Driver to drive?

[D from BC]

On Mon, 04 May 2009 23:16:47 +0100, Nobody <nobody@nowhere.com> wrote:

On Mon, 04 May 2009 08:57:05 -0700, mj wrote:

Thanks for anyone that wants to provide some ideas.

mosfet driverhttp://ixdev.ixys.com/DataSheet/99061.pdf

14 amps, well now that ought to do it. :{)

Can someone explain to me why a MOSFET would be better here than a
bipolar?

He wasn't suggesting using a MOSFET per se, but a MOSFET *driver*.

These are designed for supplying (and sinking) short pulses of high
current, in order to charge (and discharge) the gate capacitance quickly.

Yup..that was the idea.


D from BC
myrealaddress(at)comic(dot)com
BC, Canada
Posted to usenet sci.electronics.design

 

[mj]

On May 4, 4:07 pm, Jon Kirwan <j...@infinitefactors.org> wrote:

On Sun, 3 May 2009 21:21:54 -0700 (PDT), mj <eluc...@gmail.com> wrote:
snip
To try to get a bright enough flash, I got some 0.5W white LEDs that
can take a max DC forward current of 150 mA, and have about a ~3.6
forward drop, producing an intensity of 130k mcd. (Not too clear on
the mcd part.) And dem suckers is bright when you're pumping even 100
mA through them. Like squint-to-look-at-it bright. They're in a
standard 5mm package (T-1 3/4, what is up with that package name?),
though it's sturdier than most you've probably seen. The LED looks
like it's been lifting weights, and the leads are shorter and fatter.

Anyway, I have two 2n2222's hooked up as a Darlington, with +5 Vcc,
driving the front Q's base with ~15mA (with a microcontroller pin).
There's NO current-limiting resistor on the back end, where the second
transistor's collector is attached to +5v, and the emitter goes
through the LED to ground.
snip

Some thoughts about the 2N2222.  They probably can handle the pulses
of 1.5A for 200us and .4% duty (I am assuming, for now, that your
20-50 RPM is really 20 RPS = 200us/0.4%.)  However, the Rc, Re, and Rb
plus the 26mV*(1+ln(1+I/Is)) are going to suggest something on the
order of 1.9 to 2.0 volts at the base.  (I see Re=0.2, Rc=0.3, and
Rb=10 for one model I have, with a blind Is=1e-14, and I don't think
you can expect to get better than beta=30 here.)

  Vbe = 26e-3*(1+ln(1+(1.5/30)/1e-14))+1.5*(.2+.3)+(10+.2)*(1.5/30)

Which reads out at about 2V.

Since this is a darlington, I'm assuming something like this:

                             |
      about 2.7V             | <--- about 2.2V
              |     ,--------+
              v     |        |
          R1      |/c Q2     |
   ON----/\/\-----|   2N2222 |
                  |>e        |
                    |      |/c Q1
       about 2V --> '------|   2N2222
                           |>e
                             |
                             |
                            gnd

That's Q1, I'm talking about.  The Vbe of Q2 is about 0.7V and, if Q2
is considered saturated at about Vce=0.2V, I'd expect to see a Vce on
Q1 of 2.2V or so.  [Note that Q2's base is about 0.5V above Q2's
collector, so that is going to conduct a little (.2V/60mV, about 3
orders, or maybe 0.1% of the base current -- nothing to get excited
about.)]

With a 5V source above, that leaves about 2.8V for your LED.  Not the
3.6V you were talking about at 150mA.  And you want 1500mA, not 150mA!
So your circuit probably won't get there.

Here's the same circuit with 150mA as the estimate:

                             |
      about 1.45V            | <--- about 1V
              |     ,--------+
              v     |        |
          R1      |/c Q2     |
   ON----/\/\-----|   2N2222 |
                  |>e        |
                    |      |/c Q1
    about 0.85V --> '------|   2N2222
                           |>e
                             |
                             |
                            gnd

This provides about 4V compliance (not sure if you are using a
resistor on the collector leg) for your LED.  So at 150mA, it probably
has just about enough for your 3.6V requirement.

....

All this suggests to me that you aren't going to see a lot more than
150mA.  I don't have the LED model, but since it is white the LED is
blue with some phosphor used for the white appearances.  Guessing a
simple model has me taking about 2.8V as the minimum on-voltage (which
I get from (700nm/400nm)*1.6V, extrapolating from a red led) and a
model where R=(3.6-2.8)/150mA or in the area of 5 ohms.  Actually,
that seems too high to me, so that 2.8V estimate is probably wrong.
Let's assume it is closer to about 2 ohms or so (3.3V minimum.)  At
1.5A, that's still 3V all by itself.  Adding that to the 3.3V figure
gives you well more than 5V.  So again, a problem even assuming your
darlington arrangement could support a Q1 Vce of 0V, which it cannot.

Your darlington arrangement creates one problem.  Q1's Vce will be on
the order of 2V at those high currents and you don't have that kind of
headroom to spare.  Your LED itself creates another.  It's not likely
to allow 1.5A with only 5V of drive, under any circumstance.  These
are guesses, admittedly.  But what this seems to say is that you
probably need another voltage rail, at a minimum, if you want to get
up to 1.5A on your LED.

If you can live with less than that but still want a lot more than
150mA, the perhaps your LED will allow ... hmm ... say (4.4V-3.3V)/2
... or about 500mA, let's call it, assuming you can limit your BJT
switch to a Vce of 0.6V or less.  And no more than (4.8V-3.3V)/2 or
about 700mA.  I think that's the best you can hope for.  But I'd plan
no more than 500mA, after some testing first.  In this case, you can
keep your rail, maybe, but you have to lose the darlington.

Jon

Thanks, Jon that's a very helpful analysis. I'll have to scope it out
in the next couple of days. And I'll consider a higher voltage rail
(that just means soldering that 7805 on the MCU board, where I'd left
it out before... oh, yeah, and probably decoupling caps if I'm
snapping off pulses like that...)

If 500-700 mA gives me the brightness I want, fine. I'm not looking to
laser etch anything. I just want LEDs that aren't pitfully dim. Your
discussion gives me hope that I can get there.

I actually don't have a current-limiting resistor on the collector
leg. When occasionally a software glitch leaves the LED on (I switch
it off quick), it's bright. Once it even started going a bit green,
but I shut it down just in time. (That color change is unmistakable.)
And it gets hot after just a few seconds.

As for the LED analysis, I'm only slowly figuring out how to model
LEDs in my head; I'll go through your discussion above in detail when
I have time.

Does anyone here have a favorite resource or book about circuit design
with LEDs? I've found a few good websites, but many of them are mostly
app notes for somebody's IC. I've had a great time with TLC5940s, but
they're overkill if all I want to do is flash.

Thanks again.

--Mark

 

[whit3rd]

On May 3, 9:21 pm, mj <eluc...@gmail.com> wrote:

I'm looking for ideas on how to make an LED flash so brightly at a low
duty cycle

Since the LED is only on 0.4% of the time, max, it still simply isn't
very bright. The strobe works--I can see the frozen image on the
spinning disk--but the light is simply anemic.

So, I'm wondering if anyone here knows how to design a circuit that
can dump an amp and a half through an LED for, say, 200 microseconds
at a time or less, at 20-50 Hz.

Firstly, I'd put a trickle through the LED at all times (maybe half a
milliamp)
so the storage capacitance doesn't have to be reloaded each flash.
Then, with a blocking diode, connect to a flyback switched inductor.
The current in the inductor builds, when it reaches Ipeak you
turn off the input, and the current continues to flow through the
only other connection, the LED with its blocking diode now forward
biased.

Taps on the inductor will allow impedance matching to both the
charging supply and the LED. It's just about the same kind of
circuit as an old auto ignition.

That's how the old flashlamp strobes worked; of course, the dynamic
range of a discharge lamp allows lower duty cycles, at really
large peak currents.

 

[Eeyore]

flipper wrote:

"marcodbeast" <its@casual.com> wrote:
Eeyore wrote:
Archimedes' Lever wrote:
Jim Thompson wrote:

Success!

See...

http://analog-innovations.com/SED/TROLLFEEDER.jpg

Had to resort to NewsProxy until Agent gets a "References:" filter.

Will now just add, to Agent...

999 Delete: Subject:TROLLFEEDER

Then I won't even see the "TROLLFEEDER" tag.

Someone tell NymNuts, it _is_ universal, presently covering NymNuts,
Eeyore and Slowman follow-ups.

So, as far as I'm concerned, these "folks" don't exist anymore ;-)

...Jim Thompson

JimBob Brainlees Fart's head finally exploded.

It has been quite enjoyable watching him sink deeper and deeper
into his stupidity based seclusion desires.

Have fun being a net recluse. That has to be one of the most
retarded acts ever performed.

I have to agree with you.

The USA claims to be so in favour of 'free speech' yet it's the
Americans here who don't want to hear views that are contrary to
their own.

That's how they retain their cockeyed worldview. The right wing lie
aquariums (Fox, CNS, Newsmax, WND, etc.) their keepers built for them have
one universal feature - they're designed from the bottom up to make them
think that any other info sources, where they might hear actual facts, are
out to get them. There is literally no right wing k00khaus that doesn't
expend quite a bit of effort demonizing what they call the Mainstream Media,
can't have the dupes finding out they are in a fantasy world. =)

Congratulations on the near perfect emulation of a dog barking at his
own reflection.

DOPE !

If you want to see or hear what foreign media are saying, there's this thing
called the 'internet' that'll give you the full picture. You know, you can read
foreign newspapers and stuff.

When there's shit going on in the Middle East, I often visit Al Jazeera to see
their take on it. You might be surprised to see it's not all one sided.
http://english.aljazeera.net/

Graham

 

[Eeyore]

Jim Thompson wrote:

Why can't any of these nutcases understand that Freedom of Speech does
NOT require me to listen? Nor does it protect these whiners from
being offended... or that "offense" is a self-inflicted wound?

Thompson, you remind me of a snail retreating into its shell.

Graham

 

[Eeyore]

Bob Eld wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote

In the mean time the Arctic, Greenland and the Antarctic keep melting
and ice breaking up. Explain that. Me thinks you are "out to lunch."

No, the Arctic ice is recovering, can't say much about the others but
these things happen normally all the time. Temps go up and down without
human
intervention. AGW is treating the planet as if it should be in stasis.

Graham

Wrong! The arctic sea ice recovered slightly from the 2006 minimum but as of
April 2009, it was less in area than 1979-2000 average.

Picking numbers at random again. The current trend is that the Arctic ice is
thickening.

Icebergs are normal. What do you think sank the Titanic ?

Graham

 

[JeffM]

Rich Grise wrote:

Does googlegroups even have filters?

They are readily available:

http://groups.google.com/group/comp.arch.embedded/msg/7229473dd5232f65?q=on.ANY.site+holysmoke+MANY-ways-to-filter-Google-Groups-screens+zz-zz+penney+qq+source9
news:c0e2d186-9307-49d1-9a29-ff48dd403049@z16g2000prd.googlegroups.com

 

[Eeyore]

Raveninghorde wrote:

"Bob Eld" <nsmontassoc@yahoo.com> wrote:
"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote

In the mean time the Arctic, Greenland and the Antarctic keep melting
and ice breaking up. Explain that. Me thinks you are "out to lunch."

No, the Arctic ice is recovering, can't say much about the others but
these things happen normally all the time. Temps go up and down without human
intervention. AGW is treating the planet as if it should be in stasis.

Graham

Wrong! The arctic sea ice recovered slightly from the 2006 minimum but as of
April 2009, it was less in area than 1979-2000 average. Furthermore, the
trend line is a downward slope and the Arctic on average has lost 40% of its
pre 1980 ice. Also, new ice formed is now very thin and is vulnerable to the
present melt season. You delude yourself if you think GW does not exist. The
evidence is clear for anybody with half a brain to observe. See
http://nsidc.org/arcticseaicenews/index.html

Just last week a chunk of ice the size of Manhattan broke of one of the
Antarctic shelves and Greenland is melting at an advanced rate. Because of
the loss of ice the earth's albedo is decreasing causing a positive feedback
effect with increased solar absorption.

The antartic ice is above long term trend:

http://arctic.atmos.uiuc.edu/cryosphere/iphone/images/iphone.anomaly.antarctic.png

No surprise, the world is COOLING.

Grham

 

[Eeyore]

Rich Grise wrote:

On Mon, 04 May 2009 03:57:51 +0100, Eeyore wrote:
jcdrisc@melbpc.org.au wrote:

As a regular reader of the electronics postings I am heartily sick of
all the advertising for clothing, shoes and vanity items. I recall in
the old
days these would be deleted by a moderator.

Only in a moderated group

I can only assume Google's advertising
policies are a bit out of control. We have a situation where the
majority of the group is polluted by this garbage.
I would hope something is done.

Google could easily do one very simple thing that would partly help.
Delete posts linking to blogspot.com but somone inferred a while back
that they own it, so maybe that wouldn't work.

However email filters work rather well and I doubt Google couldn't afford
something similar for Usemet posts.

A concerted bombardment of google with complaints to the top level is
IMHO the only likely answer. Anyone know the addresses of the board
members, senior management etc ?

It would fall on deaf ears. How do you think google got so stinking rich?

How about hiring some bots to perform a DoS attack on Google ?

Graham

 

[Eeyore]

John Larkin wrote:

We don't stock lard in the machine ship.

Ship ?

It attracts ants.

Don't breed ants in your building then.

Graham

 

[z]

On May 4, 1:29 pm, Raveninghorde <raveninghorde@invalid> wrote:

The antartic ice  is above long term trend:

http://arctic.atmos.uiuc.edu/cryosphere/iphone/images/iphone.anomaly....- Hide quoted text -

- Show quoted text -

and the arctic ice is below long term trend
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg

"Objection: The Antarctic ice sheets are actually growing, which
wouldn't be happening if global warming were real.

Answer: There are two distinct problems with this argument.

First, any argument that tries to use a regional phenomenon to
disprove a global trend is dead in the water. Anthropogenic global
warming theory does not predict uniform warming throughout the globe.
We need to assess the balance of the evidence.

In the case of this particular region, there is actually very little
data about the changes in the ice sheets. The growth in the East
Antarctic ice sheet indicated by some evidence is so small, and the
evidence itself so uncertain, the sheet may well be shrinking.

But even this weak piece of evidence may no longer be current. Some
recent results from NASA's GRACE experiment, measuring the
gravitational pull of the massive Antarctic ice sheets, have indicated
that on the whole, ice mass is being lost.

Second, ice-sheet thickening is not inconsistent with warming! Warmer
climates tend toward more precipitation. The Antarctic is one of the
most extreme deserts on the planet. As it warms, we would expect it to
receive more snow. But even a whopping warming of 20 degrees -- say,
from -50 degrees C to -30 degrees C -- would still leave it below
freezing, so the snow wouldn't melt. Thus, an increase in ice mass.

While on the subject of ice sheets: Greenland is also growing ice in
the center, for the same reasons described above. But it is melting on
the exterior regions, on the whole losing approximately 200 km3 of ice
annually, doubled from just a decade ago. This is a huge amount
compared to changes in the Antarctic -- around three orders of
magnitude larger. So in terms of sea-level rise, any potential
mitigation due to East Antarctic Ice Sheet growth is wiped out many
times over by Greenland's melting."
http://www.grist.org/article/antarctic-ice-is-growing

On a related note: I have rejected the entire concept of "summer as a
warm season", as I notice that the ice sheet around the door seals of
my freezer gets larger only during this so-called "warm season". If
summer were truly a warm season, there would be LESS frost on the door
of my freezer then, obviously! Do not fall prey to the chicken-little
claims of these meteorologists that it gets warmer in summer; they are
controlled by the refrigerator cartel! It's well known that any
meteorologist who goes against the doctrine that it gets warmer in the
summer is blacklisted and can't get a decent job. This is not how
science is done; skeptics are not stilled by a phony "consensus"; more
research is needed to provide scientific proof that it gets warmer in
summer, before we destroy the economy by investing huge funds in
refrigeration and air conditioning!!

 

[Jim Thompson]

On Tue, 5 May 2009 08:25:21 +1000, "David L. Jones"
<altzone@gmail.com> wrote:

alertjean@rediffmail.com> wrote in message
news:98e3f191-fdd5-4ee2-900d-347854303bf4@j12g2000vbl.googlegroups.com...
On May 4, 8:58 am, "keith...@gmail.com" <keith...@gmail.com> wrote:
On May 4, 12:46 am, alertj...@rediffmail.com wrote:

Based on trends in mask and design costs for standard cells, vs. FGPA
capabilities, do
you believe the number of new designs per year executed in standard
cells will increase
or decrease in the future as compared with a baseline of 2007 ?

I think it will increase, what do you think ?

I think you're nuts, but you can ignore history at your peril.

Dave..You are smart..It was an exam question. But I am not convinced
by the answer professor gave me...that FPGAs will takeover standard
cell designs thereby reducing the number of standard cell designs. I
think as the performance and power of FPGAs will be bad compared to SC
designs, SC designs are always going to be winners
and I dont think FPGAs will take over.

It's very hard to quantify this stuff. Do you base the figures on actual
shipped chip quantity?, number of design implemented? etc.
Standard cell ASIC's require a massive NRE investment, and this effectively
puts a cap on the number of customers who can afford to design ASIC's.
If you base the argument on number of people implementing new designs, then
FPGA's will win hands down, as even Joe Blog Hobbyist can implement FPGA's.
If you look at the EDA market, then ASIC customers are getting fewer and
fewer (like down to a number you can start to count on your hands), but FPGA
tool use has been exploding in numbers for a long time. So in that respect
your professor is right.

Cost-conscious digital can't help but go to some form of
array-based...

But there will always be a big niche for custom ASIC's, the market won't
vanish.

Dave.

And analog/mixed-signal ASIC's will continue... which is why I
continue to get requests.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Stormy on the East Coast today... due to Bush's failed policies.

 

[z]

On May 4, 2:43 pm, Richard the Dreaded Libertarian
<freedom_...@example.net> wrote:

Anthropogenic Global Warming was debunked in the 1970's. That's why they
changed the name to "Climate Change".

Hope This Helps!
Rich

good to see you're keeping right up there with cutting edge science.
hey, i hear they have mobile phones now you can carry around in your
pockets! i don't believe it. You need something like this 1970's
Telephone Bag: http://www.lapochette.com/day12.html

 

[Jon Kirwan]

On Mon, 4 May 2009 23:41:47 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:

In article <49FF72C5.5B08D62F@hotmail.com>, Eeyore wrote:

Bob Eld wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote

In the mean time the Arctic, Greenland and the Antarctic keep melting
and ice breaking up. Explain that. Me thinks you are "out to lunch."

No, the Arctic ice is recovering, can't say much about the others but
these things happen normally all the time. Temps go up and down without
human
intervention. AGW is treating the planet as if it should be in stasis.

Graham

Wrong! The arctic sea ice recovered slightly from the 2006 minimum but as of
April 2009, it was less in area than 1979-2000 average.

Picking numbers at random again. The current trend is that the Arctic ice is
thickening.

It is not thickening - it is at an extreme of thinness, notably with
much more than usual of its coverage being by thin first-year ice.

The area coverage compared to 1979-2000 average did indeed make a major
uptick in the past few months, almost up to the 1979-2000 average. And
last time it was lowest compared to 1979-2000 average for a specific time
of year may be as recently as late January 2009.

http://www.nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png

SNIP

- Don Klipstein (don@misty.com)

Yes, though I wouldn't call it "up tick." It's just that the seasonal
loss of surface area is a bit slow, so far. They note: "Compared to
previous Aprils, April 2009 is near the middle of the distribution
(10th lowest of 31 years). The linear trend indicates that for the
month of April, ice extent is declining by 2.8% per decade, an average
of 42,400 square kilometers (16,400 square miles) of ice per year."

Jon

 

[erg]

On May 4, 11:43 am, Tim Williams <tmoran...@gmail.com> wrote:

On May 4, 9:56 am, Anon <a...@domain.invalid> wrote:

Some very basic calculus is helpful.  A solution is given at
http://www.mathrec.org/old/2003jul/solutions.html

Riddle:

There is a rabbit in the middle of a perfectly circular pond.  An
agent is trying to get the rabbit.  The rabbit swims exactly away from
the agent.  After a few seconds, the agent's head explodes.  Why?

Ya know, if the agent always seeks the closest path (with no
underlying intelligence to escape the following scenario), the rabbit
(if it were more intelligent) could follow a zig-zag path.  As soon as
it moves somewhat to the right, the agent sees this and moves in that
direction.  The rabbit, noticing the reduced distance, changes
direction immediately.  As it crosses the diameter the agent is
standing on, the agent reverses direction.  The opposite then happens,
ad nauseum, until the rabbit reaches the shore safely.

Theorem 1: The rabbit can reach the shore regardless of the agent's
relative speed.
Theorem 2: Either the agent's head explodes, or the Church-Turing
Theorem is false.

Theorem 2 follows from taking the limit as delta x approaches zero
(that is, the width of the zig-zag).  In the limit, the rabbit appears
to proceed in a straight line, exactly opposite the agent (this also
works if the rabbit simply moves in exactly this path, with no
infinnitessimal shaking).  The agent cannot decide which direction to
go, because his distance-o-meter is saying both directions are equal.
In terms of angle, sign(tangent(theta)) is undefined (where sign(x) is
+1 when x > 0, -1 when x < 0, and either 0 at x = 0, although sign(0)
may sometimes defined as +1).  So now it's an undecidable problem, and
if the agent somehow succeeds, a lot of theorems (including those
about decidability) are wrong, or the agent's head simply
explodes. ;-)

_I_ would award your solution the prize, at any rate.

At least it forces us to make the agent's strategy explicit.

 

[John Larkin]

How's this?

ftp://jjlarkin.lmi.net/PAD5.JPG

This diode is roughly +-20 fA at +-0.1 volts!

John

 

[Eeyore]

Don Klipstein wrote:

Raveninghorde wrote:

The antartic ice is above long term trend:

http://arctic.atmos.uiuc.edu/cryosphere/iphone/images/iphone.anomaly.antarctic.png

Antarctic sea ice area is indeed above long term trend of since
observations began, but to a lesser extent in square kilometers than
Arctic sea ice has been running low over the past few years. The world
has experienced a loss of sea ice.

Sea Ice is an irrelevance. It merely shows mild warming of the oceans which we know
about anyway. It won't flood anywhere since it occupies no more space when melted.

Graham

 

[Eeyore]

Don Klipstein wrote:

Eeyore wrote:
Bob Eld wrote:

Wrong! The arctic sea ice recovered slightly from the 2006 minimum but as of
April 2009, it was less in area than 1979-2000 average.

Picking numbers at random again. The current trend is that the Arctic ice is
thickening.

It is not thickening - it is at an extreme of thinness, notably with
much more than usual of its coverage being by thin first-year ice.

Right, the ice is recovering. Maybe I should have been clearer ?

Every trend is going the opposite way to the AGW hypothesis.

Graham

 

[Eeyore]

Jon Kirwan wrote:

On Mon, 4 May 2009 23:41:47 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:

In article <49FF72C5.5B08D62F@hotmail.com>, Eeyore wrote:

Bob Eld wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote

In the mean time the Arctic, Greenland and the Antarctic keep melting
and ice breaking up. Explain that. Me thinks you are "out to lunch."

No, the Arctic ice is recovering, can't say much about the others but
these things happen normally all the time. Temps go up and down without
human
intervention. AGW is treating the planet as if it should be in stasis.

Graham

Wrong! The arctic sea ice recovered slightly from the 2006 minimum but as of
April 2009, it was less in area than 1979-2000 average.

Picking numbers at random again. The current trend is that the Arctic ice is
thickening.

It is not thickening - it is at an extreme of thinness, notably with
much more than usual of its coverage being by thin first-year ice.

The area coverage compared to 1979-2000 average did indeed make a major
uptick in the past few months, almost up to the 1979-2000 average. And
last time it was lowest compared to 1979-2000 average for a specific time
of year may be as recently as late January 2009.

http://www.nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png

SNIP

- Don Klipstein (don@misty.com)

Yes, though I wouldn't call it "up tick." It's just that the seasonal
loss of surface area is a bit slow, so far. They note: "Compared to
previous Aprils, April 2009 is near the middle of the distribution
(10th lowest of 31 years). The linear trend indicates that for the
month of April, ice extent is declining by 2.8% per decade, an average
of 42,400 square kilometers (16,400 square miles) of ice per year."

Fretting over one year to the next is INSANE.

Graham

 

On May 4, 8:49 pm, Rich Grise <richgr...@example.net> wrote:

On Mon, 04 May 2009 00:41:58 +0000, Don Klipstein wrote:
"Eeyore" <rabbitsfriendsandrelati...@hotmail.com> wrote in message

Some REAL science at last, notably illustrating that the effect of CO2
in the atmosphere is nearly already at saturation level and more can
contribute very little to temperature rise.

http://brneurosci.org/co2.html

  Which claims that water vapor accounts for 90-95% of the "Greenhouse
Effect", and that CO2 accounts for 4.2-8.4% of it.

  The Wiki article on "Greenhouse Effect" says 9-26% for CO2 and 36-70%

The very concept of "greenhouse gases" is ludicrous in the first place.

For "ludicrous" read "too complicated for Rich to understand".

Not only is it based on Venus, which has so much CO2 with H2SO4 clouds
that its atmospheris pressure at ground level is approx. 90 atmospheres,
or 1350 PSI, but it very studiously evades the fact that a living, dynamic
atmosphere is NOT a huge pane of glass.

The idea of "greenhouse gases" predates our knowing that the surface
of Venus is stinking hot, is total nonsense, which we've explained to
Rich here previously - in the thread "OT - Hansen acknowledges solar
forcing". He made the claim on the 26th January 2009, and we explained
to him how thoroughly he'd got it wrong onver the next day or so.

Not only does he produce nonsense, he repeats it when he should know
better.

--
Bill Sloman, Nijmegen