Light_controlled_one_shot_timer

Published:2009/7/24 4:57:00 Author:Jessie | From:SeekIC

Fig. 15-38 In this circuit, comparator A1 is used to sense a change in photodiode current, and A2 operates as a one-shot timer and is triggered by A1. The A2 output switches low for about 60 seconds after the light source is interrupted. The circuit operates at normal room-lighting levels. Circuit sensitivity can be adjusted by changing the values of the l-MΩ/2-MΩ resistors, but the ratio of these resistors should be constant. Figures 15-30B and 15-30C show the pin connections and electrical characteristics, respectively. Harris Semiconductor Linear & Telecom ICs. 1991. p. 4-22.



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