Telephone pager alarm enhancement and method therefor

摘要

Vibration of a pager is sensed by a piezoelectric crystal. A buffered output of the crystal is connected through a low pass filter to an input of a retriggerable monostable multivibrator having a period of approximately twenty milliseconds. In response to the twenty millisecond multivibrator being retriggered to provide a recognition pulse having a duration of approximately three seconds, a latch is set. An output of the latch drives an LED circuit that provides a visual indication of a page. In response to the latch being set, an astable multivibrator provides alarm pulses having a duration of approximately eight seconds with a thirty second interval therebetween. The output of the latch and the output of the astable multivibrator drive an audio alarm circuit through a selector switch. When the switch is thrown in one direction, the setting of the latch causes the alarm circuit to provide a continuous audible sound. When the switch is thrown in the other direction, the setting of the latch causes the alarm circuit to provide eight second bursts of sound at thirty second intervals.