traffic light circuit

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hami007

Joined Oct 26, 2008
14
i have build a traffic light circuit (three LEDs) by using 555 timer and 4017 decade counter
but i also wanna show count down on 7 segment display (such that it will count down till green led is on then reset) how can i make it help me out thx
 

Bernard

Joined Aug 7, 2008
5,228
Here is a brief outline for yellow light count-down. The 555 is speeded up to supply count-down clock & counted down to supply lights.Fast clock at 1pps, is gated with yellow output to drive a 74C192, BCD UP/ DN counter which is pre-loaded to "5" or other desired count; BCD output to 4511, BCD to 7 seg. disp. May require a little more logic control.
 

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