| 摘要 |
There is provided a spindle-shaped two-part housing (10) comprising a battery compartment (11) and a working compartment (12), each formed of polyacetal copolymer of Shore D hardness 80. The respective housing portions (11, 12) are joined with threaded portions (14, 15) and sealed by O-ring (16). Each tapered outer end portion is pierced by a bore (17) intersected by an axial bore (21) passing into an end flat (20) to secure the apparatus to nets. The portion (12) has a floor portion (22) comprising a central end wall portion (23) and an annular land (24) that has adhesively bonded thereto the periphery of a piezoelectric sound generator assembly (27). Adhesively secured to an intermediate land (31) and extending across the bore is a circuit assembly (32) built on circuit board (33) and including programmable driver means for driving the piezoelectric sound generator assembly (27) via leads (33). The circuit assembly is powered via a pair of coaxial spring contacts (34, 35) contacting a battery and in response to immersion by water terminals (36). The circuit board (33) and the inner end of the female threaded portion (15) is filled with an epoxy resin encapsulant plug (37) of Shore D hardness 80, forming a resonant system with the housing (10) and piezoelectric sound generator assembly (27).. C-4 |
