Electrical Engineering

Gnintendo

00:31

if I have a small IC barometer, do I view the GND pin as connected to the input voltage with a negligible voltage drop across the device?

I can't figure out what else it would be

this is what I'm looking at: sparkfun.com/datasheets/Sensors/Pressure/MPL115A1.pdf

I'm not worried about the SPI or anything at all, I'm just working on conceptually getting it hooked up correctly

Code Assassin

00:48

Hey guys so I have a question(I'm a total EE noob, so please bear with me). I'm following this tutorial: www.instructables.com/id/Music-Party-Facebook-Connected-Arduino-Powered-/#step1

and I have already soldered some header pins onto the RFID Reader. Now I need to connect the Wifly Shield onto RFID reader. I'm not sure what I'm supposed to do, however I did realize that in their video they connected it via wires. I have some hookup wire but I'm not sure how to go about it(https://github.com/lifegraph/arduino-wifi-setup#soldering-the-wifly-xbee-form-factor)

MLM

@ThePhoton The A0-A2 are to address the chip if you have multiple. I think I need to implement the MOSI line to pipe in those commands

coding_corgi

01:41

Yo yo yo! I am back! :]

Is it okay to write PWM signals to a motor without any transistor stuff?

anorton

02:02

@coding_corgi Hi! Are you working with a servo?

oh wow. Just noticed how late my response was. :P

coding_corgi

02:14

@anorton Still here, sorry...

@anorton No motor,

@anorton You didn't seem to notice that I retired from stackexchange.com.... Hmmm...

yesterday, by coding_corgi

I have made my decision to retire from stackexchange.com (unless I have a question that really needs to be answered) Goodbye all!

@anorton Still here?

anorton

02:35

Sorry... I saw that my response was really late, and decided that you had probably left. silly me. :)

I don't really have experience with motors... only servos. :\

I'm sorry that you're retiring! :o

(I've been out of the chatroom for a while)

coding_corgi

@anorton <jk>Stupid you...</jk> :] I have no life, I am always going to stick around around here, just not as obsessive as before (meaning hanging around here all day), Oh, thanks though...

anorton

oh. ok. I thought that by retiring, you meant that you would delete your account, and leave forever! :(

I'm glad to hear that you'll at least be around some times. :D

coding_corgi

@anorton Don't worry about me leaving! I learn so much here!

anorton

I could say the same thing--I've learned quite a bit on SE (between all the sites)

coding_corgi

@anorton Don't worry, I will still have more hours in here than you... ;]

anorton

02:42

You wanna bet? :D I have the fanatic badge on Math.SE...

(100 consecutive days)

I missed a single stupid day, otherwise I'd be close to 200 now...

coding_corgi

@anorton I know, being around non-techy people makes you feel smart, but when you look around in SE, I feel like a retard

anorton

@coding_corgi so true

coding_corgi

@anorton Now, now, don't beat your self up for a gEEky-little badge, :]

@anorton Ooooh, that has to suck

anorton

Yeah...

coding_corgi

@anorton Sadly, I misused this account, made it like two years ago, asked stupid silly questions, and never used it until I get an Arduino, I mean really...

anorton

02:44

ah...

Oh--here's a room you might be interested in... chat.stackoverflow.com/rooms/291/rebol-and-red

Ping rebolbot

coding_corgi

@anorton I no rebel

anorton

;)

Seriously--look at it; it's a full fledged chatbot ;)

coding_corgi

@anorton Whatcha doing?

anorton

not much, other than pinging RebolBot.

:D

coding_corgi

Are you near Fairfax, VA?

anorton

02:48

Umm... not really close, but still within a few hours drive. I'm in Roanoke, which is close to Blacksburg (Virginia Tech), and also close to Lynchburg

maps.google.com/…

coding_corgi

@anorton Oh, you could've had gone to one of these awesome stores: microcenter.com/site/stores/fairfax.aspx

anorton

very cool indeed! :)

coding_corgi

@anorton Yes, all money (sadly) goes to that store... :[

;]

anorton

haha

coding_corgi

@anorton Shhhh!!! It's not funny! :]

anorton

02:51

:D I know... I feel your pain.

coding_corgi

@anorton Trying to figure out which temperature control (permanent) soldering iron to get, I am going to but another cheap one, just to see if I mastered soldering.... I keep busting my tips!

anorton

Cool!

I just got a cheap pencil iron, so I'm going to get started down the soldering road soon... I just have to clear enough time (and enough space on my workbench!)

coding_corgi

@anorton Not the busting tips part, which reminds me, I am running out of solder

anorton

@coding_corgi True... the temperature control part was cool, though. (Ok... so it's actually pretty warm, but that's a different story...)

coding_corgi

@anorton My workbench is always so messy and I have OCD! Bad combination, half the time I am cleaning up!

@anorton Wanna hear something cool about my solder's flux?

anorton

02:55

Sure!

ok... I need to go. 'night

coding_corgi

@anorton My cheap (test) soldering iron get's hot, like really hot, like not needed hot, so sometimes I apply solder to the tip of my iron and the solder blasts off in every direction like fireworks, leaving trails of smoke, and sometimes hitting my with teenie drops of flux

@anorton Ahh... Bye, Good night!

Stacey Anne

03:52

good morning everyone

Can anyone see the difference between the first two items in the search here: mouser.com/Search/Refine.aspx?Keyword=UX60SC-MB-5ST

The Photon

@StaceyAnne $0.18 at qty 1?

More seriously, I'm going to guess either one of them is lead-free or they came on different size reels.

Just double-checked. The one with the (80) suffix is on a reel of 1500, the other one is on a reel of 1000.

Stacey Anne

you're probably right about the reels. the datasheet doesn't indicate what the 80 means, which confused me

The Photon

It's bizarre how Mouser passes through the price difference when they buy identical parts on different reel sizes.

3rd line looks like the same part again with (01) suffix, reel of 1000, but priced the same as the (80) part!

Stacey Anne

I also saw the termination style was solder instead of SMT, but how can SMT not be solder?

The Photon

@StaceyAnne from the datasheet, the pn should end in -5S8 instead of -5ST for a through hole part, which Hirose also calls a "solder" termination.

Stacey Anne

04:04

oh, ok. then it's a mistake on mouser's part

so that termination should be SMT since the part no is obviously the SMT part

The Photon

@StaceyAnne Yeah, but did the put the wrong part number or the wrong termination style? Don't order the full reel !

Stacey Anne

I'm only ordering 6, don't worry

next question: is there some degree of consistancy between connector footprints from manufacturer to manufacturer for the same connector?

I just realised the RJ45 connector i chose has become a whole lot less available in the few months between the schematic design and now

The Photon

@StaceyAnne Do you feel lucky?

There's some chance you'll find an alternate with compatible footprint, but it's kind of up to luck what part you picked if you didn't specifically look for that feature when you picked the part.

Stacey Anne

ok

Gnintendo

04:25

Can I use any metal nearby as a makeshift GND for my antistatic wristband?

because...I have an air vent in a very convenient location :<

The Photon

04:39

@Gnintendo You want to be grounded to the same thing the parts you're working on are grounded to.

Gnintendo

04:54

@ThePhoton so the board itself, generally?

vvavepacket

ThePhoton hw r u

The Photon

@Gnintendo If the board has a connection to the building ground, I'd rather connect to the building ground.

Gnintendo

@ThePhoton and if it doesn't? or should I make it connect to the building GND while working on it?

@ThePhoton at the lab we have GND wires that go to a stake driven 40 feet into the ground, but I'm looking for the best solution to use in my dorm room

Anindo Ghosh

grEEtz

vvavepacket

05:10

greetz

The Photon

@Gnintendo If you have a budget, get an ESD work mat for your desktop and ground that. Usually they also have a place to plug in your wrist strap.

Gnintendo

@ThePhoton hmm, my current work mat is just a silicon cooking mat (to solder on, mostly)

The Photon

@Gnintendo Probably not the best esd protection...

Gnintendo

@ThePhoton pfft, only semi-conductive (actually, dunno, not really privy on the molecular structure of 'silicon' mats)

The Photon

@Gnintendo Probably an excellent insulator.

Anindo Ghosh

05:23

@Gnintendo Silicone is not silicon, i.e. it's not a semiconductor. In fact, silicone is an excellent insulator, therefore not excellent for ESD protection.

Gnintendo

@AnindoGhosh eeehhhhhhh

@AnindoGhosh but it is excellent for keeping solder from burning holes in my desktop!

:<

Anindo Ghosh

@Gnintendo True

Gnintendo

well I won't be even touching any ICs or SMT circuits for a while (while in my dorm room, at least), all basic through-hole, so it shouldn't really be an issue until I can scrap up an ESD mat?

jippie

good monring

Gnintendo

in the meantime, is there anything remotely useful I can do with the antistatic wristband?

Stacey Anne

07:10

how do board manufacturers handle cut tape packaging for small production runs? Do I need to buy something like a digireel, or can I give the manufacturer CT and they deal with it? Or should I just ask?

Anindo Ghosh

07:44

@StaceyAnne Just ask. The assembly shop I use is happy with cut tape, they just want two extra parts on the tape "just in case", one for each end, which they generally return if unused.

Stacey Anne

Ok. Thanks @AnindoGhosh

PeterJ

08:34

@AnindoGhosh, not that there's anything wrong with your answer because the question doesn't state it but I guess the person wanting to PWM a motor over +/- 10V mentions the negative voltage as a way to reverse the motor as well.

Anindo Ghosh

@PeterJ Yes, I thought about that, and figured that if the question adds such a requirement, I can always edit the answer accordingly.

PeterJ

@AnindoGhosh, fair enough.

yogece

13:51

@rawbrawb hi

rawbrawb

@yogece hello

coding_corgi

14:28

Yo yo yo!

coding_corgi

14:51

WTF?! I am seeing lots of crazy questions like this recently:

-1

Q: LED Shut Off Time

I am looking for information on how much time it takes for a typical LED to shut off long enough that the light can no longer be detected by human eye.

led

Looks like government workers from Area 51 don't need a college education or any at all!

@PeterJ Yo

coding_corgi

15:15

@W5VO Do people ask questions like the one above a lot?

W5VO

@coding_corgi Meh, the only "weird" thing is that he's not aware that the human eye is the constraining factor

coding_corgi

@W5VO Huh, the other day someone was asking a question about sound waves making humans itchy, nausea, etc. !

@MLM Yo

MLM

@coding_corgi Hey

coding_corgi

@MLM Whatcha doing?

MLM

@coding_corgi school

coding_corgi

15:24

@MLM Well duh! Is this study hall, or AP class?

MLM

@coding_corgi none, everyone has macbook air tho

coding_corgi

@MLM Hmmm... My school (that I will go to next year) (the lower school) has 'tablets' which are HPs that you can write on, when I toured I didn't see one sheet of paper, the students do all their work on their tablets, the high school has macbooks though...

MLM

@coding_corgi the webfilter blocks stackexchange sites at home :\ except stackoverflow

coding_corgi

@MLM Eeesh!How 'bout some hacking? ;]

MLM

@coding_corgi sure... I have tried to repeal the block but they havent done anything

archive.lightspeedsystems.com/Archive/…

coding_corgi

15:36

@MLM Is it on some server or something?

MLM

@coding_corgi ye they set up their own proxy

but i think it just hosts the lightspeed script

coding_corgi

@MLM Do you have nmap?

MLM

@coding_corgi no?

coding_corgi

@MLM Do you have telnet?

MLM

@coding_corgi don't know, never use mac

coding_corgi

15:41

@MLM Open up the terminal and type telnet or nmap to see if you have them

@MLM You can get nmap here:

nmap.org/dist/nmap-6.25.dmg

@MLM Never had a .dmg file, you might have to extract it...

MLM

@coding_corgi I'll pass

coding_corgi

@MLM You can do a lot with nmap, scan an entire network, devices (for ports), etc.

jippie

17:20

good morning

coding_corgi

@jippie Yo!

@jippie Did you get the dragon (programmer) yet? If so, how do you rate it?

coding_corgi

17:33

@jippie Still here?

coding_corgi

18:39

@DavidKessner Yo!

David Kessner

@coding_corgi Oy!

What's up?

jippie

19:06

Got myself a nice new Arduino today :)

for free :)

coding_corgi

@DavidKessner That LED answer was good, the question wasn't...

@jippie How?

Anindo Ghosh

@jippie Leonardo compatible with WiFi?

coding_corgi

@jippie Looking good! I have the same wifi module!

The Photon

@jippie It looks like it's even a Dutch Arduino...

jippie

@AnindoGhosh yes

@ThePhoton yes

has a color sensor, wifi

Anindo Ghosh

19:09

@jippie what are the key advantages? And what price?

The Photon

WTH single chip draws 40 A?

0

Q: Differential remote sense circuit for 0.85V DC/DC supply

I have this sort of odd requirement and I'm wondering if someone with experience might have some advice on a circuit to use. I have a chip that draws 40 Amps of current at 0.85V with +/3% tolerance. Now normally I would use a DC/DC supply with a differential remote sense feature to counteract ...

power-supply op-amp

jippie

@ThePhoton LED krant is translated to 'ticker' not sure if that is a good translation.

@AnindoGhosh €0,=

The Photon

@jippie "array" maybe? It's a bunch of LEDs you can light up in different patterns?

coding_corgi

@jippie WTF?!

rawbrawb

@ThePhoton probably an Intel processor on it's core Voltage

jippie

19:11

@AnindoGhosh oh ok, bus fare was 5€

@ThePhoton it shows scrolling characters

coding_corgi

@jippie :]

Anindo Ghosh

@jippie Marquee?

The Photon

@jippie ....Forgot what that is called... Isn't there a Dutch company that dominates the market for making those things as electro-mechanical displays?

jippie

@AnindoGhosh in HTML that does the same as on the Arduino clone, yes

Anindo Ghosh

@jippie So two of them would be twice that cost?

The Photon

19:12

@AnindoGhosh Bus fare from India would be much higher.

Anindo Ghosh

@ThePhoton True.

jippie

they're 'sold' out unfortunately :(

it even came with a free cable and batteries

Anindo Ghosh

@jippie Oh well

jippie

there should be an external EEPROM too

etotaal.nl/upload/schemapakket%20Helios%2C%20e-totaal.pdf

@AnindoGhosh yes so sad. It was a free gadget on an electronics exhibition.

think I have to suspend my FPGA book for a couple of days now.

coding_corgi

@jippie You got a good deal...

@jippie Wow, this guy sounds like Woz, i guess he needs a Steve to make money...

rawbrawb

19:37

@jippie I was curious as to how the transistor course is going for you.

jippie

@rawbrawb The MOSFET course? It didn't really answer my expectations

so I dropped out

@rawbrawb I'm curious how @Kortuk would answer that question.

rawbrawb

@jippie Interesting ... how? He is an awesome author ...

jippie

It was too much semiconductor physics to my liking, too many e-powers, natural logarithms etc. and too little about how it translates to engineering.

@rawbrawb but I dropped out, maybe I missed the best part.

jippie

20:04

time for bed

/me is out

clickkk

David Kessner

20:55

@jippie I'm so sorry. Is it contagious?

@coding_corgi Thanks!

coding_corgi

21:16

@DavidKessner The guy seems a little crazy... I wonder what he would do with the info...

David Kessner

@coding_corgi I don't know. But I feel the need to create a sock puppet account solely for the purpose of writing outlandish questions.

coding_corgi

@DavidKessner Ha ha!

@anorton Yo!

anorton

hi

coding_corgi

@anorton Whatcha doing?

anorton

crashing after finishing up my tutoring job at the community college. :)

David Kessner

21:19

Fake Question: How can I reliably cause a tantalum cap to go into a thermal runaway condition?

coding_corgi

@DavidKessner Do you have any knowledge (I bet you do) on controlling motors?

David Kessner

@coding_corgi Yup.

anorton

@DavidKessner Ask that on main... :P See how many up votes it gets!

The Photon

You ever have one of those problems where the best way to solve it would be to spend a week on the beach in Tahiti? How can I convince my boss of this solution?

coding_corgi

@anorton Huh... Sounds like snack time...

anorton

21:20

yup

Anyway--walking away from computer for a bit...

coding_corgi

@anorton GET TEH OREOS!

David Kessner

Fake Question: I keep shorting out my non-rechargeable lithium batteries and they won't explode or release toxic smoke. Can anyone tell me what I am doing wrong? Tag=Arduino

2

coding_corgi

@DavidKessner Hmm.. I seem to have two strange motors that I would like to control, I tried several circuits (they all look the same) sending a PWM signal (I think) from a pontimeter to the transistor, but my motor doesn't run, I connect my motor to VCC and GND and it runs perfectly!

@DavidKessner Ha ha!

David Kessner

@coding_corgi Schematic?

coding_corgi

@DavidKessner Ok... Ummm... Let me see....

David Kessner

21:24

@coding_corgi A pot can't spit out PWM on it's own, and most pots can't handle the current of a motor directly. If you don't have a circuit between the pot and the motor then you're not going to get anywhere.

coding_corgi

@DavidKessner Really? Because I just hooked up my motor to a pot, and it worked....

@DavidKessner Scroll down: robotroom.com/PWM5.html

David Kessner

Fake Question: I want to design a circuit that can email me when a sensor trips, but I don't want to use any IC's. Just resistors and caps. Where do I begin?

3

@coding_corgi Did you use the circuit that is marked, "Lame! Do not use"?

coding_corgi

@DavidKessner Ha ha! Okay, Kessner, we get it...

@DavidKessner Scroll down further

David Kessner

@coding_corgi That circuit does not show a pot. Where's the pot?

coding_corgi

@DavidKessner With me, I don't want to use my tiny85 yet, or should I?

David Kessner

21:30

@coding_corgi Well, the PWM signal needs to come from somewhere-- and it won't come from a pot. You could feed the pot into an ADC on the MCU, if it has one. And the MCU can spit out the PWM.

coding_corgi

@DavidKessner Ok... (think I just wasted last night)

David Kessner

@coding_corgi Yeah, I hate when that happens.

coding_corgi

21:47

@DavidKessner Tell me about it

@anorton You must be filling up a grocery cart up in that kitchen! JK, JK! ;]

Rocketmagnet

22:37

Hello everyone

coding_corgi

@Rocketmagnet Yo?

Rocketmagnet

Yo

@coding_corgi Can you help me out, I'm being thick.

coding_corgi

@Rocketmagnet ?

Rocketmagnet

OK. I've got 240v AC, and I want to use a transformer to step it down to 6v.

Simple.

Only problem is, I can't seem to find a suitable transformer at Farnell.

coding_corgi

@Rocketmagnet 6V AC or DC

Rocketmagnet

22:41

AC

I just need a transformer

All that turns up on Farnell seem to be very expensive ones, or low voltage ones, etc.

coding_corgi

@Rocketmagnet Hmm... I really actually have no knowledge in power supplies, I just started EE, would you like to see a helpful video on power supplies?

Rocketmagnet

Am I searching for the wrong term.

Thanks. I'll keep looking.

coding_corgi

@Rocketmagnet Wait, that doesn't make sense... 6V AC will change from 0 to 4V then to ground, etc.

Right?

Rocketmagnet

huh?

coding_corgi

@Rocketmagnet Huh! :]

The Photon

22:50

@Rocketmagnet, newark.com/jsp/search/… ?

coding_corgi

@ThePhoton Doesn't AC move like that?

(

12 mins ago, by coding_corgi

@Rocketmagnet Wait, that doesn't make sense... 6V AC will change from 0 to 4V then to ground, etc.

)

The Photon

@coding_corgi Yeah, but if it didn't the transformer wouldn't work.

coding_corgi

@ThePhoton Oh... So the transformer would give you a steady 6V AC?

The Photon

@coding_corgi Steady meaning it keeps changing back and forth between -4.2 V and +4.2 V, yes.

coding_corgi

@ThePhoton So it switches back (1V by 1V) and forth or it jumps?

The Photon

22:58

@coding_corgi It should be changing sinusoidally.

Alternating current

In alternating current (AC, also ac), the flow of electric charge periodically reverses direction. In direct current (DC, also dc), the flow of electric charge is only in one direction. The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage. AC is the form in which electric power is delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves. Audio and radio signals carried on electrical...

coding_corgi

23:27

@ThePhoton Thanks...

rawbrawb

23:58

@ThePhoton oops ...- 8.5 to + 8.5 ... :-D

Transcript for

Electrical Engineering