Abstract: A pulse generator for spark erosive machining of a conductive workpiece, including a d.c. voltage source, a switching element such as a switching transistor connected in circuit with an inductive coil and the work gap across the voltage source, and a high frequency transformer, where one winding of the transformer is connected in parallel with the voltage source and the other winding is connected in parallel to the series circuit consisting of the inductance coil and the work gap. When the switching element is turned on, a machining pulse is applied to the gap; when the switching is turned off, stored energy in the inductance coil is dissipated across the gap and, owing to the transformer connection, generates a recuperation current flowing into the voltage source. The switching element is preferably controlled on the basis of the magnitude of the current flow through the circuit.