Generalized de Bruijn graphs

We study the graphs of transitions between states of nonautonomous automata that provide, with independent equiprobable input signs, an equiprobable distribution on the set of all states in the minimum possible number of cycles, as is the case of the de Bruijn graphs corresponding to shift registers. It is proved that in the case of a binary input alphabet, there are at least $12r-33$ pairwise nonisomorphic directed graphs with $2^r$ vertices that have this property. All graphs of this type with 8 and 9 vertices are found.