TWO_COLOR_LED

Published:2009/7/1 22:33:00 Author:May | From:SeekIC

Dual LED D2 shows green when normally off momentary switch S1 is moved to START and shows red when moved to STOP. Latching circuit using two 7404 TTL inverters setves as run and haltflip-flop and also debounces switch. Momentary contact at START toggles latch, biasing green LED, D1 shorts R2, leaving R1 to limit forward current to about 20 mA for green, R1 and R2 limit current for D1 and brighter red LED to about 10 mA for momentary contact at STOP.-E. W. Gray, LEDs Light Up Your Logic, BYTE, Feb. 1976, p 54-57.



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