PI fast approaching VLF sensitivity

[Kev]

Hi,
Minelab's new patent to counteract solder joints eddys within the head. Reducing as much inherent machine noise as possible, note this method is for VLF also.
UXO testing on Minelabs a couple of years back showed poor ground handling in paleosols with high mag viscosity, common in former South East Asian battlefields. So this may be a move to improve performance in this and goldfields areas.

http://www.patentstorm.us/applicatio...14/claims.html

Cheers
Kev.

[golfnut]

kev I dont get it

what is this?


Steve

[Comp]

At a quick glance, it looks to me as i they coat any metallic bits in the head with a magnetic/ferrite coating, which 'shields' the metal from the magnetic field, and stops induced Eddy currents, and reducing sensitivity.....

{But I could be wrong, its fairly heavy going!!! LOL!!}

Cheers, Fred

[Kev]

Fred that's how I understand it too.
When you use thick multistrand wire as Minelab do on their PIs, you end up with 2 big slugs of solder in the head. It seems that only certain types of ferrite will do the trick. Nickel and aluminium ferrite composites would surely be out.

Cheers
Kev.

[golfnut]

they could use a miniature brass crimp ferrule instead !

[Kev]

Hi golfnut,
The brass will be as bad as solder, actually I wonder if RoHS solders have caused this to become more of a problem? That reminds me of some shield strips that are used for gaps around instrument cases, one type I was fiddling with is made of some sort of metal but are almost invisible to a PI. I don't know if I'd trust it inside a search head though, lots of bother if you get a bad connection.
HH
Kev.

[Skippy]

Surely copper-to-copper connections would work? Eg. copper crimps, spot-welds possibly?

[Mechanic]

Hi Guys,

Why not just solder and insulate each individual strand separately?

Cheers Mick

[Skippy]

I suppose because the coil wire is multi-strand enamelled, they are relying on the heat of soldering to burn off the enamel.

[Kev]

Hi Guys,

Why not just solder and insulate each individual strand separately?

Cheers Mick

Mick that is how we as home brewers could do it, but can you imagine them doing this in a production line setting, and when you consider you'd need to individually insulate each minor joint?
Even with Malaysian wages as low as they are it would take an army of girls?

HH
Kev.