need of a counter
Let imagine you want to make a project which count how many times a switch pressed or how many people enter in room. Projects of this type are need a counter to count pulse generated by sensor or by pressing of switch. There are many type of counter based on difference aspects like decade or 4 bit counter, synchronous or asynchronous counter, Up/Down counter, so you need to choose according your project. here we go with decade counter using CD4017
CD4017 decade counter
more about CMOS ICs and other counter ICs
pin diagram and work of each pin
4017 count applied input pulse on pin on. 14 when goes to high (on the rising-edge), which may be an clock pulse or output of sensor
One output (from Q0-Q9) high at a time for corresponding count and rest are at low volt.
reset (active high): for normal count reset should be low and to reset counter at 0 a high pulse applied to reset pin.
Disable (active high): Disable counter when high and counter disabled until a low pulse is applied, during disable high counter ignore input clock pulse
÷10 output: high for 0-4 and low for 5-9, so it provide a frequency=(clock frequency)/10. it is use as carry for next counter stage
Note: To count less then 9, output is directly supplied to reset pin (example: we want to count 0 to 6, then Q7 output is connected to reset pin) to reset counter to zero.
component required
- CD4017 decade counter IC ------------------ 1
- Resistor 330 ohms --------------------------- 10
- LED ( any colour ) --------------------------- 10
- Switch ( SPST push to make ) -------------- 2
- connector ( 2 pin ) ---------------------------- 2
- battery ( 9v ) ---------------------------------- 1
circuit diagram
In this project we connect 10 LEDs, one with each pin to show how counter work and at the place of LEDs any other devices can be use like transistor switch, relay driving circuit, to control gates or flip-flop etc
Circuit use a clock pulse switch ( SPST type ) which apply pulse to pin 14. when switch pressed a high voltage is applied to pin and counter increments to one and next output pin goes high.
Disable input are grounded directly because generally it is not used and here not required
Reset switch are used to reset counter. it is necessary because when counter is powered up it show any no. randomly and reset are used to set it back to 0
330 ohm resistor are used with LEDs to avoid burning
pin 12 are not connected because we not use next counter circuit so no need of carry
PCB layout
use this PCB layout to make PCB using any method you know and mount component according to fig. shown next
put this image file in a MS office Doc file and print
NOTE:don't resize this image else component no fit in their pad
PCB layout with component
PCB after component mounting
nice to understanding counter...
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