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
henry Marotte says
Swagatam, Hello. Does this circuit increment on its own? i want to use a circuit like this for incrementing 0-99 from a simple dry closure, in this case a lap counter for racing, and do not want to have it increment on its own. Just wondering, thanks.
Henry Marotte
Swagatam says
Hello Henry, this circuit will not increment on its own. The count will increment once each time the switch SW1 is pressed
Dhruv Vijay Parmar says
hello swag I have a temperature Measurement device which displays temperature using senor probe with lm35 in probe for sensing…..problem is anyone can make probe using lm35 and measures it i want a config or circuit that makes it solely measure using my probe and not other who make it…in short basically i want to make my device smart by using only my lm35 probe with extra circuit and should not display anything when used by other made probes please help….Thanks and regads
Swagatam says
Hello Dhruv, you can change the format of the +/- out pinouts of the probe so that they cannot be recognized and while connecting to another probe the pinouts will not match and the LM35 will not function. Adding an external circuit will change the behavior and characteristics of the LM35 and then the probe cannot be used in its standard form.
Dhruv Vijay Parmar says
Thanks swagatam for your reply…but the problem is there are hardly three pins and one can just do several combinations to find out the +/- pin in a bid to copy and make…in meanwhile can you suggest me some Digital temperature ICs….where we can enable a security code??…Thanks and Regards
Swagatam says
Thank you Dhruv! Yes, the 3 pins can be swapped through different combinations for getting the right combination. In that case you can put a 4rth or 5th dummy pin to create confusions. I don’t think there are any temperature sensor ICs which can be programmed with a security code. Unfortunately I do not have any information about such ICs.
Dhruv Vijay Parmar says
yess this is a considerable option for me… thank you so much swagatam meanwhile there’s a digital IC ds18b20 where there’s a unique 64-bit code if by any chance we can write that code of ours that would be great to validate on software side
Swagatam says
You are most welcome Dhruv! Actually my expertise in electronics is limited to designing small circuits only. My knowledge of coding for programming is absolutely nil, so writing codes is something too complex for me.
Burhan Erkardes says
hello Swag says I need a counter with 2 numbers, but I want this counter to count as much as the number I gave, so if it counts according to the data I have written, can we do it and how do I need it? thank you so much ……sorry for my englisch.
Swagatam says
Hello Burhan, you can try the following designs:
https://www.homemade-circuits.com/5-digit-frequency-counter-circuit/
How to Cascade IC 4033 in Multiple Digit Counter Display
Claudio says
Dear Swagatam ?… how to change the circuit so that it can even go back 99-0? thanks for every suggestion. Claudio
Swagatam 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 ?
Swagatam 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://www.homemade-circuits.com/2011/12/simple-frequency-counter-circuit.html