Click here to get back home

400Hz Power and Modern Laptop Power Brick
 Home | NewsGroups | Search | About
Login Password
Register Now! Lost Password?
 comp.sys.laptops    Post an article   get this group's latest topics as an RSS feed add this group's latest topics to your My MSN content add this group's latest topics to your My Yahoo content
Subject Author Date
400Hz Power and Modern Laptop Power Brick Chris 01-31-2007
Get Chitika Premium
Posted by Chris on January 31, 2007, 3:49 pm
Please log in for more thread options
 I've read a few posts on using 115 VAC 400Hz power (commonly found on
aircraft) with a standard laptop power brick. Everything I've seen
basically amounts to "try at your own risk" or "didn't hurt my
laptop". Does anyone have switching power supply design experience
that may be able to shed a little light on why this would or would not
be a good idea for a modern laptop power brick. My extremely limited
testing with a multimeter/oem power brick/400Hz input shows that the
the power brick outputs the correct DC voltage. I would feel a little
better plugging it into the $6000 laptop we bought if I could check
for ripple output voltages at 400Hz compared to 60Hz with a scope. If
that turns out to be a non-issue then then the next worry would be
early failure of the power brick (minor concern) and safety issues
such as the brick catching on fire (slightly less minor concern).

Any info or reading suggestions much appreciated.


Posted by M.I.5¾ on February 1, 2007, 3:06 am
Please log in for more thread options
> I've read a few posts on using 115 VAC 400Hz power (commonly found on
> aircraft) with a standard laptop power brick. Everything I've seen
> basically amounts to "try at your own risk" or "didn't hurt my
> laptop". Does anyone have switching power supply design experience
> that may be able to shed a little light on why this would or would not
> be a good idea for a modern laptop power brick. My extremely limited
> testing with a multimeter/oem power brick/400Hz input shows that the
> the power brick outputs the correct DC voltage. I would feel a little
> better plugging it into the $6000 laptop we bought if I could check
> for ripple output voltages at 400Hz compared to 60Hz with a scope. If
> that turns out to be a non-issue then then the next worry would be
> early failure of the power brick (minor concern) and safety issues
> such as the brick catching on fire (slightly less minor concern).
>
> Any info or reading suggestions much appreciated.
>

Laptop switch mode power supplies (or indeed any switch mode supply) will
work quite happily off a 400 Hz supply. We do it all the time. The ripple
will be more or less the same as the power supply part is separated from the
mains input by a DC bridge. The rating plate says 50-60Hz simply because
that is what will be encountered by the vast majority of users. As it
happens, they also work perfectly from DC (but do require a higher voltage
~150 volts for US supplies and ~300 volts for Europe - though most supplies
are universal).

Power supplies containing a mains transformer won't work at all from 400Hz
(but otherwise sustain no damage). These power supplies must not be run
from DC.



Posted by SARPaul on February 1, 2007, 7:58 am
Please log in for more thread options
>
>
>
>
> > I've read a few posts on using 115 VAC 400Hz power (commonly found on
> > aircraft) with a standard laptop power brick. Everything I've seen
> > basically amounts to "try at your own risk" or "didn't hurt my
> > laptop". Does anyone have switching power supply design experience
> > that may be able to shed a little light on why this would or would not
> > be a good idea for a modern laptop power brick. My extremely limited
> > testing with a multimeter/oem power brick/400Hz input shows that the
> > the power brick outputs the correct DC voltage. I would feel a little
> > better plugging it into the $6000 laptop we bought if I could check
> > for ripple output voltages at 400Hz compared to 60Hz with a scope. If
> > that turns out to be a non-issue then then the next worry would be
> > early failure of the power brick (minor concern) and safety issues
> > such as the brick catching on fire (slightly less minor concern).
>
> > Any info or reading suggestions much appreciated.
>
> Laptop switch mode power supplies (or indeed any switch mode supply) will
> work quite happily off a 400 Hz supply. We do it all the time. The ripp=
le
> will be more or less the same as the power supply part is separated from =
the
> mains input by a DC bridge. The rating plate says 50-60Hz simply because
> that is what will be encountered by the vast majority of users. As it
> happens, they also work perfectly from DC (but do require a higher voltage
> ~150 volts for US supplies and ~300 volts for Europe - though most suppli=
es
> are universal).
>
> Power supplies containing a mains transformer won't work at all from 400Hz
> (but otherwise sustain no damage). These power supplies must not be run
> from DC.

Also, you can check for any ripple in the output DC by setting your
DMM or VOM to AC and measure across the DC output - if it reads 0.0
you have no ripple.
Paul


Posted by M.I.5¾ on February 1, 2007, 10:38 am
Please log in for more thread options

>
>
>
>
> > I've read a few posts on using 115 VAC 400Hz power (commonly found on
> > aircraft) with a standard laptop power brick. Everything I've seen
> > basically amounts to "try at your own risk" or "didn't hurt my
> > laptop". Does anyone have switching power supply design experience
> > that may be able to shed a little light on why this would or would not
> > be a good idea for a modern laptop power brick. My extremely limited
> > testing with a multimeter/oem power brick/400Hz input shows that the
> > the power brick outputs the correct DC voltage. I would feel a little
> > better plugging it into the $6000 laptop we bought if I could check
> > for ripple output voltages at 400Hz compared to 60Hz with a scope. If
> > that turns out to be a non-issue then then the next worry would be
> > early failure of the power brick (minor concern) and safety issues
> > such as the brick catching on fire (slightly less minor concern).
>
> > Any info or reading suggestions much appreciated.
>
> Laptop switch mode power supplies (or indeed any switch mode supply) will
> work quite happily off a 400 Hz supply. We do it all the time. The
> ripple
> will be more or less the same as the power supply part is separated from
> the
> mains input by a DC bridge. The rating plate says 50-60Hz simply because
> that is what will be encountered by the vast majority of users. As it
> happens, they also work perfectly from DC (but do require a higher voltage
> ~150 volts for US supplies and ~300 volts for Europe - though most
> supplies
> are universal).
>
> Power supplies containing a mains transformer won't work at all from 400Hz
> (but otherwise sustain no damage). These power supplies must not be run
> from DC.

Also, you can check for any ripple in the output DC by setting your
DMM or VOM to AC and measure across the DC output - if it reads 0.0
you have no ripple.

--------------

If it reads 0.0 you most likely have a dead multimeter. Unlike an
osilloscope, which has a blocking capacitor when set to AC, most multimeters
actually detect the average or RMS (depending on the meter) of the input
when set to AC. The DC output itself has both an average value and an RMS
value that is not zero. In the case of the average sensing instrument, it
is calibrated to read the RMS value, but only for a sine wave. The meter
will read either the DC voltage or a value 1.11 times the DC voltage. If it
does read only the AC ripple, then you actually do have one of the few
meters that block the DC (no true RMS instrument will do this). The really
good ones (and expensive) offer 3 options, DC, RMS AC or RMS DC+AC.

Of course, you can always add a blocking capacitor of your own in one of the
leads. A few tens of nanofarads should be adequate for a switch mode
supply. I would be very surprised if the ripple were any different (but it
won't be zero - not for a switch mode supply).



Posted by Chris on February 1, 2007, 10:28 am
Please log in for more thread options
>
>
>
>
> > I've read a few posts on using 115 VAC 400Hz power (commonly found on
> > aircraft) with a standard laptop power brick. Everything I've seen
> > basically amounts to "try at your own risk" or "didn't hurt my
> > laptop". Does anyone have switching power supply design experience
> > that may be able to shed a little light on why this would or would not
> > be a good idea for a modern laptop power brick. My extremely limited
> > testing with a multimeter/oem power brick/400Hz input shows that the
> > the power brick outputs the correct DC voltage. I would feel a little
> > better plugging it into the $6000 laptop we bought if I could check
> > for ripple output voltages at 400Hz compared to 60Hz with a scope. If
> > that turns out to be a non-issue then then the next worry would be
> > early failure of the power brick (minor concern) and safety issues
> > such as the brick catching on fire (slightly less minor concern).
>
> > Any info or reading suggestions much appreciated.
>
> Laptop switch mode power supplies (or indeed any switch mode supply) will
> work quite happily off a 400 Hz supply. We do it all the time. The ripp=
le
> will be more or less the same as the power supply part is separated from =
the
> mains input by a DC bridge. The rating plate says 50-60Hz simply because
> that is what will be encountered by the vast majority of users. As it
> happens, they also work perfectly from DC (but do require a higher voltage
> ~150 volts for US supplies and ~300 volts for Europe - though most suppli=
es
> are universal).
>
> Power supplies containing a mains transformer won't work at all from 400Hz
> (but otherwise sustain no damage). These power supplies must not be run
> from DC.

>From what I read last night, what you've said makes sense including
running the power supply off of DC. I'm a little confused by your
last comment though. If you're immediately stepping down the mains
voltage with a transformer designed to to run at 60 or 50 Hz wouldn't
it easily handle the same voltage at 400Hz?


Similar ThreadsPosted
Laptop fell, now power-up goes to instant power-down; any hope? May 5, 2007, 12:10 am
POwer adaptor to power laptop and LCD monitor July 30, 2007, 4:19 pm
Re: Laptop runs on battery power but not A/C power December 25, 2007, 1:28 pm
When AC unplugged Power Meter keeps saying 100% batter power remaining October 15, 2007, 2:54 am
PS/2 port on modern laptop July 24, 2006, 10:50 am
I use a 45 watt power supply instead of a 75 watt power supply for my laptop February 21, 2007, 5:31 pm
laptop power November 1, 2005, 4:22 pm
Should Laptop Power On without RAM and HDD? January 30, 2006, 12:17 pm
Laptop won't power on! help June 29, 2006, 6:52 am
Laptop with no power February 11, 2007, 5:21 pm

Our other projects:

Art Dolls, Fairies and Mermaids - Sunnyfaces.net

Roy's Linux, Programming and Search Engines messages

1-Script XML SitemapXML Sitemap