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Build Your 7 Segment LED Counter with a 74LS90
This straightforward circuit is suitable for tallying events, such as a customer counter found in retail locations, or for any application requiring the measurement of discrete occurrences. The design accommodates TTL logic signals, and its functionality can be readily extended (refer to the accompanying documentation).
Circuit Diagram
Seven Segment Display Guide
Components:
- R1-R7 – 470 Ohm, 1/4 Watt Resistors
- U1 – 74LS90 TTL Binary Counter Integrated Circuit or 7490, 74HC90
- U2 – 74LS47 TTL Seven Segment Display Driver Integrated Circuit or 7447, 74HC47
- DISP1 – Common Anode 7 Segment LED Display
- MISC Board, IC Sockets, Wiring
Additional Information about Integrated Circuits
74LS90
The 74LS90 is a versatile bipolar TTL (Transistor-Transistor Logic) binary counter integrated circuit. This particular IC functions as a 16-stage binary counter, meaning it can count up to 65,536 pulses. It’s a fundamental building block in digital logic systems. The IC is characterized by its low power consumption and reliable operation within a wide temperature range. It’s commonly employed in applications needing precise counting and sequencing.
Notes:
- All input pulses must be compatible with TTL logic. They should not exceed 5V nor fall below ground potential.
- Further digits can be added by constructing additional identical circuits, connecting the junction between pins 11 and 6 of the 74LS90 and 74LS47 to pin 14 of the 74LS90 in each new circuit. Expansion can continue indefinitely to achieve the desired number of digits.