Conradi, Mark S., and Hilary T. Fabich. “Precision Current Regulator for NMR Electromagnets.” Journal of Magnetic Resonance 320 (November 1, 2020): 106830.
https://doi.org/10.1016/j.jmr.2020.106830
When using electromagnets or non-persistent superconducting magnets, the field stability can be directly proportional to the current stability. We present here a simple design for a current regulator based upon a high-precision, dc-dc fluxgate transformer. The output current and NMR frequency are stabilized by about a factor of 50, over times of order one hour. The method can be applied to essentially any current supply.