General. The pressure component which the Germans have successfully combined with their acoustic and magnetic firing units consists essentially of a pressure-detecting device which detects and operates on negative pressure differentials; an associated electrical cicuit is controlled by the device. When a negative pressure differential is de-tected by the device, a switch contact is made for the duration of the detected diffe-rential, provided that the actuation falls within the desing limits of the device.

The operational characteristics of the two type of pressure components are control-led, with the exception of sensitivity, by the arrangement and constants of the electrical circuit associated with each. These constants determine the period of circuit closure re-quired to record an actuation, and also determine whether the pressure component will be of the integrating or non-integreating type. Indirectly, they also determine the degree to which such disturbing effects as wave motion will affect the pressure component.