IC 555 is connected similarly in the above circuit to form an astable multivibrator. The output of IC555 at pin no. 3 is connected to pin no. 10 of IC 4020 to provide clock pulses. The counter IC4020 counts the pulses and the output is obtained through the LEDs in ring shape. All the LEDs are connected at a center point which is grounded. Here also the speed is adjustable using preset 500kΩ.