Re: [gentoo-user] Re: Python precision

[Marc Joliet]

Am Fri, 21 Sep 2012 02:31:45 -0400
schrieb Philip Webb :

[...]
> > 120919 Marc Joliet described how to set a level of precision:
> 
> Thanks too, but that's not what I wanted: it's not for printing,
> but simply to limit the display to eg  4  decimal places, not  16 ;
> the calculations still wb as accurate, but the output easier to read.
> Is that possible with Python ? -- ie a setting in  ascript.py 
> to tell Python to display only the 1st  4  places in all output
> without any further input from the user when doing the calculations;
> presumably it wb a command s/he could enter when in interactive mode too.

I couldn't find anything for regular python on the fly (except by using the
"decimal" module, see
http://docs.python.org/library/decimal.html#module-decimal), but I found out
that IPython can do this by configuring its output formatters appropriately. To
limit to 6 decimal places, my configuration would look like this:

  c.PlainTextFormatter.float_precision = '6'

I would expect that all they do is implement hook functions that you could also
put in place yourself, but to find out how to do it would require more digging
than I have time for right now. Maybe you will find something first :) .

HTH
-- 
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup


signature.asc
Description: PGP signature

Re: [gentoo-user] Re: Python precision

[Helmut Jarausch]

On 09/21/2012 08:31:45 AM, Philip Webb wrote:

120920 Willie WY Wong wrote:
> Unless you want to load the math module every time you start Python,
> it is perhaps better to create an alias in Bash
> using the `-i' option of Python:
>   alias python-calc='python -i loadmath.py'
> or if you only need one single command
>   alias python-calc='python -i -c "from math import *"'
> which will give you an interactive session with math functions  
preloaded.


Yes thanks: the 2nd is the simplest way to do what I want.

> 120919 Marc Joliet described how to set a level of precision:

Thanks too, but that's not what I wanted: it's not for printing,
but simply to limit the display to eg  4  decimal places, not  16 ;
the calculations still wb as accurate, but the output easier to read.
Is that possible with Python ? -- ie a setting in  ascript.py
to tell Python to display only the 1st  4  places in all output
without any further input from the user when doing the calculations;
presumably it wb a command s/he could enter when in interactive mode  
too.




You could subclass the builtin float class like

#!/usr/bin/python3
class myfloat(float) :
  def __init__(self,value):
super().__init__(self,value)
  def __str__(self):
S= super().__str__()
return S[:5]

X=3.1415926
print(myfloat(X))


Helmut.

Re: [gentoo-user] Re: Python precision

[Philip Webb]

120921 Marc Joliet wrote:
> 120921 Philip Webb  wrote:
>> Is that possible with Python ? -- ie a setting in  ascript.py 
>> to tell Python to display only the 1st  4  places in all output
>> without any further input from the user when doing the calculations;
>> presumably it wb a command s/he could enter when in interactive mode too.
> I couldn't find anything for regular python on the fly
> (except by using the "decimal" module, see
> http://docs.python.org/library/decimal.html#module-decimal

Yes, I found that too, but it requires typing 'Decimal' or 'D'
every time you want the shorter output (grimace).
What I would like is something which applies globally to the output,
but it looks as if there's nothing available.

I can do everything I need via the little script
-- I can predefine variables there ! --
& I don't mind loading "math" every time,
as I have no other present use for interactive Python.
I am now a bit ahead of where I was when I first asked (smile).

Thanks for this & the other reply.

-- 
,,
SUPPORT ___//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT`-O--O---'   purslowatchassdotutorontodotca

Re: [gentoo-user] Comparing kernel configurations...

[Paul Hartman]

On Thu, Sep 20, 2012 at 8:29 PM,   wrote:
> Hi,
>
> are there any tools beside diff, vimdiff, kdiff3 and such which
> supports one in comparing two differen .config from the linux kernel?

sys-kernel/kccmp is in portage.

*  sys-kernel/kccmp
  Latest version available: 0.3
  Latest version installed: [ Not Installed ]
  Size of files: 13 kB
  Homepage:  http://stoopidsimple.com/kccmp/
  Description:   A simple tool for comparing two linux kernel .config files
  License:   GPL-2

Re: [gentoo-user] Kernel options and udisk

[Volker Armin Hemmann]

Am Mittwoch, 19. September 2012, 16:18:34 schrieb Dale:
> Volker Armin Hemmann wrote:
> > Am Mittwoch, 19. September 2012, 01:51:49 schrieb Dale:
> >> Raffaele BELARDI wrote:
> >>> On 09/18/2012 11:03 PM, Dale wrote:
> >>> And every day I hear about them finding more oil and gas that they
> >>> didn't know was there before.
> > 
> > I am sure everybody would love to hear about those findings. Especially
> > the
> > CEO's of BP, Shell etc.
> 
> Actually, the former CEO of Shell was on Fox Business not long ago
> talking about some HUGE finds.  He said that we, the USA, are sitting on
> some of the largest oil fields.  Here is one article I found but not
> sure this is the same one the Shell guy was talking about since this
> article is a few months old.
> 
> http://www.usatoday.com/money/industries/energy/story/2012-05-15/1A-COV-ENER
> GY-INDEPENDENCE/54977254/1
> 
> Quoting from that:
> 
> "It's no pipe dream. The U.S. is already the world's fastest-growing oil
> and natural gas producer. Counting the output from Canada and Mexico,
> North America
>  erica> is "the new Middle East," Citigroup analysts declare in a recent
> report."
> 
> Note it said fastest growing producer.  You have to find it and be able
> to get it up before you can produce it.  Yea, one day we will run out
> but that's a good long ways off.  We could get hit by some asteroid or
> something that just completely destroys the planet and everything on it,
> including all that oil and gas that people want to save up on.
> 
> Have you heard about the new wells being drilled in North Dakota by any
> chance?  They are drilling for oil like crazy up there.  That is just
> one that I recall seeing on the news a good bit recently.  There are
> plenty of other finds.

I also heard about gas in drinking water thanks to fracking. Do oil companies 
drilling in deep water because it is cheap, save and fun? Or do they want to 
go and drill in the Arktis because it is so lovely there? Hardly. There is a 
difference between 'something is there' and 'the prize and risk are worth it'.
Do you remember that Gulf incident? BP surely hopes not. You should get used 
to it.

and here:
http://oilsandstruth.org/world-running-out-oil-says-exceo


> 
> > Fact is, we are running out. The stuff that is found is either very hard
> > to get - or not very much. Oh, and very little to start with. Consider
> > current consumption.
> 
> Fact is, the same could be said for the Sun too.  Science already says
> it will run out of fuel one day.

And now you went full stupid. There is a difference between 'a couple of 
decades' and '4 billion years'. But thanks for posting. That said a lot about 
you. I don't even care about the rest of your posting. This is plonk worthy 
stupid. So I stop right there, I don't want to get any of that.

-- 
#163933

[gentoo-user] Re: virtualbox - serial port

[Grant Edwards]

On 2012-09-21, Mick  wrote:
> On Tuesday 18 Sep 2012 18:49:33 Joseph wrote:
>> On 09/18/12 15:59, Grant Edwards wrote:
>> 
>> [snip]
>> 
>> >> I'm in group "tty", so I can not figure it out why virtualbox is
>> >> complaining.
>> >
>> >What happens when you do "cat /dev/ttyS0"?
>> 
>> It is working know. It was my error :-/
>> I had it selected "host pipe" and it should be "host device'
>> One of those days :-)
>
> Mine looks like this:
>
> $ ls -l /dev/ttyS0
> crw-rw 1 root uucp 4, 64 Sep 21 06:16 /dev/ttyS0
>
> and the user (me) is a member of the uucp group.  Not sure if this is
> a more correct way to configure it ...

Adding the user to the group that owns the device is the usual way to
do give users access to hardware.

-- 
Grant Edwards   grant.b.edwardsYow! Of course, you
  at   UNDERSTAND about the PLAIDS
  gmail.comin the SPIN CYCLE --

Re: [gentoo-user] Kernel options and udisk

[Dale]

Volker Armin Hemmann wrote:
> Am Mittwoch, 19. September 2012, 16:18:34 schrieb Dale:
>> Volker Armin Hemmann wrote:
>>> Am Mittwoch, 19. September 2012, 01:51:49 schrieb Dale:
 Raffaele BELARDI wrote:
> On 09/18/2012 11:03 PM, Dale wrote:
> And every day I hear about them finding more oil and gas that they
> didn't know was there before.
>>> I am sure everybody would love to hear about those findings. Especially
>>> the
>>> CEO's of BP, Shell etc.
>> Actually, the former CEO of Shell was on Fox Business not long ago
>> talking about some HUGE finds.  He said that we, the USA, are sitting on
>> some of the largest oil fields.  Here is one article I found but not
>> sure this is the same one the Shell guy was talking about since this
>> article is a few months old.
>>
>> http://www.usatoday.com/money/industries/energy/story/2012-05-15/1A-COV-ENER
>> GY-INDEPENDENCE/54977254/1
>>
>> Quoting from that:
>>
>> "It's no pipe dream. The U.S. is already the world's fastest-growing oil
>> and natural gas producer. Counting the output from Canada and Mexico,
>> North America
>> > erica> is "the new Middle East," Citigroup analysts declare in a recent
>> report."
>>
>> Note it said fastest growing producer.  You have to find it and be able
>> to get it up before you can produce it.  Yea, one day we will run out
>> but that's a good long ways off.  We could get hit by some asteroid or
>> something that just completely destroys the planet and everything on it,
>> including all that oil and gas that people want to save up on.
>>
>> Have you heard about the new wells being drilled in North Dakota by any
>> chance?  They are drilling for oil like crazy up there.  That is just
>> one that I recall seeing on the news a good bit recently.  There are
>> plenty of other finds.
> I also heard about gas in drinking water thanks to fracking. Do oil companies 
> drilling in deep water because it is cheap, save and fun? Or do they want to 
> go and drill in the Arktis because it is so lovely there? Hardly. There is a 
> difference between 'something is there' and 'the prize and risk are worth it'.
> Do you remember that Gulf incident? BP surely hopes not. You should get used 
> to it.
>
> and here:
> http://oilsandstruth.org/world-running-out-oil-says-exceo
>

I also remember the people that died trying to go to the moon but we did
it anyway.  I have heard a lot of people talking about fracking and all
sort of myths about it.  I have not seen proof that is in drinking
water.  Even so, I have a well that we drove here and we drank off it
for years.  It has a HUGE iron count and turns white clothes orange. 
There is always something in water.  It's just what water does.  That is
why it gets filtered before it is used for drinking.  By the way,
fracking has been around for something like 60 years.  Not all the oil
that has been found recently requires fracking either.  So, don't just
point to fracking and then claim that all oil is bad.

The website you linked to is against oil from my google search.  It
would be like quoting Al Gore for global warming, climate change or
whatever they call it this week. 

>>> Fact is, we are running out. The stuff that is found is either very hard
>>> to get - or not very much. Oh, and very little to start with. Consider
>>> current consumption.
>> Fact is, the same could be said for the Sun too.  Science already says
>> it will run out of fuel one day.
> And now you went full stupid. There is a difference between 'a couple of 
> decades' and '4 billion years'. But thanks for posting. That said a lot about 
> you. I don't even care about the rest of your posting. This is plonk worthy 
> stupid. So I stop right there, I don't want to get any of that.
>

Care to explain away that we could get hit my some asteroid too? 
Yellowstone could erupt again and kill us all.  Better get your "I'm
scared of everything" hat on. 

Who knows it is a couple decades?  That was the thinking years ago
BEFORE finding all the new reserves of gas and oil. 

Careful calling someone stupid.  It could come back and name calling on
the list is not a good thing.  You should know better.

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how 
you interpreted my words!

Re: [gentoo-user] Kernel options and udisk

[Michael Mol]

On Fri, Sep 21, 2012 at 3:15 PM, Dale  wrote:
> Volker Armin Hemmann wrote:
>> Am Mittwoch, 19. September 2012, 16:18:34 schrieb Dale:
>>> Volker Armin Hemmann wrote:
 Am Mittwoch, 19. September 2012, 01:51:49 schrieb Dale:
> Raffaele BELARDI wrote:
>> On 09/18/2012 11:03 PM, Dale wrote:
>> And every day I hear about them finding more oil and gas that they
>> didn't know was there before.
 I am sure everybody would love to hear about those findings. Especially
 the
 CEO's of BP, Shell etc.
>>> Actually, the former CEO of Shell was on Fox Business not long ago
>>> talking about some HUGE finds.  He said that we, the USA, are sitting on
>>> some of the largest oil fields.  Here is one article I found but not
>>> sure this is the same one the Shell guy was talking about since this
>>> article is a few months old.
>>>
>>> http://www.usatoday.com/money/industries/energy/story/2012-05-15/1A-COV-ENER
>>> GY-INDEPENDENCE/54977254/1
>>>
>>> Quoting from that:
>>>
>>> "It's no pipe dream. The U.S. is already the world's fastest-growing oil
>>> and natural gas producer. Counting the output from Canada and Mexico,
>>> North America
>>> >> erica> is "the new Middle East," Citigroup analysts declare in a recent
>>> report."
>>>
>>> Note it said fastest growing producer.  You have to find it and be able
>>> to get it up before you can produce it.  Yea, one day we will run out
>>> but that's a good long ways off.  We could get hit by some asteroid or
>>> something that just completely destroys the planet and everything on it,
>>> including all that oil and gas that people want to save up on.
>>>
>>> Have you heard about the new wells being drilled in North Dakota by any
>>> chance?  They are drilling for oil like crazy up there.  That is just
>>> one that I recall seeing on the news a good bit recently.  There are
>>> plenty of other finds.
>> I also heard about gas in drinking water thanks to fracking. Do oil companies
>> drilling in deep water because it is cheap, save and fun? Or do they want to
>> go and drill in the Arktis because it is so lovely there? Hardly. There is a
>> difference between 'something is there' and 'the prize and risk are worth 
>> it'.
>> Do you remember that Gulf incident? BP surely hopes not. You should get used
>> to it.
>>
>> and here:
>> http://oilsandstruth.org/world-running-out-oil-says-exceo
>>
>
> I also remember the people that died trying to go to the moon but we did
> it anyway.  I have heard a lot of people talking about fracking and all
> sort of myths about it.  I have not seen proof that is in drinking
> water.  Even so, I have a well that we drove here and we drank off it
> for years.  It has a HUGE iron count and turns white clothes orange.
> There is always something in water.  It's just what water does.  That is
> why it gets filtered before it is used for drinking.  By the way,
> fracking has been around for something like 60 years.  Not all the oil
> that has been found recently requires fracking either.  So, don't just
> point to fracking and then claim that all oil is bad.
>
> The website you linked to is against oil from my google search.  It
> would be like quoting Al Gore for global warming, climate change or
> whatever they call it this week.
>
 Fact is, we are running out. The stuff that is found is either very hard
 to get - or not very much. Oh, and very little to start with. Consider
 current consumption.
>>> Fact is, the same could be said for the Sun too.  Science already says
>>> it will run out of fuel one day.
>> And now you went full stupid. There is a difference between 'a couple of
>> decades' and '4 billion years'. But thanks for posting. That said a lot about
>> you. I don't even care about the rest of your posting. This is plonk worthy
>> stupid. So I stop right there, I don't want to get any of that.
>>
>
> Care to explain away that we could get hit my some asteroid too?
> Yellowstone could erupt again and kill us all.  Better get your "I'm
> scared of everything" hat on.
>
> Who knows it is a couple decades?  That was the thinking years ago
> BEFORE finding all the new reserves of gas and oil.
>
> Careful calling someone stupid.  It could come back and name calling on
> the list is not a good thing.  You should know better.


Guys, this fell into politics, one of those categories of things you
don't discuss in polite company. Not that I'm accusing anyone of being
polite, it's just that these aren't issues that can generally be
resolved, and it's certainly not something that comes anywhere close
to being on-topic here.

Now, could we go back to discussing software, packages, electronics
and amplifiers? I found that portion of the thread utterly
fascinating...

-- 
:wq

Re: [gentoo-user] Kernel options and udisk

[Alan McKinnon]

On Fri, 21 Sep 2012 15:25:49 -0400
Michael Mol  wrote:

> Guys, this fell into politics, one of those categories of things you
> don't discuss in polite company. Not that I'm accusing anyone of being
> polite, 

Phew, glad to hear that last bit. You had me worried for a second, what
with my reputation to uphold and all


> Now, could we go back to discussing software, packages, electronics
> and amplifiers? I found that portion of the thread utterly
> fascinating...

That's a good idea. Would you like to hear about Hitachi Class H amps?

I'm forever fascinated that I seem to be the only person that ever
heard of them. Most techies know A, AB and B. Some know Class C but I
get blank looks everywhere I mention Class H...

-- 
Alan McKinnon
alan.mckin...@gmail.com

Re: [gentoo-user] Kernel options and udisk

[Michael Mol]

On Fri, Sep 21, 2012 at 3:45 PM, Alan McKinnon  wrote:
> On Fri, 21 Sep 2012 15:25:49 -0400
> Michael Mol  wrote:
>
>> Guys, this fell into politics, one of those categories of things you
>> don't discuss in polite company. Not that I'm accusing anyone of being
>> polite,
>
> Phew, glad to hear that last bit. You had me worried for a second, what
> with my reputation to uphold and all
>
>
>> Now, could we go back to discussing software, packages, electronics
>> and amplifiers? I found that portion of the thread utterly
>> fascinating...
>
> That's a good idea. Would you like to hear about Hitachi Class H amps?
>
> I'm forever fascinated that I seem to be the only person that ever
> heard of them. Most techies know A, AB and B. Some know Class C but I
> get blank looks everywhere I mention Class H...

I would indeed. And a primer (or reasonable reference for someone with
just a technician's amateur radio license) on class C. :)

-- 
:wq

[gentoo-user] x2go and KDE

[Paul Hartman]

Hi,

I am trying x2go for the first time. Everything worked easily so far
(except x2go client on MS windows does not support ecdsa keys and does
not tell you this in the error message...).

LXDE and XFCE work normally, but KDE has no taskbar panel! The desktop
shows up, the activities button on top-right corner of screen is
there, I can right-click on the desktop, Alt-F2 to launch programs,
etc. But for some reason my taskbar panel is not there. Of course I
prefer to use KDE and it is the one that does not work. :) I have
normally used nomachine nxserver and KDE works fine there.

Has anybody else here encountered this problem or have any ideas about
what to do?

Thanks

Re: [gentoo-user] Kernel options and udisk

[Dale]

Michael Mol wrote:
> On Fri, Sep 21, 2012 at 3:15 PM, Dale  wrote:
>> Volker Armin Hemmann wrote:
>>> Am Mittwoch, 19. September 2012, 16:18:34 schrieb Dale:
 Volker Armin Hemmann wrote:
> Am Mittwoch, 19. September 2012, 01:51:49 schrieb Dale:
>> Raffaele BELARDI wrote:
>>> On 09/18/2012 11:03 PM, Dale wrote:
>>> And every day I hear about them finding more oil and gas that they
>>> didn't know was there before.
> I am sure everybody would love to hear about those findings. Especially
> the
> CEO's of BP, Shell etc.
 Actually, the former CEO of Shell was on Fox Business not long ago
 talking about some HUGE finds.  He said that we, the USA, are sitting on
 some of the largest oil fields.  Here is one article I found but not
 sure this is the same one the Shell guy was talking about since this
 article is a few months old.

 http://www.usatoday.com/money/industries/energy/story/2012-05-15/1A-COV-ENER
 GY-INDEPENDENCE/54977254/1

 Quoting from that:

 "It's no pipe dream. The U.S. is already the world's fastest-growing oil
 and natural gas producer. Counting the output from Canada and Mexico,
 North America
  is "the new Middle East," Citigroup analysts declare in a recent
 report."

 Note it said fastest growing producer.  You have to find it and be able
 to get it up before you can produce it.  Yea, one day we will run out
 but that's a good long ways off.  We could get hit by some asteroid or
 something that just completely destroys the planet and everything on it,
 including all that oil and gas that people want to save up on.

 Have you heard about the new wells being drilled in North Dakota by any
 chance?  They are drilling for oil like crazy up there.  That is just
 one that I recall seeing on the news a good bit recently.  There are
 plenty of other finds.
>>> I also heard about gas in drinking water thanks to fracking. Do oil 
>>> companies
>>> drilling in deep water because it is cheap, save and fun? Or do they want to
>>> go and drill in the Arktis because it is so lovely there? Hardly. There is a
>>> difference between 'something is there' and 'the prize and risk are worth 
>>> it'.
>>> Do you remember that Gulf incident? BP surely hopes not. You should get used
>>> to it.
>>>
>>> and here:
>>> http://oilsandstruth.org/world-running-out-oil-says-exceo
>>>
>> I also remember the people that died trying to go to the moon but we did
>> it anyway.  I have heard a lot of people talking about fracking and all
>> sort of myths about it.  I have not seen proof that is in drinking
>> water.  Even so, I have a well that we drove here and we drank off it
>> for years.  It has a HUGE iron count and turns white clothes orange.
>> There is always something in water.  It's just what water does.  That is
>> why it gets filtered before it is used for drinking.  By the way,
>> fracking has been around for something like 60 years.  Not all the oil
>> that has been found recently requires fracking either.  So, don't just
>> point to fracking and then claim that all oil is bad.
>>
>> The website you linked to is against oil from my google search.  It
>> would be like quoting Al Gore for global warming, climate change or
>> whatever they call it this week.
>>
> Fact is, we are running out. The stuff that is found is either very hard
> to get - or not very much. Oh, and very little to start with. Consider
> current consumption.
 Fact is, the same could be said for the Sun too.  Science already says
 it will run out of fuel one day.
>>> And now you went full stupid. There is a difference between 'a couple of
>>> decades' and '4 billion years'. But thanks for posting. That said a lot 
>>> about
>>> you. I don't even care about the rest of your posting. This is plonk worthy
>>> stupid. So I stop right there, I don't want to get any of that.
>>>
>> Care to explain away that we could get hit my some asteroid too?
>> Yellowstone could erupt again and kill us all.  Better get your "I'm
>> scared of everything" hat on.
>>
>> Who knows it is a couple decades?  That was the thinking years ago
>> BEFORE finding all the new reserves of gas and oil.
>>
>> Careful calling someone stupid.  It could come back and name calling on
>> the list is not a good thing.  You should know better.
>
> Guys, this fell into politics, one of those categories of things you
> don't discuss in polite company. Not that I'm accusing anyone of being
> polite, it's just that these aren't issues that can generally be
> resolved, and it's certainly not something that comes anywhere close
> to being on-topic here.
>
> Now, could we go back to discussing software, packages, electronics
> and amplifiers? I found that portion of the thread utterly
> fascinating...
>

Kewl.  I have built amps from scratch but not 

[gentoo-user] Re: x2go and KDE

[Paul Hartman]

On Fri, Sep 21, 2012 at 2:53 PM, Paul Hartman
 wrote:
> Hi,
>
> I am trying x2go for the first time. Everything worked easily so far
> (except x2go client on MS windows does not support ecdsa keys and does
> not tell you this in the error message...).
>
> LXDE and XFCE work normally, but KDE has no taskbar panel! The desktop
> shows up, the activities button on top-right corner of screen is
> there, I can right-click on the desktop, Alt-F2 to launch programs,
> etc. But for some reason my taskbar panel is not there. Of course I
> prefer to use KDE and it is the one that does not work. :) I have
> normally used nomachine nxserver and KDE works fine there.
>
> Has anybody else here encountered this problem or have any ideas about
> what to do?
>
> Thanks

Replying to myself with a workaround... It seems to solve itself if I
resize the window once the session has started.

Re: [gentoo-user] Kernel options and udisk

[Alan McKinnon]

On Fri, 21 Sep 2012 15:52:17 -0400
Michael Mol  wrote:

> On Fri, Sep 21, 2012 at 3:45 PM, Alan McKinnon
>  wrote:
> > On Fri, 21 Sep 2012 15:25:49 -0400
> > Michael Mol  wrote:
> >
> >> Guys, this fell into politics, one of those categories of things
> >> you don't discuss in polite company. Not that I'm accusing anyone
> >> of being polite,
> >
> > Phew, glad to hear that last bit. You had me worried for a second,
> > what with my reputation to uphold and all
> >
> >
> >> Now, could we go back to discussing software, packages, electronics
> >> and amplifiers? I found that portion of the thread utterly
> >> fascinating...
> >
> > That's a good idea. Would you like to hear about Hitachi Class H
> > amps?
> >
> > I'm forever fascinated that I seem to be the only person that ever
> > heard of them. Most techies know A, AB and B. Some know Class C but
> > I get blank looks everywhere I mention Class H...
> 
> I would indeed. And a primer (or reasonable reference for someone with
> just a technician's amateur radio license) on class C. :)
> 

IIRC this was back in the late 70s or early 80s. Someone at Hitachi
figured that amps (like code) spent 90% of their time doing 10% of the
effort. If you had a 100W amp, it wasn't trying to drive 100W into the
speakers all the time - only when the input signal was large enough.

And yet, the power source for the output stages was permanently running
at 70V or so (that's what it takes to get 100W into speaker coils back
then). A transistor isn't a perfect isolator when biased off, so some
of that voltage gets dropped somewhere (across the output transistors)
and the result is a lot of wastage.

wikipedia has a quite good summary of the usual classes - A, B, AB, C &
D:

http://en.wikipedia.org/wiki/Electronic_amplifier#Class_C

But, Class H. A Hitachi engineer had a brilliant idea:

Run the damn thing class A all the time (for the audio quality) but at
around 24V. Heat generated is minimal. The power supply had a fancy
voltage tripler circuit and when the input warranted it, the supply
voltage would (very rapidly) switch over to the full 70V and the amp
would deliver the full rated output. There was fancy circuitry in place
to avoid distortion at the switch on point of course, but that is a bit
OT.

An interesting take on the problem. Mechanical engineers do this all
the time with engines - turbos only kick in when you need the power
boost they provide, the rest of the time the motor is in regular mode.

I've promised myself for years since my apprentice days that I would
one day built a valve amp from a kit. There's something about the warm
glow from the tubes on a winter night that is appealing :-) I'd better
hurry up and get on with it, I read that decent quality valves are
becoming scarce and are generally only available from (what used to be)
the USSR.




-- 
Alan McKinnon
alan.mckin...@gmail.com

Re: [gentoo-user] Gentoo is the best linux distro

[Allan Gottlieb]

On Thu, Sep 20 2012, Paul Hartman wrote:

> In newer version of portage you can add "fixlafiles" to FEATURES and
> there is no need to manually run the lxfilefixer program.

Thanks.  I hadn't seen this before.  It is in the make.conf man page for
my system which is ~amd64.  So I assume "newer versions of portage" does
not require the 2.2 (masked, but used by some on this list).

Thanks again,
allan

Re: [gentoo-user] Kernel options and udisk

[Samuel Ports]

Modern version
http://www.babeland.com/hitachi-magic-wand/d/2487

Sent from my iPhone

On Sep 21, 2012, at 5:18 PM, Alan McKinnon  wrote:

> On Fri, 21 Sep 2012 15:52:17 -0400
> Michael Mol  wrote:
>
>> On Fri, Sep 21, 2012 at 3:45 PM, Alan McKinnon
>>  wrote:
>>> On Fri, 21 Sep 2012 15:25:49 -0400
>>> Michael Mol  wrote:
>>>
 Guys, this fell into politics, one of those categories of things
 you don't discuss in polite company. Not that I'm accusing anyone
 of being polite,
>>>
>>> Phew, glad to hear that last bit. You had me worried for a second,
>>> what with my reputation to uphold and all
>>>
>>>
 Now, could we go back to discussing software, packages, electronics
 and amplifiers? I found that portion of the thread utterly
 fascinating...
>>>
>>> That's a good idea. Would you like to hear about Hitachi Class H
>>> amps?
>>>
>>> I'm forever fascinated that I seem to be the only person that ever
>>> heard of them. Most techies know A, AB and B. Some know Class C but
>>> I get blank looks everywhere I mention Class H...
>>
>> I would indeed. And a primer (or reasonable reference for someone with
>> just a technician's amateur radio license) on class C. :)
>>
>
> IIRC this was back in the late 70s or early 80s. Someone at Hitachi
> figured that amps (like code) spent 90% of their time doing 10% of the
> effort. If you had a 100W amp, it wasn't trying to drive 100W into the
> speakers all the time - only when the input signal was large enough.
>
> And yet, the power source for the output stages was permanently running
> at 70V or so (that's what it takes to get 100W into speaker coils back
> then). A transistor isn't a perfect isolator when biased off, so some
> of that voltage gets dropped somewhere (across the output transistors)
> and the result is a lot of wastage.
>
> wikipedia has a quite good summary of the usual classes - A, B, AB, C &
> D:
>
> http://en.wikipedia.org/wiki/Electronic_amplifier#Class_C
>
> But, Class H. A Hitachi engineer had a brilliant idea:
>
> Run the damn thing class A all the time (for the audio quality) but at
> around 24V. Heat generated is minimal. The power supply had a fancy
> voltage tripler circuit and when the input warranted it, the supply
> voltage would (very rapidly) switch over to the full 70V and the amp
> would deliver the full rated output. There was fancy circuitry in place
> to avoid distortion at the switch on point of course, but that is a bit
> OT.
>
> An interesting take on the problem. Mechanical engineers do this all
> the time with engines - turbos only kick in when you need the power
> boost they provide, the rest of the time the motor is in regular mode.
>
> I've promised myself for years since my apprentice days that I would
> one day built a valve amp from a kit. There's something about the warm
> glow from the tubes on a winter night that is appealing :-) I'd better
> hurry up and get on with it, I read that decent quality valves are
> becoming scarce and are generally only available from (what used to be)
> the USSR.
>
>
>
>
> --
> Alan McKinnon
> alan.mckin...@gmail.com
>
>