| 摘要 |
A scatter type of smoke detector wholly supplied by a dry cell battery includes a clock circuit applying energy pulses to an LED light source which directs light pulses on a smoke sensing path. Light pulses scattered by smoke generate detection pulses in a photo diode whose amplitude is dependent on the smoke density. The clock pulses and detection pulses are applied to a control circuit including a dual, data-type flip-flop logic circuit and a threshold circuit driving an alarm horn. If the smoke density, and hence the detection pulse amplitude, exceeds a predetermined level the control circuit energizes the alarm in a continuous mode. If the battery drops below a preselected level the control circuit is actuated in an intermittent mode.
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