Here NE 555 was wired as astable Multivibrator which is capable of generating a square wave the period of the square wave was determined by means of external component connected to IC 555.The astable Multivibrator does not require any external trigger.The output pulse was then given to the input of the IC CD 4033.For each pulse the output of the CD 4033 advances by one count.The output of the IC2 was wired to the 7 segment a,b,c..g as shown in the figure.Then the pulse from the decoder lights up the seven segment on a sequence.The switch S1 was used here to initiate the counting.Diode D1 was used here to prevent the risk of accidential polarity reversal.
This is very easy and simple circuit that can be done at home very easily.Enjoy electronics.
