| 摘要 |
A motion responsive alarm system including a motion sensor having a housing with a rotatable disk therein, a slot in the disk and a ball bearing in the slot and being loosely confined within an annular chamber in the housing surrounding the disk. The disk contains a plurality of orifices which pass between an LED on one side of the disk and a phototransistor on the other. A signal from the phototransistor is sent to a triggering circuit by interrupting light transfer between the LED and the phototransistor. The circuit includes a novel oscillator having a duty cycle of 10% which drives the LED in the sensor. An alternate state device is coupled to the sensor and the oscillator for generating alternate state outputs only during sensing of motion. A one-shot circuit generates a motion pulse each time motion is sensed. A pulse interval timer and gate determine if the pulses are to be gated to a timer or blocked. The timer is reset by these pulses and does not generate an alarm unless a predetermined period of time passes. The device may be coupled to a self-contained breathing apparatus and is energized only when the breathing apparatus mask is being worn by the user.
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