Electrical Engineering - 2013-09-06

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4:45 AM

morning

5 hours later…

9:19 AM

Gents how do I close a question?

The problem has shifted and can be refocused with another question instead of constantly updating the same question

3 hours later…

12:06 PM

@Volcano, did you work it out? I think you should have a delete button next to edit etc under the question although you'll get an error if it has answers.

I figured it out 10 minutes ago, so I will place an answer for it in a bit

12:27 PM

Getting my prototype tested to NFP-99 this AM in clinical engineering. Keep your fingers crossed

@Volcano, just noticed it and that was a better way to go about it by answering yourself instead of deleting the question. You can accept your own answer too assuming you're not looking for any further suggestions not it's solved.

@PeterJ Thank you. I am forced to answer it in 12 minutes.

@ScottSeidman, are we crossing our fingers that the design passes or that the people conducting the test won't get electrocuted and catch on fire?

xD

@PeterJ Both would work! Should pass, completely isolated patient sensor, and the sensor is ISO10993 epoxy coated under USP VI heat shrink--not that the clin eng guys will care about that, but I also have to get it through a research subjects review board. If I can get those guys to classify it in a certain way, I can get a local clinical device exemption instead of having to nurse it through the FDA.

1 hour later…

1:59 PM

user image

2:09 PM

@ScottSeidman Yup. Looks like a label.

1 hour later…

3:13 PM

morning

@jippie Hey, it's not morning there!

@DavidKessner it is morning somewhere in the world

@jippie We can hope.

Hey, Who is this Stephen Collings guy? Did he use a different name before?

Is it just me, or has this week just had a flood of really stupid questions (and answers)? Unrelated to the troll.

3:25 PM

any sign of my mentor past 30 minutes?

@jippie Yes.

@jippie Mentos is mint candy, right? Look behind the couch cushions.

@ThePhoton He's been a user for 1 year, 7 months...

Oh you ruined my joke

@DavidKessner Yeah, but I don't remember ever seeing that name before this week. I'm guessing he changed his username.

@ThePhoton Must have. I don't remember it either.

3:28 PM

I cut my teeth in RF telemetry with Rocket Position tracking and Polar Bear migration beacons, but never have done Cats.

Is that what is commonly called "a dead givaway"?

missed it, I was typing a comment on an arbitrary answer @DavidKessner

is there techniques to reuse the energy in snubber instead of dissipate it in snubber resistor?

@EwokNightmares how much energy would be dissipated in your snubber and what ratio is that to the total available energy in the source?

@jippie energy in source is the wall power

so approx 0

ahh

i think . .

and the energy dissipated in snubber is depending on how bad i wind my transformer

and that is probably very bad

i'm estimated 15uH leakage inductance

3:37 PM

oh no the answer is deleted, now I never know what a cat with a yagi antenna looks like

it would be nicer to redirect that energy to something useful instead of turn it into heat on a resistor just protecting my switch

@EwokNightmares replace the cap with a neon light bulb :-p

@jippie i was thinking I could maybe charge a prius with it instead

but i guess baby steps

@EwokNightmares not with all the snubbers in the world ;o)

3:54 PM

@jippie I thought Prius owners ARE snubbers!

@jippie maybe I can use the heat off the snubber resistor to create a current in dissimilar metals and harvest this for prius charging if I can get the correct thermal paste

4:26 PM

Hello all! (no time of day reference)

@rawbrawb Yo.

@DavidKessner It's seems our long lost pooch is still having an undue influence on you. :)

@rawbrawb Nah, I did "Yo" and "Oy" long before it went mainstream. :)

I suspect that Stephen Collings is going back and editing his posts in an attempt to put his stuff on the main EE.SE page. Damn, I wish I thought of that! :)

@DavidKessner Two terms from sub-cultures, neither of which are strongly present in Boulder. Just doing your bit to ensure culture diversity remains? You could invent your own Boulder Homie slang and combine the two terms YooY!

@rawbrawb Oyyo!

4:38 PM

@DavidKessner one too many edits and it turns into Community doesn't it?

@rawbrawb I don't know.

He's edited 13 posts in the past 3 hours.

@DavidKessner I saw you guys discussing him having been around before (name change ?) ... it certainly looks like it.

And he's edited many times that in the past week.

He's been around for 1 year, 7 months. Almost all of his edits have happened since June. Weird. (I'm not calling BS on this, just pointing out that it's interesting. I don't have issues with his edits.)

@DavidKessner he used to be Remiel. see first comment here electronics.stackexchange.com/questions/61633/…

@rawbrawb Still doesn't sound familiar. But then again, I'm doing good to remember the names of my kids.

4:45 PM

@DavidKessner first born, second born etc. is so hard?

@rawbrawb I usually resort to Thing 1 and Thing 2.

user image

@DavidKessner I was just about to answer with "I am Sam" but you beat me to it. So they are house wreckers are they?

@rawbrawb They certainly have their moments.

@DavidKessner I know someone who named their four kids with names starting with 'A'.... Using A1, A2, A3, and A4 works :)

@W5VO not as bad as George Foreman (sp ?) ...

4:49 PM

@rawbrawb No... the names are actually different

@rawbrawb Does George Foreman name his kids after stake sauce?

Steak.

I just have difficulty remembering them

These are my kids: A1, Heinz 57, Preparation H...

@DavidKessner I'm sooo glad they don't read this chat ... they would be in therapy for years ... Mind you . they probably will be anyways.

@DavidKessner Nope, all the Boys are .... wait for it .... "George Foreman"

from wiki - His five sons are George Jr., George III ("Monk"), George IV ("Big Wheel"), George V ("Red"), and George VI ("Little Joey").

does anyone know of screw terminal blocks that fit a breadboard?

gravitech.us/3teblbroutb.html

not like 3 connections but more like 10+ or so

4:59 PM

@jippie search for terminal blocks with 0.1" pin spacing

but the metal pins may be too large for a regular breadboard

@W5VO hammer!

@rawbrawb you know what works better than a hammer?

@jippie a cat!

two hammers

@jippie nope! a bigger hammer

5:01 PM

@rawbrawb <Facepalm>

@jippie Seems like an oxymoron.

@W5VO actually I wouldn't mind if I had to improvise a break out PCB, but I don't want to have to design a PCB from start

@DavidKessner yeah I know, it is pretty much for ease of plugging and unplugging and being able to move it to a veroboard eventually

@DavidKessner I want to be able to make a test setup from a breadboard, but I need to connect long stranded wires

@jippie I mean... all you gotta do is a search at your favorite parts distributor for terminal blocks with 0.1" spacing. On Digikey, you can get up to 12 in a row for about $2.50

hmm I didn't try digikey ...

but I can't order there anyway

@jippie Who do you use?

mouser?

whatever webshop that sells to consumers

5:11 PM

~_~ digikey will sell me parts just fine.

because you reside on theire premises

you use farnell?

@jippie If you call being about 1,000 miles away as "residing on their premise"

come on guys, I'm not ordering 5$ stuff from a site that has a 50$ minimum order amount and $20 shipping on top

farnell has minimum??

5:14 PM

@jippie Why do you think we asked you where you ordered?

@W5VO I must be misusing the digikey site, I only find 3.5mm+

@jippie digikey.com/product-search/en/connectors-interconnects/…

terminal blocks - wire to board is the category

@W5VO I don't own a company, don't wok in industry (sadly enough) I have to order my stuff from small webshops that do consumer orders

@jippie and none of that would matter if you lived in the US ;)

@W5VO I was on that page before, must have made a bad selection :)

what is the difference betwwen screw and screw rising cage clamp? The last one is east to google images for ..

5:19 PM

I can spend $5 on shipping on a $0.10 part from Digikey/Mouser and have it delivered to my house. I'm assuming you can do that in the EU, but maybe with a different supplier.

@jippie They may be the same thing, depending on what each manufacturer calls their stuff

I have mouser at walking distance from my home, they charge 20€

but "rising cage" means that a clamp rises up from the bottom to hold the wire at the top

ahh ok I see

just "screw" might be that, or something moving from top to bottom. Probably functionally equivalent

Anyways I have some images and stuff I can google for now, thnx @W5VO

5:22 PM

np

@jippie The problem is "long wires" is incompatible with "breadboard". Even if it was solid wire and could be inserted then the weight alone would tend to pull the wires from the breadboard. And I don't think that a terminal block would help.

What you want is for the breadboard to be mounted on something else, like perf-board. And having good connectors mounted on the perf-board.

@DavidKessner I can use sticky tape, no problem. It's just for a proof of concept that I can't have on my desk. Then if I have to reprogram the microcontroller I don't want to have 12 loose wires that need replugging

@DavidKessner wingshieldindustries.com/products/screwshield

a bit like those, but those have the annoying Arduino pitch

@jippie Yeah, annoying Arduino.

I actually have those wings and they are brilliant

but not for the board I'm working with now, as it has regular pitch

@jippie Calling them "wings" is stupid. (Not your fault, I know.)

5:31 PM

@jippie They don't have a will-call window?

I don't care what they're called, they are brilliant for wiring longer leads. I don't like pushing wires into the on board connecters

@ThePhoton like a drive-in Mouser?

@jippie Kinda

Pay online, pick up at their dock so you don't have to pay for shipping.

not that I'm aware of. Didn't read it in their ... whatchamacallit page on their website

I could give them a call I guess after the weekend

When did Mouser become "a wholly-owned subsidiary of Berkshire Hathaway Inc."?

@ThePhoton at least a few years ago. I think it used to be TTI, then maybe Berkshire bought TTI

5:36 PM

@W5VO Sounds right. Another page says they're a subsidiary of "TTI, a Berkshire Hathaway company".

@ThePhoton are you trying to find my home address? :-p

@jippie I can cover your whole country with my thumb on any map of Europe.

github.com/JorgeAparicio/bareCortexM cool project

Just got an STM32 to drive a stepper motor

Using electricity no less

@joeforker I'm working on an Arm Cortex-M4 based stepper motor project.

Using TI, not ST.

How are the TI parts? Different datasheet style anyway

Miss the AVR's ridiculous 40mA per pin though

But the configurable 5V tolerant GPIO with an open-drain option is great

Are you doing complicated stepper motor control logic or is the rest of the M4 for something else?

What's the proper way to halt the main loop and just let the ISRs do all the work?

5:55 PM

@joeforker forever while loop?

@joeforker sleep?

sleep and wake-on-interrupt

@joeforker I could have used a simple 8-bit thing for what I'm doing, but the TI ARM based launchpad is super cheap.

And I hate 8-Bit micros.

Cheap transistors are fun

why is @wouter<tab> never in chat?

Looks like the WFI instruction would do what I want. Wondered how much poking peripherals versus special instructions it would be on ARM

6:10 PM

does the phrase time step too small have a certain emotional trigger for anyone else?

i've been playing DDR lately

@joeforker I love Double Data Rate! I'm almost up to the level of Auctioneer!

?

Heard good things about the sequel

time for beer

oh no! I only have Westies 12 and 8 left (cc @Kortuk)

my fridge is empty

6:26 PM

i didn't know what vermouth was and drank it straight out of the bottle last week

tasted like soy sauce and vinegar

@EwokNightmares Get a fresh bottle.

But still don't drink it straight.

@ThePhoton i think it must have been 20-30 years old

we found it

its ok there won't be a next time

@EwokNightmares My point is, just because you don't like old Vermouth from the back of the cupboard doesn't mean you don't like vermouth. If you tried a 20 year old bottle of Budweiser and didn't like it, would that mean you don't like beer?

@ThePhoton I agree but it has this taste in my mouth I can still remember

maybe it will fade

what is vermouth suppose to taste like?

6:42 PM

@EwokNightmares red/sweet or white/dry?

I think there's also white sweet vermouth but I haven't tried it.

It's basically just wine with some spices added. Probably to cover up the fact that only mediocre grapes are used.

It's good for cooking with or making a martini (gin and dry vermouth) or manhattan (whiskey and sweet vermouth).

@ThePhoton sounds like glühwein but you didn't mention hot.

mead?

@jippie Probably not much different.

@jippie Although sweet vermouth is sweeter and dry vermouth is dryer than the gluehwein I've had.

@EwokNightmares are you asking if vermouth is anything like mead?

@ThePhoton yes

i had that recently too and it was sweet but bad tasting

@EwokNightmares Not really at all, then.

@EwokNightmares Mead that I've had was really dry. Too dry for my taste. But I haven't had much mead.

@EwokNightmares What you had sounds like what they do to popularize some drinks. Like woodchuck cider or Kleinemanns(?) lambics.

Make drinks that sound like they should be sweet or fruity (but are actually fairly dry) and make them sweeter...

6:50 PM

there are lot of sweet beers here

it makes me sick after a while

Lindeman's lambic is what I was thinking.

@EwokNightmares Where?

in the US

by chicago

everyone drinks something called 2 brothers

@EwokNightmares I like some sweet beers, but Lindeman's over-does it.

@ThePhoton yes a few sips is nice hehe

7:11 PM

Since the conversation is all about beverages, have any of you ever heard of, or tasted, Old Monk dark rum?

@AnindoGhosh you don't drink do you? Or are you asking just in case you decide to do it? :)

7:56 PM

I guess that was a segue for @AnindoGhosh to go off and sample some "Old fart rum"

@rawbrawb Old Monk was a staple back when I was in college. I stopped drinking only in 1999. June 19th, 1999.

@rawbrawb And no, I'm a near teetotaler now. Breezers, perhaps 4 or 5 a year tops.

is it a safe analogy water hammering in a faucet to the flyback voltage across a switch?

@AnindoGhosh So your either had an event that was seared into your memory or an event that you don't recall that should have been seared into your memory...

@rawbrawb Seared. Definitely seared. I wasn't the victim, merely an interested party, though.

@AnindoGhosh were you either a extreme alcoholic or something else happened that day for you to remember your last rum?

8:01 PM

@EwokNightmares Not really. A water hammer is the supply running into the stoppage. Fly back is the device itself trying to maintain flow.

or it is just your very good memory

@EwokNightmares Oh, I wasn't drinking that day, I was the designated driver. :-) More later, gotta go for now, sorry.

@rawbrawb but is not the water pipes trying to maintain current flow?

with the momentum of the water

@EwokNightmares yep that's what I said.

@EwokNightmares And yes, some dates I have a great memory for, basically any non-recurring date of any event in my life (i.e. I cannot remember birthdays or anniversaries)

8:02 PM

@rawbrawb you said the device itself maintains flow, but I don't exactly see that any different than pipe maintaining flow

@EwokNightmares But you don't see the tap itself sucking like all get out trying to get more out of the pipe.

I'd say it's more like a resonant circuit than anything... not sure of an exact analogy

but the drain of my mosfet rings in resonance as well

@W5VO It's lenz's law, not resonance. If you stored that kickback that then re-energized the inductance then you could say it was resonance.

@W5VO resonant circuit in reference to water analogy or to the electrical circuit?

8:07 PM

I'd almost say the analogy of water hammering is like a neon relaxation oscillator

see resonance innovyze.com/news/fullarticle.aspx?id=561

@EwokNightmares maybe I'm more familiar with the electrical side of this analogy >_>

@W5VO I guess when I say resonance, the water smashes into the valve then moves back and then smashes again

til dies out

@W5VO Oh I see, Hmmm ... that maybe works.

@rawbrawb It's not perfect, but I'm not sure what the exact mechanical analogy would be

8:10 PM

Inductive spark
Used in induction coils, similar to water hammer, caused by the inertia of water

from wikipedia

i guess similar != safe analogy tho

@W5VO I thought you were talking about the inductance ... oops, should have knkow better. But this works, especially is you look at it like a transmission line.

@EwokNightmares Pure nonsense. Wiki is a bad source. The distinction is that one is happening in the source (pipes) and the other is happening because of device properties itself. You are getting the kick back ONCE you disconnect, the supply doesn't see it, your FET does and dies.. For it to be the same the down stream water (from the tap) would have to come back and kill the tap.

gotta go guys ----

your valve sees it

just as your fet does

..

8:26 PM

i think the pipes bursting would be analogous to voltage breakdown in the windings

8:40 PM

@W5VO found a local terminal screw block supplier with reasonable prices :)

9:25 PM

I wander how high quantities Apple buys components for their iphones in

they can sell their 5W wall chargers for $5 online

that is about price of my flyback converter IC at 1 qty

@EwokNightmares Well, Apple has an annual revenue of about $140 billion... (doing math...)

@DavidKessner there must be a better number to work off than that :P

In the first two quarters of 2013, they sold about 85 million iPhones. Sales typically slow down for the second half, so let's say that they sell 60 million units. That's still 145 million iPhones for 2013.

user image

each one must have a charger

for each year

there is that many people on iphones??!?!?!

@EwokNightmares Probably 50% of them buy chargers. I haven't bought one for a few phones now.

9:39 PM

oh I thought it came with them

@EwokNightmares No. Cheapskates!

that is amazing tho

It does come with a USB cable, however.

i wish I could order parts in those qty to brag about my BOM

I know that when I have an annual volume of 100k the salespeople wet themselves. I don't want to think what they'd do with 1m, much less 145m!

Salespeople from our distributors that is.

9:41 PM

yes, its always good to inflate your nrs a bit when you deal with those people

might get free trips and lunches

@EwokNightmares I get those anyway. Usually I give them a realistic range of numbers, which has it's own bogosity and inflation in it from our own marketing/sales people.

i wander if they would still take me to lunch when they see me on the sidewalk with a cup of coins and bum cloths

doubtful

@EwokNightmares Ewok, who? I have no idea who you are talking about! :)

the salespeople who are so eager to please when you are making something new and cool

@EwokNightmares They are eager when you do one (or more) of three things: 1. Get them excited about what you're designing. 2. Have a good chance of making them money. 3. Make them look good in the eyes of their bosses. Master them and you will have an ally worth having!

9:47 PM

@DavidKessner yes, they definitely can pull through with good deals

but I dislike the fake friendliness

1 of the old FAE who came for a meeting at my old job to sell us a FPGA added me on linkedin recently and i thought this is nice of him

the next day I have emails into my work address from his sales partner trying to sell me things

For #3: Sometimes sales people need to meet quotas on presentations or whatever, especially when they have out of town people to parade around. I always tell them that if they are struggling to meet their quota that I'll help them out even if their stuff doesn't quite apply to me. They really appreciate that.

@DavidKessner did not know that

I usually enjoyed the FAEs and felt bad for them to work with their sales partners

@EwokNightmares More than just deals: they are more likely to go the extra mile for you, and provide technical assistance when they would not normally. Or get you more eval boards or samples for free.

but it all comes back to money and business for them

not always but net positive

@EwokNightmares Yes, it does. But they can, especially in a smaller city like Denver, think more long term. So they can think 2 to 5 years ahead, and not just with the current project of the day.

9:53 PM

it is silly when they ask you to come to their FPGA training course and it is just 1-2 hours of FPGA use and the rest of the day is reserved for "networking" and they watch fotball all day together and skip out of work

@EwokNightmares I haven't see that. Unless you are talking about the customers skipping out. Of course, we have a large Xilinx office just down the street so that might have something to do with it.

@DavidKessner I mean the FAE and sales person will host a event for its customers with the premise to train technology

@EwokNightmares Yeah, they do that here. But normally it is more than just 2 hours of actual stuff and 6 hours of networking.

those are the good days

i think it is great to be in touch with engineers from these companies

they are experts

Yup.

9:58 PM

Did you work in california before?

@EwokNightmares I used to work both in San Diego, and in Silicon Valley.

@DavidKessner was it stressful there with so much competition?

@EwokNightmares Not really. It was during the heyday (mid to late 1990's). There was plenty of work to go around.

@DavidKessner you work in colorado now?

@EwokNightmares Yeah. Boulder, CO.

10:03 PM

@DavidKessner do you like it better?

California seems very hot . .

@EwokNightmares Absolutely! CO isn't cool in the summer. Was almost 100F earlier this week. I grew up in CO, and I like it a lot. When my wife and I had our first kid we wanted to own a home-- and that is just stupid in CA. Prices are way over-inflated.

@DavidKessner CO looks beautiful and I've heard its the best for skiing and snowboarding in the US

@EwokNightmares It's amazing. California has other things to offer, but most of it is just too big, too expensive, too over the top, and everything starts to look the same. Good to visit, but that's it.

Where are you?

@DavidKessner Near chicago

its ugly here :P

do you ski/snowboard?

@EwokNightmares I've heard that.

@EwokNightmares I do a little. I brew out my ACL a few years ago and I haven't been doing much skiing since then. SOme, but not a lot. Mostly hiking and fly fishing.

10:08 PM

I only came here to work and I'm staying to get experience but do not plan to live here long term

hiking and fishing is fun

ACL?

Anterior cruciate ligament

The anterior cruciate ligament (ACL) is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle (analogous to the knee), based on its anatomical position, it is also referred to as the cranial cruciate ligament. The ACL originates from deep within the notch of the distal femur. Its proximal fibers fan out along the medial wall of the lateral femoral condyle. There are two bundles of the ACL—the anteromedial and the posterolateral, named according to where the bundles insert into the tibial plateau. The ACL attaches in front of the intercond...

I crashed while skiing-- going 40+ MPH.

owwww

just thinking of knee injuries makes me shudder :P

@EwokNightmares Yeah, that's what I said! Well, that an some profane language.

maybe ask scott seidmann to make you a cyborg knee

@EwokNightmares I got a super-cool carbon fiber and titanium knee brace. I wear it when I am skiing, or doing other risky activities.

10:12 PM

@DavidKessner what % back to full performance do you get with that on?

@EwokNightmares After surgery, without the brace, I'm at maybe 90%. The brace doesn't really improve that, but it prevents me from messing it up again.

ah that is better than I thought it would be

@EwokNightmares They have the surgery thing down fairly well now.

I'm outta here. Have a good weekend!

same

take care

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