Definitely an interesting topic. It's funny, I hadn't
read this thread till today, but yesterday I was just
musing on how interesting radio must have sounded in
the spark gap erra with DC and various freqs of AC
being used. I wonder why the military and aviation
decided to use 400 HZ, and you probably know that the
phone system uses 25 HZ AC ring current. Just think,
if everybody'd stuck to DC we wouldn't have to deal
with 60 HZ RFI. On the other hand, getting
inadvertently zapped by 120 volts DC might be a bit
more dangerous, I once heard, because your muscles
would contract and not let you let go. It's doubtfull
that the high voltage power line cancer scare would
have occurred.
--- Martin McCormick <[log in to unmask]>
wrote:
>         I think you'll find that to be an
> interesting topic.  There is
> a lot more than one might think that went on in the
> early part of the
> twentieth century and latter part of the nineteenth.
>
>         A number of cities in the East did use DC
> and continued to do
> so for several years in to the twentieth century.  I
> remember a test
> record that was shipped with Talking Book machines
> in the early
> sixties that warned people not to plug their Talking
> Book machine in
> to a DC outlet.  Apparently, you could do that in
> some places.  Just
> think, back in the early part of the twentieth
> century, most of the
> things people used that were electrically powered
> were electric lights
> and heaters, all of which would run just as well on
> DC as AC.
>
>         Old AM radios that used the common 4-tubes
> and a rectifier
> design would work just fine on DC as long as you had
> the plug facing
> the correct direction in the outlet.  If it was
> wrong, the tubes would
> light up, but you wouldn't hear any sound.
>
>         Brush-type electric motors that use a field
> excited by the
> power are called universal motors and will run on
> both DC or AC but
> usually run better on DC.  The thing is that they
> would have worked on
> either AC or DC.
>
>         In the Niagra Falls area, the AC was 25
> Hertz at first.  Very
> big electric motors work well at this low frequency.
>  I think the New
> York City Subway used and may still use that
> frequency for motors.
>
>         Southern California used to use 50 Hertz
> power until sometime
> around 1930 or so.
>
>         I ran across a web site for the Pasadena
> Power and Water
> Department in which they gave a brief history.  It
> seems as though in
> 1906, they had a mixture of 50 and 60 Hertz.  The
> power station was
> originally first used for street lighting so it
> powered up at Sundown
> and ran until daybreak at which time it was shut
> down until the next
> evening.
>
>         The Hoover Dam was originally designed for
> 50 Hertz operation
> but the engineers decided they could safely just run
> the water wheels
> faster to produce 60-HZ AC in order to standardize.
>
>         I live in Oklahoma which was Indian Teri
> tory until it became a
> state in 1907.  The power history here is not nearly
> as varied as it
> is on the East and West Coasts because by the time
> people of European
> decent begin building cities here, the US was moving
> towards 60 Hertz
> as the standard line frequency.
>
>         I heard rumors that Oklahoma Gas and
> Electric had DC service
> to buildings in down-town Oklahoma City for
> industrial purposes, but
> as far as I know, most towns here have always been
> 120-volt 60 HZ for
> the primary service.  Of course, the distribution
> system has gotten
> beefier as demand increases, but that is true
> everywhere.
>
>         I once got to examine an electric meter
> built in 1910.  It was
> a baby version of the same construction that modern
> electric meters
> have.  The only difference was that the 1910 meter
> only had one phase.
> No 220-volt service yet.  I think it also may have
> had one less hand
> because people just didn't use nearly the amount of
> electricity then
> that they use now.  Otherwise, the design is the
> same as most
> watt-hour meters today.
>
> Martin McCormick WB5AGZ  Stillwater, OK
> OSU Information Technology Division Network
> Operations Group


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