This project is built around fluxgate sensors and a gradiometer chip made by Speake & Co. in the UK. It is extremely easy to build and total parts cost is around $150, less if you have a good supply of surplus hardware. The article presented here was published in the May, 2000 issue of Poptronics magazine, the online version may incorporate subsequent revisions. The version currently posted is Revision 1.2.

The fluxgate sensors and chip used in this project are produced by Speake & Co. in the UK. If you live in North or South America, the distributor is Fat Quarters Software in California. Both addresses follow. Fat Quarters is also the sole distributor of PC boards and parts kits.