well everybody knows that converter will never reach 100% efficiency, but now the good ones are above 80-85%. why can’t one built one with 95%? a 10% increase would do the same as either makeing the device 10% more efficient, or cutting 10% off the power uptake … or reducing waste heat by 10%
the problem seem to be the MOSFETs and capacitys inside. if you have only a few microF’s and switch at a few hundred kHz that charge is wasted – as heat. also the capacitors never give back what they got!
one should design a circuit that uses the capacitys by bouncing them around and redirecting them so that the electrons are not wasted, but ‘recycled, maybe as supply for a lower output voltage (e.g. use the 12V waste for the 5V supply)
i would compare it to waste heat from a powerplant – the temp and pressures go down, but then there are other stages that can make use of it (high press/low press turbines). some waste however will always be there, so there will be no 100% efficiency possible
September 5th, 2008 in
hardware stuff |
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– is it really necessary? why can’t we have nice, well programmed applications and drivers, that surrender control graciously to others after they got their job done?
or maybe just a simple time-slicing mechanism, that checks every few milliseconds that everything runs smoothly, and if need would be, takes control away from a non-nice app?
printer drivers etc could have just a simple file (let’s say a DLL), a spool file, and a log-file where they and the user looks if the print job get done …
i don’t know how the next M$-OS will look like, apparently they realized that vista is not such a wonderful development, but even the apple OS gets bigger and bigger and more complex (10.5 came as 7.5GB disk, took 90 min to install on an 1GHz G4, and uses almost 400MB RAM just to run with a few gadgets) … and my ubuntu is not much smaller (if you want KDE,QT,CUPS,ALSA,SAMBA …)
but of course, space is cheap now (4GB RAM is $60), but my fear is the millions of line of code that have thousands of errors in them, that take years and a few hacker scares to discover. the OSs now are too complex to fully troubleshoot and understand!
September 2nd, 2008 in
software stuff |
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… should not be wasted, and used only where it can not be replaced by other means e.g. airplanes/spacecraft where every pound of weight counts! everything else could carry a few more pounds of weight, e.g. a car that has 100lb more because of high-pressure-tanks for CNG looses a bit of efficiency, or a train that has to carry one car extra devoted to CNG but still weighs a few million lbs … or even ships, one could replace highly unhealthy sulfuric oil with CNG tanks (and install sails!)(old fashioned but cheap!) and not loose significant storage room/weight. exceptions could be small craft (mopeds), tractors, emergency vehicles etc (like a firetruck should carry water NOT fuel)
analogy: it’s easier to loose a few pounds of bodyfat than spending a few thousand $ on a bicyle that is lighter …
i think we should stay in DC … not washington, but Direct Current. back in the old days it was better to have your power transmitted and up/down-converted thru transformers etc. in the last 10-15 years more and more DC/DC converters were engineered, and the efficiencies went up to (i believe) the low 90% range.
think about your PC: AC comes in, gets immediately converted into DC, and thru switches and coils/capacitors downconverted to -12/-5/+3.3/+5/+12 V DC with a max power of 200-350W for a typical desktop PC, and then even your motherboard does a little bit of switching itself and supplies the CPU/RAM/PCIe etc with anything from .9V to 3.3V … everytime you convert you loose. so why not do everything in DC, and switch only once or twice?
once could built a DC system powered by solar panels, that uses e.g. 28V DC … at let’s say 100A – it’s easy to charge batteries at 26-27V, and it’s not really lethal if you should touch a wire. i’m convinced one could even change an A/C compressor to run on that! besides it’s easier to go down in Voltage than up, and not to care about a nice clean filtered sine wave – and there are RV appliances that already run on battery power!
according to an article in “solar power” magazine you end up with almost $10 per W installed: the panels are $5, install $3.80, inverters $1.20
in bigger installs the costs are down since bigger inverters cost less per W and installers can work quicker (it’s more repetition!)
my thought: pre-fabricate connectors with inverters, so the whole thing is as simple as drilling holes, plugging cables in and turning on the master switch!
another thought of course … cconserving electricity … getting better lights, newer A/C units … and improving ventilation (a little fan can help a lot)
besides i always wonder why the panels have costly aluminum all around, why not have glass plates that are held by brackets that mount it somewhere … and a few mirrors that can help getting more sunlight on the panel (cheap, cheaper …)
also why can’t we power an A/C unit with 26V DC … and 50 A … so you don’t loose anything thru the converters? at least try to use only DC/DC, i think getting a nice sine wave is cool but really not necessary in most cases
after some googling’ one finds that you’ll need about 75-80 square feet for 1 kW … and the modules are at least $ 4.75 per W. some kyocera come rated at 26V 8A for a 200W module. more $ than i expected, but maybe the $ 3.75 was only the silicon. one should produce inverters etc, or mirrors that increase output without rotating the whole assembly, which is only good on a flat rooftop!
some more numbers here: we here in the west get about 6-7 kWh max out of a 1kW panel per day, that’s about a dollar a day. without an electric-increase you got a breakeven after 10 years …
let’s say electricity prices increase 5% per year – 1.05 to the 10th is 1.63, meaning those 16 cents would turn into 26 cents
right now i would buy some panels to get started, place them in a way that will allow expansion, and not get batteries – i’d buy electricity at night or if my demand is very high. battery development will get much faster in the next years, and inverters/chargers are very expensive. as prices for panels fall i’d buy more, or some (better) batteries
i’ve seen inverters for $2k rated 3kW, that price will come down easier than the panel. of course an old fashioned lead-acid car battery is very cheap, too
utilities were asking for a 30% price-increase lately. we pay about 17 cents per kWh (incl all taxes, fees, charges etc they can come up with!). solar panels are about $ 3.75 per W, plus inverter costs etc you end up with about $4000 per kW right now. if you do the math you’ll see that even today it would pay for itself after 6-8 years, even w/o an increase! also production of silicon for cells will increase 4 fold over the next 3 years (businessweek article), could get cheaper though greater demand may stabilize the prices … but 30% more for a kWh is a LOT! guess it’s really time now to invest, at least get part of your demand covered
i’ve noticed that one of the modules that gave me some trouble is warped! guess the locking mechanism on the outer edges keep it in place (good), and the 200 pins press against it to make contact (good), but by doing do they warp the module … should not happen, but over a few years, and with lots of heat, and maybe some moisture it somehow had an effect on my module here
maybe i’ll put it in the toaster oven for a bit, after getting a replacement, just to see if it warps back
seen a few laptops recently with memory problems – guess the SODIMMs were just getting too hot. especially older DDR266 or 333 takes up about 1W per 512Mbit chip, so if you have a 16 chip module (that is 1GByte) your RAM is burning thru 16W of your precious battery power! add to that an older 3GHz P4 with 70W max and you got over a hundred watts “under the hood” ( … under the keyboard)
KEEP IT COOL! got an older P4 here, i took the DVD drive out, and will cut a few breathing holes next to the keyboard … with a nice screen above it of course
… or just get a newer laptop: the new DDR2 run on 1.8V instead of 2.5V, and despite their speedincrease consume about half as much food