What I Want To Re-magnetize...

[crshears]

...is the wee little slugs that ride on the top of the mercury meniscus in a min/max outdoor gas thermometer; the one of them that's still working gets pushed up its column by the mercury, then when the Hg recedes there's just enough attraction between it and an adjacent ferrous plate to hold it there until I reset it using an external magnet to drag it down. The other slug, though, has lost some of its magnetism and falls with descending Hg.

Obviously I can't stroke a magnet within a glass capillary tube; would some manner of flashing via electromagnet do the trick?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[waross]

I may have to change my handle to Rube G. after this:
Make a coil of 8 or 10 turns of #10 wire. Use a 15 Amp fuse.
Center the magnet in the coil.
Hit it with 120 Volts and let the fault current blow the fuse.
You may want to contain this apparatus in a suitable container to avoid a possible mercury spill in case it goes sideways.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[crshears]

...um, thanks, Bill...gulp...hope I don't end up needing to call in a HazMat team...

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[Compositepro]

I very surprised there is still mercury in use on your site. We used to play with it as children, but there are so many restrictions now that the legal liabilities and expenses are high for mercury spills.

In the 5th grade I demonstrated a home made magnetizer at "show and tell" that was much as Waross described. It was a coil of about 16 gauge wire on a wooden board connected to two nails in the board. A strip of aluminum foil between the nails was the "fuse". When plugged into a wall outlet, the fuse blew, and any iron object in the coil was magnetized. Experiments like this were a monthly feature in Scientific American Magazine titled "the Amateur Scientist".

 

[waross]

If it goes really wrong, maybe you can make me a cowboy hat. grin

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[crthompson]

I don't know if you could use it or not, but, Harbor Freight sells a tool magnetizer/demagnetizer that may do the trick. FYI, I have no affiliation with Harbor Freight, just infatuation lol. It's probably just a magnet, but it may be worth a try for just a few bucks.

 

[MikeHalloran]

I have used demagnetizers to magnetize things like screwdrivers.
Instead of slowly pulling the screwdriver away, you just switch off the AC; what are the chances of doing so near a zero crossing? About one in five, in my experience.
But I love the elegance of using a fuse to cut the power; I shall have to try that someday.




Mike Halloran
Pembroke Pines, FL, USA

 

[Sparweb]

"blowing fuses..."
I remember doing this but needing nothing of the sort. It was a while ago and memory fades... What I recall was sawing the transformer from a microwave oven in half and using only the primary. The current is high but does not blow the circuit breaker. Like MikeH said, it was hit and miss if the screwdriver would be magnetized or demagnetized, but it only took a few tries, and the job was done.

I don't know how this helps CRShears, unless he wants to wrap his mercury vial in something soft and strap it against the business end of the cut transformer core.

STF

 

[aussiejohn2]

Hi CRShears,
Can you magnetise the plate instead?
John.

 

[crshears]

Might that not cause issues with the slug that's still working correctly? Too much magnetism and I won't be able to drag that side back down...

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[crshears]

I very surprised there is still mercury in use on your site.

The "site" is on a porch / veranda post @ home; perhaps the OP should have been in the "hobbies" forum...

I sort of collect instruments, and possess:

1] a scientific mercury-filled thermometer in its original wooden box,

2] a thermocouple-based portable pyrometer,

3] three steam pressure gauges,

4] a motley collection of surplus meters scavenged from a decommissioned 230 kV transformer station I once worked at,

5] a pneumercator, retired from checking the level in a large Diesel fuel storage tank at that same site,

6] a megger, and

7] the hygrometer [with mercury-filled thermometers] that my late father used in the refrigerated stock storage room of our family-business egg grading station.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]