Self-powered computer

I have been on a crusade to build a computer of semi-normal performance that can be powered without the use of an electrical socket. Ever.

The goal I set is, it must perform on par with a 200 MHz Pentium. It must be able to run Windows XP and F@H. It must have a minimum of 192 MB of RAM. And it must not ever need a wall socket.

And this leads me to lots of questions...
First, questions for electrical engineers. I've considered 3 possible power sources.
1) Solar. The most obvious and readily available. However it's expensive as hell and provides jack for power. A window-sized panel gives 75W peak.
2) Thermocouples. When two different metals are used to make a circuit, say iron-copper-iron, and you heat the joints between metals, it produces an electrical current. This is how deep-space probes at the boundaries of the solar system are powered (with uranium providing the heat) They're extremely easy to build, however I am unsure of their stability, reliability, and power output.
3) Microwaves. My satellite produces 12 and 17v on two rails at 1100 mA and 850 mA respectively. About 14 watts. (13.2 and 15.3 respectively) And it is enough to power the satellite and switch (just not the DVR box). It gains this power entirely from the satellite signal itself. Thus it should be possible (though I don't, as yet, know how) to build a microwave power device. It seems the best power output for cost, though, so far.

Any suggestions?

Next is the battery. I need something that can provide approx. 1 KWh over the course of 8 hours (100w peak), but can also be charged while it's being drawn from, using a residual and variable DC input.

Then, finally, a good DC to AC converter.


The next question is the computer. It would definitely need to be a very low-wattage system. VIA immediately comes to mind. Their tiny, tiny processor the Eden and Eden ULV uses 7.5w at 1.5 GHz and 3.5w at 1.0 GHz. (And perform on par with a P333 and P233 respectively). They also have a 2.5w 400 MHz, but it's performance can't meet my specs.
Their nano-ITX is super-small and consumes extremely little power.

My question here is for suggestions on very low-watt DDR266-400 pair of 128+64 chips (or 128+128 or 256, tho i imagine less = less watt consumpt.)
Also a super-low wattage HDD of at least 10 GB.



Money is not a major issue, i'm willing to sink up to $2k into this project.

what about an exercise bike with a generator? lol. i dont really know where you'll get that much steady power unless you go the ultra low power via system. maybe if you could make some kind of generator turbine that your house's water supply ran through, so whenever you ran water it would generate some power... or throw a solar panel on the roof, if you go with a little low power board it'll probably have a single voltage input, that is relatively lower, like 5 or 12, in which case you could just go solar > batteries > regulator > mboard, or you could even regulate multiple rails off of the batteries, and jsut put together a bank of batteries to the capacity you'll need, and make sure the solar cah recharge them quick enough to have it run over night again. i'd say probably a laptop hard drive or a cf microdrive on an IDE adapter. then find some of the fastest ram that runs on lowest voltages average with good overclocks, you could underclock it to 266 and drop the voltage and power consumption and it would run cooler.

Have you considered what type of screen to use?

Why not use all of these methods together? Battery is a must for backup/soaking up extra electricity. First thing is to get the total wattage you need for the system you want then set about actually looking for ways to construct it.

It won't have a screen that's used normally. So that's not an issue.

According to VIA, the entire computer uses 40W peak, plus the CPU's wttage, without HDD. No reply if that counts memory too.

This is really more of an electrical engineering experiment than anything plausible or cost efficient.
I just want to play Doom on a solar-powered desktop.

Im going to suggest using laptop parts for obvious reasons.

Don't use an DC to AC converter. You need 12V max when no display is involved so only produce 12V max. a converter introduces more unwanted powerlosses. And then the power has to be transformed down again causing even more. A solar panel is good since it can give you 12V, 5V and 3,3V which you all need.

Use laptop drives, or if you dont need a large or fast hard disk get a couple 8GB compact flash cards. they'll cost you a bit but they draw next to nothing and can be connected directly to an IDE port withought an interface circuit. (other than the adaptor to convert the socket sizes.) use laptop optical drives. If you dont want to use a laptop mainboard at least use a mobile cpu although laptop mainboard+cpu+ram will reduce the power greatly.
I say build a windmill turbine with an alternator on it, throw a solar panel on the roof, and use any other means of mechanical drive, like mentioned attaching an alternator to a turbine in line with your house water line, The satilite is an interesting idea, but it might be hard to achive. Ispect the circuit in your receiver to see how its power supply works. Put thermo couples in your water system to generate electricity. For batteries, use a couple 12v dry cells. at least 50A/h. For a power supplu your best bet is a DC/DC switching regulator to run direcly off the batteries. It will have to handle at least 16v input because a dry cell is charged at around 14.5v. Also for alternators you should measure the non regulated voltage and if it drops below the regulators mininimum then have a micro controller cut power to the feild coil. Alternators need power to run their feild coil and if they arent spinning fast enough to keep up with the feild coild demand, it too will start to drain your batteries. If you live by a stream or something you could try and get a permit to build a water wheel .

1 sec... im sure this has already been invented *THINKS DEEPLY*..... o yeh it has its called a laptop... lol

asusradeon said:

1 sec... im sure this has already been invented *THINKS DEEPLY*..... o yeh it has its called a laptop... lol

Click to expand...

if you read, he said NEVER connect to an outlet, which means to recharge the battery also

o ok lol ive been told

you cud recharge the battery from an exercise bike..

Great ideas, Skeith.

Honestly, I dunno how the satellite works, either! But I didn't want to sacrifice the $100 to tear mine apart (I like TV a /little/), so I bought a used one off a neighbor for $10 and tested.
Once i've peaked it like a normal satellite, i'm measuring 19V of DC current at 500 mA peak, rounded up. 9.5 watts. It doesn't flucruate much at all, and seems dependant on the satellite's signal quality. Lowest it dropped when peaked at 19V at 300 mA, 5.7 watts this morning when it was pretty cloudy and threatening to rain. Still not bad. It provides a reliable supplement to any other power source, like solar.

I'm not keen on the excersize bike thing, and a water turbine would be too difficult with no free-flowing water nearby. Plus, it would still rely on a resource I pay for, defeating the purpose. =D I mean, this needs to be self-powered. Thus requiring no additional money (repairs aside) once it's built, and minimal human maintainance to power.

This is fun, though. XD Best project i've done since the 9x AA battery pack I hooked to my bike, which powered a standatd 52x CD-ROM drive and desktop stereo speakers. Mobile ghetto boombox! Got about a half hour of battery life. I really didn't expect it to work, but apparently, CD-ROM drives aren't terribly picky about their voltage and curent input. They just work.

This project is interesting, I will have to keep up with it.

You say your satellite receiver gets all its power from the satellite reception? over the air? almost 10 watts? You're lucky if that satellite up there has 10W power for the whole continent of north america. So wherever the power comes, it's NOT from the satellite

It could be from the satilite. Just as solar cells are excited by visible light in the electromagentic spectrum and generate electricity perhaps theres something in the satilite that generates electricity when excited by microwaves. Light and microvaves are the same thing, just at very different frequancies, so if it can be done with light i dont see why it couldent be dont with microwaves.

A TV satellite has ~50-100W transmission power. That's for an area of millions of squaremiles. Yes there are receivers (AM radio tho) which get their power only from the radiowaves and which can power a small headphone. But those radio recievers use only milliwatts or microwatts, not 10W. If they did, our brains were all cooked by now, seriously (a mobile transmits with 2W max and there are already concerns of them being harmful due to that power).

It depends, Ive heard that microvae radiation from a microwave oven is bassicly harmless unless the magnetron is fitted in its propor resonant cavity. (aka taking the magnetron out and pointing it at you is supposed to be harmless) I personaly wouldent try it because there is still the risk, not to mention the 200ma of about 4-6kv potential on the magnetron, heh i think the voltage in those things is more hazardous that the radiation.

You could go with an AMD Geode instead of a VIA chip. It's low powered and because it's based on the Thoroughbred core it would kick a VIA chip's *** in performance.

Since he wants to play doom3, I'd say something better than a C3 with some FPU and SSE wouldn't be a bad idea. The mobo for a geode will use more power than a C3 mobo tho

i think he just wanted to play the original doom. since he was trying to get the same performance as a 200mhz pentium i think doom3 is out of the question.