On Sun, 04 Oct 2009 03:31:58 -0500, The Daring Dufas
wrote:
Michael A. Terrell wrote:
George wrote:
The Daring Dufas wrote:
krw wrote:
On Sat, 03 Oct 2009 00:22:41 -0500, The Daring Dufas
wrote:
Bill wrote:
How about getting rid of all those batteries in various devices in
the home and connecting the battery connections to one central battery?
That is to run separate wires when wiring a home and these would
carry say 12 volts DC. There would be a central large battery and
battery charger like the type used in a computer UPS.
Then at each electronic gizmo which needs a battery, use a "battery
eliminator" along with a voltage regulator to supply it with the
correct voltage. And plug this into a nearby 12 volts DC "outlet".
This could provide battery power to smoke detectors, carbon monoxide
detectors, HVAC thermostat, security system, clocks, digital
thermometers, computer UPS, phone answering machine, etc.
Then only ONE battery to worry about...
A 9 volt battery eliminator picture...
http://www.wirelessmicrocolorcam.com... 7a77410624ea
My suggestion would be for a 48 volt DC system.
Think "transformer".
Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC.
The maximum "safe" voltage. There is a reason power transmission is
in the hundreds of KV. AC.
The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages.
You really want to waste power, don't you?
The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
Not everyone wants to waste ten times the power they use.
Do you have the slightest clue of what the discussion
is about? It's a hypothetical discussion about a DC power
distribution system for a home. I neither seek to impose
a standard or ridicule the ideas of others. I do have about
four decades of experience with all things electrical and
electronic but sadly, I don't know everything. I wish I did.
TDD
I am guessing his point was that linear regulators such as the 78xx
series are quite inefficient.
and have a 35 volt limit on the input voltage. Even if one could
handle 48 VDC at the input, a 7805 with a 1 amp load would waste 43
watts as heat just to power a 5 watt load.
I was thinking about the 35 volt limit and the fact that the
78xx regulators are linear regulators but for low power needs
what's a power resister and a 78xx regulator going to waste?
The same as the ratio of the voltages. For a 5V device, you're
wasting 7 times as much as you use. Most people don't consider that
smart.
DC to DC converters are a lot cheaper than they used to be
and for a heavy load like a laptop I would use something like
that. A "greenish" home with things like LED lighting and
thermoelectric refrigeration could be an interesting use for
a 48 volt DC system in a home. An LCD TV, a surround sound
system and all manner of the electronic gizmos that we can't
live without these days could be adapted to a 48 volt DC
system. I don't remember the part numbers but I remember a
line of controllers made by Linear Technology Corporation
that have input voltages that can range up to 60 volts DC
and provide a constant DC output regardless of the varying
DC input. There are some interesting developments with thermo-
electric air conditioning and I think that a 48 volt DC power
source would be great for that. For someone living off the
grid, a 48 volt system could use 12-2 Romex instead of a large
wire size needed for a 12 volt system to carry the increased
current. I find it an interesting concept.
Could be smart.