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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Hipervids.com 7 Segment LED Counter Saturday, May 29, 2010 9:22:12 AM

Nice simple circuit. Do you know how fast it can count? Ive simulated it at 160 hz and works fine.

anonymous 7 Segment LED Counter Saturday, May 29, 2010 6:27:55 AM

Why this display the randum ? What is wrong? Why this start number 1? Who could explain this?

anonymous 7 Segment LED Counter Monday, April 19, 2010 10:19:16 PM

the inconsistant counting is usually due to bouncing... look up switch/NAND latching

Simon 7 Segment LED Counter Friday, March 05, 2010 7:41:06 AM

Hi I'm looking for advice on a SIMPLE counter circuit, with two gap sensors, ie an entry-exit system, two decade counters and two triple 7 segment displays. Meaning that it can count from 0-99 ( but I only need 71) and it can count down in the case of exits

janu 7 Segment LED Counter Tuesday, February 09, 2010 3:20:35 AM

what should be given to the count in input.....??? n thanx 4 the circuit:)

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.

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Hipervids.com	7 Segment LED Counter	Saturday, May 29, 2010 9:22:12 AM
Nice simple circuit. Do you know how fast it can count? Ive simulated it at 160 hz and works fine.
anonymous	7 Segment LED Counter	Saturday, May 29, 2010 6:27:55 AM
Why this display the randum ? What is wrong? Why this start number 1? Who could explain this?
anonymous	7 Segment LED Counter	Monday, April 19, 2010 10:19:16 PM
the inconsistant counting is usually due to bouncing... look up switch/NAND latching
Simon	7 Segment LED Counter	Friday, March 05, 2010 7:41:06 AM
Hi I'm looking for advice on a SIMPLE counter circuit, with two gap sensors, ie an entry-exit system, two decade counters and two triple 7 segment displays. Meaning that it can count from 0-99 ( but I only need 71) and it can count down in the case of exits
janu	7 Segment LED Counter	Tuesday, February 09, 2010 3:20:35 AM
what should be given to the count in input.....??? n thanx 4 the circuit:)
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.