Home > Circuit Bricks > Decade Counter
UPDATED:.21:02 21 October 2013

  • This circuit will count input pulses and sequentially turn on, one of ten outputs.
  • It can also divide a clock frequency by 10
  • Ideal for sequencing functions one after the other.

The circuit is based around the 4017 counter IC. It is a CMOS type and can work from a wide voltage range. The circuit shown will count input pulses at the clock.

The outputs can only drive a few mA so unless connecting to other logic devices, you will need a driver.

Leave inputs as they are if not using them.

It is a digital device and works with logic level inputs. A high refers to +v and low refers to 0v.


Circuit Diagram
  • Clock - A high pulse on this input increments the sequence
  • Enable - A high input will stop the counter.
  • Reset - A high input will reset the counter to zero.


The outputs (Out0-9) will turn on one after the other on every rising pulse of the clock. Only one is on at any one time.

Clk/10 output is high during the first 5 outputs and low for the last 5 - dividing the clock frequency by 10.

The 4017B counter comes in an 16pin DIL package. The pin connections are below.

Note: Enable is active low.

If possible use an IC holder so the IC can be removed easily and is not damaged from excessive heat while soldering.
IMPORTANT: Try not to handle the pins of the IC too much. They do have protection diodes connected inside but CMOS types are very sensitive to static charge.
Links to circuits using the 4017B


Written by Phil Townshend - 2008
www.edutek.ltd.uk - Working Electronics For Students & Teachers