Two Digit Up Down Counter Circuit

We are offering Two Digit Up Down Counter Circuit enables users to count from 0 to 99 in up as well as down mode at any instant of counting. two digit updown counter is suitable for many applications such as clock generator, frequency meters etc. The circuit uses updown counter ic1 & ic2 and bcd to seven-segment decoder ic3 & ic4. The clock circuit and updown switching is neither designed using four nor gate ic5. Two 7-segment displays in common cathode configuration are used to display the count.

About the circuit :
When power is switched on, the clock pulses generated by rc network build around two nor gates in ic5 is fed to the clock input pin1 of ic1 & ic2. As a result counting starts in up or down mode depending on the logic present at updown mode pin10. If pin10 is at high level, counter starts up counting and starts down counting when it is at low level. This logic is set with two nor gates in ic5 and toggle switch s1. When s1 is in up position, pin 10 goes logic high and when s1 is in down position, it gives logic low. Reset switch s2 is used to reset the counter. In this case, displays show 00 in two 7- segment displays and counting starts again.

At every clock pulse, count increases by one in up mode and decreases by one in down mode. The clock-in terminal (pin5) of ic1 is connected to clock-out terminal (pin7) of ic2. Thus when ic1 completes counting from 0 to 9 in up mode or 9 to 0 in down mode ic2 starts counting. The display can be shown on two 7- segment displays named as dis1 and dis2.

The speed of counting can be set with the aid of pot p1. The number of digits the counter provides can be extended by adding more counterdecoderdisplay stages.