Re: USB microscopes for very small SMT

In article <e%f%k.13419$Ws1.13272@xxxxxxxxxxxxxxxxxxxx>,
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krw wrote:
In article <_ke%k.7882$as4.6552@xxxxxxxxxxxxxxxxxxxx>,
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krw wrote:
In article <7Zc%k.7873$as4.1969@xxxxxxxxxxxxxxxxxxxx>,
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Joel Koltner wrote:
"Joerg" <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote in message
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For example, one classic mistake I find in my consulting practice is the use
of too high impedances in low-energy sensing circuits. A little moisture, a
little dirt, and it'll be on the fritz. The right way is to use low
impedances and then pulse-measure. But it seems universities don't teach
that stuff anymore.
They're concentrating on "low power" (what every laptop needs, right?) so the
students naturally gravitate towards high-impedance designs...

Laptop designers seemed to have "un-learned" that as well. Until
recently when the Intel Atom came out and (some) laptop designers
"re-learned" the art. When Howard here in the NG mentioned the Samsung
NC-10 and I saw it gets >6h, like my old Compaq Contura used to, I
honored that laptop performance with an order. Seems others have done
the same since I initially received a backorder notice despite the fact
that "in stock" was mentioned. Should arrive in a few days :-)
6hr batter life isn't the only design point for laptops. Many/most
are being used as desktop replacements, so battery life is *maybe*
a secondary parameter. In my case, two hours is good enough but I
need high resolution, external display capability, large disk(s),
and all the other stuff that used to be the sole domain of
desktops. Sure, I'd like a three day battery, but I'm not going to
give up any other aspects of my laptop to get it. In fact, newer
laptops *are* better than those of five or six years ago, taking
all of the parameters into account.

Well, for desktop jobs in the office I use ... a desktop.

Don't know about you, but mine is difficult to carry. Trust me,
you are the oddity. ;-)


Why would I ever want to schlepp it around in the office?


I often encounter folks who are quite unfamiliar with the scheme of
saving battery power via pulse action instead of high impedance.
The designers of these devices are well aware of these power-saving
schemes, and far more. ...

When I see a fan and hot air coming out of a laptop no matter what you
set in the "energy management" tab I do have my doubts here. For
example, the old Compaq could throttle the uP down to a few MHz. That's
how they got 6h out of a standard old-tech NiCd. For years. Until all
the rough flights and nail-it-to-the-runway landings caused the frame of
this laptop to fracture :-(

I don't have any doubts. People *use* laptops and demand desktop
performance from them. Guess what, that takes power no matter how
you (time) slice it.


Depends on the job. Once this little Samsung arrives it'll probably
accompany me on 80-90% of trips. The remainder will have to be handled
by the big laptop because it has more horsepower.

Which is precisely my point.

People don't want to have to decide which computer to use based on
what they think they might be doing. They want it all. What
happens if the job changes *after* you've left home? Do you buy
multiple copies of all your tools? Keep multiple copies of all
your documentation? ...up to date? No thanks (decided not to buy
an eeePC for this reason), I'll carry my one full size laptop with
me even though I'm limited to 2-3 hours on the battery.

... It's a matter of design (and that
necessarily means marketing) priorities.

Sometimes it's necessary that engineers question decisions by marketing.
Got to be careful here, since I married a marketeer ;-)

Question all you want, the answer is the same. Customers demand
performance. Laptops aren't toys anymore. Few use both laptops
and desktops anymore. They take their work with them. Licensing
agreements don't help but data isn't all that portable either.


I do not have much faith in many marketeers. Just like the big three
auto makers blundered so much in that domain resulting in people buying
imports. They assumed people wanted certain products. The minor issue
was that people didn't want them.

You're going to let engineers in the back room make SKU and
inventory decisions?

Students need to re-learn the old art of obtaining some of their wisdom
from non-academic sources. I'd venture to say that >50% of the knowledge
I use in my practice is from non-academic sources. App notes, Internet,
ARRL books and such.
This stuff is standard design practice. There aren't any secrets
here. The processor datasheets lay it all out. Do not, however
that a given computation has a minimum power requirement. If you
draw that time out (your "pulse action") you only waste more
energy.

That's what I thought as well, that folks know this. But, example:
"Don't you have to keep the bridge current running until you are sure
the uC code has finished and can read the ADC?" ... "No, the value is
being stored." ... "But it can't be, the code may not have gotten to
that point." ... "See that 74HC4051 there? It's set up as track-and-hold
so the value will be stored in the film cap over there." ... "Oh."

How much of that is going on inside your laptop?


It was an example from the analog world. Want one from the world of
laptops? Ok:

There is absolutely no reason, zero, nada, zilch, why a processor has to
keep idling at close to a gigahertz while the user is sitting in front
of a laptop, pondering a text entry for a long time or answering a call
on their cell phone. Yet they do.

There is very good reason. It doesn't save much to have it running
at half that. If you want to save significant power you have to
turn things *OFF*. Then it takes time to get them back.

Almost 20 years ago the old engineers
at Compaq understood that, the designers of most "modern" laptops
obviously do not understand that.

Utter nonsense.

Ok, back then it wasn't fully
automatic but I knew when I had to write a module spec on a flight
across an ocean I'd better switch it to low speed. Made no difference
while entering text but it stretched the battery life all the way to the
coast of Ireland. I still remember a guy next to me getting really
pissed when his super-expensive Thinkpad shut down and I kept tapping
away another three hours. Especially after he saw that mine was an old
economy-class Contura. While I had my document completed he had the
privilege to do a jet-lagged late night typing session once he got to
the hotel. I went to the bar and had a couple of cold ones.

His was a desktop, with legs. Yours a "lite". Different design
point.

Intel's Atom is a step in the right direction. Here's hoping that they
don't screw it up again like they did with the divestiture or
cancellation of product line such as their CPLD in the 90's. Their stock
price indicates that they really need a killer app and product, and soon.

Intel will screw up a wet dream.

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