An apparatus and method for a ventilator system which may be operated over a high range of frequencies from zero (0) to fifty (50) hertz as may be predetermined. A high frequency oscillator (14) has a pneumatically operated piston drive device (16) which may be operated at a predetermined frequency, a predetermined stroke length, and at a predetermined ratio between the time periods for the pressure stroke and the suction stroke. The piston (76) is operated from a plurality of solenoid operated valves (91). A microprocessor (92) controls the electronic operation of the valves (91) by suitable output signals.
