Mains failure

[Dave Plowman (News]

Ah - OK. I'll not try it then. ;-)

[Dave Plowman (News]

EMI also produced 1/4" tape machines very soon after WW2. The BTR1 even looked Teutonic. ;-)

I've seen machines which run at 30 ips, but never 60. On what became standard play tape and 10" reels, 60 ips would only allow a 7 1/2 minute recording. And if the original paper tape was thicker... Nice and easy to edit, though.

The cassette speed is actually 1 7/8ths ips - half 3 3/4ths. And 1 7/8ths was used on reel to reel machines before the Compact Cassette arrived. And things like dictaphones. Half that speed was also available on some. Although quoted as 15/16ths.

[Dave Plowman (News]

Yup - I'd guess the speed chosen was done so with the smallest gap they could produce at the time.

[NY]

If the German Magnetophon was the original "tape recorder" that set the standard for speed, I wonder why they opted for a speed of 77 cm/sec rather than rounding it to 75 or 80. Physics/engineering gives the approximate value, but humans set the exact number used - and if it was me, I'd go for a round number in whatever units I was using. Ampex would seem to have done this, by then rounding 77 cm/sec (30.31 ips) to 30 inches/sec.

[Dave Plowman (News]

It's very difficult to find out just how a particular figure was arrived at.

The 64 minutes of a 'red book' CD seems to have been based on the maximum recording time of a PCM U-Matic tape - the most common digital recorder at that time.

It could be experiments were done using an existing motor and shaft (capstan) diameter. And if that worked OK, became the standard.

[Max Demian]

I thought originally the tape was steel. (Cut you in half if it came adrift.)

PAL VHS was roughly 15/16ths for SP. (No wonder sound quality was bad on the "linear tracks".) 15/32nds for LP. Don't know about EP: that was three times the capacity so I suppose a third of SP.

[soup]

Nothing to do with Power. We have a corded phone as an emergency back-up it is kept in a cupboard for when the electricity goes off.

No memory needed nothing beyond basic telephony phones can be had from about £5, hardly expensive. Doesn't take the brains of an archbishop to unplug the 'proper' phone and plug in the emergency phone.

Mind you if the socket is (as usual) mounted near the floor she might have a hard time getting down to it. If the hall socket is still there could the Emergency phone not be left plugged into that?

Just had a thought, at her age are her eyes/fine motor skills a bit iffy? Then maybe this :-

m (Amazon linky) will do the job

[Fredxx]

I thought a CD was 74 minutes, as per Beethoven's Ninth Symphony?

[Owain Lastname]

I've written down the number for power cuts, but for anyone else I'd need to, um, power up the IP phone to find the number.

Owain

[charles]

you need to write them all down on a piece of paper; you can put the time there, too.

[Robin]

we have them as contacts in mobile phones, which can be charged from cars or power banks if necessary

[Biggles]

On 14/03/2021 11:28, Dave Plowman (News) wrote: <Snipped>

<Snipped>

I have a wired BT handset adjacent to my broadband router and cordless phone base station. An Openreach engineer asked me why I had two handsets next to each other. I explained that one would still work in a power cut, he seemed surprised at the answer.

[Dave Plowman (News]

Ah - the Marconi-Stille. A replacement for the Blattnerphone. But that was well before tape recorders as we knew them. Early 30s.

[Dave Plowman (News]

Sorry, typo. All sorts of reasons given, but happens to be the maximum recording time on an NTSC U-Matic tape, allowing for line up space. And we subsequently know that a CD can easily exceed 74 minutes without new hardware or codex.

[Dave Plowman (News]

If there was a regional power cut, how long would mobile phone masts keep going?

At one time a telephone exchange kept going on batteries for quite a while.

[JNugent]

They developed the Magnetophon up to a standard where it was better than disc and became the default medium for pre-recorded broadcast and studio recording (especially with improved requirements of lower-noise vinyl LP, EP and 45 single as the consumer end-product). The German original was good, but not that good.

They had more to worry about than tape-recording, so yes.

[JNugent]

Yes - I didn't think that one through!

[JNugent]

Oh, Ampex definitely improved the recording / replay head technology.

Then they famously gave a machine or two to Bing Crosby, who invested in the company and wanted to be able to pre-record his radio shows, and he passed one on to Les Paul. The rest, as they say...

[JNugent]

I have read that the time capacity of CD was based on the length of the piece of (symphonic) music which was the favourite of the then-boss of Sony.

[JNugent]

That was wire, rather than tape, I think. That was known internationally before WW2 and was not necessarily a German development.

Tape was only feasible once the plastic base became available (acetate for the originals?).