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Originally Posted by rodentmacbeastie /img/forum/go_quote.gif
I am looking at some crazy ideas for cooling anyway, so the extra heat will not be a problem. My Box-o-Goodies is going to be one vintage looking stereo cabinet abou 24" wide, 16" high and 12" deep. Inside that box I will have a HTPC with ESI Juli@ outputing I2S to a Buffalo DAC with NP D1 I/V stage. The DAC will receive DSD as well from a Denon spinner. The Aikido is next to a Firstwatt F1. I figure the F1 will handle a full ranger like a good HP amp handles cans, I got used to control and less distortion. This will be cooled by two liquid cooling systems. One will cool the air in the whole box(sealed to control humidity) by mounting a rad core inside as well. The second will directly cool the F1 and now maybe the Aikido buffers. I bought some Peltier thermoelectric plates to play with. When I build my house I am going to integrate these elements into my hot water heater and aircon systems. I am thinking that, since I have moving water on the land I will build a small generator from a car alternator(generator). The 12V DC is great for the lights, fans, Peltier plates, etc. I was thinking about running the DAC, Aikido, PC, and F1 off DC-DC power supplies. The only appliances that need AC are the TV and fridge. If I build a HT I would like to build a projector using LEDs as a light source and run it off DC as well. I guess I could wire four 12V batteries with relays to cut charge lines when the power is on. I could use one battery for the DAC and PC, three batteries in series for the 30V D1 rails, and all four wired in series for the 48V. I am sure the F1 would fit in there somewhere. If you have any other ideas or simple DC-DC 12V power supplies to get me the 30V+/- for the D1 and the 48V B+ for the Aikido. I am not so learned yet, this is all just ideas.
The benefits of a 12V DC house:
- less electrical stress on us.
- less noise in the power.
- less heat generated by conversion between AC and DC.
- free power and the infrastucture would cost half.
- "the man" has to mind his own business.
- less issues with Thai monsoons making things go boom.
- less expensive power capacitors.
I would use an invertor to get my 220V AC if it is necessary, but I am afraid that it will introduce lots of noise. I guess I could convert the power to 220V and use dual 55V transformer to convert the power from 220V to balanced 110V. This way I could use it easily in Canada and buy the big transformer in Thailand to act as a 220V/110V converter. This should also remove any noise introduced by the inverter.
On a different note... Is there not a way to use two of these boards in a balanced push/pull set-up and remove all of the output caps?
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I don't want to discourage your plans, but there are some potentially large issues with the system. I can only imagine that Thailand has high humidity in the summer. Anytime you have a radiator or Peltier, you are going to have condensation. The fans and pumps used to circulate the water and cool the rads will make a lot of line noise so they would have to be on isolated power systems.
DC power systems lost out to AC due to current and voltage drops. A 12Vdc home will require huge cabling and the current draw for a device on 12Vdc will twice that of the same device at 24Vdc, and it's lower yet for AC. Battery based systems have their own disadvantages too, and you will see more variation in voltage on a 12Vdc system than a 220Vac system. For ease of math, let's say your secondaries are 22Vac to produce the 31Vdc in a regular PSU. If your house AC system browns out 15% and you drop to 187Vac, you'll have 18.7Vac on your secondaries and still have 26.4Vdc at the V-reg. Your amp will stay at 24Vdc, but your V-reg will run a little hot. Using a 12Vdc system and a see a 10% drop due to high demand loads, or more likely, low output from wind turbines, solar, or water, and your incoming voltage drops to 10.8Vdc and your secondaries drop to 21.6Vdc. Not so good... So you have to step up higher and regulate back down which involves power supply again and you need to step up high enough to minimize the percentage of voltage drop at the device. Most of the designers I really respect played around with various battery or DC only systems and all came back to AC power supplies with filtered AC feeding linear regulated power supplies.
If your going completely off-grid than you either go without power at times or you need a generator. The generators on the market are designed to either output very high voltage DC or regulated AC. The DC out gensets are designed for use with RE systems and the RE system has the inverter built into it. The "regulated" AC gensets are that in the most generous of terms unless you spend big bucks... But I think the cost killer will still be the very large wire gauges needed to prevent voltage drops within the house. You would have to run 6 or 8 gauge where 14ga can be used for 120Vac and probably still be limited to 10A on a circuit versus 15 or 20 with AC. Actually, dedicated outlets could get you up to 60A at 220Vac if you panel is up to the task. Our Jenn Air oven and range is on a 40A 220Vac circuit by itself. It was in the house when we moved in, so I'm actually looking forward to replacing it with a much less power hungry stove, though we don't use the range top attachments that really suck up the power.
I think co-generating your own power is awesome and I'm a member of the American Solar Energy Society here in the States. Our next house will be built to much higher energy efficiency standards and have solar hot water, solar PV panels, and hopefully wind turbines as well. BUT, my house will still be grid tied. I just plan to make more electricity than I use and sell the excess power to the grid. Once hydrogen systems become cost effective, I will divert the excess energy into generating and storing hydrogen.
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