If you're passionate about digital electronics, chances are you've come across the 74LS90 decade counter IC. This tutorial will guide you through building a simple yet functional 0 to 9 digital counter using the IC 74LS90, with the help of a clear schematic diagram and simulation. This project is ideal for electronics students, hobbyists, and anyone curious about how digital counters work.
🔧 What is the 74LS90?
The 74LS90 is a decade counter IC that can count from 0 to 9 in binary (BCD - Binary Coded Decimal). It has four output pins (QA to QD) and internal flip-flops configured to count automatically with clock pulses.
🖼 Circuit Overview
Due to high demand from readers, we're sharing the full schematic here for easy access. The diagram uses:
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IC 74LS90 (Decade Counter)
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IC 74LS74 (Dual D-Type Flip-Flop)
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IC 74LS47 (BCD to 7-Segment Decoder)
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Common Anode 7-Segment Display
You’ll find a simulation file included for better understanding, so you can pause and replicate the circuit manually if needed.
⚠️ Note:
Make sure to connect:
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Positive power supply to pin 5 (74LS90) and pin 16 (74LS74)
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Ground to pin 10 (74LS90) and pin 8 (74LS47)
Even if not shown in the diagram, these connections are essential.
📋 Component List
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1x 74LS90
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1x 74LS74
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1x 74LS47
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1x 7-segment display (common anode)
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Resistors (330Ω for segments)
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Clock source (e.g., NE555 or manual button)
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Power supply (5V regulated)
🧠 Understanding the Pinouts
If you're unsure about the pin functions, you can refer to the official datasheets of the 74LS series. The video by Robo3001 explains it well — it's worth checking out for deeper understanding.
🧪 Simulation Available
To make things easier, we’ve also included a simulation that you can open in tools like Proteus or Multisim. You can test the circuit virtually before soldering anything.
🔚 Final Thoughts
This project is a great way to understand binary counting and the functionality of digital logic ICs. The 74LS90 is still widely used in learning environments due to its simplicity and reliability.
Whether you’re preparing for a class project, building a DIY counter for a scoreboard, or just exploring electronics, this guide gives you a solid foundation.
📌 Don't forget to test your wiring before applying power, and always double-check the orientation of your ICs!
🎥 Video Credit: Robo3001
💬 Questions or feedback? Drop a comment below!
