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An elderly gentlemen told me that they once had both AC and DC outlets in the same building, with no visible difference. Flourescent tubes accidentaly plugged into DC lit up in one end only and only once...

Oops... that's nice!
Vienna was converted from DC to AC around the 1950ies I think, most likely area by area. Some parts of Vienna already had AC power as early as 1903. The first district, i.e. the medieval inner city had both DC and AC, as well as the second district. All other districts had DC only, except for the 10. district which was AC only (mostly industry there). These districts already had 3ph AC available, I assume 127/220V.

I think I remember my brother telling me that the American expatriate Paul Bowles once attempted to make some ethnographic recordings somewhere in Africa (probably Morocco, since he lived there for many decades). After awhile trying to get the tape recorder to work, he (or one of his assistants) figured out that it was an AC-only machine, and the mains power was DC. Embarrassed and disappointed, he tried to explain the problem to his hosts.

They said something like, "That's OK, you can come back when the electricity is right." As if electricity were weather, and changed daily!

My dad bought a new Technics receiver in 1978. I remember reading the owner's manual (I was 10 at the time), and it warned explicitly against plugging the appliance into 120V DC supply. I was mystified as to where you might find this, but it went on to explain that some ships had DC circuits.

I remember reading a few years ago that 120VDC was very common on ships until the late '50s. The last of these ships would have been retired in the early '80s, so some of them would have still been around when I was reading this manual.

[This message has been edited by yaktx (edited 11-29-2005).]

[This message has been edited by yaktx (edited 11-29-2005).]

Like in 15 years when the area has been converted to AC!


Interesting on the DC supplies on board ships. I know some AC supplies on ships and aircraft are 400 Hz.

"I know some AC supplies on ships and aircraft are 400 Hz."

Thats because electromagnetic equipment (Xfrmrs and motors) are much smaller and lighter at 400Hz. Also for some of the Servos and gyros need really high speed motors to function. Synchronus speed at 400Hz is 24,000RPM versus 3000@50HZ or 3600@60Hz
But you knew that, right?



[This message has been edited by IanR (edited 12-01-2005).]

Plugging your 60 or 50 hertz alarm clock into one of those will REALLY make time fly.

I haven't heard of 400Hz being used on ships, but I believe it is used in aircraft because less iron is required in transformers and therefore less weight. It's interesting that some of the expensive US test instruments around here (eg; HP, Fluke, Tektronix) is rated for use on 400Hz mains.

I remember some years ago seeing one of the brochures for either a cross-Channel or North Sea ferry which made a point of warning people that the outlets on board supplied 220V at 400Hz.

I think that 400Hz on ships is more a military thing than on civilian vessels.
Most US Naval ships and Subs have two to three electrical systems; a high voltage DC system, 60Hz general distribution and 400Hz for the radar and missile guidance systems.
As for Aussie240's comment on test equipment.
That is probably due to the fact that the military is a very high paying customer.
I work at a military contractor and we don't think twice about droping a quarter of a million on a 100GHz spectrum analyzer or 100K on a digital O-scope. Heck, as I type this I am looking at a cabinet containing about 2 million worth of test equipment. And my lab is one of the smaller ones on campus!
We have several that are much larger.

[This message has been edited by IanR (edited 12-02-2005).]