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Going astray? hopefully we are not magnetic

Re: Going astray? hopefully we are not magnetic

Postby malky_c » Thu Feb 15, 2018 8:07 pm

Sunset tripper wrote:At least maps cant be given reverse polarity and if you are freezing to death in a bothy you can always light a fire with your map as a last resort.


I think you can get the same effect with a Samsung Galaxy smartphone...if it hasn't already self-combusted way before you reach the bothy :wink:
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Re: Going astray? hopefully we are not magnetic

Postby mynthdd2 » Thu Feb 15, 2018 9:11 pm

all a bit pointless anyway as the earths magnetic field is well overdue to flip..... what is the annual rate of field to grid (and vv) adjustment?
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Re: Going astray? hopefully we are not magnetic

Postby madprof » Thu Feb 15, 2018 10:27 pm

Dave Hewitt wrote:Not in themselves, but the electrics are when they're switched on, are they not? Certainly judging by the audible radio interference if a phone that's been left nearby gets an incoming call (a frequent problem with radio interviewees who are routinely asked by producers to turn off their phones before going on air), then I'd not want a "live" one anywhere near my compass. PS - My phone cover uses velcro!


The EM radiation given off by a phone call is nothing to do with it. If you are worried about your compass being exposed to electromagnetic radiation then keep it away from bright sunlight. :wink:

But...

I got my compass out and stuck it next to my Galaxy S8. Turned on, but screen off. Case (with magnetic clasp) removed.

Turns out it does deflect my compass. I am not sure if this is because the phone itself has had bits of its casing magnetised by the clasp over time, or whether the phone itself is doing it. Could be the wireless charging coils, I dunno.

Fact is I keep my phone in a case with a magnetic clasp and now I am going to keep my compass in the other pocket. Somewhat amusingly this is marked as the "phone" pocket, which is way too small to contain a modern smartphone.
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Re: Going astray? hopefully we are not magnetic

Postby Sunset tripper » Thu Feb 15, 2018 10:35 pm

Are there not magnets in mobile phone loudspeakers?
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Re: Going astray? hopefully we are not magnetic

Postby Dave Hewitt » Thu Feb 15, 2018 11:47 pm

madprof wrote:I got my compass out and stuck it next to my Galaxy S8. Turned on, but screen off. Case (with magnetic clasp) removed.

Interesting, ta. I've been experimenting too! I'm no scientist, so it's a case of doing a bit of empirical research and seeing what happens. Dug out an old compass that I don't use on the hill and brought the phone close to it, switched off. There was a deflection of around 20 degrees. Then switched on the phone and did the same thing again: bigger deflection, around 30 degrees. There was almost no deflection however if I brought the battery end of the phone close to the compass - it only happened with the top end which has the screen and what I assume is the receiving/transmitting device. On that evidence I'll certainly still be keeping the phone and compass in different places just as I've done until now.

I should add that it's not at all a smartphone - not 100% sure of the model but it appears to be a Nokia 1110i or something very similar. Think I've had it since at least 2007 and it does all I need it to do - have never fancied internet or mapping stuff on a phone on the hill.
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Re: Going astray? hopefully we are not magnetic

Postby rgf101 » Fri Feb 16, 2018 10:38 am

Sunset tripper wrote:Are there not magnets in mobile phone loudspeakers?

There are. I ended up with a reversed compass after a day of hiking with both compass and phone in the same pocket. Luckily I wasn't relying on it, and it was reversed back again with a little effort.

Even completely powered off my phone will make the compass needle swing about.
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Re: Going astray? hopefully we are not magnetic

Postby Cairngorm creeper » Fri Feb 16, 2018 11:48 pm

For a while we were foolish enough to attach the lanyard on the compass to the rucksack with a small metal karabiner. It was enough to put the reading out by a few degrees. My OH’s was worst than mine and he was most miffed that my bearings were consismore accurate than his. Luckily we never got into any serious difficulties over it but easily could have.
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Re: Going astray? hopefully we are not magnetic

Postby ChrisButch » Sun Feb 18, 2018 5:40 pm

If you have an Osprey daysack, the two small pockets, one on each side of the hip belt, are very useful for this purpose. Each has room for either a compass or a (small) phone but not both, so it's easy to carry them on different sides without the risk of them ending up in the same place accidentally.
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