[en] The slow extraction of a beam at the synchrophasotron with small time fluctuations became possible after constructing the following systems: stabilization of the magnetic field on a flat top to a sufficiently small ripple level at which the beam current feedback system begins to operate normally (with stability); operation of the additional winding located on the pole faces of the synchrophasotron magnet (active filter); an extracted beam feedback system. Last system changes the extraction velocity of circulating particles and also allows to choose the value of extracted beam current. The reached time homogeneity of the beam current when ace system are in use is about 90%. Now three systems are under operation. 15 refs.; 5 figs.; 1 tab