7 Segment LED Counter
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).
7 Segment Display Reference
Parts:
R1-R7_______470 Ohm 1/4 Watt Resistor
U1__________74LS90 TTL BCD Counter IC
U2__________74LS47 TTL Seven Segment Display Driver IC
DISP1_______Common Anode 7 Segment LED Display
MISC________Board, 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.