How to tell if a magnet is alnico or ceramic?

[zaboomafoo]

Is it possible to tell if a magnet is alnico or ceramic, just by looking at it? I have one magnet which was in a humbacker pickup. It was sold as an alnico pickup, however I think it is not. Pickup was muddy, very hot (over 13K).

I have another ceramic bar, from a fender MIJ humbacker. That one is black. this one is bright in colour.

Thanks,
Frank

[Yves]

If it's black, it's likely that it is ceramic.
Alnico is a metal alloy, so it clearly looks like metal at least if it comes "polished".

Since it is a metal alloy, it conducts current as opposed to ceramic. So if you have doubt and have an ohm meter, you can test it this way.

[zaboomafoo]

If it's black, it's likely that it is ceramic.
Alnico is a metal alloy, so it clearly looks like metal at least if it comes "polished".

Since it is a metal alloy, it conducts current as opposed to ceramic. So if you have doubt and have an ohm meter, you can test it this way.

Thanks for the tip. I measured the magnet which I was not sure and it shows 0, so it must be alnico.

Interesting is that ceramic magnet gives reading of about 300k.

Now the next question - can I tell which type of alnico it is?

Thanks,
Frank

[David King]

You can try comparing the strength of it, fully charged, to some known magnets of the same size which are also charged to saturation. Alnico V will be quite bit stronger than Alnico II or III.

[kevinT]

Thanks for the tip. I measured the magnet which I was not sure and it shows 0, so it must be alnico.

Interesting is that ceramic magnet gives reading of about 300k.

Now the next question - can I tell which type of alnico it is?

Thanks,
Frank

It looks like you're measuing the magnet with an Ohm meter which won't work.

To measure the strength of a magnet you'll need a gauss meter.

Even then you generally would need the magnet fully charged to determine the grade and that would require a magnet charger. The reason would be you could have a weakened A5 that would measure as a a fully charged A2 for example... so you would generally need the mags fully charged to determine the grade. At least that is how I do it.

Some folks, I think possum, have used an LCR meter for that sort of thing as well.

[zaboomafoo]

It looks like you're measuing the magnet with an Ohm meter which won't work.

I used ohm meter to check if the magnet is alnico or ceramic, as David suggested. I was not trying to measure its strength.

I don't have all the tools for measuring it. I guess I could do a primitive test, maybe attach small piece of metal on a string and see how close I need to bring the magnet before it pulls it?

How much of a difference is when going from alnico 2 to 5 (both fully charged)?

[kevinT]

ow much of a difference is when going from alnico 2 to 5 (both fully charged)?

I did some readings a while ago comparing the different magnet strengths.

http://music-electronics-forum.com/t4515/

[David King]

One way to measure strength is with a stretchy spring tied to a hunk of iron inside a graduated glass cylinder.

Easiest way is start with a stack of small steel washers and see how many you can hold up with the magnet.

[Zhangliqun]

Ceramic magnets weigh a good deal less than Alnico's so hold a known Alnico in your hand and this magnet in the other.