Very high permeability cores free to a good home

[Sengcid]

I have a number of Telcon size 12C (large) cores (perm > 200,000) to give away. Anybody fancy having a go at a DC current ratiometer using the fluxgate null detector technique (c.f. Guildline 15ppb DC resistance bridge)? Pls pm if interested.

[Echo88]

How would you go about realizing the null detector with an existing core as this needs a very special construction technique?
It should be possible to build a DCC-bridge by rewinding an existing DCC transducer (with already present zero flux core) like the Ultrastabs/Danfysik ones available used on ebay. Ive never continued this project though.
Happy to see if i can infect someone with the idea, who then realizes it 

[Sengcid]

I am having problems with the PM
The cores are SM200. See atttached.