7 Segment LED Counter

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This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily (see Notes).

Schematic

7 Segment Display Reference

Parts

Part	Total Qty.	Description	Substitutions
R1-R7	7	470 Ohm 1/4 Watt Resistor
U1	1	74LS90 TTL BCD Counter IC	7490,74HC90
U2	1	74LS47 TTL Seven Segment Display Driver IC	7447,74HC47
DISP1	1	Common Anode 7 Segment LED Display
MISC	1	Board, Sockets For ICs, Wire

Notes

All pulses to be counted are to be TTL compatible. They should not exeed 5V and not fall below ground.

You can add more digits by building a second (or third, or fourth, etc...) circuit and connecting the pin 11-6 junction of the 74LS90 and 74LS47 to pin 14 of the 74LS90 in the other circuit. You can keep expanding this way to as many digits as you want.

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Comments

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anonymous BCD counter Thursday, January 28, 2010 3:27:19 PM

can anyone tell me wether a bcd counter is a combinational or a sequential circuit?

FROILAN of roxas CITY 7 Segment LED Counter Tuesday, January 05, 2010 9:08:22 AM

Anyone can show me a diagram of a timer or 24 sec.shot clock using 7-segment display? thanks

anonymous 7 Segment LED Counter Wednesday, December 30, 2009 9:10:25 AM

how can I reset this circuit?

shashank 7 Segment LED Counter Thursday, December 24, 2009 9:12:29 PM

Thanks this is the circuit i was searching for . thanks very much !!!!!!!!!!!!!!!!!!!!

Deurgist 7 Segment LED Counter Tuesday, December 22, 2009 11:37:47 AM

This is in response to questions regarding counting up irradically, and by two's (ironically, they have similiar answers). The issue is what is known as electrical "bouncing". This means the hi to lo transition state of the timers output - tho on an active lo (to the counters input) - it "spikes" just high enough to be registered as another pulse (counting in multiples). How to fix? Well you may have guessed it - by "debouncing" - time to google.

nette 00-99 count up count down timer... Sunday, October 18, 2009 11:45:45 PM

guys... pls do help me how to connect using 74ls247 and 74ls192 so that i can make a count up count down timer... tnx2 just mail me her net_kichay@yahoo.com... tnx2

SRowe 7 Segment LED Counter Sunday, October 18, 2009 5:04:49 PM

would it be possible to have this count up in 2's or 5's... instead fo just 1's? if so how would you go about making it work so like one momentary button push makes the counter jump up in 2's or whatever cheers

anonymous Help! Added 555 timer for this counter. Wednesday, September 23, 2009 1:34:16 AM

I built this circuit using 555 timer Astable as my pulse. My problem is that it skips numbers. Like it will count from 1 to 4 then 7 and back to 1. Some times its random numbers. I thought I might have had some bad chips but I replaced them with new ones. For the 555 timer I am using R1 10k R2 100k and 10uF for a frequency of .068Hz. Doesn't any body have any suggestion why this might be skipping numbers?

Danpher 7 Segment LED Counter Monday, September 14, 2009 10:58:42 PM

i am about to design a 24-second shot clock using the seven-segment light emitting diode....if you have an idea on this matter, kindly send to me steps to be followed in makikng such device....

nina 7 Segment LED Counter Sunday, September 13, 2009 3:03:47 PM

hi! i was just wondering, i am looking for a circuit that counts up to 12...can i get any help with that?..esp on how to expand this particular circuit to be able to do that. thanks!

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anonymous	BCD counter	Thursday, January 28, 2010 3:27:19 PM
can anyone tell me wether a bcd counter is a combinational or a sequential circuit?
FROILAN of roxas CITY	7 Segment LED Counter	Tuesday, January 05, 2010 9:08:22 AM
Anyone can show me a diagram of a timer or 24 sec.shot clock using 7-segment display? thanks
anonymous	7 Segment LED Counter	Wednesday, December 30, 2009 9:10:25 AM
how can I reset this circuit?
shashank	7 Segment LED Counter	Thursday, December 24, 2009 9:12:29 PM
Thanks this is the circuit i was searching for . thanks very much !!!!!!!!!!!!!!!!!!!!
Deurgist	7 Segment LED Counter	Tuesday, December 22, 2009 11:37:47 AM
This is in response to questions regarding counting up irradically, and by two's (ironically, they have similiar answers). The issue is what is known as electrical "bouncing". This means the hi to lo transition state of the timers output - tho on an active lo (to the counters input) - it "spikes" just high enough to be registered as another pulse (counting in multiples). How to fix? Well you may have guessed it - by "debouncing" - time to google.
nette	00-99 count up count down timer...	Sunday, October 18, 2009 11:45:45 PM
guys... pls do help me how to connect using 74ls247 and 74ls192 so that i can make a count up count down timer... tnx2 just mail me her net_kichay@yahoo.com... tnx2
SRowe	7 Segment LED Counter	Sunday, October 18, 2009 5:04:49 PM
would it be possible to have this count up in 2's or 5's... instead fo just 1's? if so how would you go about making it work so like one momentary button push makes the counter jump up in 2's or whatever cheers
anonymous	Help! Added 555 timer for this counter.	Wednesday, September 23, 2009 1:34:16 AM
I built this circuit using 555 timer Astable as my pulse. My problem is that it skips numbers. Like it will count from 1 to 4 then 7 and back to 1. Some times its random numbers. I thought I might have had some bad chips but I replaced them with new ones. For the 555 timer I am using R1 10k R2 100k and 10uF for a frequency of .068Hz. Doesn't any body have any suggestion why this might be skipping numbers?
Danpher	7 Segment LED Counter	Monday, September 14, 2009 10:58:42 PM
i am about to design a 24-second shot clock using the seven-segment light emitting diode....if you have an idea on this matter, kindly send to me steps to be followed in makikng such device....
nina	7 Segment LED Counter	Sunday, September 13, 2009 3:03:47 PM
hi! i was just wondering, i am looking for a circuit that counts up to 12...can i get any help with that?..esp on how to expand this particular circuit to be able to do that. thanks!