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 for Counter

7 Segment Display Reference

7 Segment Display Reference


Total Qty.
R1-R77470 Ohm 1/4 Watt Resistor
U1174LS90 TTL BCD Counter IC7490,74HC90
U2174LS47 TTL Seven Segment Display Driver IC7447,74HC47
DISP11Common Anode 7 Segment LED Display
MISC1Board, Sockets For ICs, Wire


  1. All pulses to be counted are to be TTL compatible. They should not exeed 5V and not fall below ground.
  2. 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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7 Segment LED Counter
Wednesday, July 09, 2014 1:04:58 PM
Can the ls90 counter be substituted for an ls193 counter?
7 Segment LED Counter
Tuesday, April 29, 2014 5:41:50 PM
The 555 isn't a particularly good clock source for many counters, because it has ringing in the level transitions that cause multiple counts evident as skipped numbers. A more reliable solution for a general-purpose clock would be a single CMOS inverting Schmitt trigger such as 1/6th of a CD40106BE. Place a timing resistor between the input and the output of the inverter, and a timing capacitor from the inverter input to ground. For a slow clock rate that will result in a visible counting rate, use a 1 megohm resistor and a 1 microfarad capacitor. If you use a polar capacitor, make the (-) lead ground. The clock output is the inverter output. Connect the 5 unused inverter inputs to ground. If you're adamant about using the 555, sometimes a small capacitor (100 to 1000pF) connected from its output to ground eliminates the miscounts, but this is not a recommended solution because it may not work with all 555s and all counters under all conditions.
7 Segment LED Counter
Monday, March 19, 2012 8:12:36 AM
What is the exact position when you transfer all those in the breadboard?
7 Segment LED Counter
Monday, March 12, 2012 6:57:21 PM
gee! thanks it helped me a lot for we have a final project 0-99 counter God bless
16 pin keypad to 7447
Sunday, February 26, 2012 2:45:19 PM
Been looking for a simple schematic of connection between a 16 pin keypad and a 7447 chip. The purpose is to display on a 7 segment the number being pushed. Also, we plan on adding in microcontroller connection between the keypad and the 7447, to designate a code being entered. Any help would be greatly appreciated.
7 Segment LED Counter
Friday, January 13, 2012 3:54:01 PM
hi,can anyone teach me how to attach it with rfid so that the rfid reader can count how many cards are tagged.please help me
flash-Point Ballistics
7 Segment LED Counter
Wednesday, December 28, 2011 8:21:21 PM
Can you show me how to setup the IR portion to trigger the count?
7 Segment LED Counter
Friday, August 05, 2011 9:53:00 PM
my desire to play with SevensegmenLED, welcome to digital. if use 12V try get IC 4518 decode counter and 4511 Seven segmen driver. Add Transistor to pull more current, it can drive 4-5 Leds for each segmenline that you can assign as "Big" Seven segmen. (assume one LED need 25mA so 25x4 serial LED=100mA enough for one Tr BC547 / 9014 )
Sonny Eugenio
7 Segment LED Counter using 12 volts
Wednesday, May 11, 2011 6:38:31 AM
I would like to use bigger 7 segment displays which will be powered by 12 volts supply. I was considering of using dual voltages. Can I use 12 volts to power the common anode pins of my 7 segment displays leave the rest of the circuit at 5 volts? I was wondering if this would work.
7 Segment LED Counter
Thursday, March 24, 2011 9:20:35 AM
What about the customer's way out ? its gonna counte twice that way
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