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

  • This circuit will count input pulses and output the number in binary.
  • It is very useful for creating long timing periods.
  • Also used to divide astable frequencies.

There are 3 binary counters shown below. The only difference between them is the number they can count up to. These types are very simple and are known as ripple counters.


Circuit Diagram, 7 stage
  • Clock - A low pulse on this input increments the sequence
  • Reset - A high input will reset the counter to zero.


7-stage binary counter (4024B)

The outputs Q1-Q7 carry the binary count from:

Binary = 000 0000 to 111 1111

Decimal = 0 to 127

12-stage binary counter (4040B)

The outputs Q1-Q12 carry the binary count from:

Binary = 0000 0000 0000 to 1111 1111 1111

Decimal = 0 to 4095

Circuit Diagram, 12 stage

14-stage binary counter (4020B)

The outputs Q1-Q14 carry the binary count from:

Binary = 00 0000 0000 0000 to 11 1111 1111 1111

Decimal = 0 to 16383

(Note: Q2 and Q3 are not available outputs)

Circuit Diagram, 14 stage

By connecting an astable to the clock input of a fixed frequency, the counter outputs can be used as timed outputs. For example, if an astable of 1 Hz is connected to the clock, then the outputs will go high after the following number of 1 second pulses:
Q1 = 1 pulse
Q2 = 2 pulses
Q3 = 4 pulses
Q4 = 8 pulses
Q5 = 16 pulse
Q6 = 32 pulses
Q7 = 64 pulses, (1 min approx)
Q8 = 128 pulses, (2 mins)
Q9 = 256 pulses, (4 mins)
Q10 = 512 pulses, (8 mins)
Q11 = 1024 pulses, (16 mins)
Q12 = 2048 pulses, (32 mins)
Q13 = 4096 pulses, (1 hour approx)
Q14 = 8192 pulses, (2 hours)

By adjusting the clock frequency, you can obtain longer and shorter delays, and by cascading them, (joining 2 counters in series with the last output from the first counter connected to the clock of the second) gain delays of days, weeks or even months.

Connect a driver and an output device to one of the outputs so it activates when that output goes high.

For Q7 to equal exactly 1 min, clock frequency = 1.067Hz
For Q11 to equal exactly 1 hour, clock frquency = 1.138Hz

The counter packages and connections are shown below

7-stage, 4024B
14 pin

12-stage, 4040B
16 pin

14-stage, 4040B
16 pin

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.
If possible use an IC holder so the IC can be removed easily and is not damaged from excessive heat while soldering.
Links to circuits using binary counters

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