You're right re the "AA5" radios. I have several Zenith TransOceanics
here and the manuals say they'll work on either 120VAC or 120VDC when
not on their internal battery pack. The instructions are common sense:
plug the radio in and turn it on; if it doesn't work, reverse the plug
and it will play.
An electrician from Salt Lake once told me that there were a few
isolated neighborhoods in new York City that were still running DC
(dunno the voltage but think it was 110V) into the 1970's and that Sears
still made washers with DC motors for that market and that New York City
still had a market back then for 110VDC/110VAC inverters to allow those
homes to use AC appliances. Dunno whether he was blowing smoke or not.
But the RCA TV-radio that came out in the late '60's would work on
either 120VAC or 120VDC. AFB sold it so this might lend credence to
what my electrician friend said.
Back in 1964, I heard a Brazilian on 20-meter CW who sounded like he was
running 25Hz AC and another Brazilian who was running a rotary spark gap
(the rough tone was 100Hz); he was only 10kHz wide which is monstrous by
today's standards but miraculous using a spark transmitter. He must
have had one heck of an L/C network!
Anyone ever heard a Poulsen Arc transmitter? Aside from Fessenden's
alternator, this arc transmitter was used to generate continuous waves
(sufficiently continuous for phone tranmissions).
Wouldn't it be cool if there were a side on the Net with sound files of
spark transmitters, Pulsen arc transmitters and Alexanderson Alternator
transmitters (though these last wouldn't sound any different than a
transmitter today; they ran at about 50kHz).
Mike Freeman < K 7 U I J >
----- Original Message -----
From: "Martin McCormick" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, November 07, 2003 1:35 PM
Subject: Re: OT - Line Voltages, Frequency in History
> 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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