On 10/02/2011 20:33, geoff wrote:
>
> Or a pacemaker (not in his leg) ...
>
>
> http://cgi.ebay.co.uk/NEODYMIUM-MAGN...0622401713?pt=
> LH_DefaultDomain_3&hash=item2a0def20b1
>
>
> couldn't resist that one
>
> delivery 4-6 days
>

Different league, but I got some Neodymium notice board magnets from
eaby to replace the rubbish we normally have. Bloody great they are.

--
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#www.cuore-sportivo.co.uk

Using the patented Mavis Beacon "Hunt&Peck" Technique, Champ
<(E-Mail Removed)> typed
>On Thu, 10 Feb 2011 22:31:55 +0100, ofnuts <(E-Mail Removed)>
>wrote:
>
>>>>
>>>>http://cgi.ebay.co.uk/NEODYMIUM-MAGN...-/180622401713
>>>>?pt=LH_DefaultDomain_3&hash=item2a0def20b1
>
>>> Don't they make those medical insert thingies out of non-magnetic metals -
>>> like stainless steel or titanium?
>
>> Stainless steel is magnetic...
>
>But surgical steel mostly isn't.
>
>The various bits of surgical steel and titanium in my body set
>airports sensors off less than half the time I go through them. In
>fact, barely more often than they used to go off before I was part
>android.

Airport metal detectors don't rely on the metal being magnetic.

If you remember, the little metal detector I brought to France found
your tin leg quite successfully.

--
Wicked Uncle Nigel - "He's hopeless, but he's honest"

Contains moderate bullshit and simulated opinions.

Champ wrote:
> On Fri, 11 Feb 2011 13:34:59 +0000, Wicked Uncle Nigel

>> Airport metal detectors don't rely on the metal being magnetic.
>
> Well, whatever they do make them out of, they don't reliably go off.

There has to be some minimum threshold or they'd be going off from the
rivets in denim jeans, etc., essentially rendering them useless.

On Fri, 11 Feb 2011 16:01:09 GMT, Champ wrote:

>>Airport metal detectors don't rely on the metal being magnetic.
>
> Well, whatever they do make them out of, they don't reliably go off.

There's also an element of random selection. Which is better than racial
profiling and harder to beat.

<(E-Mail Removed)> wrote in message
news:ij244a$oua$(E-Mail Removed)...
> ian field <(E-Mail Removed)> wrote:
>>
>> > Stainless steel is magnetic...
>>
>> The stainless used by Kerry ultrasonics to make cleaning tanks wasn't.
>>
>> The very low grade stainless with higher ferrous content and lower
>> chromium
>> content for kitchen sinks & washing machine drums usually is.
>
> FWIW None of my pots & pans were magnetic enough to ork with an
> induction hob.


I thought that worked by eddy currents.

Like the drag cup in a speedo - its made of aluminium and not magnetic, but
the spinning magnet spinning next to it drags it round.

The drag cup is like a shorted turn so the energy imparted to it causes it
to move - if you locked the drag cup and spun the magnet fast enough the
energy would heat the drag cup, I sort of imagined that's how an induction
hob worked.

ian field wrote:
> <(E-Mail Removed)> wrote in message
> news:ij244a$oua$(E-Mail Removed)...
>> ian field <(E-Mail Removed)> wrote:
>>>> Stainless steel is magnetic...
>>> The stainless used by Kerry ultrasonics to make cleaning tanks wasn't.
>>>
>>> The very low grade stainless with higher ferrous content and lower
>>> chromium
>>> content for kitchen sinks & washing machine drums usually is.
>> FWIW None of my pots & pans were magnetic enough to ork with an
>> induction hob.
>
>
> I thought that worked by eddy currents.
>
> Like the drag cup in a speedo - its made of aluminium and not magnetic, but
> the spinning magnet spinning next to it drags it round.
>
> The drag cup is like a shorted turn so the energy imparted to it causes it
> to move - if you locked the drag cup and spun the magnet fast enough the
> energy would heat the drag cup, I sort of imagined that's how an induction
> hob worked.

My guess is the resistivity of the pots & pans is fairly critical to making
an induction hob work. According to Wikipedia, heating due to ferromagnetic
hysteresis accounts for at most 10% of the heating, the rest is from eddy
currents through the resistive bulk material.

http://en.wikipedia.org/wiki/Induction_cooker

On 11/02/2011 16:59, Mark Olson wrote:
> ian field wrote:
>> <(E-Mail Removed)> wrote in message
>> news:ij244a$oua$(E-Mail Removed)...
>>> ian field <(E-Mail Removed)> wrote:
>>>>> Stainless steel is magnetic...
>>>> The stainless used by Kerry ultrasonics to make cleaning tanks wasn't.
>>>>
>>>> The very low grade stainless with higher ferrous content and lower
>>>> chromium
>>>> content for kitchen sinks & washing machine drums usually is.
>>> FWIW None of my pots & pans were magnetic enough to ork with an
>>> induction hob.
>>
>>
>> I thought that worked by eddy currents.
>>
>> Like the drag cup in a speedo - its made of aluminium and not
>> magnetic, but the spinning magnet spinning next to it drags it round.
>>
>> The drag cup is like a shorted turn so the energy imparted to it
>> causes it to move - if you locked the drag cup and spun the magnet
>> fast enough the energy would heat the drag cup, I sort of imagined
>> that's how an induction hob worked.
>
> My guess is the resistivity of the pots & pans is fairly critical to making
> an induction hob work. According to Wikipedia, heating due to ferromagnetic
> hysteresis accounts for at most 10% of the heating, the rest is from eddy
> currents through the resistive bulk material.
>
> http://en.wikipedia.org/wiki/Induction_cooker
>

Don't they have to be *really* flat as well?

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 GTV TS GT 3.2 V6
Triumph Sprint ST 1050: It's blue, see.
#www.cuore-sportivo.co.uk

On Fri, 11 Feb 2011 17:05:51 +0000, Catman <(E-Mail Removed)>
wrote:


>> http://en.wikipedia.org/wiki/Induction_cooker
>>
>
>Don't they have to be *really* flat as well?

Where flat = as close as possible. Square laws and distance and ****.
--

steve auvache