? "Tomi Holger Engdahl" ?????? ??? ??????
...
"Bill" writes:

"bob haller" wrote in message

...all wall wart devices could be designed to accept a standard
voltage.,....... same for a cell phone charger standard to cut down on
trash


That is another interesting idea!

Many "wall warts" provide DC to all these electronic gizmos. So perhaps
connect these to the DC system - do away with the "wall warts".

So the central battery would provide battery backup AND DC power to
electronic gizmos (instead of using wall warts).

One problem whigh you might ecounter when powering devices from
one DC power supply: Ground loop. If you feed everythign with
one power supply, is is very asy to get noise problems to system
if those parts were originally designed t work with their wall warts
what provide isolated power. Then worst case would be if one equipment
would have - side grounded to case and other one + connected to case...

This could help to solve another problem which is voltage surges. The
"whole
house" DC electronic power supply in the home could be well protected
from
voltage surges, thus you don't need surge protectors at every outlet
where
an electronic device is plugged in.

There are whole house surge protectors that plug to main electrical
panel. The DC power distribution system on the other hand could have
it's own surges when things are plugged in and out...

Also these electronic gizmos would continue to work during power outages.

As to voltage drop, make the main supply 24 volts DC if necessary. That
should give you over 12 volts DC at the end of the line.

24V distributed around and locally converted to 12V or whatever needed
is a working idea. A suitable switch mode power supply circuit could do
that (and provide isolation if needed). The problem here is that you
need that small converter box near the outlet.. not much different from
small switch mode type wall wart in size. If you plan to hide those
things inside wall electrical box, then it would not be much different
than having the wall warts hidden somewhere inside the wall
(many same problems).
Indeed. Many things have proprietary wall warts anyway, with ferrite stubs
(like my turntable/RIAA preamp compo, each came with its own 16 V wall
wart;the preamp, a Cambridge Audio (www.cambridgeaudio.com) 540 PP moving
magnet preamp, 16 V with a ferrit stub, the turntable, a Pro-ject
(www.project-audio.com_ )Debut III with a physically (and probably
electrically) same 16 V wall wart, with the same male jack, but without a
ferrit stub). The only place I've seen that has a dc grid, is a 300 MW steam
power station, fossil fired with brown coal, but I have forgotten the
details, since it's been 15 years or so. It's in Kozani, west macedonia (not
the country, province of Greece). They needed it for the excitation circuits
of the main alternators. While large AC trasformers have a very high
efficiency (99% at full load) wall warts have a much lower, 50% IIRC. And if
they're DC/DC it needs more advanced technology. Not mentioning needing
probably #4 wires for the DC grid of a residence....



--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr