Abstract: A bistable electronically controlled pneumatically powered transducer for use, for example, as a valve mechanism actuator in an internal combustion engine is disclosed. The transducer has an armature including a piston which is coupled to an engine valve, for example. The piston is powered by a pneumatic source and includes pneumatic and hydraulic damping as it nears its destination postion. The armature is held in each of its extreme positions by pneumatic pressure under the control of control valves which are in turn held in their closed postions by permanent magnet latching arrangements and are released therefrom to supply air to the piston to be pneumatically driven to the other extreme position by an electromagnetic arrangement which temporarily neutralizes the permanent magnetic field of the latching arrangement.