The proposed 00-99 digital counter becomes very handy in places where you need to keep the people organized in some specified order.
Operating details of the digital counter
As may be referred the circuit employs the popular 555 IC to genearte the pulse clocks. The pulse counting is done with the help of SW1. A couple of CMOS ICs 4026B respond to these clocks and become directly responsible for running the 7-segment display.
Since the last digit is restricted to 99, the first 4026 activates the second, when it crosses from 9 to 0. (see the pin 10 of the first 4026 that enters the clock input of the second).
When the circuit is first powered, it may not start its count from a zero, so a momentary reset activation becomes necessary and is implemented using the switch (SW2). Pressing this switch the account resets the circuit and starts the count from zero (00).
It may be interesting to see that a pulse is applied to pin R "RESET" in each integrated circuit.
Circuit Diagram
Parts List for the discussed digital counter circuit
IC1: 555
IC2 = IC3 = 4026B
DS1 DS2 = = 7 segment display
C1 = C2 = C3: 0.047uF
R1: 10K 1 / 4W
R2: 1M 1 / 4W
R3: 33K 1 / 4W
Switches SW1 = SW2 = normally open push to ON switches
Claudio says
Dear Swagatam ?… how to change the circuit so that it can even go back 99-0? thanks for every suggestion. Claudio
Swag says
Dear Claudio, this circuit cannot be used in the reverse order, however after some searching I could find the following design, perhaps this might do the job
https://www.homemade-circuits.com/wp-content/uploads/2018/07/up-down-digital-counter.jpg
Claudio says
Thanks Swagatam … help me to understand … a square train of impulses generates the increment and the other, inverted, generates the decrease? Thank you so much. Claudio ?
Swag says
Hi Claudio, yes that may be correct, I got this schematic from a Youtube video but the video was incomplete so I could not confirm the working of the design
Henrik Lauridsen says
Dear Swagatam,
Thank you for sharing all your great circuits and please continue the great work.
To this circuit a have a couple of questions which I hope you will explain to me.
1: Would you be so kind to show the pin numbers of IC2 and IC3. I mean what is the pin of CE, the pin of DE and so on.
2: Shouldn’t the IC2 & IC3 be connected to VCC and VSS?
3: How do I set the IC1 (555) to automatic / manual clock (pulse)
Best regards,
Henrik
Swagatam says
Thank you Henrik, the circuit was taken from some other site, I did not check the details.
I have updated the 4026 pin data at the bottom of the article, please match it accordingly.
CE = clock enable
yes IC2, IC3 Vcc/Vss are not shown and these must be connected with the supply rails.
SW1 can be used for manual clocking, if not pushed the IC will continue with its automatic pulsing
Sriram Kp says
hai, the above circuit will work as 0-99 seconds display. How to change this circuit as 0-99 minutes circuit with the total two 7 segment display? Like, after every minute only the number should get increament in display. Pls help..
Swagatam says
Hi, just replace IC1 with a 1 minute 555 astable circuit
Sriram Kp says
I tried to find a 555 astable circuit with 60 seconds off and 1 second ON. but not able to find. Could u pls provide me a circuit for that?? Thnkx…
Swagatam says
use any online 555 calculator software for determining the resistor values for it…the duty cycle results will give the ON/OFF periods..
Sufyan Gull says
i want the circuit which will only increment when i push the button ……………………………and reset the reading when i push the button ….?????.
Swagatam says
you can use the following circuit
https://homemade-circuits.com/2011/12/simple-frequency-counter-circuit.html