Abstract: An electronic closed loop servomechanism for sensing a physical force such as ambient pressure and electronically powered means for performing useful work controlled by said servomechanism. The servomechanism may be used in a breathing gas system such as scuba employing a demand regulator wherein conventional mechanical control components of the demand system are replaced with the servomechanism, including differential pressure sensing and electronically driven components. Also, the servomechanism may be used in a breathing gas system employing a pressure step down, datum input type of regulator, as in a scuba first stage regulator, wherein conventional components of the first stage system are replaced with the datum-input controlled servomechanism, including differential pressure sensing and electronically driven components.

Abstract: A collapsible spar buoy made of separable sections having a flag and requiring no conventional, additional float device. A central section and a base member entrap air to serve as a float. This central section houses all the other components when the buoy and flag are stored. The flag may be conventionally mounted or centrally mounted so that its mass is centered with respect to the mass of the buoy; thus the buoy and flag assume a vertical attitude in the water.