Power Supplies, Saving Money, and switching vs. Linear?
Andrew(N)
much! So one-by-one I am changing things to be more power-conscious.
Starting with a big linear 12V power supply. Altronics 12V, 4A type
linear power supply with battery backup: standard for alarms (a few
years back). I currently draw about 500 ma continuously, (Not sure what
my peaks are, but bells and sirens are powered separately.
This draws around 1.1 A on the AC line, so 132 Watts continuously. Big
transformer, always warm. Seems wasteful.
IF I SWITCH TO A NEWER, SWITCHING POWER SUPPLY, say the Elk P412 (or
any other you recommend) WOULD I DRAW MEASURABLY LESS AC CURRENT?
I am powering various motion detectors, InfraRed repeaters (Niles), a
small, 7 Watt audio amplifier and a few other devices. Would the 100
MV ripple on the Elk power supply bring any problematic noise along
with it?
Thanks for your suggestions
-Andrew
Frank Olson
You may save a little going with a more efficient power supply, but it
won't be significant because you aren't making any changes to the field
devices that draw the bulk of your power. Reducing the size of the
transformer won't affect things much either (the smaller one will tend
to run even hotter). Where the "savings" will come in is the
efficiencies gained in the charging circuit for the stand-by battery,
but that's about all I see as any real benefit.
In the future I would suggest posting a question like this in each group
individually (and avoid cross-posting). That way if the thread
"disintegrates into flame wars" in one group it won't affect the other.
Frank Olson
http://www.yoursecuritysource.com
(cross posted between ASA and CHA)
Dave Houston
is 6W. I doubt that your transformer is really wasting 126W as heat. Does it
get as hot as a 125W light bulb?
I suspect a wattmeter (e.g. Kill A Watt) will show a watt reading on the
primary that comes much closer to the calculated value for the secondary.
I don't have any large linear supplies but a 12VAC/500mA transformer I have
on an ESM1 shows 50mA on the primary (6VA) but only 2W using the wattmeter
mode. In Power Factor mode the reading is 0.36 which is in pretty close
agreement with the VA and W readings. The transformer presents an inductive
load so the voltage and current are not in phase.
Andrew(N)
> How did you determine the cost? How are you measuring the power? 12V and .5A
> is 6W. I doubt that your transformer is really wasting 126W as heat. Does it
> get as hot as a 125W light bulb?
The $56/month was by determined by using a WattsUpPRO wattmeter. and
multiplying KWH * Running time * Highest tier on my PG&E bill (corrected
for a monthly # of hours, of course). This was for the whole wiring closet.
I did not break into the specific AC circuit of that Altronics Power
supply with the watt meter. I have a Fluke T5 current probe. It's not
perfect, but gives an approximation. It's not as hot as a 125'er, but
that's pretty subjective. The linear regulator also generates some heat.
>
> I suspect a wattmeter (e.g. Kill A Watt) will show a watt reading on the
> primary that comes much closer to the calculated value for the secondary.
>
> I don't have any large linear supplies but a 12VAC/500mA transformer I have
> on an ESM1 shows 50mA on the primary (6VA) but only 2W using the wattmeter
> mode. In Power Factor mode the reading is 0.36 which is in pretty close
> agreement with the VA and W readings. The transformer presents an inductive
> load so the voltage and current are not in phase.
OK... So I should probably break into the circuit and use the WattsSPpro
meter to get a good reading.
Still wondering if the switcher would save money power-wise.
Thanks Dave - As Always --- Everyone appreciates you.
-Andrew
Dave Houston
are watts and if the transformer is wasting 125W it should be putting out
the same total amount of heat as the 125W bulb. It makes for a fairly good
sanity check. I find even a 25W bulb too hot to touch.
Your wattmeter should give you an accurate reading if you break the circuit.
I doubt you'll save much with a switching supply. The difference will be the
heat wasted by the transformer and linear regulator. Switching supplies also
waste some energy as heat (mine get about as warm as a 2.5W night light).
Once you have an accurate measure of the linear supply wattage you can make
a better judgement. You'll likely find that there are other devices that are
using the bulk of the power.
I'm assuming that PG&E is charging you for true power (W) and not apparent
power (VA). Most residential utility meters measure true power.
RoughRider
out of your pocket) = 509 kW/month divided by 24hrs divided by 31 days = 684
Watt continuous load. This sounds very high. You would have 2,330 BTU/hr
of heat assuming all this energy was used within your closet. It would be
very warm/hot without proper ventilation. This figure does not sound right
for what you are describing.
A linear power supply is most efficient when near fully loaded. The
transformer core magnetization current is constant no matter what the load.
A switch mode supply is more forgiving when lightly loaded.
As others have stated, check the theory on the difference between VA and W.
You are *not* paying for V x A on the AC side. You are paying for WATTS
only. Or measure and calculate V x A on the DC side and multiply by 1.25
for the power supply efficiency to reflect an approximate cost on the AC
side. A good switch mode supply should be 87 to 94% efficient while
consumer grade switchers will be slightly less (~77%).
Charging a small battery (10 AHr) isn't usually a big deal. The float
current is sufficiently small (10 to 20 mA = .28W worst case).
Turning off unnecessary parasitic loads will have a more significant impact.
Good luck.
Byron Hynes
and a regulator. FWIW.
RoughRider
and battery. However, others in the alt.energy.homepower newsgroup have
calculated that if you have commercial power, the payback on your investment
is something like 18 years. Not worth it. No business case. Hobby value
only.
Frank Olson
> It is almost free once you spend the huge $ for the panel, charge controller
> and battery. However, others in the alt.energy.homepower newsgroup have
> calculated that if you have commercial power, the payback on your investment
> is something like 18 years. Not worth it. No business case. Hobby value
> only.
I wonder how you'd feel when you're in the middle of one of the famous
California "Brown-outs", and your next-door neighbor (the one with the
solar power cells on his roof) is enjoying all the comforts of air
conditioning... :-)
Frank Olson
http://www.yoursecuritysource.com
maras
Byron Hynes
It would be handy to have one to practice with. So, yes, hobby value.
Beachcomber
>
>As others have stated, check the theory on the difference between VA and W.
>You are *not* paying for V x A on the AC side. You are paying for WATTS
>only. Or measure and calculate V x A on the DC side and multiply by 1.25
>for the power supply efficiency to reflect an approximate cost on the AC
>side. A good switch mode supply should be 87 to 94% efficient while
>consumer grade switchers will be slightly less (~77%).
>Turning off unnecessary parasitic loads will have a more significant impact.
>
There are always tradeoffs in design considerations. May I suggest
thinking about it another way....
For an alarm power supply, normally wouldn't you want that to be a
mission critical application... In other words (you want it to keep
functioning, no matter what). If that costs you more in terms of kWh
consumed, perhaps the price is worth it.
In my experience, some of these small plug in switching dc supplies
are more prone to failure when compared to a good, well designed (or
over-designed) linear supply. Generally they a pain to fix and it's
usually more convenient to replace the whole supply when it goes down.
True, they are small, cheap, and efficient, but unless they are
designed really well (adaquate cooling & heat sinks, plus fans if
necessary), switching supplies generally operate with certain
components under stress (capacitors and the critical transistors) ,
and again, in my experience, sometimes they just stop working. YMMV.
Beachcomber
Dave Houston
power supplies that can only be met by switchmode designs making it likely
that linear power supplies will soon disappear from supply channels.
While it doesn't make compelling economic sense for Andrew to replace his
linear supply, at the state level California expects the new standards to
eliminate the need for one new generating station. For China the savings
could be far greater.
Bill Kearney
controller
> and battery. However, others in the alt.energy.homepower newsgroup have
> calculated that if you have commercial power, the payback on your
investment
> is something like 18 years. Not worth it. No business case.
Well, to some the piece of mind that they're not wasting that much more in
the way of fossil fuels is worth the investment. It's not purely a matter
of costs. 18 years (and more) of not being yet another fuel consumer.
Dave Houston
Minus the fuel consumed to manufacture and transport the switchmode supply
(and its constituent parts). The case for replacement is still weak.
And the 18 years is also rather iffy. There might be some new technology
that comes along in 2-3 years that obsoletes both types of power supply.
Robert Green
news:T5qdnVPt76d...@speakeasy.net...
The solar payback equations are often predicated on unrealistically stable
electrical rates. In my neck of the woods, the rates have gone up and are
going up like never before. I think the payback will come much sooner than
in 18 years in the pure business case mode. As you point out, there's a
psychological payback, too, from not being so big a part of the overall
fossil fuel dependency problem.
I'm researching now, but the next house will mostly likely have a
southern-facing roof comprised of "solar shingles" or a similar roofing
material. The high oil prices seem to be stimulating the flow of venture
capital into solar-based technologies once again. It may also turn out
that a spectacular technological advance could radically alter the 18 year
"pay back" equation. Who could have predicted the transistor 10 years
before it appeared and how it would alter the electronic landscape? I hope
they make that advance in solar power before I sink $$$ into old technology!
--
Bobby G.
Bill Kearney
in
> >the way of fossil fuels is worth the investment. It's not purely a
matter
> >of costs. 18 years (and more) of not being yet another fuel consumer.
>
> Minus the fuel consumed to manufacture and transport the switchmode supply
> (and its constituent parts).
Everything costs something. The end result is still the same, reduction of
fossil fuel use at the residence.
> And the 18 years is also rather iffy. There might be some new technology
> that comes along in 2-3 years that obsoletes both types of power supply.
Meanwhile doing nothing helps, how?
Beachcomber
>>
>> Well, to some the piece of mind that they're not wasting that much more in
>> the way of fossil fuels is worth the investment. It's not purely a matter
>> of costs. 18 years (and more) of not being yet another fuel consumer.
>
>The solar payback equations are often predicated on unrealistically stable
>electrical rates. In my neck of the woods, the rates have gone up and are
>going up like never before. I think the payback will come much sooner than
>in 18 years in the pure business case mode. As you point out, there's a
>psychological payback, too, from not being so big a part of the overall
>fossil fuel dependency problem.
>
Doing this kind of analysis requires looking at yourself, your stage
in life, and what kind of lifestyle you expect to lead. If you are a
home flipper and look at your home as just another economic investment
that you might sell in 3 -5 years, then the numbers for a renewable
solar system might not make sense as an investment. It might make
your home more marginally attractive when it comes time to sell,
however.
However, if you are building a homestead for your family that you
intend to keep for a long, long time, it only makes sense to use fine
materials and superior constuction techniques. A fully functional
off-the grid house is one of the greatest gifts you could give to
future generations.
Beachcomber
Dave Houston
>Everything costs something. The end result is still the same, reduction of
>fossil fuel use at the residence.
But that doesn't necessarily mean an overall reduction in fossil fuel use.
Even the ABS plastic housing of either type power supply is petroleum based.
And what happens to the discarded linear supply? Its copper, steel and
plastic goes into a landfill and none of it is biodegradable. While
California has mandated more efficient wall transformers, it's governor
still drives a fleet of Hummers.
What you propose on a small scale is to transfer part of the true cost to
someone else. Its what economists call externalities and is how much of the
extractive industries like mining, petroleum, and lumber make large profits
while damaging the environment. Markets cannot deal with externalities.
>> And the 18 years is also rather iffy. There might be some new technology
>> that comes along in 2-3 years that obsoletes both types of power supply.
>
>Meanwhile doing nothing helps, how?
It _may_ reduce the total consumption of fossil fuel. When the economics are
marginal and the future is unclear, doing nothing may, indeed, be best.
There are lots of issues where neither the economics nor reduction in fuel
use are marginal like banning Hummers instead of subsidizing them through
tax deductions or taxing fuel at a level that will reduce consumption as the
Europeans do instead of subsidizing OPEC as we now do.
Thoreau wrote, "A man has not everything to do, but something; and because
he cannot do everything, it is not necessary that he should do something
wrong." It's not always clear whether something is more beneficial than
nothing.
I pay $0.06 per kWh and my monthly utility bill is usually less than $40. A
1W reduction by switching to a switcher would be inconsequential both in
dollars and in fuel savings (it would probably increase total fuel use).
That doesn't mean that when I buy something new I don't try to find the best
value both in dollar terms and in energy use. Usually, there's no choice as
the new equipment comes with a power supply (most are now switchers) but you
might have noticed that I researched the issue and posted a source for an
X-10 (and Insteon) friendly switching power supply here just a few days ago.
If you have to add a filter (enclosed in petroleum based ABS plastic) after
replacing your linear supply, it stretches the payback by a century or two.
When you have reduced your use of fossil fuels to my level, you can lecture
me. But not before.
BTW, I have the +5V regulated switch mode supply plugged into my Kill A Watt
meter to see how much energy it uses while not loaded. I'll post the results
in a few days.
Bill Kearney
True, yet neither does doing nothing.
> It _may_ reduce the total consumption of fossil fuel. When the economics
are
> marginal and the future is unclear, doing nothing may, indeed, be best.
Yep, and global warming's a myth.
> When you have reduced your use of fossil fuels to my level, you can
lecture
> me. But not before.
Um, it's not about YOU Dave and hasn't been the entire thread.
Dave Houston
In 99% of the cases I bet the wall transformer is an _unregulated_ power
supply with the linear regulator being internal to the electronic device it
powers. Almost anything that uses a wall transformer with a voltage higher
than +5V is likely to have an internal regulator. In these cases, changing
the wall transformer to a switch mode supply will do next to nothing to save
energy as the linear regulator will still waste the excess voltage as heat.
The "psychological payback" is a delusion. You can get the same "feel good"
effect by spending the cost of the switchmode supply on a cheap bottle of
whiskey.
Andrew(N)
> In 99% of the cases I bet the wall transformer is an _unregulated_ power
> supply with the linear regulator being internal to the electronic device it
> powers. Almost anything that uses a wall transformer with a voltage higher
> than +5V is likely to have an internal regulator. In these cases, changing
> the wall transformer to a switch mode supply will do next to nothing to save
> energy as the linear regulator will still waste the excess voltage as heat.
> The "psychological payback" is a delusion. You can get the same "feel good"
> effect by spending the cost of the switchmode supply on a cheap bottle of
> whiskey.
The move of this thread to Solar power is VERY interesting... Because
this is what I am doing.
I now have 28 200+ watt SunPower Solar panels on my roof feeding an
inverter that will take advantage of California's NetMetering regulation
which allows me to put power back into the grid. So, during Peak hours
(M-F Noon - 6 PM) I will be pumping watts back into the grid at the
elevated Rate. No storage batteriies in this system. System is designed
to be a 5 KW system. (Contractor is ReGrid Power, BTW). The panels and
inverter are installed, but these guys haven't gotten back out to make
the connection to my AC mains yet. This should be this week or next. The
panels are wired to give about 400V DC into the inverter and 120 V 2
phase out.
Either way... This is the reason for my huge persuit of power savings...
to cut the usage wherever possible, to get my savings up.
BTW... people are always curious. Raw system cost is arouns $47K, after
California rebates, my cost is ~34K. I might be eligible for one more
tax credit totaling ~3000. If I use power at the existing levels, and
if PG&E increases rates consistent with the past 22 years, payback is in
11 years. But, with some conservation, and if PG&E really jacks up
prices, as they are expected to do, then payback could be in as few as 8
years.
My goal is not to be self sufficient, nor to get my bill to 0. That
would be stupid. The real goal is cut off the top two or three tiers
where electricity is as high as $.31 / Kwh.
This is why I am running around with a spreadsheet and two Watt's Up
power meters measuring everything. This linear supply is hard-wired, so
I could only put an amp-clamp on it. I will try to put a cheater cord on
it for a while and re-measure the actual wattage soon.
Thanks everyone for the interesting discussion.
-Andrew
Dave Houston
article a few years back.
http://magazine.audubon.org/features0109/beyond_oil.html
Robert Green
news:44207747...@cisco.com...
<stuff snipped>
> The move of this thread to Solar power is VERY interesting... Because
> this is what I am doing.
>
> I now have 28 200+ watt SunPower Solar panels on my roof feeding an
> inverter that will take advantage of California's NetMetering regulation
> which allows me to put power back into the grid. So, during Peak hours
> (M-F Noon - 6 PM) I will be pumping watts back into the grid at the
> elevated Rate. No storage batteriies in this system. System is designed
> to be a 5 KW system. (Contractor is ReGrid Power, BTW). The panels and
> inverter are installed, but these guys haven't gotten back out to make
> the connection to my AC mains yet. This should be this week or next. The
> panels are wired to give about 400V DC into the inverter and 120 V 2
> phase out.
The simple fact that there are contractors to choose from means that solar
is chugging along, maybe at the Altair or TRS80 stage parallel in the PC
world. The people who are installing now, like you, are creating the
roadmap for the future. It was interesting to watch the technology jump in
the PC world because it's similar to what's happening in solar. People take
the plunge and then report on their experiences, good and bad. That
inspires one or two more people to do it until a critical mass is reached
and some chain reaction starts. Every time I read about you or someone like
Mr. Baber converting to solar in a big way, it chips away at my fears of
getting into something that may not pay off or work as well as imagined.
> Either way... This is the reason for my huge pursuit of power savings...
> to cut the usage wherever possible, to get my savings up.
Early adopters have to ignore or at least wink at the "business model" that
says the conversion is not cost efficient or at least won't be for X numbers
of years. I think it's great you've been able to just ignore that "X" years
payback predictions. From where I sit, those projections are not generally
very valid. Back in the early days of the IBM PC people assumed that PC's
were limited because the physical size of memory chips (at that time)
prevented PC's from having very much memory. Predictions can't accurately
factor technological breakthroughs into their equations. I have 4GB in a
box no bigger than the original IBM PC but more powerful than any computer
on earth 20 years ago.
While we can't say for sure what will happen in solar technology, we *can*
predict their *will* be breakthroughs because there always have been.
People rise to challenges. The challenge now is to reduce our need for
foreign oil for a number of reasons; some economic, some political, some
humanitarian.
> BTW... people are always curious. Raw system cost is arouns $47K, after
> California rebates, my cost is ~34K.
Exactly my point! People always want to know the bottom line! By posting
here, you've started a little ripple in what some day will be a very big
pond. There are strong forces opposing solar: the oil industry, the power
industry and even the government itself (sunlight is not yet taxable but is
litigated far more often than 20 years ago). Solar power is taxed once when
you buy the equipment, but not thereafter. Look at your power bill and see
how much the government gets. They don't want solar, either, but they
grudgingly support it with a few meager task breaks. California, at least,
has realized that its survival may depend on solar self-sufficiency.
> I might be eligible for one more tax credit totaling ~3000.
How insubstantial a reward for trying to do the right thing. I wonder how
much solar the US could have built with the $ and manpower being spent on
Iraq? Any mathematicians able to tell us how much a rebate $100B would
provide? Assume there are about 110 million "households" in the country
and maybe half of them would be suitable for solar.
> If I use power at the existing levels, and
> if PG&E increases rates consistent with the past 22 years, payback is in
> 11 years. But, with some conservation, and if PG&E really jacks up
> prices, as they are expected to do, then payback could be in as few as 8
> years.
The equation could tip the other way, though. That's part of the risk
equation that my wife fears. What if they tax solar arrays by the square
foot? You can't exactly hide them. There are powerful economic interests
aligned against solar and they give steamer trunks full of money to
lawmakers everywhere, every year to make sure the balance stays tipped in
their favor. I wish people would make solar a campaign issue instead of the
ones that the press loves so much, like gay marriage. )-:
> My goal is not to be self sufficient, nor to get my bill to 0. That
> would be stupid. The real goal is cut off the top two or three tiers
> where electricity is as high as $.31 / Kwh.
You're casting an important vote with the only voting mechanism that seems
to work anymore - the dollar!
> This is why I am running around with a spreadsheet and two Watt's Up
> power meters measuring everything. This linear supply is hard-wired, so
> I could only put an amp-clamp on it. I will try to put a cheater cord on
> it for a while and re-measure the actual wattage soon.
I did that with Kill-o-watt when the power prices here just about double.
There are so many little devices in a house that draw a few watts here and
there that it adds up. I've designed a summer/winter configuration where I
switch to CFL's and low-draw power supplies in the summer where there's a
double whammy for electrical use: the rates double again and the spill heat
is a liability now, where it's really an asset in the winter.
> Thanks everyone for the interesting discussion.
Thanks for your report. Discussions like this cause a lot of percolation in
people's minds, especially when they're writing that check to the power
company.
As for predictions, I seem to recall in the Popular Science mags of the '50s
that we would be now living in an age of nearly cost-free nuclear power.
Har-har!
--
Bobby G.
E. Lee Dickinson
"Dave Houston" <nob...@whocares.com> wrote:
> The "psychological payback" is a delusion. You can get the same "feel
> good"
> effect by spending the cost of the switchmode supply on a cheap bottle of
> whiskey.
18 year payback. 50 year payback. Whichever. As one who is still going to
be around 50 years from now, and who expects to have grandchildren around
150 years from now, the suggestion of masking environmental apathy with
alcohol-inuced 'warm and fuzzies' bothers me a little bit.
It's too bad the phrase "for the benefit of future generations" has been
pilfered for use as hollow political rhetoric. Those of us in our twenties
probably would have liked to use it in an argument every now and then.
I'm not making a statement one way or another about switchmode supplies.
Small potatoes. But ending the argument with, "Screw that, lets get drunk
instead"... I'm just a little irked by that attitude.
Dave Houston
a intensive course in reading and comprehension - but that appears to be
rather typical of your generation. Nowhere did I in any way suggest what
you've claimed I argued and I really resent stupid jerks who misunderstand
and/or misrepresent what I did write.
And I really, really resent repeated personal attacks from someone who
clearly is incapable of understanding anything more complex than 2+2.
My argument is that patting oneself on the back for taking marginal actions
that have some nebulous "psychological payback" is utterly ridiculous and
counter-productive (a waste of psychological energy) when Hummers get 13MPG,
many SUVs get little more, and we subsidize them through current tax laws.
NASA's chief environmental scientist thinks we have less than 10 years to
reduce and start reversing greenhouse gas emissions before we reach a
tipping point with regard to the polar ice caps. I suspect we've already
passed that tipping point. In either case, "psychological paybacks" won't
cut it nor will replacing existing linear supplies with switchmode supplies.
It requires real efforts with real paybacks. Countries like China and Brazil
seem to be far ahead of us in making real and meaningful efforts.
Overall, solar is currently one of the least efficient alternative energy
sources although new, spray-on photo-voltaics that also work with IR may
change that. But, no matter how efficient they become, they're not likely to
work well under water.
This is not to disparage Andrew's efforts to reduce his energy use. But, I
suspect he'll find far fatter targets than this particular power supply.
E. Lee Dickinson
"Dave Houston" <nob...@whocares.com> wrote:
> And I'm irked by nitwits who demonstrate time and time again their need
> for
> a intensive course in reading and comprehension - but that appears to be
> rather typical of your generation.
Agreed.
> And I really, really resent repeated personal attacks
(snip)
Dave, I didn't attack you. I said I was irked by the attitude. I didn't
insult you, call you names, flame you, or any of the other things you did in
response. You, I rather like and admire for your knowlege and willingness to
contribute "to the record" as you've put it. My response, I had hoped, would
be comparable to this: My fiancée blowdries her hair at 6 in the morning. I
find that annoying, but I don't find *her* annoying.
I suppose you can argue that my parsing of your post into "Screw that, lets
get drunk instead" falsely characterized both you and your intended message.
I see that I misstook your comments (see below) and appologize for that.
Also, so that I can properly apologize for my 'repeatted attacks,' could you
post them? I just did a google search on all posts of mine that included
references to you, and I haven't come up with anything. I'd like to clear
that up because, as I said, I value your input.. especially as my own home
control projects grow in scope.
> from someone who
> clearly is incapable of understanding anything more complex than 2+2.
22, right? Or is it something with Pi in it? Man. Where's my calculator?
[Dave clarifies his argument for adleminded youngers like myself]
Again, referencing my fiancée: There have been times we've argued for an
hour, only to discover we actually agreed, and one of us had simply
misunderstood the other.
I agree wholeheartedly with you in saying, if I may paraphrase, that people
(and governments) take small meaningless steps, just to make themselves feel
warm and fuzzy, and to put on an air of environmental responsability. While
every littlebit may count, what we're really in need of is an overhaul in
both energy production and usage effeciency.
To that, I'd be glad to raise a glass of cheap whiskey. Except maybe I
should stick to milk.
ELD
Robert Green
step back and take a breath?
My best guess, although probably wrong, is that Dave was reacting to
perceived criticism of his choice to use a regulated PS for his new project.
If I recall, it was the most cost-effective solution. Since Dave's new
devices will all be run 24x7, there's really nothing to be gained from using
a switch mode power supply. I think, as so often happens, that the thread
migrated to solar power and energy conservation in general so it seemed that
we were still discussing Dave's power supply choice when in fact we were
talking about reducing energy consumption across the board.
Please, either side, correct me if I am wrong.
I also think Dave was making the point that it's pointless to pee in the
dark to save $.0004 worth of juice when Exxon tankers drop entire shiploads
of oil on the Alaskan shores and major power plants are excused from
reducing their power plant CO emissions.
ELD, I believe, correctly countered that every little bit helps or hurts, so
we have to think locally as well as globally. While it's way off topic for
CHA, *I* think we may eventually prove that capitalism can't survive in its
present form of caring only what stock market cares about on a very short
term basis. There's no real room in that model to account for greenhouse
gases or environmental protection or any kind of realistic long term
planning.
Personally, I'm betting on a surprise ending for civilization, like the
collapse of the earth's crust from pumping out all that oil. :-)
--
Bobby G.
Dave Houston
for X-10/Insteon co-existence) is a switch mode supply. Unregulated power
supplies cost about the same as regulated supplies (whether linear or
switchmode) so there's only a slight savings by eliminating an internal
linear regulator. There's a bit more saved by being able to design a
slightly smaller printed circuit board.
In the roZetta (and transceiver successor) designs, I'm still using a 3.3V
linear regulator to supply the xPort module from the regulated +5V supply.
The DIY designs leave the choice of power supply to the user (unregulated +
internal regulator, regulated linear or switchmode wall transformers)
although I still recommend the same +5V switchmode supply as it's the most
efficient.
I was reacting to the accusation that I was recommending getting drunk
instead of saving energy when I was actually equating a cheap drunk with the
"feel good" non-energy saving recommendations of others.
Dave Houston
http://www.nytimes.com/2006/03/24/science/earth/24melt.html?pagewanted=all
http://www.nytimes.com/2006/03/22/business/22emission.html?pagewanted=all