[Elecraft] Local Noise Problem

[Jim Brown]

On 4/3/2011 3:24 AM, David Cutter wrote:
> I'm looking forward to a time when all domestic lighting can be run 
> from a 12V supply at the main switchboard. 

Be careful what you wish for. A major advantage of higher voltage 
distribution is that copper losses are much less, and much smaller 
copper conductors are required.  This makes the 240V system used in much 
of the world superior to the 100V and 120V systems used in Japan and 
North America. It gives 240V a 20:1 advantage over 12V.

More important, try a quick calculation for the cost of converting every 
building in the world from the existing 120VAC or 240VAC to your 12VDC.  
Remember -- none of the old wiring is sufficient, so one must rip out 
the walls and start over. Please tell me when this is going to happen -- 
I want to buy stock in the copper industry, because the price is going 
to multiply by a factor of at least 5X, because copper is going to 
become VERY scarce.

In addition, distribution of power as an AC voltage means that it is 
easily transformed from one voltage to another by transformers that 
don't make electrical noise. The electrical noise produced by switching 
power supplies to do that would wipe out all radio communications!

73, Jim  K9YC