IC-4017 IC-4017 CMOS-Decade counter/divider When we build the 10 LEDs running light for hobby. Often use IC-4017 CMOS-IC. This really neat chip contains a counter and a decoder circuit, that can show a single output pin for each count from 0 to 9. And also use to build all kinds of timer, LED sequencers and controllers circuits. Look at the Figure below is block diagram of inside IC-4017. The IC 4017 counts with 5 D-type flip-flops. Decoding and control is by 16 inverters and 15 gates. block diagram inside CD4017-IC The importance Pins look at table below. 1.) Pin 16 is positive power supply and pin 8 is a ground. The power supply range of 3 volts to 16 volts and Maximum power supply voltage at pin 1 must not much than 18 volts. 2.) Pin 13 is Clock enabled pins to controls the clock. When it is “0” logic, the clock is enabled and the counter advances one count for each clock pulse. When “1” logic, the clock input is stop,