arranged electromagnetic actuators 42 44 which are independently connected to the blades 14 16 respectively and simultaneously driven by a control circuit not shown which is connected to preferably a dc power source not shown the actuators 42 44 respectively include coil assemblies 46 48 permanent magnets 50 52 and stationary armatures 54 56 both the actuators 42 44 are mounted in closely spaced axial relationship to each other on the 25 block 22 by upstanding support plates 57a c each of the coil assemblies 46 48 include excitation windings 58 wrapped about a plastic bobbin 60 the bobbins 60 are connected to the blades 14 16 the windings 58 are connected by the leads 62 to the control circuit the bobbins 60 are slidable on the stationary armatures 54 56 which are made of ferromagnetic material it will be appreciated that the supports 57a c limit displacement of the coil assemblies 46 48 the permanent magnets 50 52 are preferably of the rare earth type such as samarium cobalt and have their fields extending so as to encompass the coils in the illustrated embodiment they are arranged so that a north pole of the magnet 50 faces the coil assembly 46 while a south pole of the permanent magnet 52 faces the coil assembly 48 the coil assemblies 46.