A magnetic field control system for a variable field NMR spectrometer.

The magnetic field specifications necessary for use as part of a variable field NMR spectrometer are outlined. Although the widely used commercial magnet systems provide a high degree of temporal field stability and accuracy, they are relatively costly. This publication describes a novel and inexpensive magnet power supply, with field control provided by a Hall effect device. The system has been used successfully to determine in vitro NMR relaxation times and the magnetization transfer characteristics of human thyroid and breast tissues.