1. A MAGNETIC AMPLIFIER FOR CONTROLLING THE CURRENT TO A LOAD FROM AN ALTERNATING VOLTAGE SOURCE, COMPRISING A FIRST SATURABLE REACTOR CONNECTED IN SERIES WITH THE ALTERNATING CURRENT SOURCE AND THE LOAD, A CIRCUIT INCLUDING A SECOND SATURABLE REACTOR AND A SERIES CONNECTED RECTIFYING ELEMENT BOTH BEING IN PARALLEL WITH SAID FIRST SATURABLE REACTOR, AND A TWO-TERMINAL CONDITION-SENSING VARIABLE IMPEDANCE ELEMENT CONNECTED IN PARALLEL WITH SAID RECTIFYING ELEMENT AND IN SERIES WITH SAID SECOND SATURABLE REACTOR.