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  #31  
Old February 19th 11, 11:25 PM posted to rec.photo.equipment.35mm
Alan Browne
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On 2011.02.19 11:26 , Dennis Boone wrote:
If one knows the voltage for the laptop, they could make a 12 to 24 V
input DC|DC converter that outputs the right voltage to the laptop. (A
technician with nothing to do in his spare time should be able to get
the parts, assemble and test this in no time).


Um, it's not quite trivial. Most boost converters are low-current
devices. Most laptops these days require between 5 and 8 amps, at
their nominal input voltage, to operate. That's a lot of current
for a throw-together project.


Who said "boost converter"?

5 - 8 amps? Why? Most laptops run around 30 - 50 W. So at 18V or so
that would be a measly ~3A output.

DC-DC converters are what are in the power bricks for laptops: Xfrmr
takes 100 - 250 VAC down to 18 - 36, thence a bridge rectifier, thence
into the DCC converter and out to the laptop at the desired voltage.

http://www.vicr.com/cms/home/product...cro-converters

is an example of a basic DCC converter. For a laptop the "micro"
would do with the supplier configuring it for the desired voltage.

We've put these together for field demos (unattended systems with solar
to battery - no inverters at all - just a good charge controller to the
batteries). Assign it to a bushy tailed tech, tested it and off it
went. Other option is to assign it to whatever engineering coop student
happens to be chained to a desk.

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  #32  
Old February 20th 11, 12:01 AM posted to rec.photo.equipment.35mm
Bill Graham
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Alan Browne wrote:
On 2011.02.19 11:20 , Savageduck wrote:


An other option would be something like a Honda 1000 W generator.
Quiet, pretty efficient, light. (We've used them for all manner of
field testing (1000, 2000W versions).


That must be what the local bands use when they play gigs at our Saturday
Market and the parks.....It is amazingly quiet, and yet puts out enough
power to drive the amplifiers that these groups use.

  #33  
Old February 20th 11, 12:41 AM posted to rec.photo.equipment.35mm
Noons
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Alan Justice wrote,on my timestamp of 20/02/2011 5:50 AM:


One reason to replace my computer on the internet is that OE6 does not
handle some of the graphics, so some sites are not accessible, and I can't
upgrade using Win 98, which I can't upgrade with low RAM etc. I have
Charter cable for TV, but I get such awful service that I won't give them
more money for internet. If I need better internet acces temporarily, such
as uploading images to my website, I go to a public computer nearby. So I
figure I could get a portable computer to use at home and on the road. I
only need a display that is good enough for reviewing in the field. So
what's the difference between a "netbook," a "notebook," and a "laptop?"
(For someone who started computer programming in 1969, I sure haven't kept
up.)




For your purposes there is not much difference nowadays, other than capacity of
disks and screen size. Rules of thumb (not to be cast in stone):

netbooks: small 10" screen, disk around 150GB mark, memory at around 1GB.
Very light, great for saving images on the road and for quick presentations but
little else. They usually have great connectivity.

notebook: medium 13" screen, disk around 300GB, memory at 2GB.
Mostly for portable use like a netbook, but in a pinch can do desktop work.

laptop: 15" and larger screen, disk starting at 500GB, memory starting at 4GB.
With care in selection of desktop screen, it can replace a desktop computer for
most folks. It is a heavy beast though, so don't count on carrying it in a hand
purse...


As to which can replace a general purpose desktop, I'd go for a laptop. Mine is
also a Samsung but with 1TB of disk, 8GB of memory, 64-bit Win7 and a corei5
cpu. It's a beast but I run multiple virtual boxes inside it for database
testing, so that's a special need. It was relatively cheap, considering the
specs. You don't want to know about my desktop...

However, I don't think any laptop out there will do a good job for colour
handling with a native screen, with some very rare - and expensive! -
exceptions. If you want to do even average image editing you'll need a good
desktop screen to connect the laptop to, with correct profiles and colour
balanced. That is expensive, so be prepared for the hit. You don't need an
Eizo Flexscan, but a mall special won't do either.

Having said that, with patience and care you can get pretty near to a good setup
by just loading the appropriate profiles for whatever desktop screen you pick,
taking care to check it on some of the sites used for colour testing and
balancing the lot with something like Adobe Gamma, which comes free with
Photoshop Elements. I used a similar setup for years and it works fine.

Just be aware that a laptop used as a desktop will never be as fast as a same
generation dedicated desktop. But if all you want is the occasional internet
access and basic to medium image processing, then it works perfectly fine.

Count on a grander and a half for the laptop and half a grand for the screen,
plus ancillary bits and pieces. But of course prices vary wildly and you may be
able to get a much better deal.
  #34  
Old February 20th 11, 03:01 PM posted to rec.photo.equipment.35mm
Alan Browne
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Posts: 12,640
Default DL in the field

On 2011.02.19 18:25 , Alan Browne wrote:
On 2011.02.19 11:26 , Dennis Boone wrote:
If one knows the voltage for the laptop, they could make a 12 to 24 V
input DC|DC converter that outputs the right voltage to the laptop. (A
technician with nothing to do in his spare time should be able to get
the parts, assemble and test this in no time).


Um, it's not quite trivial. Most boost converters are low-current
devices. Most laptops these days require between 5 and 8 amps, at
their nominal input voltage, to operate. That's a lot of current
for a throw-together project.


Who said "boost converter"?

5 - 8 amps? Why? Most laptops run around 30 - 50 W. So at 18V or so that
would be a measly ~3A output.

DC-DC converters are what are in the power bricks for laptops: Xfrmr
takes 100 - 250 VAC down to 18 - 36, thence a bridge rectifier, thence


Oops. 100 - 250 down to about 12 - 30 VAC, thence ...

into the DCC converter and out to the laptop at the desired voltage.

http://www.vicr.com/cms/home/product...cro-converters

is an example of a basic DCC converter. For a laptop the "micro" would
do with the supplier configuring it for the desired voltage.

We've put these together for field demos (unattended systems with solar
to battery - no inverters at all - just a good charge controller to the
batteries). Assign it to a bushy tailed tech, tested it and off it went.
Other option is to assign it to whatever engineering coop student
happens to be chained to a desk.



--
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  #35  
Old February 20th 11, 03:25 PM posted to rec.photo.equipment.35mm
Dennis Boone
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Who said "boost converter"?

Automobile electrical systems put out 12-15 volts DC. Most laptops
these days want 18-19 volts. Sounds like a boost converter to me.

5 - 8 amps? Why? Most laptops run around 30 - 50 W. So at 18V or so
that would be a measly ~3A output.


Actually, most current laptop ship with 60-90+ watt supplies, depending
on whether you want them to charge and operate at the same time.

If you're starting with 12V and require 18V output at 90W, it's pretty
easy to need 8A input.

I'd guess netbooks are a somewhat lighter load, though I haven't
looked it up.

De
  #36  
Old February 20th 11, 04:54 PM posted to rec.photo.equipment.35mm
Alan Browne
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Posts: 12,640
Default DL in the field

On 2011.02.20 10:25 , Dennis Boone wrote:
Who said "boost converter"?


Automobile electrical systems put out 12-15 volts DC. Most laptops
these days want 18-19 volts. Sounds like a boost converter to me.

5 - 8 amps? Why? Most laptops run around 30 - 50 W. So at 18V or so
that would be a measly ~3A output.


Actually, most current laptop ship with 60-90+ watt supplies, depending
on whether you want them to charge and operate at the same time.


And they're over rated to the need by a good margin.

If you're starting with 12V and require 18V output at 90W, it's pretty
easy to need 8A input.


In the case that Paul outlined I suggested two batteries in series which
would cut the current by 2 at the input. Not that it's needed.

(For the particular Vicor modules I linked to, it's not possible to
"user define" a 12 V input for a specific voltage output, 18 V minimum
input is needed. So a series of two batteries is ideal).

Most laptops I've seen work below 60W. There are those big honkers that
likely go up to 100W - maybe more.... but taking one of those on a trip
seems insane to me unless I'd be in one hotel for a week or more. Even
then, lugging it to/through the airport would be a disaster, esp. with a
couple plane changes enroute.

We have a monster hp laptop at work, I'll try to look at its brick tomorrow.

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  #37  
Old February 21st 11, 02:47 PM posted to rec.photo.equipment.35mm
Savageduck[_3_]
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On 2011-02-21 05:42:43 -0800, whisky-dave said:

On Feb 19, 4:26*pm, (Dennis Boone) wrote:
* If one knows the voltage for the laptop, they could make a 12 to 24

V
* input DC|DC converter that outputs the right voltage to the laptop.

*(A
* technician with nothing to do in his spare time should be able to ge

t
* the parts, assemble and test this in no time).

Um, it's not quite trivial. *Most boost converters are low-current
devices. *Most laptops these days require between 5 and 8 amps, at
their nominal input voltage, to operate. *That's a lot of current
for a throw-together project.


I think Apple advise not to run a laptop without the battery present
as the 'power' from the converter isn't enough to fully drive the
laptop.
Although it's probbaly be OK for most things.


Current MacBook Pros do not have a user replaceable battery. I am not
sure of the lesser MacBooks. My Old PowerBook Pro (a PPC or non-Intel)
machine has a user replaceable battery and it is possible to run that
without the battery. That option is not possible with the Intel
MacBooks.

....and as I have said I use the Kensington Power Inverter which is able
to power the MacBook Pro 85W power supply without issue.
http://us.kensington.com/html/17163.html



You _can_ get these things, but they're typically the size of your
laptop's existing power supply. *Some laptop vendors actually put
the functionality in the laptop supplies in the first place. (Dell)
Otherwise, look at the likes of Targus.

De



--
Regards,

Savageduck

  #38  
Old February 21st 11, 08:22 PM posted to rec.photo.equipment.35mm
Eric Stevens
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On Mon, 21 Feb 2011 05:42:43 -0800 (PST), whisky-dave
wrote:

On Feb 19, 4:26*pm, (Dennis Boone) wrote:
* If one knows the voltage for the laptop, they could make a 12 to 24 V
* input DC|DC converter that outputs the right voltage to the laptop. *(A
* technician with nothing to do in his spare time should be able to get
* the parts, assemble and test this in no time).

Um, it's not quite trivial. *Most boost converters are low-current
devices. *Most laptops these days require between 5 and 8 amps, at
their nominal input voltage, to operate. *That's a lot of current
for a throw-together project.


I think Apple advise not to run a laptop without the battery present
as the 'power' from the converter isn't enough to fully drive the
laptop.
Although it's probbaly be OK for most things.


Apart from anything else, the battery acts as a giant smoothing
capacitor and smoothes out most of the ripple and harshness of the
power supplied by most invertors.


You _can_ get these things, but they're typically the size of your
laptop's existing power supply. *Some laptop vendors actually put
the functionality in the laptop supplies in the first place. (Dell)
Otherwise, look at the likes of Targus.

De


Regards,

Eric Stevens
  #39  
Old February 22nd 11, 05:35 AM posted to rec.photo.equipment.35mm
Pete[_9_]
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On 2011-02-21 23:25:46 +0000, Eric Stevens said:

At one stage my business owned an early Cromemco computer the power
supply of which was equipped with capacitors the size of bean cans.
There was a lot of construction work going on in the district and one
day we experienced a power supply glitch long enough to cause all the
fluorescent lights go out and then have to go through their restart
procedure. The large capacitors of the old Cromemco enabled it to just
sail right on through all of this even though it was running three
users at the time.


Now that's what I call a power supply. Most products have a "sour
supply": a half second glitch and they shut down; acidic comments
follow...

--
Pete

  #40  
Old February 22nd 11, 03:29 PM posted to rec.photo.equipment.35mm
Savageduck[_3_]
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Posts: 16,487
Default DL in the field

On 2011-02-22 05:59:12 -0800, whisky-dave said:

On Feb 21, 2:47*pm, Savageduck wrote:
On 2011-02-21 05:42:43 -0800, whisky-dave said:


Le Snip



Current MacBook Pros do not have a user replaceable battery.


The air doesn't either.


So? You are not going to randomly remove that battery either if you are
using a MacBook Air.


I am not sure of the lesser MacBooks. My Old PowerBook Pro (a PPC or non-Intel)
machine has a user replaceable battery and it is possible to run that
without the battery. That option is not possible with the Intel
MacBooks.


Well yes if you buy a new Mac but perhaps the better option for the OP
would be a cheaper laptop such as old old Mac or even PC type
which I believe most have user replaceable batteries


At no time have I suggested which "laptop" he should consider. He can
buy whatever works for him. I have just remarked on some nominal
differences between "Netbook" & "Laptop" portable computers. I used my
experience as an example, and I have been using Apple computers since
1983.
He seems to be a Windows user, and I have no idea if he would, or would
not care to switch OS at this stage, or if he would be comfortable
switching. (Though I suspect he would be quite happy if he did. There
are others in this NG who have who are happy with the move.)

...and as I have said I use the Kensington Power Inverter which is able
to power the MacBook Pro 85W power supply without issue.
http://us.kensington.com/html/17163.html


That might be the same or similar one to my friends which 'blew up'
although I thought his was 65W.


Correct, the PPC G4 Powerbook & MacBook portables use a 65W power
supply, and they are normally functional with voltage input range of
100-240V 50/60Hz. Current Mac portables us a 60W power supply for
portables with displays 13" and smaller, and 85W for 15" & 17"
PowerBooks.

But it was blown by using an inverter (UK inverters give out ~230V).
he uses his powerPC macbook G4 1.5GHz 15" on a boat and this one time
forgot to use a surge protector. Although we can't prove it, it
stopped the
laptop battery charging. He brought a new charger, no luck so he took
the labtop
back to an Apple store where they tried a new battery which worked
fine.
The 5 amp surface mount fuse in the laptop was OK as we tried that
first.

His inverter has also died so whatever caused this spike from his
diesel generator
did something nasty blowing up the inverter, PSU and battery or at
least that appears
to be what happened.


I can't speak for what might, or might not have happened to the setup
your friend was using with diesel generator.

So just a warning really, I hear on a mac podcast that USians are more
likely to suffer brownouts
and surges, lightning than we in the UK are generally speaking.
I can only speak for my bit of London and I can't remember a powerout
in the last 10 years.


I have the occasional power outage out here at the lake. The cause can
be anything from a lightning strike, a localized PG&E transformer
issue, sometimes an accident where a utility pole has been damaged
miles from my home. For that eventuality I have a UPS which does a good
job of giving me time to shut down safely, and which provide a degree
of protection against power surges. For those extended outages I also
have a Honda 3000W portable generator (this one is not all that
portable, or as quiet as I would like), which provides 110/240V output
and 12V charging when I need it. That has been around twice a year.


--
Regards,

Savageduck

 




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