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THE 4017B DECADE COUNTER
V. Ryan © 2005 - 2022
 
 

PDF FILE - CLICK HERE FOR PRINTABLE WORKSHEET BASED ON THE EXERCISE BELOW

 

The 4017B is an integrated circuit which has been designed to count pulses. It has 16 pins and looks like any other 16 pin integrated circuit.

 
 
 

They can be used in timing circuits and are often used to switch on and off LEDs or motors or other circuits. They are versatile and relatively simple to put together. Counters such as the 4017B are cheap and yet surprisingly useful.
The 4017B is most useful when combined with a timer such as a 555 based circuit. The pulse from the 555 timer can be used to activate the 4017B circuit.

 

 
 
A good example is seen below. A 555 astable circuit is used to pulse the 4017B at regular intervals. The pulse from the 555 IC is generated from pin 3. In the circuit seen below, pin 3 of the 555 IC feeds into pin 14 of the 4017B (called ‘clock in’). When this occurs pin ‘A’ of the 4017B emits current, lighting its LED. The next pulse from the 555 IC results in pin ‘B’ of the 4018B IC emitting current and lighting its LED.
 

Continuous pulsing by the 555 IC results the LEDs of the 4017B turning on and off in sequence, creating a ripple effect.
In this circuit a reset switch has been added. When pressed, counting will start again at pin ‘A’ of the 4017B IC.

   

 
 
 

The wires from the battery snap and also the ones from the toggle switch are fed through small holes in the PCB. This ensures that they cannot be accidentally pulled off the circuit easily.
A number of 4017B IC circuits can be connected together by connecting pin 10 (divide by 10 pin) to the input on the next 4017B IC. The outputs will change at one tenth the speed of the first 4017B IC. Linking the 4017B ICs together in this way allows for long interval timers to be made.

   
   
   
Below is a 'manually operated 4017B circuit. Note: each time SW3 is pressed the next LED illuminates. SW2 is the reset switch.
   
 
FURTHER DETAIL - CIRCUIT DIAGRAMS - 4017B
 
 
 
 
 

QUESTIONS:

1. Build a 4017B Decade Counter using either a breadboard and components OR simulation software such as Crocodile Technology. Add a 555 timer to pulse the decade counter.

   

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