Traffic Light Schematic

Hello. I m a 1st yr engnr stdnt. i made a circuit Project (Traffic light). & it dosnt changes lights by itself?

The schematic can be found at ( http://www.kpsec.freeuk.com/projects/trafficlight.htm )… when i touch the one leg of potentiometer which is connected to the (trigger) and (threshold) of 555 timer. it changes from red to green and then again green to red.. and skips yellow…

I don’t have time to work out the sequences, but your schematic is a little different than this one:

http://www.doctronics.co.uk/4017.htm

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Traffic Light System – Electronic Design Project