Patent US 4,285,339

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.