter?

►

user61389

@abdullahkahraman those are group resistors, if I'm not mistaken.

abdullah kahraman

@CamilStaps Yeah, sorry, added "group" later on.. Group of resistors I meant :)

They are in series with the ADC and they are connected to the Spartan FPGA as far as I can see.

Anindo Ghosh

@abdullahkahraman They are on pins D0B D1B and so on, the data lines. Check against the pinout in the datasheet. Therefore most likely protecting those pins.

@abdullahkahraman I assume you mean the resistors on the traces to the right of the 9648

abdullah kahraman

@AnindoGhosh Yeah..

@AnindoGhosh These ones on the left

Anindo Ghosh

1:10 PM

@abdullahkahraman Yeah probably protecting the data pins

abdullah kahraman

@AnindoGhosh Hmm.. I don't understand why they want to protect those from the FPGA.

Anindo Ghosh

@abdullahkahraman no.clue

@camil, what that chap wants is approximately 0 to 5 volts to be converted to 5 to 0 volts. A "y = 5 - x" function.

user61389

@AnindoGhosh that's what I read from his title as well, but ... ah, now I see

user61389

:)

abdullah kahraman

@AnindoGhosh But with that, he will lose some range..

Anindo Ghosh

1:15 PM

@abdullahkahraman That's a trade-off. A bit of tweaking of the gain for an inverting amp will give him back the range. I'm writing up an answer for him.

abdullah kahraman

@AnindoGhosh And I think he wants to trim the range of pressure sensor, too.

Specifically, the controller will need to be at 100% PWM when the pressure is 0, and 0% PWM (off) when the pressure is at 43 PSI or 2.2VDC.

So he wants to make a 0 ... 2.2 VDC to 5 ... 0 VDC converter.

@AnindoGhosh Set the gain to 2.27 and then invert the output, this is what he should do, right?

Anindo Ghosh

@abdullahkahraman Yep.

Anindo Ghosh

1:42 PM

Olin beat me to my nicely formulated answer. :-)

user61389

He uses MCP parts even for op-amps!

Anindo Ghosh

@CamilStaps hehehehehe

@CamilStaps Well, I try to use TI parts - it's just whatever manufacturer you are most familiar with.

user61389

Yes of course, but it's noteworthy as he is a certified design partner :)

Anindo Ghosh

@CamilStaps And that's different from an independent yet avid supporter of TI, how?

OK now hush. The board manufacturer came back with some drastic limitations on land patterns, I have a few boards to redesign, right from land pattern stage.

abdullah kahraman

@AnindoGhosh Sorry I made you busy.. :)

user61389

1:50 PM

@AnindoGhosh Not really, you're right.

user61389

@AnindoGhosh good luck!

abdullah kahraman

@AnindoGhosh He is my uncle, I had to choice..

user61389

@abdullahkahraman now make yourself busy and redesign your TCP/IP standard so that it accepts my packets! :)

abdullah kahraman

@CamilStaps lol

user61389

0

Q: Interactive Art with Wodden Mirrors- youtube video

http://www.youtube.com/watch?v=BZysu9QcceM This video shows a mirror made up of moving wooden pieces. Please have a look. He achieves different intensity levels by motion of the wooden pieces and placing different light sources on the top. But how did he achieve this motion? Did he really used ...

motor design

user61389

1:53 PM

Awesome video!

abdullah kahraman

Pheeww, I have finally finished my homework.

It is so satisfying to version control everything I work on, even my homeworks :)

user61389

@abdullahkahraman what system do you use?

PeterJ

@abdullahkahraman, finisihing off IPv7? Anyway I'd better head off....

abdullah kahraman

@CamilStaps bitbucket.org/cebrax/afs-devi-3/src

user61389

@abdullahkahraman does it work nicely?

abdullah kahraman

2:05 PM

@PeterJ Nah, that is already finished.. I am waiting for IPv6 to become old enough before releasing that. Btw it is not v7, it is v8.. Don't you learn? It is going 4-6-8..

@CamilStaps Yeah, I am using Github for Windows with it. No complicated stuff, simple, fast.

user61389

@abdullahkahraman okay, nice, got to check that out

Anindo Ghosh

BTW those wooden mirrors are most likely stepper driven.

abdullah kahraman

@AnindoGhosh Should I brag about how Olin's schematic is ugly, in the comments?

user61389

@AnindoGhosh ah yes I agree, reading your answer

user61389

@abdullahkahraman if you do that I'll brag about all your non-tikz circuits, ok?

abdullah kahraman

2:13 PM

@CamilStaps He always, rightfully, complains about how people draw schematics.

@CamilStaps Do you think my non-tikz circuits are ugly?

user61389

@abdullahkahraman ah okay, then you may :)

user61389

@abdullahkahraman no not at all, but I don't think his schematic is particularly ugly either

abdullah kahraman

@CamilStaps Yeah, comparing to his other schematics, this one is ugly.

user61389

I see :)

abdullah kahraman

@CamilStaps Check this out for example:electronics.stackexchange.com/a/67543/5035

user61389

2:18 PM

What program makes this actually?

abdullah kahraman

@CamilStaps Then check this one out, you will understand why I hate CircuitLabs electronics.stackexchange.com/a/67535/5035

@CamilStaps He uses Eagle.

user61389

@abdullahkahraman heh, I know, there's a feature-request on meta for auto-resizing

Anindo Ghosh

@CamilStaps It's ugly because the decoupling cap ground line is badly positioned, for one thing.

user61389

@AnindoGhosh is it about that? I thought about style of the symbols and so. You guys should just ignore me :)

Anindo Ghosh

@CamilStaps Go re-read the answer, I picked up a very important point - if those motors had been servos the video would have had a continuous underlying whining sound.

user61389

2:21 PM

@AnindoGhosh I thought of that as well but perhaps there were servos without that sound?

Anindo Ghosh

@CamilStaps No, a servo necessarily has to undergo continuous correction - adding hysteresis reduces this a lot, but there would still be an occasional whine - multiplied by that many motors.

abdullah kahraman

@AnindoGhosh Why servos have whine? Do you mean they whine while they turn? I have never controlled a servo in my life..

user61389

@AnindoGhosh Okay

abdullah kahraman

@AnindoGhosh Do you mean this whining sound in the background, sort of 50 Hz ish:

►

user61389

@abdullahkahraman I think he does. The pixels in the mirror turn all the time, so the noise would be constant

abdullah kahraman

2:27 PM

@CamilStaps I mean the background noise, when the hand is constant, we mean the same thing, right?

@AnindoGhosh I also don't understand why a stepper motor will not need any power to hold in position?

user61389

@abdullahkahraman oh, no, I mean when they turn :) the background noise isn't that just of the camera or something else? I never heard such thing with a servo, only when they turn.

Anindo Ghosh

Actually, the mirror is using servo motors. I guess the clacking of the wooden blocks covers up the servo noise.

@abdullahkahraman Fixed magnet steppers do not need power for holding, only for stepping.

@CamilStaps Depending on the sensitivity of the servo, even a slight breeze would cause each servo to undergo a correction, so whine-whine-whine.

user61389

@AnindoGhosh didn't know that, cool

abdullah kahraman

@AnindoGhosh Ooh, I see..

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