Traffic light system using 555 timer

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Peacock
Posts:5
Joined:Wed Feb 22, 2017 12:57 pm
Traffic light system using 555 timer

Post by Peacock » Wed Feb 22, 2017 1:57 pm

I want to build a traffic light system that uses only the 555 timer with astable and monostable configuration only (without decoder or counter). Please help me.....

Junaid_Shahid
Posts:110
Joined:Tue Feb 14, 2017 9:00 am

Re: Traffic light system using 555 timer

Post by Junaid_Shahid » Wed Feb 22, 2017 1:58 pm

Peacock wrote:
Wed Feb 22, 2017 1:57 pm
I want to build a traffic light system that uses only the 555 timer with astable and monostable configuration only (without decoder or counter). Please help me.....
I suggest that you connect the 555s (configured as monostables) in a ring.

For example, say you wanted just a red, amber and green lights on for say 1 minute, 15 sec and 1 minute respectively.

Mono A would drive the Red light and be set for 1 min
Mono B - amber
Mono C - Green.

When the outoput of Mono A goes low, it triggers Mono B, when Mono B goes low it triggers Mono C. The cycle re-starts when Mono C goes low.

You may need a pulse to start the sequence when the power is switched on, but I suspect it won't be necessary as the monos will quickly lock into the correct sequence.

A counter or shift register solution would be more elegant.
Recommended Tutorial: Traffic Signal Control using 555 Timer

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