Ein besonders einfacher stromstabilisator höchster qualität für elektromagnete

A type of current stabilizer for magnet, used in nuclear magnetic resonance experiments (fig. 3), is described. A high dynamic stability (1:20 000 at 1.6 A, input voltage variations ±5%, load variations 10%) is obtained using a diode with a wolfram filament, which represents a stage with an extremely high amplification in the feedback loop. A high thermal stability is provided by means of a diode which is practically insensitive to normal room temperature changes, as it is evident from eq. (3).

In spite of a relatively high time constant of the heater filament—in connection with fig. 3—owing to the great inductance of the magnet, it is possible to obtain a very quick answer to sudden changes of input voltage.

Measurements were made with a precision potentio-meter of an accuracy 1:100 000 and results agree within 20% with theoretical considerations.