| 摘要 |
A portable, self-contained underwater signalling device adapted to be worn by a diver. A waterproof housing has contained therein an acoustic sound generator, a power source and a three-position switch and circuit board connected in circuit between the power source and sound generator. The three-position switch provides an off or open position, a momentary on position and a full on position. The circuit board may vary the frequency of the signal output of the sound generator when the switch is in the constant on position to generate a pulsed frequency or a constant frequency.
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