Super magnet effect on detectors and coils

[Hawkear]

At the request of my wife have recently bought a two door metal stationary type cabinet so that I can store ALL my prospecting gear in one place.
To retain the larger items - detector, coils I use super magnets with hooks stuck to the metal walls.
My question is however would the proximity of these super magnets to coils and detector control box have any permanent deleterious effect on them?
Maybe a question for the more electronically savvy of our members.
Edit I have since emailed Minelab for advice and will post any reply.

 

[user 12139]

GPX coils, no issue at all. However for the detector, if it has any sort of EPROM or RAM, the magnets may cause problems with loss of data. I’m not sure if the GPX uses non volatile mem, best to wait for ML to respond. Most detectors have memory of some sort so it’s good you asked

 

[Hawkear]

As usual in my experience got a quick response from Minelab Customer Care regarding my query about strong magnets and detectors.
They advised that the matter had been referred to their engineers and that the set up as shown in my photo should be fine.
What they did specify however was not to keep the detector directly touching the magnet as that could potentially cause issues although that would still be low risk.
That clarifies some nagging worries I had and am happier now.

 

[Hilux]

From what I understand when the magnets like the ones you have used are placed on a metal surface the flux path for the magnetic field is closed so very little external metal field remains. The flux or magnetic lines of force go out of the magnet face into the sheet metal. They travel through a short section of the sheet metal and then back into the periphery of the shield over the magnet. I can't remember what it is but there's a particular name for the cup over the back of the magnet.

The normal RAM/SRAM/NVRAM and other circuitry is impervious to static magnetic fields. I had to check but even the more recent FRAM (ferroelectric RAM about 10 years old??) is immune.

It's a different kettle of fish if the unit is turned on and strong magnets are moved around close by!

 

[bicter]

I can't remember what it is but there's a particular name for the cup over the back of the magnet

Mumetal ?

 

[aussiefarmer]

I had rare earth magnets on my pick , I seriously had to hold the pick above head height to stop warbles..
I see your concern and would be worried about circuit boards and batteries.
Better safe than sorry and pop rivet or screw hooks in..imo.

 

[Hilux]

Mumetal ?

Nah not Mumetal - I'd forgotten about Mumetal. It used to be used in old school CRT oscilloscopes around the tube. I think it was meant to be very expensive.

The back cup part is just soft steel and closes the magnetic loop rather than blocking it as such - thats how I understand it anyway!

There's some neat pics here of how the field is constrained;

https://www.kjmagnetics.com/blog.asp?p=mounting-magnets
Bugger, now I'm going to spend the rest of the night googling magnet stuff!

 

[grubstake]

I had rare earth magnets on my pick , I seriously had to hold the pick above head height to stop warbles..

I'm picturing you in the bush with your pick held high and anybody seeing you, running off in the opposite direction to escape the homicidal madman!

 

[Big Johno]

As usual in my experience got a quick response from Minelab Customer Care regarding my query about strong magnets and detectors.
They advised that the matter had been referred to their engineers and that the set up as shown in my photo should be fine.
What they did specify however was not to keep the detector directly touching the magnet as that could potentially cause issues although that would still be low risk.
That clarifies some nagging worries I had and am happier now.

Speaking of magnetic fields !
About 3 months ago I had a pacemaker, defibrillator all wifi controlled wired into me. the cardio gave me a list of what I couldn't do ie no arc welding over 100 amps etc. This troubled me as I have GPX 5000 with some big coils and a SDC so I contacted Minelab and they couldn't help me enough. They took the model number of my new toy and their engineer contacted the US company who makes them to discuss it with them. Result was it is a risk to detect with the big coils as the magnetic fields produced can effect the defiler, if using them I have to swing with the arm opposite to my defib unit and take extra care not to get my upper body directly above the coil while kneeling and using the scoop. Which I may add is a real pain, slows the day down greatly. BUT I can still get out there although my condition does play on my mind in remote areas like WA or Tibaburra etc

 

[Hilux]

Speaking of magnetic fields !
About 3 months ago I had a pacemaker, defibrillator all wifi controlled wired into me. the cardio gave me a list of what I couldn't do ie no arc welding over 100 amps etc.

I had a work colleague have the same implant Johno. He used to cross his unused arm across his chest when MIG welding - it did nothing but it mad him feel safer! He went on for year and nearly cracked the century. He was still welding and fabricating stuff well into his 90's!

 

[FindSumStuff]

The soft iron bar put across the magnet to short the magnetic field is called a keeper. It helps preserve the field strength of older style alnico magnets. Super magnets tend to permanently loose field strength when getting too hot say more than about 80 deg C. Especially a pain in stepper motors.

 

[Hilux]

The soft iron bar put across the magnet to short the magnetic field is called a keeper.

Keeper! That's the word. Cheers.

 

[larry303]

Big Johno, you are right to be wary..in 1998 a close mate in his early 50's had Pacemaker etc fitted....he was a Supervisor at Holdens at Elizabeth SA....he had reasonable recuperation period, and was fine...being a workaholic he went back to work which involved <apparently> standing next to, & walking past ,some of their huge manufacturing machinery..he died within a fortnight, while at work....I'm no Doctor ,however his widow told me they believe it was the magnetism in the massive motors responsible.....true story..he had always been a very fit 6' tall/thin bloke and had little inkling he needed a Pacemaker etc..he did a lot of walking in the Bush where I lived at the time..the irony was he was quite wealthy with numerous Investment Property's..he did not need to go back to work..his widow wished he hadn't...good luck...

 

[geof_junk]

Johno see if your ICD is capable of allowing a MRI if so I would not worry. However some ICD will give an alarm if it sense a strong magnet field. When it happen to me nothing showed up when the information from the ICD was downloaded. Magnets were a problem in early Pacemakers because they used reed switches, that not the case these days.

 

[jetz1984]

Just by the way, you are best to avoid massage chairs too if you have a pace maker. The chairs have strong magnets in them! Good luck