| 摘要 |
MOTION DETECTOR A motion detector has an infrared sensor for detecting a moving infrared energy source and for generating a current which charges a timing capacitor. The timing capacitor is commonly connected to the threshold and trigger input terminals of one timer in a conventional LM 556 dual timer package. The discharge output terminal of the timer is used for flowing current to a light source or other indicator device. When the timing capacitor voltage exceeds the threshold reference voltage, the discharge output pin is rendered conductive, and the indicator device is rendered active. When motion of the infrared energy source ceases, the timing capacitor is allowed to discharge, and, when the capacitor voltage falls below the trigger reference voltage, the discharge output terminal is rendered non-conductive. A photocell is coupled to the control voltage input terminal of the timer for varying the threshold and trigger reference voltage levels in response to ambient light. In this manner, the light source or other indicator device will be rendered active only when the ambient is dark e.g., during night time. To latch the lights or other indicator devices in the active state, the trigger, threshold and reset input terminals of the second timer in the package are connected 80 that, when the power switch is turned off and then on in a relatively short time, the discharge output terminal of the second timer is maintained in a conductive state irrespective of the presence or absence of the moving infrared energy source. T14/8904-6
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