The Tekatch-Welch Magnetometer

Design Considerations

In building this magnetometer, we had several design goals:


Schematic

Component Links
Code for PIC16F876
Tcl/Tk Script for Viewing Data
Image Gallery
Note that the pictured circuit uses a MAX233 chip!

Results
January 6, 2004 - Things are working much better now! The magnetometer is currently sitting in a closed closet on the top shelf and the temperature changes are much reduced. Our plot below shows the difference signal between two FGM-3h's (red) and the temperature difference between the two LM92's (blue). A clean geomagnetic signal is seen! The approximate conversion between difference counts and nT is 6.7 difference counts per nT for two oppositely oriented FGM-3h's counted over an interval of 2*0.983 seconds. The Ottawa traces for the same interval are shown below ours. (Ottawa is 500 km northeast from our location.)