why 12V?

[Bill Wright]

So many things run on 12V DC. Firstly, why has that become the standard?
Is it all because of the nominal voltage of a car battery?
Secondly, wouldn't 24 or 48V be more convenient for many things?

I heard a few years back something about new cars being 48V in the near
future. Did it ever happen?

Bill

[Bill Wright]

On 07/03/2017 20:37, Bill Wright wrote:

> I heard a few years back something about new cars being 48V in the near
> future. Did it ever happen?

I just googled it. It didn't happen.

Bill

[dave]

There was a plan in the 1980s to change cars to (I think) 32v. The idea
was to reduce the weight and cost of copper needed in a car by a factor
of about three. If the voltage was made any higher then
double-insulation and other safety measures would be needed, increasing
the cost. In the event the copper price reduced and the idea was shelved.
--
Dave

[Woody]

"Bill Wright" <wrights...@f2s.com> wrote in message
news:o9n5la$3t0$1...@gioia.aioe.org...

There seems to be or have been a number of 'standard' voltages.
6V was used on motorbikes and some cars - the 'Puddle Jumper' a.k.a.
Renault 4 for example - and those big torches of which the battery
formed part of the unit.
9V for portable radios - remember the PP3 and PP?
12V - nuff said
19V seems to be a very common voltage for laptop chargers
24V for commercial vehicles and trains(?)
48V for telephone systems and associated microwave links and nowadays
fibre equipments and always positive earth
90V used to be used for batteries in old portable valve radios
(remember them Bill?)
100V was also common - I used to have a SMPS mared 100/12 i.e. 100V
12A

I bet there's a lot more, but equally for battery supplies I would
think there is more 12V and 48V than anything else.


--
Woody

harrogate3 at ntlworld dot com

[NY]

"Bill Wright" <wrights...@f2s.com> wrote in message
news:o9n5la$3t0$1...@gioia.aioe.org...

> So many things run on 12V DC. Firstly, why has that become the standard?
> Is it all because of the nominal voltage of a car battery?

I would imagine so. 12V can easily be made out of six 2V lead-acid cells
(for a car) or eight 1.5V batteries (for a portable radio etc).

I'm not sure how 5V became the standard for USB power.

[Graham C]

On Tue, 7 Mar 2017 20:37:00 +0000, Bill Wright
<wrights...@f2s.com> wrote:

>So many things run on 12V DC. Firstly, why has that become the standard?
>Is it all because of the nominal voltage of a car battery?
>Secondly, wouldn't 24 or 48V be more convenient for many things?
>

>Bill

Slightly OT but I've been trying for years to find the reason behind
airfield runway lighting which is standardised at 6.6 amps.

Because of the high power necessary these are wired in series to cut
down on conductor requirements and provide constant brightmess down
the line. Most are dimmable but 6.6 amps corresponds to 100%
brightness. Clearly the wattage of the bulb determines the
brightness.

Originally during WWII each lamp was fed from a 1:1 transformer which
continued the circuit if a bulb filament failed. There were also
'thin-paper' cutouts and later zener type devices used to maintain the
circuit in the event of a lamp failure.

Even by the end of WWII constant current regulators were in use with
the thin-paper cut-out system to prevent the sytem going into 'domino
mode' if one, then two, then three lamps failes etc.

But why 6.6 amps?

GrahamC

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Graham.]

TTL logic must figure strongly in the answer.


--

Graham.
%Profound_observation%

[Graham.]

Why 6.3A for many valve heaters?

And why 3.14159265359 diameters in a circumference?

Go on Bill, tell us why?


--

Graham.
%Profound_observation%

[Paul Ratcliffe]

On Tue, 07 Mar 2017 23:48:00 +0000, Graham <graham...@mail.com> wrote:

> Why 6.3A for many valve heaters?

FFS... 6.3V (and 0.3A typically).

[Graham.]

I have to concede a definite brain fart there.



--

Graham.
%Profound_observation%

[Bill Wright]

On 07/03/2017 23:48, Graham. wrote:

> And why 3.14159265359 diameters in a circumference?
>
> Go on Bill, tell us why?

It's purely the result of us having eight fingers and two thumbs.

Bill

[Chris Green]

Graham. <graham...@mail.com> wrote:
>
> Why 6.3A for many valve heaters?
>

Er, 6.3 volts, not amps.

--
Chris Green
·

[Jim Lesurf]

In article <f7hubclm1if6pogff...@4ax.com>,

Graham. <graham...@mail.com> wrote:

> Why 6.3A for many valve heaters?

> And why 3.14159265359 diameters in a circumference?

Overlooking the slip wrt units, the above made me wonder if the real choice
for heater voltages was actually 2*pi Volts.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

[Paul Cummins]

In article <o9n5la$3t0$1...@gioia.aioe.org>, wrights...@f2s.com (Bill

Wright) wrote:

> So many things run on 12V DC. Firstly, why has that become the
> standard? Is it all because of the nominal voltage of a car
> battery?

A car has never been 12v though.

In the 1980s, when I became aware of things like this, a Car's electrical
system was 13.2v nominal, and 13.8v was what was considered to be
available to power Radios etc when the engine was running.

Nowadays, my "old" Mk1 Focus supplies 14.5v when the car is running, and
drops to about 13.7 when stopped.

None of that looks like "12v nominal" to me.

--
Paul Cummins - Always a NetHead
Wasting Bandwidth since 1981
Please Help us dispose of unwanted virtual currency:
Bitcoin: 1LzAJBqzoaEudhsZ14W7YrdYSmLZ5m1seZ

[Woody]

"Paul Cummins" <agree2...@spam.vlaad.co.uk> wrote in message
news:memo.2017030...@postmaster.cix.co.uk...

> In article <o9n5la$3t0$1...@gioia.aioe.org>, wrights...@f2s.com
> (Bill
> Wright) wrote:
>
>> So many things run on 12V DC. Firstly, why has that become the
>> standard? Is it all because of the nominal voltage of a car
>> battery?
>
> A car has never been 12v though.
>
> In the 1980s, when I became aware of things like this, a Car's
> electrical
> system was 13.2v nominal, and 13.8v was what was considered to be
> available to power Radios etc when the engine was running.
>
> Nowadays, my "old" Mk1 Focus supplies 14.5v when the car is running,
> and
> drops to about 13.7 when stopped.
>
> None of that looks like "12v nominal" to me.
>

I think the missing word is 'nominal'?

[NY]

"Graham." <graham...@mail.com> wrote in message
news:7vgubcpren23ehrkk...@4ax.com...

It's a while since I did electronics. Is 5V (or thereabouts) based on
physical properties of the silicon for the transistors in TTL? I probably
knew this at one time...

[Chris Green]

Jim Lesurf <no...@audiomisc.co.uk> wrote:
> In article <f7hubclm1if6pogff...@4ax.com>,
> Graham. <graham...@mail.com> wrote:
>
> > Why 6.3A for many valve heaters?
>
> > And why 3.14159265359 diameters in a circumference?
>
> Overlooking the slip wrt units, the above made me wonder if the real choice
> for heater voltages was actually 2*pi Volts.
>

I suspect it's likely that it was actually for use with lead acid
batteries which, when fully charged are rather more than 2 volts per
cell.

Though 6.3 volt heaters were always in mains powered valves in my
experience, those with indirectly heated cathodes. All the battery
valves with directly heated filaments were 1.5 or 2 volts.

--
Chris Green
·

[NY]

"Graham." <graham...@mail.com> wrote in message

news:f7hubclm1if6pogff...@4ax.com...
> Why 6.3V for many valve heaters?

>
> And why 3.14159265359 diameters in a circumference?

And why is the standard film frame rate 24?

Why did someone come up with 24, rather than a rounder figure like 25? I
could understand 16 or 32, since those can be formed by successively
dividing 1 second by 2.

I realise that persistence of vision governs the *approximate* value -
20-something was found empirically to be the lowest speed at which movement
could be perceived and flicker was not too intrusive.

I wonder if 24 was based on the length of film of a certain frame size (eg
24x18mm for 35mm film) being a whole number of inches (talk about mixing
your units - length of film in feet, width in mm, size of gram in mm).


Wikipedia https://en.wikipedia.org/wiki/Frame_rate says "Many theaters had
shown silent films at 22 to 26 FPS which is why 24 FPS was chosen for
sound." as if it is obvious that from a range of 22-26 fps you'd choose to
standardise on 24 rather than 25. Maybe I'm applying too much numerical OCD
to it, in thinking that if you have a free choice you choose either
multiples of 5 or 10, or else powers of 2. :-)

[Jim Lesurf]

In article <EY2dnXozNroUdCLF...@brightview.co.uk>, NY

I'm trying to recall if RTL or DTL used 5Volts. I did briefly use some
RTL/DTL as an undergrad.

But yes, IIUC the old TTL standard devices tended to be quite fussy about
the rail voltage.

[The Other John]

On Wed, 08 Mar 2017 11:43:12 +0000, NY wrote:

> And why is the standard film frame rate 24?

Was it set by the Merkins? If so could it be because of their 60Hz
mains? You would get 5 positive and negative mains peaks per frame if my
sums are right, thus avoiding strobing effects.

--
TOJ.

[Max Demian]

On 08/03/2017 11:29, Chris Green wrote:
> Jim Lesurf <no...@audiomisc.co.uk> wrote:
>> In article <f7hubclm1if6pogff...@4ax.com>,
>> Graham. <graham...@mail.com> wrote:
>>
>>> Why 6.3A for many valve heaters?
>>
>>> And why 3.14159265359 diameters in a circumference?
>>
>> Overlooking the slip wrt units, the above made me wonder if the real choice
>> for heater voltages was actually 2*pi Volts.
>>
> I suspect it's likely that it was actually for use with lead acid
> batteries which, when fully charged are rather more than 2 volts per
> cell.

That's right, it's from US car radios. US cars always used to have 6V
(nominal) batteries, varying from 5-7V according to charge, and 6.3V was
the best compromise voltage that enabled them to work all right when the
voltage was low, and not blow when it was high. The HT was from a
vibrator power pack (oo-er missus), 150V I think.

> Though 6.3 volt heaters were always in mains powered valves in my
> experience, those with indirectly heated cathodes.

I suppose they used (some of) the same valves as were used in car
radios. I suppose we must have imported a lot of US valves, or we would
have used 12.6V heaters from our car radios. (My family had a big
Mullard radio, bought in 1940 from pre-war stock (for 12gns), which had
6.3V heater valves, with side contact bases.)

> All the battery
> valves with directly heated filaments were 1.5 or 2 volts.

The pentode output valve in the usual series was 3V centre-tapped so the
valve filaments could be wired in series across a 7.5V LT battery.

--
Max Demian

[Peter Duncanson]

Well, 24 is a round two dozen.

--
Peter Duncanson
(in uk.tech.digital-tv)

[Brian Gaff]

No, I imagine you could feel 48v, something like the line volts of a
telephone.
to be honest I think you are probably right in the car battery analogy. Its
kind ofstuck like that but not everywhere. I have a tv here where the psu
claimes to be 18v.

Boats operated on double 12 at one time, and many fighting ships use 300hz
AC.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please!

"Bill Wright" <wrights...@f2s.com> wrote in message
news:o9n5la$3t0$1...@gioia.aioe.org...

[Brian Gaff]

I can recall the first car radio I ever saw. it had a vibrator pack for
generating the ht as it was all valves inside. Motorola made it and the
tuning seemed to be via cores on string that was wound in and out of coils.
One assumes this was less troublesome than capacitors?

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
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Blind user, so no pictures please!

"Woody" <harro...@ntlworld.com> wrote in message
news:o9n9ar$j3f$1...@dont-email.me...

[Bill Wright]

On 08/03/2017 10:59, Paul Cummins wrote:
> In article <o9n5la$3t0$1...@gioia.aioe.org>, wrights...@f2s.com (Bill
> Wright) wrote:
>
>> So many things run on 12V DC. Firstly, why has that become the
>> standard? Is it all because of the nominal voltage of a car
>> battery?
>
> A car has never been 12v though.
>
> In the 1980s, when I became aware of things like this, a Car's electrical
> system was 13.2v nominal, and 13.8v was what was considered to be
> available to power Radios etc when the engine was running.
>
> Nowadays, my "old" Mk1 Focus supplies 14.5v when the car is running, and
> drops to about 13.7 when stopped.
>
> None of that looks like "12v nominal" to me.
>

A lead acid battery under load will be down to 12V before very long.

Bill

[Roderick Stewart]

On Wed, 08 Mar 2017 11:42:21 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>> >>I'm not sure how 5V became the standard for USB power.
>> >
>> > TTL logic must figure strongly in the answer.
>
>> It's a while since I did electronics. Is 5V (or thereabouts) based on
>> physical properties of the silicon for the transistors in TTL? I
>> probably knew this at one time...
>
>I'm trying to recall if RTL or DTL used 5Volts. I did briefly use some
>RTL/DTL as an undergrad.

Yes they did.

>But yes, IIUC the old TTL standard devices tended to be quite fussy about
>the rail voltage.

I've always assumed 5V was chosen simply because it's easy to produce
from a 6V battery.

Rod.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[Woody]

"Roderick Stewart" <rj...@escapetime.myzen.co.uk> wrote in message
news:fke0ccle4dd3fj13k...@4ax.com...

> On Wed, 08 Mar 2017 11:42:21 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
>
>>> >>I'm not sure how 5V became the standard for USB power.
>>> >
>>> > TTL logic must figure strongly in the answer.
>>
>>> It's a while since I did electronics. Is 5V (or thereabouts) based
>>> on
>>> physical properties of the silicon for the transistors in TTL? I
>>> probably knew this at one time...
>>
>>I'm trying to recall if RTL or DTL used 5Volts. I did briefly use
>>some
>>RTL/DTL as an undergrad.
>
> Yes they did.
>
>>But yes, IIUC the old TTL standard devices tended to be quite fussy
>>about
>>the rail voltage.
>
> I've always assumed 5V was chosen simply because it's easy to
> produce
> from a 6V battery.
>

Actually probably not. TTL was very pernickety about supply voltages,
+/- 100mV was about the limit but they could and did draw quite a bit
of current which was by no means constant.

The only method of regulating a nominal 6V down to 5V would be a
switching regulator - quite acceptable and easily achieved today but
20+ years ago it was a different kettle of fish. A series pass
regulator needs some headroom - for something like a 7805 about 2.3V
would be needed which is clearly not available, so the only option
would be a zener diode which either has to draw the balance of the
current needed to cause the necessary voltage drop across a resistor,
or provide the control for a series pass transistor. The downside
is/was that the voltage tolerance of a zener is probably outside the
TTL supply tolerance, and the zener regulation is pretty poor versus
temperature.

IME if TTL supply was required from a battery supply it would be 9V -
such as a PP9 - or higher so that a series pass regulator could be
used.

[R. Mark Clayton]

On Wednesday, 8 March 2017 17:09:59 UTC, Roderick Stewart wrote:
> On Wed, 08 Mar 2017 11:42:21 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
>
> >> >>I'm not sure how 5V became the standard for USB power.
> >> >
> >> > TTL logic must figure strongly in the answer.
> >
> >> It's a while since I did electronics. Is 5V (or thereabouts) based on
> >> physical properties of the silicon for the transistors in TTL? I
> >> probably knew this at one time...
> >
> >I'm trying to recall if RTL or DTL used 5Volts. I did briefly use some
> >RTL/DTL as an undergrad.
>
> Yes they did.
>
> >But yes, IIUC the old TTL standard devices tended to be quite fussy about
> >the rail voltage.
>
> I've always assumed 5V was chosen simply because it's easy to produce
> from a 6V battery.

IIRC it was chosen because it was easy to produce from 6.3VAC used for heaters in valves.

I don't know why they were 6.3V

Some chips like 2708 EPROMS needed + & - 12V supplies to program as well.

[Graham.]

On Wed, 08 Mar 2017 09:27:07 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:

>In article <f7hubclm1if6pogff...@4ax.com>,
> Graham. <graham...@mail.com> wrote:
>
>> Why 6.3A for many valve heaters?
>
>> And why 3.14159265359 diameters in a circumference?
>
>Overlooking the slip wrt units, the above made me wonder if the real choice
>for heater voltages was actually 2*pi Volts.
>
>Jim

Surely that would be irrational ;-)


--

Graham.
%Profound_observation%

[Graham.]

On Wed, 8 Mar 2017 11:43:12 -0000, "NY" <m...@privacy.net> wrote:

Record speeds is the obvious progression to this discussion, and I've
found this which you may find interesting. 78.2608RPM anyone?

http://www.aes.org/aeshc/docs/recording.technology.history/speeds.html

And no mention of sixteen and two turds.

Like owning a passport, an American learning a foreign language is a
bit subversive?

Just a thought.


--

Graham.
%Profound_observation%

[charles]

In article <o9pip5$7ko$1...@dont-email.me>,

Woody <harro...@ntlworld.com> wrote:

> "Roderick Stewart" <rj...@escapetime.myzen.co.uk> wrote in message
> news:fke0ccle4dd3fj13k...@4ax.com...
> > On Wed, 08 Mar 2017 11:42:21 +0000 (GMT), Jim Lesurf
> > <no...@audiomisc.co.uk> wrote:
> >
> >>> >>I'm not sure how 5V became the standard for USB power.
> >>> >
> >>> > TTL logic must figure strongly in the answer.
> >>
> >>> It's a while since I did electronics. Is 5V (or thereabouts) based
> >>> on
> >>> physical properties of the silicon for the transistors in TTL? I
> >>> probably knew this at one time...
> >>
> >>I'm trying to recall if RTL or DTL used 5Volts. I did briefly use
> >>some
> >>RTL/DTL as an undergrad.
> >
> > Yes they did.
> >
> >>But yes, IIUC the old TTL standard devices tended to be quite fussy
> >>about
> >>the rail voltage.
> >
> > I've always assumed 5V was chosen simply because it's easy to
> > produce
> > from a 6V battery.
> >


> Actually probably not. TTL was very pernickety about supply voltages,

[Snip]
I remember seeing a TTL based unit where the PSU had gone way over voltage.
All the chips had boiled their encapsulation. It didn't work any more
either.

--
from KT24 in Surrey, England

[David Woolley]

On 08/03/17 17:09, Roderick Stewart wrote:
> I've always assumed 5V was chosen simply because it's easy to produce
> from a 6V battery.

No it isn't. If you are talking "dry" cells, the normal design endpoint
voltage is 0.9V per cell, or 3.6v, which is well outside the supply
voltage tolerance for TTL logic, even before the regulator drop.

[David Woolley]

On 08/03/17 19:52, Graham. wrote:
> Surely that would be irrational ;-)

Certainly something to meditate on, transcendentally.

[Woody]

"charles" <cha...@candehope.me.uk> wrote in message
news:5619ba92...@candehope.me.uk...

It was much more entertaining to cook CMOS despite their much greater
voltage range. The chip would usually blast its way out of the
encapsulation leaving the encapsulation complete bar a hole in the
top!

[Indy Jess John]

This from Wikipedia:
"The earliest rotation speeds varied widely. Most records made in
1900–1925 were recorded at 74–82 revolutions per minute (rpm). Edison
Disc Records consistently ran at 80 rpm."

Jim

[Stephen]

On Wed, 8 Mar 2017 16:13:40 -0000, "Brian Gaff"
<bri...@blueyonder.co.uk> wrote:

>No, I imagine you could feel 48v, something like the line volts of a
>telephone.

FWIW 48v DC for telecom equipment is 1 of the few world wide
standards. You can get a belt from it but it is normally treated as
reasonably safe for shock hazards (although welding and sparks are a
different problem).

you missed out the classic electric vehicles - milk floats and stacker
trucks?

In real life telecom battery systems tend to be 4 glorified "deep
discharge" expensive 12v sealed batteries which look pretty similar to
car batteries with attitude......

some of the PoPs at work with older PSTN switches have entire rooms
full of battery strings - with lots of hazard warnings given the
amounts of acid involved, and the risks of hydrogen generation.

huge manufacturing scale will mean common components get re-used where
that makes sense.

> to be honest I think you are probably right in the car battery analogy. Its
>kind ofstuck like that but not everywhere. I have a tv here where the psu
>claimes to be 18v.
>
>Boats operated on double 12 at one time, and many fighting ships use 300hz
>AC.
> Brian

Stephen Hope stephe...@xyzworld.com
Replace xyz with ntl to reply

[Jim Lesurf]

In article <o9pip5$7ko$1...@dont-email.me>, Woody <harro...@ntlworld.com>
wrote:

> The only method of regulating a nominal 6V down to 5V would be a
> switching regulator - quite acceptable and easily achieved today but
> 20+ years ago it was a different kettle of fish. A series pass
> regulator needs some headroom - for something like a 7805 about 2.3V
> would be needed which is clearly not available, so the only option
> would be a zener diode which either has to draw the balance of the
> current needed to cause the necessary voltage drop across a resistor,
> or provide the control for a series pass transistor.

In principle you could probably engineer a diode or series of a couple of
diodes to drop about 1V and have them in series with the 6V supply. But it
would seem a bit of a daft way to do it when you can simply make a decent
5V supply by other means.

[Graham.]

I've got a Caruso 78 that is actually marked 80RPM



--

Graham.
%Profound_observation%

[NY]

"Graham." <graham...@mail.com> wrote in message

news:qh63cc5qfiqslbp6o...@4ax.com...

> I've got a Caruso 78 that is actually marked 80RPM

I've got a shellac-on-aluminium disc made by the BBC of a talk that my
grandpa made on Children's Hour some time in the 1950s. It's nominally 78
rpm, but must have been recorded at a slightly slower speed because
grandpa's voice sounds slightly too high-pitched (*). He is also using a
standard BBC announcer's accent instead of his own educated West Riding
accent, which has some *very* odd vowels. I think he must have overdone the
RP accent, so you got phrases such as "like a ballett fram a gan" (like a
bullet from a gun). I teased him mercilessly about it when he first played
it to me. He said that he deliberately over-emphasised the RP accent as a
protest when he was told that his own accent was not acceptable on national
radio, and accidentally-on-purpose let slip the odd northern vowel to make
it clear where he came from and that it was all a charade.


(*) One way to tell would be to look for the nominal 50 Hz mains hum in the
spectrum and correct the speed until the hum was exactly 50 Hz.

[Vir Campestris]

Merkin TV is of course (almost exactly) 30Hz.

Andy

[charles]

In article <GNCdnVz9XYeIW1zF...@brightview.co.uk>, Vir

It was once, but with the arrival of color it became 59.94Hz

Charles

[NY]

"charles" <cha...@candehope.me.uk> wrote in message

news:561a4c9d...@candehope.me.uk...

I never understood why NTSC needed to have its frame and line rate tweaked
but PAL and SECAM didn't. Was it caused/exacerbated by the non-alternating
of the colour info? Was it fortuitous that European and UK PAL systems and
French SECAM didn't have to alter when colour was introduced, or were those
systems designed "better" than NTSC in some way?

Was it a baseband video restriction or a restriction in the US broadcast
system that was best solved by tweaking the baseband signal rather than the
broadcast spec?

Do *all* NTSC systems use 59.94 (maybe to remain compatible with US)?

Presumably now that analogue is very much less common, the NTSC could *in
theory* have gone back to 60.0 Hz for digital production and broadcast.

[charles]

In article <ENOdnWwFssNCTFzF...@brightview.co.uk>, NY

<m...@privacy.net> wrote:
> "charles" <cha...@candehope.me.uk> wrote in message
> news:561a4c9d...@candehope.me.uk...
> > In article <GNCdnVz9XYeIW1zF...@brightview.co.uk>, Vir
> > Campestris <vir.cam...@invalid.invalid> wrote:
> >> On 08/03/2017 12:44, The Other John wrote:
> >> > On Wed, 08 Mar 2017 11:43:12 +0000, NY wrote:
> >> >
> >> >> And why is the standard film frame rate 24?
> >> >
> >> > Was it set by the Merkins? If so could it be because of their 60Hz
> >> > mains? You would get 5 positive and negative mains peaks per frame
> >> > if my sums are right, thus avoiding strobing effects.
> >> >
> >> Merkin TV is of course (almost exactly) 30Hz.
> >
> > It was once, but with the arrival of color it became 59.94Hz

> I never understood why NTSC needed to have its frame and line rate
> tweaked but PAL and SECAM didn't. Was it caused/exacerbated by the
> non-alternating of the colour info? Was it fortuitous that European and
> UK PAL systems and French SECAM didn't have to alter when colour was
> introduced, or were those systems designed "better" than NTSC in some
> way?

It's over 50 years since I learned the reason. As far as I can remember it
was to prevent patterning from the sound carrier on the broadcast system.

> Was it a baseband video restriction or a restriction in the US broadcast
> system that was best solved by tweaking the baseband signal rather than
> the broadcast spec?

> Do *all* NTSC systems use 59.94 (maybe to remain compatible with US)?

Those that rmained in monochrome stayed with 60Hz. The last one within the
USA (sort of) was the United Nations tv coverage which remained in mono for
a long time,

> Presumably now that analogue is very much less common, the NTSC could *in
> theory* have gone back to 60.0 Hz for digital production and broadcast.

Yess, probably, but why bother. It would involve a fair bit of expenditure
to change something that's been around for about 60 years.

[Paul Ratcliffe]

On Wed, 8 Mar 2017 11:43:12 -0000, NY <m...@privacy.net> wrote:

> Why did someone come up with 24, rather than a rounder figure like 25?

Why do you think 25 is rounder than 24?
24 is divisible by 2, 3, 4, 6, 8 and 12.
25 is only divisible by 5.
What makes a round number anyway (in your opinion) ?

> Maybe I'm applying too much numerical OCD to it, in thinking that if you have
> a free choice you choose either multiples of 5 or 10, or else powers of 2.

Yes, you are.

[NY]

"Paul Ratcliffe" <ab...@orac12.clara34.co56.uk78> wrote in message
news:slrnoc3mhv...@news.pr.network...

> On Wed, 8 Mar 2017 11:43:12 -0000, NY <m...@privacy.net> wrote:
>
>> Why did someone come up with 24, rather than a rounder figure like 25?
>
> Why do you think 25 is rounder than 24?
> 24 is divisible by 2, 3, 4, 6, 8 and 12.
> 25 is only divisible by 5.
> What makes a round number anyway (in your opinion) ?

One that is a multiple or sub-multiple of the base that I count in - 10.
That trumps (not of the Donald variety!) all other considerations.

>> Maybe I'm applying too much numerical OCD to it, in thinking that if you
>> have
>> a free choice you choose either multiples of 5 or 10, or else powers of
>> 2.
>
> Yes, you are.

Fair enough.

Given a totally free hand in setting any numerical standard, I'd always
round it to the nearest 10 or 5.

Sometimes there other considerations. For example, in packaging tin cans etc
into boxes, 12 is a better number than 10 because it has factors that are
more similar (3 and 4), and a 3x4 "almost square" box is easier to manage
than a "long thin" 5x2 box.

I suppose in an ideal world we'd have been born with five fingers and a
thumb on each hand, learned to count in base 12 with symbols for 10 and 11,
and then we'd have had the advantages of 3x4 boxes etc and yet would regard
12 as more natural than 10.

I suppose in days when division circuitry was analogue rather than digital,
it makes sense to choose standards such as number of TV lines to have lots
of small factors - hence 405, 525 and 625. Interesting that the competitor
to Baird had 240 lines - an even number which must have made interlacing
more difficult in days when one field was made up of a half-line at the
beginning and a half-line at the end to interleave the two fields (when the
vertical deflection was a continuous sawtooth rather than a staircase).


Someone raised the issue of 24 fps being 5 half-cycles of US 60 Hz mains, so
no strobing. What about in 50 Hz countries? Did they have to use DC lights
to avoid strobing? Do TV and film lights use DC (or very long persistence
with AC) to avoid strobing now? I imagine that filaments have long enough
persistence but what about HID and LED lights - in the latter case these are
normally pulsed at very high frequency, but presumably not for TV where they
need to be DC or else alternating banks of LEDs 180 degrees out of phase so
there's always half of them lit.

[Paul Cummins]

In article <slrnoc3mhv...@news.pr.network>,

ab...@orac12.clara34.co56.uk78 (Paul Ratcliffe) wrote:

> > Maybe I'm applying too much numerical OCD to it, in thinking that
> if you have
> > a free choice you choose either multiples of 5 or 10, or else
> > powers of 2.
>
> Yes, you are.

Mrs C insists on turning the car radio up in steps of 5 - which was great
with the old Sonichi DAB radio, but is less good with the Ford 6000.

--
Paul Cummins - Always a NetHead
Wasting Bandwidth since 1981
Please Help us dispose of unwanted virtual currency:
Bitcoin: 1LzAJBqzoaEudhsZ14W7YrdYSmLZ5m1seZ

[Johnny B Good]

On Wed, 08 Mar 2017 16:18:01 +0000, Brian Gaff wrote:

> I can recall the first car radio I ever saw. it had a vibrator pack for
> generating the ht as it was all valves inside. Motorola made it and the
> tuning seemed to be via cores on string that was wound in and out of
> coils.
> One assumes this was less troublesome than capacitors?
> Brian

In the case of car radio antenna setups, permeability tuning (aka,
variable inductance tuning) allowed the whip antenna to act as a pretty
effective resonant capacitive probe type for the LW and MW wavebands.

Even a 2 metre long whip antenna represents only about 1% of the
wavelength of a MW broadcast transmission at the high frequency end of
the band. Such a short, unloaded whip antenna acts as an electric field
probe antenna at these frequencies and below.

In order to get the highest signal voltage into the antenna tuned
circuit we need to minimise the tuning capacitance contributed by the
screened feeder and the evil necessity of an antenna/feeder padding
trimmer capacitor in parallel with the whip antenna's own, desirable
capacitance and maximise the inductance component that makes up the
required LC product to tune into frequencies across the range of the MW
(and optional LW) band(s).

For the American MW band, this requires a variable C or L with a max:min
ratio of 10.6:1 (in the UK and Europe, the requirement is a more modest
9.3:1). Since using a variable C results in reduced sensitivity as we
tune from the HF end to the LF end of the band[1] along with the
likelihood that the "stray capacitance" will more likely be in the
neighbourhood of 100pF rather than the more typical 30pF of a
conventional radio thus requiring a 1000pF variable tuning capacitor
rather than the more typical 300 to 500pF variety, the obvious solution
is to vary the L instead using movable iron dust cores which are able to
provide comfortably more than the 10.6:1 variation required allowing
trimming adjustments to be made in both the L and C values to calibrate
the frequency/wavelength tuning scale.

The reason why permeability tuning is rarely, if ever, used in
conventional radios is down to the additional costs involved over a dual
or triple gang tuning module based on the ubiquitous 2 or 3 gang air
spaced tuning capacitor. The issue is simply a matter of attaining the
best cost/benefit ratio which, in the case of the MW/LW car radio
restricted to the use of a very short whip antenna, is obtained by the
use of permeability tuning in preference to capacitive tuning.

[1] Such an antenna system can be considered to be the equivalent of a
capacitive volt dropper where the capacitance of the exposed whip aerial
(although effectively in parallel with the 'strays' and the trimmer
connected across the variable inductor as far as the tuned frequency
equation is concerned) can be considered as being in series with a
voltage source, in this case the electric field of the passing radio
waves.

If this circuit is tuned by a variable capacitor, the aerial voltage of
this capacitive volt dropper will reduce as we tune from the HF end to
the LF end of the band. Varying the inductance component to retune the LC
combination instead, eliminates this problem completely, hence its use in
AM car radios designed to utilise a short voltage probe whip antenna to
permit reception whilst on the move.

--
Johnny B Good

[Bill Wright]

On 09/03/2017 18:12, Graham. wrote:

> I've got a Caruso 78 that is actually marked 80RPM
>

I've got La Paloma on an 80rpm.


Bill

[Bill Wright]

On 09/03/2017 22:20, charles wrote:

> Yess, probably, but why bother. It would involve a fair bit of expenditure
> to change something that's been around for about 60 years.
>

That's probably why Hil hasn't divorced me.

Bill

[Johnny B Good]

On Tue, 07 Mar 2017 23:37:04 +0000, Graham. wrote:

> On Tue, 7 Mar 2017 22:21:58 -0000, "NY" <m...@privacy.net> wrote:
>
>>"Bill Wright" <wrights...@f2s.com> wrote in message
>>news:o9n5la$3t0$1...@gioia.aioe.org...

>>> So many things run on 12V DC. Firstly, why has that become the
>>> standard?
>>> Is it all because of the nominal voltage of a car battery?
>>

>>I would imagine so. 12V can easily be made out of six 2V lead-acid cells
>>(for a car) or eight 1.5V batteries (for a portable radio etc).

>>
>>I'm not sure how 5V became the standard for USB power.
>
> TTL logic must figure strongly in the answer.

It sure does! Since the days of the very first hobbyist kit computers in
the mid to late 70s, the logic components have all been sourced from the
famous 7400 TTL series "Logic Family". The very first IBM PC had very
few, if any, dedicated VLSI (or even just LSI) chips being made up almost
exclusively of TTL logic chips to provide the 'logic glue' for the Intel
8088 cpu that IBM's cash starved fledgling PC division chose as a cheap
way to fabricate a 16 bit class desktop computer using cheap off the
shelf 8 bit data bus components.

Although the technology has moved on to cmos based chips, initially a
logic family given the base number 4000 (and still available) and able to
work on supply voltages ranging from a low of 3 to a high of 15, the cmos
versions of the 7400 TTL logic family were characterised to operate at
the standard 5v logic levels to retain compatibility as were the later
dedicated VLSI chips used to replace the original TTL logic glue chips to
reduce fabrication costs of the later motherboards where most of the
costs lay simply in the physical size of said motherboards and the
mounting of dozens of TTL chips where a single VLSI chip could now
suffice.

The 5 volt rail has been a standard supply rail in all versions of the
PC PSU from the earliest PC PSU through the AT and into the still current
ATX class PSUs. The addition of a 3.3 volt rail which was a mobile chip
voltage standard used by notebook (laptop) computers, didn't show up as a
standard rail voltage until the advent of the ATX class of PSU where it
appeared as an extra rail voltage rather than a replacement for the 5
volt rail.

Although modern CPUs have been using low voltage cores for some two
decades now (give or take a year or three - it's definitely been more
than 15 years), there's no point in getting the ATX PSU to provide a
voltage lower than 3.3 in order to directly power cpu cores which are now
typically using voltages as low as 1.2v at currents that can peak above
100 amps.

Such low voltage high current supplies are best generated local to the
cpu socket via programmable high efficiency switching converters drawing
their power from the 12 volt rail which can provide the required voltage
regulation at current demands that can exceed 100A and at voltages that
can be programmed in 5 or 10 mV increments over the range 0.8 to 1.5
volts or thereabouts. A 5% variation of a 1v supply is a mere 50mV.
There's no easy or efficient way to provide such low voltages at such
high power levels directly from the PSU.

The 5 volt standard is unlikely to vanish from the desktop (or even
notebook) PC any time soon since it's such a useful voltage to power USB
kit and internal peripherals. The time of its eventual demise in whatever
new PSU standard that will eventually replace the now venerable ATX
standard, is likely to coincide with the loss of the 3.3 and -12 volt
rails (the -5v rail disappeared from the ATX spec a few years ago now),
reducing the supply rails down to a single 12 volt rail (probably split
into separately monitored groups to allow detection of overloads that
could potentially melt a wire if such protection was solely reliant on
detecting, for example, the 30 odd amp's worth of overload that would be
needed to trip a 360W rated PSU).

Enthusiasts of low power ITX kit have been using this "Single 12 volt
rail PSU" concept for a few years now (and it's a technique that's not
just limited to ITX kit, it can be applied to low and medium power ATX
machines just as effectively).

In this case, special ATX 20 and 24 pin MoBo psu connectors complete
with switching converters to provide the -12v, the 3.3 and the 5 volt
rails powered by the single 12v supply which also directly feeds the 12v
pins allows the machine to be powered from a high efficiency 12v power
brick not unlike a high power laptop charging brick (usually rated
somewhere in the region of 90 to 120 watts output).

Additional switching converter power modules may be needed to power up
peripherals such as SSDs and HDDs, I can't recall whether the ATX adapter
header allowed for the extraction of the 5 and 3.3 volt (and 12 volt) to
power such peripherals or not. In a low power setup, this could be a
useful option otherwise excessive demands on the 3.3 and 5 volt rails
would best be served by additional converter modules (assuming the 12v
power brick can take the additional strain, of course).

An updated single rail PSU scheme would see main boards with power
conversion modules already built in to locally generate any 5 or 3.3 or
-12 (or even -5) volt rails to power their circuitry. Such main boards
could therefore still provide the standard 5 volt power to their USB
ports.

A change to single rail PSUs won't necessarily signal the demise of the
5v standard. There are no clear signs of it disappearing for another
decade or three since it's such a useful low voltage DC voltage source to
power the logic chips inside of most peripheral devices or gadgets with
modest power requirements.

Any such USB connected peripherals with power demands in excess of the
classic 2.5W limit are probably better powered from a dedicated PSU
rather than be allowed to add additional stress on the PC's PSU anyway.

The USB3 power management protocol that allows (IIRC) for up to 30 watts
to be drawn by a peripheral is a feature I find rather troubling. I
suppose if the feature can be limited or disabled in the MoBo setup when
there's an obvious overload risk to the PSU chosen to power the system,
it would be ok otherwise I'd be concerned that plugging in a 'greedy' usb3
peripheral could end up triggering a catastrophic power outage event.

--
Johnny B Good

[Johnny B Good]

On Wed, 08 Mar 2017 17:09:58 +0000, Roderick Stewart wrote:

> On Wed, 08 Mar 2017 11:42:21 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
>
>>> >>I'm not sure how 5V became the standard for USB power.
>>> >
>>> > TTL logic must figure strongly in the answer.
>>
>>> It's a while since I did electronics. Is 5V (or thereabouts) based on
>>> physical properties of the silicon for the transistors in TTL? I
>>> probably knew this at one time...
>>
>>I'm trying to recall if RTL or DTL used 5Volts. I did briefly use some
>>RTL/DTL as an undergrad.
>
> Yes they did.
>
>>But yes, IIUC the old TTL standard devices tended to be quite fussy
>>about the rail voltage.
>
> I've always assumed 5V was chosen simply because it's easy to produce
> from a 6V battery.
>

That wasn't the reason. I think 5 volt was chosen because it was a nice
round number and a voltage close enough to the optimum (whatever that was
at the time).

As regards this 'myth of fussiness about rail voltage', there's no basis
in fact for this. Provided the voltage rails were properly decoupled to
suppress noise artefacts and also properly regulated, the Vcc rail had a
tolerance of +/-10% (4.5 to 5.5 volt) range over which the TTL chips were
guaranteed to meet all their specifications in full.

It's no accident that the 5v rail in the PC, AT and ATX specs all
mandate a +/-5% tolerance to guarantee that the TTL would never be asked
to operate outside of its voltage tolerance limit.

As for burning TTL devices out with excess voltage, they were specced to
withstand a maximum of 7 volts for 10 seconds or less. That 7 volt limit
represents a 40% over-volting event which seems quite generous
considering that they're intended to be powered from a regulated noise
free 5 volt source maintained to a +/-5% tolerance rather than directly
from a set of four AA carbon zinc torch cells.

[1] A specification claim that was mirrored in the cmos versions of the
original TTL logic family - in this case a generously conservative claim
- it needed the 5VSB rail on the 'Silent Assassin' versions of those
infamous Bestec PSUs used in E-Machines PCs, to go to 8 or 9 volt,
usually overnight (unless you were in the habit of switching the mains
power off), before the cmos based chipsets finally started to fail (in
subtle and interesting ways to begin with).

--
Johnny B Good

[Johnny B Good]

On Tue, 07 Mar 2017 23:11:59 +0000, Graham C wrote:

> On Tue, 7 Mar 2017 20:37:00 +0000, Bill Wright <wrights...@f2s.com>
> wrote:
>
>>So many things run on 12V DC. Firstly, why has that become the standard?
>>Is it all because of the nominal voltage of a car battery?

>>Secondly, wouldn't 24 or 48V be more convenient for many things?
>>
>>Bill
>
> Slightly OT but I've been trying for years to find the reason behind
> airfield runway lighting which is standardised at 6.6 amps.
>
> Because of the high power necessary these are wired in series to cut
> down on conductor requirements and provide constant brightness down the
> line. Most are dimmable but 6.6 amps corresponds to 100% brightness.
> Clearly the wattage of the bulb determines the brightness.
>
> Originally during WWII each lamp was fed from a 1:1 transformer which
> continued the circuit if a bulb filament failed. There were also
> 'thin-paper' cutouts and later zener type devices used to maintain the
> circuit in the event of a lamp failure.

Presumably the transformer would go into saturation when the lamp
filament failed open circuit.

What exactly are "'thin paper' cutouts"? I've never come across this
phrase before and google is no help, not even when I give it the
"electric light" hint.

>
> Even by the end of WWII constant current regulators were in use with the
> thin-paper cut-out system to prevent the system going into 'domino
mode'
> if one, then two, then three lamps fails etc.
>
> But why 6.6 amps?
>
>
I'm guessing this is a compromise between filament thickness and length
and lamp contact ratings along with copper costs in the power
distribution.

A 6.6 amp filament is a pretty thick and robust filament that can
provide a few thousand hours of service life at a reasonably good
efficacy. Given the constant current drive, this not only allows
surviving lamps to continue working without being overstressed, it also
greatly enhances the life of the lamps by eliminating or significantly
reducing the switch on "Inrush Current" that such a lamp would otherwise
be faced with if used on a constant voltage low impedance supply.

The current rating of a lamp is a critical parameter in a system whereby
a string of such lamps are operated in series (constant current generator
or not). For a given best efficacy and specified lamp life, there's an
optimum power level for any chosen filament voltage (filament length)
(or, if you prefer, an optimum filament voltage for any chosen power
level).

Do you happen to know the lamp wattage (and type)? I think there are
graphs of optimum voltage versus power rating for various filament lamp
types somewhere on the net. I'd be very surprised if those lamps aren't
somewhere on the optimum plot line of those graphs.

--
Johnny B Good

[Woody]

Nice to see JBG is back to usual length standards. I thought he must
have been ill with a one-liner last week!

[Graham.]

What are the limits of the US "AM" band? In the distent past I have
owned sets with CONELRAD markings and I don't recall any extra tuning
range. I know they use 10kHZ spacing.




--

Graham.
%Profound_observation%

[sp...@potato.field]

On Fri, 10 Mar 2017 10:34:55 +0000
Graham. <graham...@mail.com> wrote:
>What are the limits of the US "AM" band? In the distent past I have
>owned sets with CONELRAD markings and I don't recall any extra tuning
>range. I know they use 10kHZ spacing.

Perhaps he means station bandwidth limits - US stations go up to 5Khz whereas
in europe its 4.5. AFAIK the actual band itself is the same width.

--
Spud

[Ian Jackson]

In message <o9u0i4$1dt5$1...@gioia.aioe.org>, sp...@potato.field writes

US stations are spaced at 10kHz, and Europe are 9.

As for CONELRAD:
https://en.wikipedia.org/wiki/CONELRAD
At one time, US radio amateurs were obliged (when operating) every 10
minutes to monitor one of the CONELRAD frequencies and, IIRC, to close
down immediately if an alert was being broadcast. My first ARRL handbook
(in 1960) had a section devoted to an add-on device that automatically
interrupted what the amateur was doing, and indicated the presence of an
alert.
--
Ian

[sp...@potato.field]

On Fri, 10 Mar 2017 11:25:14 +0000
Ian Jackson <ianTAKETHI...@g3ohx.co.uk> wrote:
>In message <o9u0i4$1dt5$1...@gioia.aioe.org>, sp...@potato.field writes
>>On Fri, 10 Mar 2017 10:34:55 +0000
>>Graham. <graham...@mail.com> wrote:
>>>What are the limits of the US "AM" band? In the distent past I have
>>>owned sets with CONELRAD markings and I don't recall any extra tuning
>>>range. I know they use 10kHZ spacing.
>>
>>Perhaps he means station bandwidth limits - US stations go up to 5Khz whereas
>>in europe its 4.5. AFAIK the actual band itself is the same width.
>>
>US stations are spaced at 10kHz, and Europe are 9.

And divide by 2 for each sideband you get a max bandwidth of 5 and 4.5Khz
respectively.

--
Spud

[Woody]

<sp...@potato.field> wrote in message
news:o9u2kd$1i3a$1...@gioia.aioe.org...

Actually not. There is a 1KHz guard space between slots, so the 9KHz
stepping is actually 8KHz of bandwidth.

In practice the audio response above 3K5Hz so was rolled quite steeply
off so the chances of adjacent channel interference were in theory
reduced.

[charles]

In article <tMA1EQEa...@g3ohx.co.uk>,

I remember buying a pocket radio in the 1960 and the dial had the 2
conelrad frequencies marked on it - no other stations, just rather crude
frequency markings

[Ian Jackson]

In message <o9u2kd$1i3a$1...@gioia.aioe.org>, sp...@potato.field writes

But spacing is not bandwidth.

10kHz spacing gives you a maximum audio bandwidth of 5kHz (which is what
you're referring to).

It should actually be a bit less to allow a bit of a guardband between
signals.

However, AIUI, in the USA, stations in the same area are spaced at least
20kHz apart, and this allows the audio spectrum to be the full 5kHz (or
even increased somewhat) while not causing undue sideband spatter over
far-off stations that are only 10kHz away. Whether modern
cheap-and-cheerful MW receivers are capable of making use of a bit wider
audio is questionable.
--
Ian

[sp...@potato.field]

Maybe in europe, but in the USA the AM stations had noticably better
fidelity than those in the UK when I was last there. Perhaps it was simply
better recievers or perhaps they're not so bothered about adjacent channel
interference especially given the AM stereo system they tried out which IIRC
required even more bandwidth.

--
Spud

[sp...@potato.field]

On Fri, 10 Mar 2017 14:08:54 +0000
Ian Jackson <ianTAKETHI...@g3ohx.co.uk> wrote:
>However, AIUI, in the USA, stations in the same area are spaced at least
>20kHz apart, and this allows the audio spectrum to be the full 5kHz (or
>even increased somewhat) while not causing undue sideband spatter over
>far-off stations that are only 10kHz away. Whether modern

That makes sense.

>cheap-and-cheerful MW receivers are capable of making use of a bit wider
>audio is questionable.

Given digital tuners are switchable between 9 & 10Khz stepping, one would
assume in a decent set it would have switchable filters too.

--
Spud

[Woody]

<sp...@potato.field> wrote in message
news:o9ud59$76i$1...@gioia.aioe.org...

Is it that they are using a form of vestigial sideband as used by
something from Eire on 252KHz many years ago? In effect the radio is
slightly off tune which results in a perceived improved audio HF
response.

[Graham.]

While this is all very interesting, J.B.G suggested it was the entire
band that is wider, not a given channel.

This Wikipeadia entry suggests he is correct
https://en.wikipedia.org/wiki/Medium_wave

On 15 May 1923, Commerce Secretary Herbert Hoover announced a new
bandplan which set aside 81 frequencies, in 10 kHz steps, from 550 kHz
to 1350 kHz (extended to 1500, then 1600 and ultimately 1700 kHz in
later years).
So it would appear the US uses 550 - 1700kHz vs ROW
These would appear to be carrier frequencies, not band edges.


--

Graham.
%Profound_observation%

[Graham.]

On Fri, 10 Mar 2017 17:21:50 +0000, Graham. <graham...@mail.com>

wrote:

>On Fri, 10 Mar 2017 14:30:25 +0000 (UTC), sp...@potato.field wrote:
>
>>On Fri, 10 Mar 2017 14:08:54 +0000
>>Ian Jackson <ianTAKETHI...@g3ohx.co.uk> wrote:
>>>However, AIUI, in the USA, stations in the same area are spaced at least
>>>20kHz apart, and this allows the audio spectrum to be the full 5kHz (or
>>>even increased somewhat) while not causing undue sideband spatter over
>>>far-off stations that are only 10kHz away. Whether modern
>>
>>That makes sense.
>>
>>>cheap-and-cheerful MW receivers are capable of making use of a bit wider
>>>audio is questionable.
>>
>>Given digital tuners are switchable between 9 & 10Khz stepping, one would
>>assume in a decent set it would have switchable filters too.
>
>While this is all very interesting, J.B.G suggested it was the entire

>band that is wider, not a given channel.***

>
>This Wikipeadia entry suggests he is correct
>https://en.wikipedia.org/wiki/Medium_wave
>
>On 15 May 1923, Commerce Secretary Herbert Hoover announced a new
>bandplan which set aside 81 frequencies, in 10 kHz steps, from 550 kHz
>to 1350 kHz (extended to 1500, then 1600 and ultimately 1700 kHz in
>later years).
>So it would appear the US uses 550 - 1700kHz vs ROW
>These would appear to be carrier frequencies, not band edges.

***Correction:
I should have said "not *just* a given channel"
--

Graham.
%Profound_observation%

[Graham.]

On Fri, 10 Mar 2017 16:50:46 -0000, "Woody" <harro...@ntlworld.com>

That discussion about Atlantic 252 comes up from time to time. What
seems to have happened is the station started out on 251 KHz for the
first few months then moved onto its advertised frequency later
because of a regulatory change, standardising on a 9kHz channel
spacing. There was a weak Eastern European station co-channel, and as
there was no 1KHz heterodyne, this must have moved up at the same
time.

That's not to say there weren't asymmetric sidebands, I have read at
least one account by someone who was there that there were, but
whether this was achieved by deliberate filtering or a slightly off
resonance antenna, I don't know.

Whatever the truth is, it seems that a lot of people would have had a
period of 1KHz discrepancy in their tuning giving exaggerated "top"
and sibilance to the audio, In much the same way as Droitwich's
sojourn from 200 to 198 KHz did.


--

Graham.
%Profound_observation%

[Ian Jackson]

In message <o9uda1$7dp$1...@gioia.aioe.org>, sp...@potato.field writes

Unlikely.

In any case, no one expects hi-fi from MW AM.

That said, back in the late 60s, a New Zealand friend told me that FM
radio hadn't really taken off then, as their MW AM broadcasts had much
more bandwidth than in many parts of the world. This was because they
were so far away from anywhere (even Australia), and apart from the few
large cities, their own population was fairly sparse. As a result, their
broadcasters didn't need to worry too much about interference problems.
>

--
Ian

[Vir Campestris]

On 09/03/2017 21:36, charles wrote:
> In article <GNCdnVz9XYeIW1zF...@brightview.co.uk>, Vir
> Campestris <vir.cam...@invalid.invalid> wrote:
>> On 08/03/2017 12:44, The Other John wrote:
>>> On Wed, 08 Mar 2017 11:43:12 +0000, NY wrote:
>>>
>>>> And why is the standard film frame rate 24?
>>>
>>> Was it set by the Merkins? If so could it be because of their 60Hz
>>> mains? You would get 5 positive and negative mains peaks per frame if
>>> my sums are right, thus avoiding strobing effects.
>>>
>> Merkin TV is of course (almost exactly) 30Hz.
>
> It was once, but with the arrival of color it became 59.94Hz
>

Depends whether you count the interlaced halves as separate frames.

AFAIK it was never 30p, but was filmed at 29.97 or whatever it is and
then transmitted interlaced.

Andy

[Johnny B Good]

On Fri, 10 Mar 2017 17:21:50 +0000, Graham. wrote:

> On Fri, 10 Mar 2017 14:30:25 +0000 (UTC), sp...@potato.field wrote:
>
>>On Fri, 10 Mar 2017 14:08:54 +0000 Ian Jackson
>><ianTAKETHI...@g3ohx.co.uk> wrote:
>>>However, AIUI, in the USA, stations in the same area are spaced at
>>>least 20kHz apart, and this allows the audio spectrum to be the full
>>>5kHz (or even increased somewhat) while not causing undue sideband
>>>spatter over far-off stations that are only 10kHz away. Whether modern
>>
>>That makes sense.
>>
>>>cheap-and-cheerful MW receivers are capable of making use of a bit
>>>wider audio is questionable.
>>
>>Given digital tuners are switchable between 9 & 10Khz stepping, one
>>would assume in a decent set it would have switchable filters too.
>
> While this is all very interesting, J.B.G suggested it was the entire
> band that is wider, not a given channel.
>
> This Wikipeadia entry suggests he is correct
> https://en.wikipedia.org/wiki/Medium_wave

I should bloody well hope so! :-)

I know the MW band covers close to a 3:1 frequency range in the UK and
Europe but I thought I'd best verify the exact ratio used by checking
with wikipedia which also revealed that the Yanks now benefit from an
additional 100KHz tacked on at the HF end (I was already aware of the 9
and 10 KHz transmitter channel spacings).

Since the resonant frequency of a tuned circuit made up of discrete L
and C components varies according to the square root of the LC product,
relatively small variations in the frequency range expected to be covered
by tuning with either just the L or the C component requires that the
ratio of adjustment of either the L or the C component alone has to be
the square of the ratio of the band edge frequencies. For example to tune
a range with a 3.162 ratio requires a 10:1 ratio in the range of
adjustment of either the variable capacitor or inductor chosen to effect
tuning of the radio across the frequency band in question.

My point was that with such a wide ratio of tuning capacitance, it would
have the unfortunate effect of desensitizing the LF end of the MW band if
the aerial tuning circuit was tuned using a variable capacitor. The
variable inductor tuning method (permeability tuning) neatly eliminates
this effect, hence the reason for its use in AM car radios in preference
to a tuning capacitor.

--
Johnny B Good

[Ashley Booth]

I have a piece of equipment with a 1 volt supply line!!

--


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Graham.]

I had a Weller soldering gun years ago (basically a shorted turn in a
transformer) that had an un-measurably low voltage on any instrument I
had at the time.


--

Graham.
%Profound_observation%

[NY]

"Wolfgang Schwanke" <s...@sig.nature> wrote in message
news:pq11ao...@wschwanke.de...
> According to what you read online, there was a beat between the colour
> and sound carriers that made the picture unwatchable. They couldn't
> move the sound carrier, so they moved the colour carrier to avoid the
> beat. Since the relation between colour and b&w signal must remain
> fixed for the whole thing to work, the only way to achieve that was to
> tweak the entire vision signal slightly downward. In the European
> formats the numbers are different, so no beat and no need for a tweak.
> It has nothing to do with how the signals are modulated, only their
> frequencies.

So it was "only" necessary because of modulation for broadcast (but that's
how TV is distributed so it's rather critical!) and wasn't a problem with
baseband composite video?

Couldn't they have used a different sub-carrier frequency that was still
(n+1)/2 line frequencies (for some integer value of n), so as to move the
colour sub-carrier, when modulated for broadcast, away from the sound
carrier? Aren't the values of n, both for PAL and NTSC, fairly arbitrary
within a range of values, as long as the line-frequency-multiples of the
colour spectrum fit equidistantly between those of the mono signal (hence
the (n+1)/2*line_frequency).

I've not managed to find an explanation of why it was easier to tweak the
frame and line rate slightly rather than chose a different multiple of half
the line rate for the CSC.

[charles]

In article <MImdnR0j--z-qVnF...@brightview.co.uk>, NY

I imagine the National Television Systems Committee thought about all sorts
of things and found this to be the easiest solution to implement. It
happened over 60 years ago!.

[Mark Carver]

On 10/03/2017 17:53, Graham. wrote:
> On Fri, 10 Mar 2017 16:50:46 -0000, "Woody" <harro...@ntlworld.com>

>> Is it that they are using a form of vestigial sideband as used by
>> something from Eire on 252KHz many years ago? In effect the radio is
>> slightly off tune which results in a perceived improved audio HF
>> response.
>
> That discussion about Atlantic 252 comes up from time to time. What
> seems to have happened is the station started out on 251 KHz for the
> first few months then moved onto its advertised frequency later
> because of a regulatory change, standardising on a 9kHz channel
> spacing.

No, it started on 254 kHz, and moved (along with its co-channel and
adjacent channel neighbours) to 252 a few months after launch, due
to the last acts of the GE75 plan. The upper portion of the LF band,
was rearranged after the lower half, (the move of R4 from 200 to 198 etc)

It was always branded as 'Atlantic 252' from the outset to avoid confusion.

As far a US stations are concerned, their audio fidelity is far in
excess of European ones (IME). I think that there is much wider spacing
between services (both spectrum wise, and geographically !) So although
the channels are in 10 kHz steps, I suspect Tx bandwidth exceeds this.

--
Mark
Please replace invalid and invalid with gmx and net to reply.

[Mark Carver]

On 10/03/2017 20:37, Ian Jackson wrote:

>
> In any case, no one expects hi-fi from MW AM.

The Japanese had a good stab at it:-

https://www.youtube.com/watch?v=l_ZPx64E5I0

[Mark Carver]

On 11/03/2017 19:20, Mark Carver wrote:
> On 10/03/2017 20:37, Ian Jackson wrote:
>
>>
>> In any case, no one expects hi-fi from MW AM.
>
> The Japanese had a good stab at it:-
>
> https://www.youtube.com/watch?v=l_ZPx64E5I0

And

https://www.youtube.com/watch?v=YMAPKTnJtnA

[Graham.]

Thanks Mark. The synthesizer in the car radio that I had at the time
went in 1kHz steps on LW and 9KHz on MW

Do you think the asymmetric sidebands thing is a myth?
A way a person with a little knowledge of how the medium works might
reconcile what he thought was the carrier frequency with how it
sounded when tuning through the channel?

It wasn't just the frequency change that they were economical with the
truth, they never acknowledged their Irish roots on air,
(notwithstanding the accent of their presenters)

They also used to stress the "01" of the "010" international code, no
doubt to suggest to their young audience they were dialling a London
number, albeit with rather too many digits.


--

Graham.
%Profound_observation%

[Graham.]

On Sun, 12 Mar 2017 01:52:10 +0000, damdu...@yahoo.co.uk wrote:

>On Sat, 11 Mar 2017 23:29:15 +0000, Graham. <graham...@mail.com>
>wrote:

>
>
>>>>
>>>> That discussion about Atlantic 252 comes up from time to time.
>>>

>>>It was always branded as 'Atlantic 252' from the outset to avoid confusion.
>
>>
>

>>It wasn't just the frequency change that they were economical with the
>>truth, they never acknowledged their Irish roots on air,
>>(notwithstanding the accent of their presenters)
>

>Could that be because of RTE joining up with RTL to establish the
>station and initially at least it was regarded as a fresh although
>somewhat late attempt for RTL to again cover the UK with a commercial
>national music station that they had not done in daytime since the
>early 1950's when they removed English programming from long wave.
>RTL were the majority shareholder and it was to the evening Luxembourg
>service on 208 to which listeners were invited to tune when the
>station closed at 7pm in its early days.
>Always thought it a bit of a strange decision to do it with ILR
>already established by then, if it had been done at the end of the
>sixties following the demise of the pirates and before Radio One got
>separated from Radio Two it may have got better established.
>The name Atlantic 252 even gave a nod to that era though it is more
>probable that the recent popularity if not financial success of Laser
>558 also had an influence on that name especially as least one
>presenter Charlie Wolf had been on that station.
>
>In the end ISTR that the coverage was less successful than hoped with
>the signal only really being heard well in the North of Britain which
>was awkward for their London office and they had to pay a lot for a
>leased line to Ireland to hear the output.

>
>
>>They also used to stress the "01" of the "010" international code, no
>>doubt to suggest to their young audience they were dialling a London
>>number, albeit with rather too many digits.
>

>They phoned out heck of a lot in a more modern version of Lobby Lud
>AICMFP , happened to my sister when she lived up North .
>They rang a random number and said
>“What’s the phrase that pays?”
>and if you replied
> “I listen to Long Wave Radio Atlantic 252” you got some money though
>I can't remember how much .
>
>G.Harman

Yes, listening to 252 in London was a bit like receiving Westerglen in
Manchester, when Droitwich is off the air.


--

Graham.
%Profound_observation%

[Bill Wright]

On 12/03/2017 02:53, Graham. wrote:

> Yes, listening to 252 in London was a bit like receiving Westerglen in
> Manchester, when Droitwich is off the air.

As Hil and I looked round the British Cemetery in Normandy our stroppy
teenage daughter insisted on sitting in the van listening to Atlantic 252.

Bill

[Mark Carver]

On 12/03/2017 02:53, Graham. wrote:

> Yes, listening to 252 in London was a bit like receiving Westerglen in
> Manchester, when Droitwich is off the air.

It was bloody marvelous in North West Scotland, the only thing we could
consistently receive on the car radio touring around up there, though
the same 10 records over and over and over and over and over and over
and over and over and over and over and over and over and over and over
and over and over and over again got very tiresome, (Though that's Heart
FM's business model, so it works I assume)

[Mark Carver]

On 11/03/2017 23:29, Graham. wrote:

> Thanks Mark. The synthesizer in the car radio that I had at the time
> went in 1kHz steps on LW and 9KHz on MW

My car radio of the time went in steps of 9 kHz on Long Wave, but
....200-209-218-227-236-245-254..... So the '2 kc harmonisation' in
1988/9 wasn't very helpful !

> Do you think the asymmetric sidebands thing is a myth?

In short yes. I can't see any technical need for it, and Altantic 252
was a low cost enterprise, so producing asymmetric sidebands is going to
cost (one way or another)

[Paul Cummins]

In article <vu49cc5ghk9n9k2g6...@4ax.com>,

damdu...@yahoo.co.uk () wrote:

>
> In the end ISTR that the coverage was less successful than hoped
> with the signal only really being heard well in the North of Britain
> which was awkward for their London office and they had to pay a lot
> for a leased line to Ireland to hear the output.

I had surprisingly good reception in central Guildford, and Farnborough
at the time. Less good in a car, impossible on a personal stereo of the
vintage, and so there were far less 15-34 yr olds listening than they
wanted.

It woul be good to see it back on DAB nowadays, perhaps instead of one of
the "Global-Clone" pop stations. Who the hell listens to Heart Extra?

--
Paul Cummins - Always a NetHead
Wasting Bandwidth since 1981
Please Help us dispose of unwanted virtual currency:
Bitcoin: 1LzAJBqzoaEudhsZ14W7YrdYSmLZ5m1seZ

[Graham.]

On Sun, 12 Mar 2017 10:09:25 +0000, Mark Carver
<mark....@invalid.invalid> wrote:

>On 11/03/2017 23:29, Graham. wrote:
>
>> Thanks Mark. The synthesizer in the car radio that I had at the time
>> went in 1kHz steps on LW and 9KHz on MW
>
>My car radio of the time went in steps of 9 kHz on Long Wave, but
>....200-209-218-227-236-245-254..... So the '2 kc harmonisation' in
>1988/9 wasn't very helpful !
>
>
>> Do you think the asymmetric sidebands thing is a myth?
>
>In short yes. I can't see any technical need for it, and Altantic 252
>was a low cost enterprise, so producing asymmetric sidebands is going to
>cost (one way or another)

Sounds like your set achieved the asymmetry in the IF amp anyway.
Perhaps some listeners even prefered it that way.


--

Graham.
%Profound_observation%

[Ian Jackson]

In message <eikl3g...@mid.individual.net>, Mark Carver
<mark....@invalid.invalid> writes

>On 11/03/2017 23:29, Graham. wrote:
>
>> Thanks Mark. The synthesizer in the car radio that I had at the time
>> went in 1kHz steps on LW and 9KHz on MW
>
>My car radio of the time went in steps of 9 kHz on Long Wave, but
>....200-209-218-227-236-245-254..... So the '2 kc harmonisation' in
>1988/9 wasn't very helpful !
>
>
>> Do you think the asymmetric sidebands thing is a myth?
>
>In short yes. I can't see any technical need for it, and Altantic 252
>was a low cost enterprise, so producing asymmetric sidebands is going
>to cost (one way or another)

Weren't they using something like a new-fangled high-efficiency
'cross-field' aerial? If I understand things, this is something much
smaller than a full-size aerial, and has a much higher Q.

At 252kHz, the bandwidth of even a full-size aerial is pretty narrow,
and can be responsible for sideband roll-off - and hence a loss of 'top'
unless the TX audio is tailored to compensate.

I guess an even higher Q aerial could be deliberately off-tuned so that
one of the sidebands is favoured - and if so, this would be a cheap way
of achieving the desired result.
>
>
>

--
Ian

[Ian Jackson]

In message <nKV9XCB5$UxY...@g3ohx.co.uk>, Ian Jackson
<ianTAKETHI...@g3ohx.co.uk> writes

However - after some Googling - it appears that they used a conventional
aerial.
>>
>>
>>
>

--
Ian

[R. Mark Clayton]

On Sunday, 12 March 2017 13:41:20 UTC, Ian Jackson wrote:
> In message <eikl3g...@mid.individual.net>, Mark Carver
> <mark....@invalid.invalid> writes
> >On 11/03/2017 23:29, Graham. wrote:
> >
> >> Thanks Mark. The synthesizer in the car radio that I had at the time
> >> went in 1kHz steps on LW and 9KHz on MW
> >
> >My car radio of the time went in steps of 9 kHz on Long Wave, but
> >....200-209-218-227-236-245-254..... So the '2 kc harmonisation' in
> >1988/9 wasn't very helpful !
> >
> >
> >> Do you think the asymmetric sidebands thing is a myth?
> >
> >In short yes. I can't see any technical need for it, and Altantic 252
> >was a low cost enterprise, so producing asymmetric sidebands is going
> >to cost (one way or another)
>
> Weren't they using something like a new-fangled high-efficiency
> 'cross-field' aerial? If I understand things, this is something much
> smaller than a full-size aerial,

which can be anything up to a mile long!

> and has a much higher Q.

Well my watch, which is about 25 - 30mm across successfully manages to received 60kHz (about 5km wavelength!)

>
> At 252kHz, the bandwidth of even a full-size aerial is pretty narrow,
> and can be responsible for sideband roll-off - and hence a loss of 'top'
> unless the TX audio is tailored to compensate.
>
> I guess an even higher Q aerial could be deliberately off-tuned so that
> one of the sidebands is favoured - and if so, this would be a cheap way
> of achieving the desired result.

fifty years ago, I made my first radio. It was MW, and used a ferrite rod with a coil (that I wound myself). Tuning was achieved with a variable capacitor. It had AF transistor amplification. I later made a crystal set with a small piece of galena, I found out while walking in the Ochils. It worked, but worked better with an OA81.

> >
> >
> >
>
> --
> Ian

[martin...@googlemail.com]

On Tuesday, 7 March 2017 20:37:01 UTC, wrights...@aol.com wrote:
> So many things run on 12V DC. Firstly, why has that become the standard?
> Is it all because of the nominal voltage of a car battery?
> Secondly, wouldn't 24 or 48V be more convenient for many things?
>
> I heard a few years back something about new cars being 48V in the near
> future. Did it ever happen?
>
> Bill

+24v DC is used as the de facto standard for LV industrial controls, such as robots, logic controllers, relays etc. Many controls companies (such as Siemens) produce SMPSs with +24v DC output.

I recall that some car manufacturers making cars with lots of electrical gizmos such as high end Mercs were thinking of using 42V as a way of increasing the overall electrical energy available.

MR

[R. Mark Clayton]

Weight and cost of the wiring rather more.

>
> MR

[Graham.]

First they came for our spare wheels, and I did not speak out-
Then they came for our copper...
--

Graham.
%Profound_observation%

[NY]

"Graham." <graham...@mail.com> wrote in message
news:sb0gcc5ks7u7gqlqq...@4ax.com...

> First they came for our spare wheels, and I did not speak out-
> Then they came for our copper...

The fact that most cars either do not have a spare wheel or else have one
that can only be used for a max of 50 miles makes one tremendous assumption:
that punctures only happen during the opening hours of tyre-replacement
shops and that you have the time to detour to one and wait (and wait) until
the shop can repair/replace the tyre (and if replacement is needed, that
they have one in stock).

Twice I've had a puncture as I have been about to set off or have been half
way through a journey on a Sunday evening, when no tyre repair/replacement
shop would be open. Luckily both were in the days of a proper full-size
spare wheel which can run as far and as fast as the four wheels that are
normally on the car.

In both cases, I could resume my journey within the ten minutes max that it
took me to change the wheel.

Nowadays I'd have been utterly stuffed: either I'd not have been able to set
off until the following day (when the tyre place was open) meaning I'd have
had to take half a day off from work, or else I'd have had to arrange to
stay overnight somewhere in unfamiliar countryside because I wouldn't have
been able to travel the remaining 150 miles on a tyre that is only safe for
up to 50.

I would like to see it made mandatory for all cars to be designed so they
can be fitted with a full-size, full-speed, unlimited-mileage spare, to
avoid people being stranded half-way through a journey. It should have the
same tyre as the four running ones, with the only difference being maybe
steel rather than alloy.

Sadly it isn't even to choose a car nowadays on the basis of whether it has
a full-size spare, because almost *no* cars have them - there is no choice.

A puncture should be no more than a few minutes' inconvenience, not a
change-of-plan crisis.

[sp...@potato.field]

On Tue, 14 Mar 2017 15:13:06 -0000
"NY" <m...@privacy.net> wrote:
>I would like to see it made mandatory for all cars to be designed so they
>can be fitted with a full-size, full-speed, unlimited-mileage spare, to
>avoid people being stranded half-way through a journey. It should have the
>same tyre as the four running ones, with the only difference being maybe
>steel rather than alloy.

The thing is that tyres tend to be a lot more puncture resistent these days
than they used to be even a few decades ago when running over some broken
glass could knacker the thing. Also people had a habit of never changing
the spare and often you'd have someone change the tyre then carry on
barrelling down the motorway on tyre way past its use by date and if its
one mounted under the car both wheel and tyre could have been subjected to all
sorts of projectile damage over the years.

And then of course, how many people can actually change a spare? Plus on
motorways and fast A roads its almost suicidal to try.

--
Spud

[charles]

In article <7_2dnUSILdPvlVXF...@brightview.co.uk>, NY

on the other hand

tyres have come a long way since I started driving. But - the potholes
have got worse.

[sp...@potato.field]

On Tue, 14 Mar 2017 15:49:40 +0000 (GMT)
charles <cha...@candehope.me.uk> wrote:
>tyres have come a long way since I started driving. But - the potholes
>have got worse.

Potholes are usually only a problem for idiots with low profile tyres and
sports (read: rock hard) suspension. With decent sidewall depth and normal
suspension travel then short of driving over a bomb crater most cars should
be ok.

--
Spud

[charles]

that's fine if you can see them, but when the road is wet, you don't know
if it's just a puddle or a hole.

[NY]

<sp...@potato.field> wrote in message news:oa929t$sci$1...@gioia.aioe.org...

> On Tue, 14 Mar 2017 15:13:06 -0000
> "NY" <m...@privacy.net> wrote:
>>I would like to see it made mandatory for all cars to be designed so they
>>can be fitted with a full-size, full-speed, unlimited-mileage spare, to
>>avoid people being stranded half-way through a journey. It should have the
>>same tyre as the four running ones, with the only difference being maybe
>>steel rather than alloy.
>
> The thing is that tyres tend to be a lot more puncture resistent these
> days
> than they used to be even a few decades ago when running over some broken
> glass could knacker the thing. Also people had a habit of never changing
> the spare and often you'd have someone change the tyre then carry on
> barrelling down the motorway on tyre way past its use by date and if its
> one mounted under the car both wheel and tyre could have been subjected to
> all
> sorts of projectile damage over the years.

Good points. It's a shame that even when cars had spare wheels they were
either inside the car (requiring the boot to be emptied so you can lift out
the lining and the tyre) or else in a wire cage below the floor of the boot.
It would have been better if the tyre was slung in a solid housing below the
boot (as opposed to wire basket) to protect it from the elements and yet
make it easy to access.

Of course some cars (Zephyr Mark IV and French cars like Renault 16, 6 and 5
Mark I) had the tyre under the bonnet in front of the engine or else placed
in a cradle on top of the engine - very easy to get at, but rather at risk
of getting hot from the engine.

[NY]

<sp...@potato.field> wrote in message news:oa929t$sci$1...@gioia.aioe.org...

Certainly if it's an offside wheel it can be a bit hairy!

I can change a wheel in a few minutes as long as the gods are on my side and
I can get the spare out of the boot and find a solid bit of ground for the
jack (I carry a 6-inch length of floorboard to make a base for the jack on
soft ground). I once had to swap the front and rear wheels, which involved
six wheel changes, and was proud that I managed it in under half an hour -
but that was on my drive, in daylight.

The hardest part with a modern scissor jack is turning the crappy little
handle without taking the skin off my knuckles when the jack is close to the
ground before I've raised the wheel.

[Woody]

Pssst!

Buy a Passat - they have a full sized spare (or did until the latest
version for which I cannot speak,) and if your wheels are alloy so is
the spare.

The downside in my case was that they fitted Continental SportsContact
5P ex factory which has a lining of soft semi-liquid rubber on the
inside of the tread. Run over a nail and the rubber seals the hole.
Great - you have no idea you ever had a puncture until the tyre
delaminates or disintegrates at 70mph (112Kph for Martin) on the smart
motorway!

Needless to say when I changed my tyres I fitted another make
(Goodyear Eagle F1 AS3 if anyone wants to know) which both improved
the grip and the ride and seem to be lasting significantly longer than
the Contis.


--
Woody

harrogate3 at ntlworld dot com

[charles]

In article <wrydnUA6TId3r1XF...@brightview.co.uk>, NY

storing the spare wheel under the boot made it very easy to steal - in some
cases.

And nowadays with alloy wheels and locking wheel nuts, where is the correct
socket stored?

[The Other John]

On Tue, 14 Mar 2017 18:31:47 +0000, charles wrote:

> And nowadays with alloy wheels and locking wheel nuts, where is the
> correct socket stored?

And alloy wheels need tightening to the correct torque - how many people
carry a torque wrench?

--
TOJ.

[NY]

"charles" <cha...@candehope.me.uk> wrote in message
news:561cceed...@candehope.me.uk...

> And nowadays with alloy wheels and locking wheel nuts, where is the
> correct
> socket stored?

Every car I've had with locking wheelnuts, I've kept it in the glovebox.
Essential where the spare tyre is mounted in a wire basket under the floor,
and I got into the habit of doing the same for cars with the wheel in a well
within the boot. Mind you, that's been a big box because as well as the
"key" you also get a get a set ordinary non-locking bolts where they've
removed one from each wheel to fit the locking bolt.