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Computer Power - "Modified Sine" Through UPS

  • Thread starter Down Under On The Bucket Farm
  • Start date
D

Down Under On The Bucket Farm

Jan 1, 1970
0
Hi Everybody,

Please feel free to correct me on anything...

My understanding is that low-cost inverters (12v-to-mains-
voltage) usually put out AC with a "Modified Sine" wave (which
could, more honestly be called, a "Modified Square" wave.)

And, apparantly, that AC tends to cause lots of problems trying
to run computers.

I am curious:

I have my laptop computer with its external power transformer
(220v AC going to 14v DC) plugged into an APC-Brand UPS.

If I get a cheap "Modified Sine" wave inverter to run from a 12v
battery source, will the UPS unit smooth out the 220 supply to
properly function with the computer?

Thanks in advance for all of your advice...
 
T

Toby

Jan 1, 1970
0
I run my laptop and a HP deskjet printer off a 175 watt inverter without any
problems.

Just my personal experience though, no real knowledge to back it up.

Toby
 
S

Scott Willing

Jan 1, 1970
0
Hi Everybody,

Please feel free to correct me on anything...

My understanding is that low-cost inverters (12v-to-mains-
voltage) usually put out AC with a "Modified Sine" wave (which
could, more honestly be called, a "Modified Square" wave.)

Modified sine if you're selling, modified square if you're buying. :)
And, apparantly, that AC tends to cause lots of problems trying
to run computers.

No, it doesn't. It causes problems on some very specific equipment
such as laser printers and some Macs but it's rare.
I am curious:

I have my laptop computer with its external power transformer
(220v AC going to 14v DC) plugged into an APC-Brand UPS.

Your laptop undoubtedly has a switch-mode power supply (far more
complex than a transformer, though you're probably using the term
generically) and it will likely be just as happy as a clam with
modified whatever wave power.

Is the UPS a true sine wave model? Is it full-time or stand-by? The
average stand-by UPS is little more than a crudely filtered power bar
until the line fails. If it is the typical modified square wave
stand-by device, you can find out exactly how your laptop will run
from mod sq wv power simply by unplugging the input to the UPS.

I live in a house that uses modified square wave power exclusively and
I have run a full-time laptop-based office, with inkjet printer,
scanner and external disk drives without incident for more than three
years.

In fact while doing some system upgrades I ran my little laptop office
off a Statpower 125W mod square wave inverter for three months.

Aside from two Dell laptops, from time to time I've also run a Mac
Powerbook, an IBM laptop, and I recently bought a museum piece to run
some old hardware and software - a desktop 386 PC with a CRT monitor.

All's been just swell. Eventually I will upgrade to sine power, but
computers will not be the inspiration for the move.
If I get a cheap "Modified Sine" wave inverter to run from a 12v
battery source, will the UPS unit smooth out the 220 supply to
properly function with the computer?

Unless it is a full-time sinewave UPS you'd be wasting your time.
However, chances are around 99% that your fears are unwarranted in any
case, so the issue of the UPS becomes academic.

If the laptop is the only thing you want to run from a battery, you
might consider buying a 12V power supply for your laptop, e.g. from
Lind Electronics, but the cheapest, most readily available and
flexible solution will be a low-power inverter.

-=s
 
J

Jeff

Jan 1, 1970
0
Scott Willing said:
Modified sine if you're selling, modified square if you're buying. :)


No, it doesn't. It causes problems on some very specific equipment
such as laser printers and some Macs but it's rare.


Your laptop undoubtedly has a switch-mode power supply (far more
complex than a transformer, though you're probably using the term
generically) and it will likely be just as happy as a clam with
modified whatever wave power.

Is the UPS a true sine wave model? Is it full-time or stand-by? The
average stand-by UPS is little more than a crudely filtered power bar
until the line fails. If it is the typical modified square wave
stand-by device, you can find out exactly how your laptop will run
from mod sq wv power simply by unplugging the input to the UPS.

I live in a house that uses modified square wave power exclusively and
I have run a full-time laptop-based office, with inkjet printer,
scanner and external disk drives without incident for more than three
years.

In fact while doing some system upgrades I ran my little laptop office
off a Statpower 125W mod square wave inverter for three months.

Aside from two Dell laptops, from time to time I've also run a Mac
Powerbook, an IBM laptop, and I recently bought a museum piece to run
some old hardware and software - a desktop 386 PC with a CRT monitor.

All's been just swell. Eventually I will upgrade to sine power, but
computers will not be the inspiration for the move.


Unless it is a full-time sinewave UPS you'd be wasting your time.
However, chances are around 99% that your fears are unwarranted in any
case, so the issue of the UPS becomes academic.

If the laptop is the only thing you want to run from a battery, you
might consider buying a 12V power supply for your laptop, e.g. from
Lind Electronics, but the cheapest, most readily available and
flexible solution will be a low-power inverter.

A switch mode power supply used by virtually all computers (and now most
monitors) these days tend to like square waves just as much as sine waves.
It's one of the many benefits of a switch mode power supply. After all a
switch mode power supply converts and filters the incoming voltage to a high
voltage DC source.
 
M

Moojundai

Jan 1, 1970
0
I've got a computer with a ITX motherboard.
I have seen that it's possible to buy a 12V powersupply for them, and since
they can use ATX powersupplies, I expect that the 12V model can be used on
ATX, Mini-ATX, Flex-ATX aso. as well.

Last time I saw the 12v powersupply was on www.mini-itx.com

There are a few on Ebay:
http://search-desc.ebay.com/search/search.dll?soincludewords=12v+psu+itx&sotextsearched=2

As for laptops, you can get a 12v converter to use in the car, that must
give a lot less powerloss than 12v -> 220v converter -> UPS -> laptop psu ?

Peter!
 
S

Scott Willing

Jan 1, 1970
0
A switch mode power supply used by virtually all computers (and now most
monitors) these days tend to like square waves just as much as sine waves.
It's one of the many benefits of a switch mode power supply. After all a
switch mode power supply converts and filters the incoming voltage to a high
voltage DC source.

I didn't say it well enough the first time? :)

-=s
 
B

Bill Shuler

Jan 1, 1970
0
I have my laptop computer with its external power transformer
(220v AC going to 14v DC) plugged into an APC-Brand UPS.
If 14 vdc, you may be able to run directly from a 12 vdc power system.
I have a 6vdc radio which I run from 5 vdc because I had only lm7805
voltage regs in the junkbox. This is more % deviation that 12 vdc (actually
12.7 vdc with fully charges lead-acid battery, and up to 14.1 vdc during
charge) versus 14 vdc.

In-so-far as a modified square wave inverter powering computers-
I have not had any trouble using one to power this computer- an
emachines brand. To become more efficient and use less power-
I replaced the crt display with a View Sonic lcd display which operates
on 12 vdc. I also have a photoscanner that operates from 12 vdc.
Both of these, I wired directly to my 12 vdc service line. I have not
looked into the schematics for the computer or printer, so they are
both powered by a modified sqr wave inverter.

Good luck;

Bill
 
J

Jeff

Jan 1, 1970
0
Bill Shuler said:
If 14 vdc, you may be able to run directly from a 12 vdc power system.

Watch out doing that - some adaptors are current limited, so they can be
directly connected across the internal battery, thus reducing the adaptor
voltage to the internal battery voltage. It makes the electronics cheaper in
some cases.
I have a 6vdc radio which I run from 5 vdc because I had only lm7805
voltage regs in the junkbox.

You could have stuck a diode or two on the ground leg of the 7805 to bring
the voltage up a bit! Most small radios are not very sensitive to voltage
anyway. I hope it's a small radio - linear regulators are wasteful.
This is more % deviation that 12 vdc (actually
12.7 vdc with fully charges lead-acid battery, and up to 14.1 vdc during
charge) versus 14 vdc.

In-so-far as a modified square wave inverter powering computers-
I have not had any trouble using one to power this computer- an
emachines brand. To become more efficient and use less power-
I replaced the crt display with a View Sonic lcd display which operates
on 12 vdc. I also have a photoscanner that operates from 12 vdc.
Both of these, I wired directly to my 12 vdc service line. I have not
looked into the schematics for the computer or printer, so they are
both powered by a modified sqr wave inverter.

The computer will not be trivial, I'm going to work on redesigning a couple
of ATX power supplies to work on 36 to 48 V soon. A third to half of the
power supply will need to be redesigned and the main transformer rewound.
The good news it that it will end up being slighly more efficient and
simpler.
 
B

Bob Peterson

Jan 1, 1970
0
I grant you they are the best UPS technology, but running a whole house off
of one seems excessive, and kind of pricey.

James Parish said:
Nope. Most cheap UPS just have a relay that just pass the input to the
output. Get yourself a BEST POWER FERRUPS. It makes the best pure sinewave
of any UPS. It uses ferroresonate technology. I use one to power my whole
house. I just picked up off eBay a 5KVA unit to replace my 4.3KVA unit that
I'm selling to a neighbor. They have FERRUPS as small as 500KVA, I have two
as well as a 800KVA unit. Very nice units. Dewalt chargers love them.
 
C

clare @ snyder.on .ca

Jan 1, 1970
0
Nope. Most cheap UPS just have a relay that just pass the input to the
output. Get yourself a BEST POWER FERRUPS. It makes the best pure sinewave
of any UPS. It uses ferroresonate technology. I use one to power my whole
house. I just picked up off eBay a 5KVA unit to replace my 4.3KVA unit that
I'm selling to a neighbor. They have FERRUPS as small as 500KVA, I have two
as well as a 800KVA unit. Very nice units. Dewalt chargers love them.
Hey, I like the ferrups - but the Powerware 9 series is better - full
dual conversion, sine wave output, without the transients you get from
the ferrups.
Only problem is they won't run on a 12 volt syste, - need 24 for the
little unes, and I believe 48 for the big monsters.
 
C

clare @ snyder.on .ca

Jan 1, 1970
0
I grant you they are the best UPS technology, but running a whole house off
of one seems excessive, and kind of pricey.

Particularly since Ferro resonant transformers are quite in-efficient
- ie they get pretty warm when in operation.
 
S

Steve Thomas

Jan 1, 1970
0
If you do find a deal on one of the those, make sure you can handle the
weight.
The 15 KVA unit is 800 pounds.
No, that does not include batteries.

Bob Peterson said:
I grant you they are the best UPS technology, but running a whole house off
of one seems excessive, and kind of pricey.
 
J

Jeff

Jan 1, 1970
0
James Parish said:
Nope. Most cheap UPS just have a relay that just pass the input to the
output. Get yourself a BEST POWER FERRUPS. It makes the best pure sinewave
of any UPS. It uses ferroresonate technology. I use one to power my whole
house. I just picked up off eBay a 5KVA unit to replace my 4.3KVA unit that
I'm selling to a neighbor. They have FERRUPS as small as 500KVA, I have two
as well as a 800KVA unit. Very nice units. Dewalt chargers love them.

Umm, "ferroresonate" technology is very wasteful. What's the no load current
draw, and the conversion efficiency?
 
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