PERSONAL ALARM APPARATUS

摘要

Alarm apparatus (10) which generates a repetitive sound wave (14) having at least two pulses of predetermined frequencies within a predetermined interval of time. A resonator (46) generates the clock frequency therefor. The resonator may have a low tolerance of less than about 0.1 percent so that at least two pulses may be detected by a receiver (16) having a similarly low tolerance. A plug (26) is inserted into the alarm housing (20) to maintain circuitry (12) for initiating operation thereof open. Pulling of the plug from the housing allows the circuitry to close to initiate operation of the alarm. A push button (140) is provided on the end of the plug to close the circuitry for initiating operation of the alarm while the plug is inserted into the apparatus. Once the alarm has been initiated, the circuitry is such that the alarm cannot be inactivated except by removal of the internal power source (30).