Abstract: A desensitized firing circuit has a pair of diodes, a resistor, and a sevble wire loop used in combination with an existing firing circuit. With the severable wire loop intact, current flow through the resistor is shunted to ground, and the circuit operates in a sensitive mode. With the loop severed, current flows through the resistor and one of the diodes to the base of an input switching transistor, thereby maintaining this transistor in a conductive state until a sufficiently large and properly shaped negative input signal is received.

Abstract: A pressure sensor for use with a sea mine for detecting the presence of a ssing vessel by sensing a change in ambient water pressure caused by the Bernoulli effect relating to hydrodynamic flow induced by the vessel's motion. The sensor emits a responsive signal which can be used alone, or with signals from other influence sensors (acoustic and magnetic), to determine when the sea mine shoud be exploded. The sensor provides for equal sensitivity independent of the ambient pressure of the water at various depths at which sea mines may be planted, and employs electrical filters to eliminate noise.