what I have learned today.

[T42]

That mains electricity in much of Norway it the IT system where the neutral isn't earthed. That's the system used for shaver sockets in the UK. The system in Norway causes problems with some appliances designed for elsewhere.

I've been in a computer room where the sockets on adjacent walls were on different circuits.  There was 100v difference between the two "earths". You had to be careful not to touch two housings at once.

[hellymedic]

American Wire Gage differs from Imperial SWG.

[Captain Nemo]

To navigate safely with map and compass, the needle needs to be weighted differently for use in the southern hemisphere from how it is weighted for use in the northern hemisphere.

Here in the northern hemisphere the lines of magnetic flux are dipping down to the magnetic north pole. To ensure the needle remains level and the bearing does not bind, the south end is weighted. If this type of compas is used in the southern hemisphere, where the lines of magnetic flux rise up towards the equator and the north, the needle bearing may bind.

A southern hemsphere compass is weighted at the north end of the needle.

[Mr Larrington]

That must be why the virtual compass in my virtual lorry was pointing at right angles to reality in a virtual Peru this afternoon

[mark]

To navigate safely with map and compass, the needle needs to be weighted differently for use in the southern hemisphere from how it is weighted for use in the northern hemisphere.

Here in the northern hemisphere the lines of magnetic flux are dipping down to the magnetic north pole. To ensure the needle remains level and the bearing does not bind, the south end is weighted. If this type of compas is used in the southern hemisphere, where the lines of magnetic flux rise up towards the equator and the north, the needle bearing may bind.

A southern hemsphere compass is weighted at the north end of the needle.

There are compasses designed to work in both hemispheres, but I’m not sure how they do this.

[Clare]

American Wire Gage differs from Imperial SWG.

Still doesn't explain American knitting needle sizes.

[Diver300]

To navigate safely with map and compass, the needle needs to be weighted differently for use in the southern hemisphere from how it is weighted for use in the northern hemisphere.

Here in the northern hemisphere the lines of magnetic flux are dipping down to the magnetic north pole. To ensure the needle remains level and the bearing does not bind, the south end is weighted. If this type of compas is used in the southern hemisphere, where the lines of magnetic flux rise up towards the equator and the north, the needle bearing may bind.

A southern hemsphere compass is weighted at the north end of the needle.

There are compasses designed to work in both hemispheres, but I’m not sure how they do this.

They have bearings that continue to allow rotation when one end or the other is trying to point downwards. That's a lot more difficult, so therefore expensive, than balancing the needle with a small weight and supporting it on a single pivot.

[orienteer]

What about compass for use on the equator?

IGMC

[hellymedic]

American Wire Gage differs from Imperial SWG.

Still doesn't explain American knitting needle sizes.

I'm unfamiliar with American knitting needles.
At least BRITISH SWG was the same for medical needles, bicycle spokes and olde crochet hooks knitting needles.

How do American knitting needles work?

[Clare]

UK knitting needles are sized according to SWG, a size 8 needle is the same diameter as number 8 wire (4mm near enough). 000 is the largest and 14 is the smallest.

US knitting needle sizes are the other way around so 0 is the smallest and 15 is the largest which doesn't have any correlation to AWG.


Things have got a lot easier since patterns started showing needle sizes in mm.

[Kim]

I'm trying to remember if I've knowingly come across SWG for actual wire.  Normally it's either AWG for the small stuff, or - more sensibly, because it's the value you're most likely to need for strength or resistance calculations - the cross-sectional area is quoted in square millimetres.

[Clare]

Over here number 8 wire is a national treasure.

[Captain Nemo]

What about compass for use on the equator?

IGMC

Good question! The deeper I look into the compass question, the more interesting it gets. It appears that compass manufactures consider three zones: northern, southern and equitorial. Presumably the "equitorial" versions do not have any bias weighting at either end of the needle.

It is all rather accademic since Silva do what they call "global" models (for use in both hemispheres) for about £60.

[Kim]

Over here number 8 wire is a national treasure.

Ah, of course it is (file with duct tape, WD-40 and cable ties).  For some silly reason I always thought that was AWG.

[Feanor]

I'm trying to remember if I've knowingly come across SWG for actual wire.  Normally it's either AWG for the small stuff, or - more sensibly, because it's the value you're most likely to need for strength or resistance calculations - the cross-sectional area is quoted in square millimetres.

I've come across it when specifying enameled copper wire for building ferrite rod antennas.

(The Ladybird Book 'Making a Transistor Radio' uses 50 turns of 36 SWG on a 3/8" ferrite rod...)

[T42]

Right enough, I ran into SWG around 65 years ago, making a coil for a crystal set. 3" former and N hundred turns.

[JonBuoy]

A different type of wire but piano wire as used in model making still seems to use SWG

[TheLurker]

I'm trying to remember if I've knowingly come across SWG for actual wire.

You need to build more toy aeroplanes; you can't move for piano wire in assorted SWG sizes.

[Cudzoziemiec]

But presumably not when it's used for actual pianos.

[Cudzoziemiec]

The word gangue. Valueless rock in which ore is found.

[hellymedic]

Right enough, I ran into SWG around 65 years ago, making a coil for a crystal set. 3" former and N hundred turns.

I'm fairly sure (as sure as you can be after >50 years) that SWG was specified in Ladybird book instructing brother how to build a transistor radio...

[Tim Hall]

Right enough, I ran into SWG around 65 years ago, making a coil for a crystal set. 3" former and N hundred turns.

I'm fairly sure (as sure as you can be after >50 years) that SWG was specified in Ladybird book instructing brother how to build a transistor radio...

Second mention of that book in a couple of weeks. lkingscott, from the hardcore brompton fettling thread, said it was a childhood influence.

I had it too. OC71. Jumpers for goal posts.

Online version here: https://worldradiohistory.com/BOOKSHELF-ARH/Technology/Making-a-Transistor-Radio-Ladybird%20Books-1972.pdf

[T42]

Right enough, I ran into SWG around 65 years ago, making a coil for a crystal set. 3" former and N hundred turns.

I'm fairly sure (as sure as you can be after >50 years) that SWG was specified in Ladybird book instructing brother how to build a transistor radio...

Second mention of that book in a couple of weeks. lkingscott, from the hardcore brompton fettling thread, said it was a childhood influence.

I had it too. OC71. Jumpers for goal posts.

Online version here: https://worldradiohistory.com/BOOKSHELF-ARH/Technology/Making-a-Transistor-Radio-Ladybird%20Books-1972.pdf

Crikey, how modern.  When I was 9 a school chum wrote in an essay that he had made a transistor set and the teacher not only crossed it out and wrote in transmitter but put transistor into the class list of howlers.  Alongside agobigoraphy, from a bloke who wanted to write his life story.

[hellymedic]

Right enough, I ran into SWG around 65 years ago, making a coil for a crystal set. 3" former and N hundred turns.

I'm fairly sure (as sure as you can be after >50 years) that SWG was specified in Ladybird book instructing brother how to build a transistor radio...

Second mention of that book in a couple of weeks. lkingscott, from the hardcore brompton fettling thread, said it was a childhood influence.
I had it too. OC71. Jumpers for goal posts.
Online version here: https://worldradiohistory.com/BOOKSHELF-ARH/Technology/Making-a-Transistor-Radio-Ladybird%20Books-1972.pdf

Thanks for that!

50 years...

[hatler]

What about compass for use on the equator?

IGMC

Good question! The deeper I look into the compass question, the more interesting it gets. It appears that compass manufactures consider three zones: northern, southern and equitorial. Presumably the "equitorial" versions do not have any bias weighting at either end of the needle.

It is all rather accademic since Silva do what they call "global" models (for use in both hemispheres) for about £60.

I'm pretty sure that compasses as used in the yachting world are made differently (in some way) if being used in high latitudes, something to do with the magnetic field applying less torque to the needle (or something).