Memory

On Tue, 29 Apr 2014 12:09:40 +0100, "Max Demian"
wrote:

Mercury Arc Rectifier [100 yrs old]
http://www.youtube.com/watch?v=QY6V2syGnZA

Prior to the renovation of the Royal Opera House just before the Millennium,
they used mercury arc rectifiers to power the First World War submarine
motors they used for the stage machinery.

I would have loved to see that in operation. Hope it found a good
home?

In article ,
Mike Barnes wrote:
Max Demian wrote:
I used to have Beethoven's Ninth on LP, where they always have to
split the third movement, and got so used to it that I would jump if I
heard the whole thing without the split (on a radio broadcast). Then I
got it on Musicassette which split the movement in a different place,
so I would jump in two places.

This might be an urban legend but I heard that the inventor of the CD
was a big Beethoven fan, and one of the design criteria was that the
Ninth had to fit on one disc.

Urban myth. The max length was defined by the available tapes for the
U-Matic recorder. The rather odd time being down to the same tapes being
used for PAL and NTSC, but running for a longer time at 25 frames per
second. ie, a 60 minute tape at 30 fps becomes 72 at 25. 60 minute tapes
were just over 60 minutes long to allow for line up data - it was a pro
format. Hence the 74 minutes.

--
*All generalizations are false.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Max Demian wrote:
Prior to the renovation of the Royal Opera House just before the
Millennium, they used mercury arc rectifiers to power the First World
War submarine motors they used for the stage machinery.

Most theatres and cinemas had those for arc lamps and projectors, at one
time.

--
*I wished the buck stopped here, as I could use a few*

Dave Plowman London SW
To e-mail, change noise into sound.

Adrian wrote:

On Sun, 27 Apr 2014 20:31:27 +0100, Bill Wright wrote:

Katie, who is 11, was helping me in the workshop today. She told me how
some of her class been in trouble for filming the teachers covertly. Of
course I told her how, in 1965, I'd made a sound recording of our maths
teacher, with the class deliberately winding him up just to make it more
fun. I then found myself trying to explain about reel-to-reel tape
recorders. I could see that Katie just couldn't grasp the concept.
Finally she asked, "But how much memory did it have?"

I don't know whether to laugh or cry...

It's slightly scary that there's people wandering around who regard the
CD as pre-historic. I feel old.

Some years ago, I recall people remarking that BluRay was finished and
the future was holograms or that a centimetre cube would be able to
hold the complete works of..., I don't remember what.

Anyway, what happened next?

--
__________________________________________________ _

Mageia 3 for x86_64, Kernel: 3.8.13.4 -desktop-1.mga3
KDE version 4.10.5 Running on an AMD 4-core processor

On 29/04/2014 17:45, Dave Plowman (News) wrote:
In article ,
Mike Barnes wrote:
Max Demian wrote:
I used to have Beethoven's Ninth on LP, where they always have to
split the third movement, and got so used to it that I would jump if I
heard the whole thing without the split (on a radio broadcast). Then I
got it on Musicassette which split the movement in a different place,
so I would jump in two places.

This might be an urban legend but I heard that the inventor of the CD
was a big Beethoven fan, and one of the design criteria was that the
Ninth had to fit on one disc.

Urban myth. The max length was defined by the available tapes for the
U-Matic recorder. The rather odd time being down to the same tapes being
used for PAL and NTSC, but running for a longer time at 25 frames per
second. ie, a 60 minute tape at 30 fps becomes 72 at 25. 60 minute tapes
were just over 60 minutes long to allow for line up data - it was a pro
format. Hence the 74 minutes.

It's origin is more uncertain though there is a lot of association with
the 74 minutes and Beethoven's 9th.

Tapes were made of various lengths, not just 60/72 minutes. Where did
you get this inference?

http://www.snopes.com/music/media/cdlength.asp

In article ,
Fredxxx wrote:
Urban myth. The max length was defined by the available tapes for the
U-Matic recorder. The rather odd time being down to the same tapes
being used for PAL and NTSC, but running for a longer time at 25
frames per second. ie, a 60 minute tape at 30 fps becomes 72 at 25. 60
minute tapes were just over 60 minutes long to allow for line up data
- it was a pro format. Hence the 74 minutes.

It's origin is more uncertain though there is a lot of association with
the 74 minutes and Beethoven's 9th.

Tapes were made of various lengths, not just 60/72 minutes. Where did
you get this inference?

From the designers of the CD system (from the Philips side) at its launch.

--
*Yes, I am an agent of Satan, but my duties are largely ceremonial

Dave Plowman London SW
To e-mail, change noise into sound.

On Tue, 29 Apr 2014 17:57:20 +0100, Pinnerite
wrote:

Adrian wrote:

On Sun, 27 Apr 2014 20:31:27 +0100, Bill Wright wrote:

Katie, who is 11, was helping me in the workshop today. She told me how
some of her class been in trouble for filming the teachers covertly. Of
course I told her how, in 1965, I'd made a sound recording of our maths
teacher, with the class deliberately winding him up just to make it more
fun. I then found myself trying to explain about reel-to-reel tape
recorders. I could see that Katie just couldn't grasp the concept.
Finally she asked, "But how much memory did it have?"

I don't know whether to laugh or cry...

It's slightly scary that there's people wandering around who regard the
CD as pre-historic. I feel old.

Some years ago, I recall people remarking that BluRay was finished and
the future was holograms or that a centimetre cube would be able to
hold the complete works of..., I don't remember what.

Anyway, what happened next?

Flash media. That's what's happened next.
--
Regards, J B Good

On 29/04/2014 19:12, Dave Plowman (News) wrote:
In article ,
Fredxxx wrote:
Urban myth. The max length was defined by the available tapes for the
U-Matic recorder. The rather odd time being down to the same tapes
being used for PAL and NTSC, but running for a longer time at 25
frames per second. ie, a 60 minute tape at 30 fps becomes 72 at 25. 60
minute tapes were just over 60 minutes long to allow for line up data
- it was a pro format. Hence the 74 minutes.

It's origin is more uncertain though there is a lot of association with
the 74 minutes and Beethoven's 9th.

Tapes were made of various lengths, not just 60/72 minutes. Where did
you get this inference?

From the designers of the CD system (from the Philips side) at its launch.

But Philip's prototype was only 60 minutes at 14 bits?

I can't see any article that suggests that Philips were instigators of
the 74 minute 16 bit CD.

On Tue, 29 Apr 2014 16:53:02 +0100, Clive George
wrote:

On 29/04/2014 16:18, Johny B Good wrote:

[1] around the equivilent performance of a high quality cassette deck
with accurately aligned dolby level. Realistically, a C90 TDK SA tape
would only manage the equivilent of 700MiB of storage.

Really? That implies a C90 is capable of similar quality levels to CD,
and I'd be very surprised if that was the case.


What you seem to have overlooked is the extra 18 minutes of run time
compared to a 74 minute CD (C90s were typically 46 minutes or so each
way).
--
Regards, J B Good

On Tue, 29 Apr 2014 08:36:56 +0100, Andy Burns
wrote:

Simon Cee wrote:

check out 'photonics' for some amazing old
electronics... eg:

Mercury Arc Rectifier [100 yrs old]
http://www.youtube.com/watch?v=QY6V2syGnZA

Amazed that chap hasn't burned his attic down yet!

Obviously not too well up on electrical theory if it wasn't
immediately obvious to him that it was a three phase _fullwave_
rectifier designed for use with bi-phase secondary windings off a
three phase transformer. Six phase it wasn't!

--
Regards, J B Good