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Subject: Need help timing a analog circuit above a setpoin.
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Date: 12/13/02 at 11:58 AM
Posted by: M. Cryts
Hello! I have a circuit with a output of 0 to 3v.. I need to build a chrono display, basicly a stop watch that is driven by a setpoint within 0 to 3 v. For start as v. rises above setpoint and stop as it falls below setpoint. I have already tried a watch driving it with a window comarator and inverting the output with a npn trans. Had problems setting the window for reliability of the pulse to start and stop. If rise was too fast it would not start the timer. Widen the window and then a slow rise in input v. would at times go in the window and back out without crossing it completely sending the start pulse but not the stop. Would like a display and driver that is controled by a analog input to start and stop when above or below a setpoint. Can raise v. but needs to be small and low power. Thanks.
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