Abstract: An arrangement for the production of a magnetic rotary field with the help of a crossed coil pair of separate capacitance connected across each of said coils to form respective parallel resonant circuits each of which is in series with a timing circuit, a controllable voltage source and a resonant circuit switch. A timing pulse succession is fed into a program generator which supplies two 90.degree. phase shifted groups of pulses respectively consisting of starting pulses, stopping pulses, and operational pulse successions. A first switching stage is controlled in each group by the starting and stopping pulses. The first switching stage is connected ahead of the resonant circuit in series with a controllable voltage source.