Advice On Magnets Requested

[GB_Amateur]

New to this forum and I did some searching, but sorry if this has been covered before.  I'm going to buy some rare earth (neodymium) magnets to take prospecting, but want to make sure I don't do something stupid in the process.  I already have one (N52 cylinder, 1in X 1in) and know how powerful these can be.  They come in many sizes, shapes, and strengths (see CMS Magnetics website at www.magnet4sale.com for a huge selection).  My first concern:  is it possible to damage the electronics of a metal detector by getting too strong of a field closeby?

 

Second concern:  would getting too powerful of a magnet be a detriment in either cleaning up black sand or clearing a trashy areas of bits of iron?  I have one of those plastic encased plunger magnets that come with panning kits but it seems really wimpy.  But maybe wimpy is good for the purpose of cleaning out black sand at the end of panning and too strong of a magnet would be a problem?

[Tortuga]

I've got a bigger N52 magnet than what you have on the head of my pick. I'm sure it's not good to get it near the computer part of my detector so I'm just careful when I'm driving and stuff. Pick goes in the back, detector up front. I can't imagine it would do anything to the coil, just a bunch of copper wire in there.

As far as using too strong of a magnet to pick up black sand I don't think that's possible. The stronger the better. All the black sand I've collected on my magnet that's on my pick rubs off easily or I just whack the side of my pick (not the fragile magnet) on a rock and that does a good job of shaking the sand off.

[mn90403]

I have some magnets I use in my wire baskets that I use at the beach.  They collect a lot of my trash and black sand.  

 

A good thing to do is coat them before use because they do rust.  They are still useable but clean up is difficult on a rusty magnet.

 

I use my clean strong magnets with the magnet sticks you can buy at Harbor Freight when hunting for meteorites on dry lakes.

[Bear]

I tie a piece of type 3 nylon (550 cord) to my magnets and dip them in tool dip to keep them from chipping. If you do this pour the tool dip into a plastic cup because it will stick to the can!

[Glenn in CO]

We use a rare earth magnet on the end of cultivator for prospecting tailing piles, never had a problem with magnet near a searchcoil, but would not have it near a control box of the detector.

 

You might want to consider a magnet rake ( Harbor Freight has them) for metal detecting old sites that have a large amount of trash. We found Seated Coins, Indian Heads after removing the iron trash at a Railroad Stop that was in use in the 1880's.

[Steve Herschbach]

I like both the rake ideas above and think both would be good for various uses so I need to get on that. 

 

It is hard to have too powerful a super magnet. I have several I got from Doc years ago that are about 2" square and almost 1/2" thick that are scary powerful. They just rip nails from the ground. And some of the more smaller rectangular ones that are still bigger than the round disks. I have them on picks and in scoops. I think a box of cow magnets would be good along with a steel tine rake as in the post above.

 

I have never worried to much about getting them around my detectors but keep them away from your wallet. Good way to wipe every credit card instantly! The most serious danger honestly in handling super magnets is getting a finger just a little bit between one and some metal. Lots of blood blisters and outright ripped skin has come about from super magnets.

[jasong]

Some electronic devices could be damaged by a magnet even if they don't have magnetic storage media if you wave or move the magnet around. The faster it moves the higher the chance of damage.

 

As soon as you start moving a magnet then it's flux cuts different objects at a non-static rate. If that object happens to be a choke in the power circuit, or an inductor in the filtering circuit as is common with detectors, then you can induce voltage spikes. Semiconductors can be very sensitive to voltage spikes, especially microcontrollers, just a few volts too high can toast inputs, so newer detectors may be particularly susceptible.

 

If the magnet is strong enough, like the rare earth ones we put on our picks, then they'll be able to induce a not insignificant amount of current over just single wires or even PCB traces just like they do through inductors because a single straight wire is in fact an inductor too. Actually, I wonder how the new machines deal with the possibility of waving a pick magnet over the coil.

 

Anyways, it's probably not likely to happen, but moving powerful magnets around close to the control box in a rapid fashion could induce voltages high enough to toast semiconductors. Detectors have very poor shielding (well except the metal cased ones), if I put my cell phone up to the GPZ body it goes crazy (can also "hear" the gpz on a hand radio close enough to the case). So, a moving magnet will definitely induce a voltage in coils or wires inside it.