LONG_TURNOFF_DELAY

Published:2009/7/12 21:59:00 Author:May | From:SeekIC

Combination of timer, optoisolator, and bridge-triggered triac keeps AC motor or other device energized for up to 1 h after control switch is depressed momentarily. Closing of switch drops voltage at pin 2 of timer below 1/3 VCC, making timer output go high and thus tum LED on. At same time, capacitor at pin 7 begins charging. Output re-mains high until oapacitor reaches 2/3 VCC, when outputis reset to low state and motor thereby turned off.-T Mazur,Solid-State Relays Offer New to Soutions to Many Old Problems, EDN Magazine， Nov 20,1973,p 26－32.



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