From: Peter D. on
on Thursday 11 October 2007 10:25
in the Usenet newsgroup alt.os.linux.mandrake
Adam wrote:

> Moe Trin wrote:

[snip]
>> In one of your earlier posts, you had the card in the computer with
>> a 192.0.0.192 address. How did that come up?
>
> I read somewhere online that the default for HP's JetDirect cards was
> 192.0.0.192, so I tried setting eth10 to that.

Very unlikely. There should only be one device in the world with
that address. But the address range 192.168.N.M where N and M
range from 0 to 255 are private addresses which everyone may use
on their local networks.

> Aida32 found
> 169.254.45.154 / 255.255.0.0 for the Intel Ethernet card, so I tried
> setting eth10 to that, but 'ping'ing both 169.254.45.154 and 192.0.0.192
> got no responses.
[snip]

I think that there is something special about 169 as well, but I don't
remember what.

Is everybody trying to set a record for the biggest most off topic
thread? This should have been broken up into dozens of threads.


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Peter D.
From: Peter D. on
on Friday 12 October 2007 11:52
in the Usenet newsgroup alt.os.linux.mandrake
Jim Beard wrote:

>> Adam wrote:
>>> Just curious... would it be possible, in theory, to build a gadget that
>>> would plug into a household electric outlet and automatically switch in
>>> inductors or capacitors as needed? The idea being it would
>>> automatically bring the power factor closer to one, for the household or
>>> at least that one circuit, and save some money.
>>
> Peter D. wrote:
>> Yes, definitely. The better computer power supplies have Automatic
>> Power Factor Correction. Unfortunately if you have to ask questions
>> about this you are not the man to do the job. Mains voltage is
>> *dangerous*.
>
> U.S. household mains is 110V, not 220/240V. It is reasonably safe
> to do many things around the house in the U.S. that should be
> done only by a trained technician, where the higher voltages are
> in effect.

I am not an American.

Don't they have 220V supplied to the house which is then distributed
around the house twice, as 220V "high" voltage and 110V "standard"
voltage? The meter (and the best place to do power factor correction
is at the 220V connection.

BTW I have been told that if you try really hard it is possible to
electrocute yourself with 12 Volts. Also as the voltage is dropped
the current must be increased to maintain power and the risk of
fire goes up.

There is some thought that lives lost through excess fires exceed
lives saved through prevented electrocutions. 220V is safer than
110V. The lower voltage seems to have been chosen because customers
understood and accepted fires better than the new fangled electrickery.


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Peter D.
From: Christopher Hunter on
Peter D. wrote:

> There is some thought that lives lost through excess fires exceed
> lives saved through prevented electrocutions.

It's probably an erroneous thought.

> 220V is safer than 110V.

No. All site plant works from a earthed centre-tapped 110V supply - 55V
either side of earth. This is an approach also used in some domestic
installations. The idea is that 55V is insufficient (in most cases) to
kill.

> The lower voltage seems to have been chosen because customers
> understood and accepted fires better than the new fangled electrickery.

It's more likely it was chosen for /electrical/ safety.

In the house I was staying in in Maine last month, there were two supplies -
the 110V supply fed all the lighting and general wall sockets. The 220V
supply was in the kitchen and utility room - it was used for the washing
machine, cooker, and (strangely) refrigerator and deep freeze.

C.

From: Peter D. on
on Friday 12 October 2007 15:41
in the Usenet newsgroup alt.os.linux.mandrake
Christopher Hunter wrote:

> Peter D. wrote:
>
>> There is some thought that lives lost through excess fires exceed
>> lives saved through prevented electrocutions.
>
> It's probably an erroneous thought.
>
>> 220V is safer than 110V.
>
> No. All site plant works from a earthed centre-tapped 110V supply - 55V
> either side of earth.

Interesting. An isolating transformer is probably safer again. *Provided*
that none of the outputs are connected to earth you should be OK touching
an output. You become the earth and the other output cycles between
+/- 110 * root 2 volts. Note for the stupid:- this is a thought
experiment not a practical experiment.

> This is an approach also used in some domestic
> installations. The idea is that 55V is insufficient (in most cases) to
> kill.
>
>> The lower voltage seems to have been chosen because customers
>> understood and accepted fires better than the new fangled electrickery.
>
> It's more likely it was chosen for /electrical/ safety.

Yes that is the folklore I was repeating. The low voltage was
chosen for good electrical safety, at the expense of poor fire
(and overall) safety.

> In the house I was staying in in Maine last month, there were two supplies
> -
> the 110V supply fed all the lighting and general wall sockets. The 220V
> supply was in the kitchen and utility room - it was used for the washing
> machine, cooker, and (strangely) refrigerator and deep freeze.

OK American electricity is strange. Your light switches are upside down.
I assume that you have different plugs that will not fit into the
wrong socket.

In the distant future devices won't care. My shaver will accept
12 to 240 Volts AC or DC.


--
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Peter D.
From: Christopher Hunter on
Peter D. wrote:


> OK American electricity is strange. Your light switches are upside down.

I'm a Brit - I was visiting.

> I assume that you have different plugs that will not fit into the
> wrong socket.

They appeared to have two pin for the 110V and three pin for the 220V which
(I assume) are physically incompatible).

> In the distant future devices won't care. My shaver will accept
> 12 to 240 Volts AC or DC.

I have a switched-mode power supply for my laptop which will accept anything
from a car battery (about 13.8V) to in excess of 240V, AC or DC! As SMPSU
types go, this is a fairly large and quite heavy beast, and has lots of
heatsink inside it, but as far as I can see, it uses thyristors to switch
the incoming supply at high frequency, couples this through a small
transformer, and develops the 16V for the laptop through a simple
current-limiting voltage regulator.

C.