This handy Decade Counter (or sometimes called a Johnson Counter) can be used in many circuits, I will guide you through the basics and show you an example circuit.
The 4017 IC introduced in 1968 and still popular today, is a 16-pin CMOS Decade Counter which is part of the 4000 series - a family of industry standard integrated circuits which implement a variety of logic functions. They were introduced as a lower power and more versatile alternative to the 7400 series of TTL logic chips.
- Pin 01: Output 5 (the 6th sequential output)
- Pin 02: Output 1 (the 2nd sequential output)
- Pin 03: Output 0 (the 1st sequential output)
- Pin 04: Output 2 (the 3th sequential output)
- Pin 05: Output 6 (the 7rd sequential output)
- Pin 06: Output 7 (the 8th sequential output)
- Pin 07: Output 3 (the 4th sequential output)
- Pin 08: Ground (0V Rail)
- Pin 09: Output 8 (the 9th sequential output)
- Pin 10: Output 4 (the 5th sequential output)
- Pin 11: Output 9 (the 10th sequential output)
- Pin 12: ÷10 output (CO)
- Pin 13: Latch enable (LE)
- Pin 14: Clock in (CLK)
- Pin 15: Reset (RST)
- Pin 16: Vcc (voltage between +3V and +15V)
The 4017 takes clock pulses from the Clock input, and makes one of the ten outputs come on in sequence. Each time a new clock pulse arrives it will go to the next sequential output. If the Reset pin receives a high input the sequence will start again from Output 0 (Pin 3).
If the Enable pin receives a high input it pauses the counter and stops wherever it happens to be when Enable goes HIGH. The ÷10 Output is HIGH for counts 0-4 and LOW for counts 5-9.
This circuit uses a 555 Timer to generate a continuous square wave pulse which is feed into the Clock input of the 4017 IC. Each time a pulse is received the next sequential output is set to HIGH lighting the LED for that sequence.
The 4017 Decade Counter
[ATTACH=RIGHT]54828[/ATTACH]This handy Decade Counter (or sometimes called a Johnson Counter) can b