"Clifford Heath" wrote in message
...
On 26/3/20 8:47 am, Jim Wilkins wrote:
"Clare Snyder" wrote in message
...
On Wed, 25 Mar 2020 17:47:35 +1100, Clifford Heath
wrote:

On 15/3/20 8:25 am, Cydrome Leader wrote:
Has anybody remagnetized a rotary on-off mag base before? I was
thinking
about a large capacitor and some turns of wire on EI transformer
core
with the Is removed and the indicator base across the center and
one side
leg.

How are these magnetized at the factory?


Is this a mag base to mount an antenna on a car roof?

Why not get a bunch of old hard drive (rare earth) magnets, and
just
epoxy them onto the bottom of the existing mag base, and cover
with
some
thin felt for protection?

Clifford Heath
I was thinking he was talking about a mag base for a dial
indicator.

https://www.amazon.com/Indicators-St...ode=4989304011

The rotary switch that turns the magnetic pull on or off is
essential
for many machinist uses.



Yes, right, I've used those also. It wasn't clear which you meant
though.

I didn't specify the magnet or how to build the coil because I don't
have that sort of experience, beyond being an operator.

https://www.versci.com/cwnmr/index.html
The solid cabinet holds the huge electromagnet and the desktop is a
pen plotter for the output.

"This is also the basis of magnetic resonance imaging (MRI.). It
should be called "NMRI" but some people don't like that word
"nuclear."

"Signal averaging often meant scanning overnight."

Actually the output was quite clean after I spent half an hour
fine-tuning the machine. The 14,092 Gauss magnetic field needed to be
uniform across the sample to within something like 1 part in a
billion. Earth's magnetic field is about 1/2 Gauss.

As the only undergrad with an NSF summer research grant I was assigned
the after-midnight shift. After a few nights I got used to walking the
streets of a dark, deserted world.