The system controls of a pneumatically operated valve using an electrical control signal from a controller. A pilot circuit of the system has multiple piezo valves that are subject to electrical signals from the controller to provide pneumatic output signals to a volume booster circuit of the system. Relatively small volume pneumatic pilot signals from the piezo valves are used to determine the opened or closed state of higher volume valve assemblies of the booster circuit which connect or disconnect the actuator of the valve to be operated with a source of pressurized gas. Both the piezo valves and the booster valve assemblies are subjected to gas at the same operating pressure, but the surface area of pistons in the booster valve assemblies exposed to the piezo valves is substantially larger than the surface area of the pistons exposed to operating pressure such that the pneumatic signals shift the pistons even when pressure is the same on both sides thereof. Both singe-acting and double-acting embodiments are disclosed, as well as alternative versions of booster valve assemblies such as having a primary piston and a secondary piston. The secondary piston permits partial flow while the primary piston permits full flow when actuated.