Attenuating permanent magnet field strength (for reed switch)

I have a 20 x 5 x 5mm bar magnet that is too strong for my application as the magnetic field strays outside the desired area activating other reed switches.

I tried searching for "soft iron" to create a magnetic shunt linking the North and South poles but all I could find was references to transformer laminations. Putting the magnet inside a ferrite donut will make it too bulky and mumetal is very expensive.

Does anyone have any suggestions for other materials I can try?

I wonder (never tried) if putting another magnet next to the current one but facing the other way will cancel some of the magnetic field?

Have you tried "short-circuiting" it with a thin strip of steel cut from a food tin. Mumetal is the ideal shielding material but somewhat difficult to come by now that "real" oscilloscopes using CRTs are few and far between.

Alternatively have you tried shielding the reed switch with similar sheet material. This will "desensitise " them but still permit them to operate.

If you visit your local office supply shop they may be able to offer very thin self adhesive magnetic strip or disks that might suit your application better than the lump unit you have

Mumetal is the ideal shielding material but somewhat difficult to come by now that

I new someone would put me right >:( >:( :grinning:

I agree with post #2.

mikb55:
I have a 20 x 5 x 5mm bar magnet that is too strong for my application as the magnetic field strays outside the desired area activating other reed switches.

I tried searching for “soft iron” to create a magnetic shunt linking the North and South poles but all I could find was references to transformer laminations. Putting the magnet inside a ferrite donut will make it too bulky and mumetal is very expensive.

Does anyone have any suggestions for other materials I can try?

iron or steel are perfectly fine for this. mumetal is complete overkill

I have a 20 x 5 x 5mm bar magnet that is too strong for my application

Am I the only one to be thinking "so try a smaller magnet" ?

AWOL:
Am I the only one to be thinking "so try a smaller magnet" ?

No your not the only one.
Don't use a super magnet and use a small ceramic magnet.
Even a couple layers of a tin can ( really iron ) may be enough.
Get your tin snips out.
Dwight