https://github.com/broosky/squarely
A super low-frequency square wave counter using 74-series logic and 7-segment displays.
https://github.com/broosky/squarely
diy-electronics electonics experimentation integrated-circuits kicad led-display maker-project prototyping
Last synced: 3 months ago
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A super low-frequency square wave counter using 74-series logic and 7-segment displays.
- Host: GitHub
- URL: https://github.com/broosky/squarely
- Owner: Broosky
- Created: 2025-04-20T22:58:57.000Z (9 months ago)
- Default Branch: main
- Last Pushed: 2025-09-02T05:53:17.000Z (4 months ago)
- Last Synced: 2025-09-02T07:19:51.826Z (4 months ago)
- Topics: diy-electronics, electonics, experimentation, integrated-circuits, kicad, led-display, maker-project, prototyping
- Homepage:
- Size: 192 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
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Metadata Files:
- Readme: README.md
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README
# 💡 Squarely
A super low-frequency square wave counter originally built back in high school, designed for basic signal counting and hands-on hardware experimentation. It uses classic 74-series logic to drive a multi-digit display and can be expanded or tuned for various applications.
Reflecting on the original design, here are a few areas worth improving:
- Replace discrete resistors with a **resistor bank** — cleaner layout and easier substitutions
- Adjust the **555 timer's RC values** to support higher input frequencies (up to low MHz)
- Add a **third digit** to extend the count range
- Use logic chips from the same **family (e.g., 74HCXX)** for consistent behavior and performance
- Pull unused inputs **high or low** to prevent erratic logic states
- Support an **external clock input** via pin 14 (CP0) of the first 74XX90 counter for easier integration or testing
> If you found this project useful, interesting, or worth keeping an eye on, consider giving it a ⭐️.
> It helps others discover the project and motivates me to keep building and sharing more.
## 🔹 Rev 1 Schematic
![Rev 1]()
## 🔹 Rev 1
- Tracking versions.
## 🔹 General Notes
- **Input Signal Options**:
- Internal 555 timer (adjustable via RC timing)
- **External square wave source** (connect to pin 14 / CP0 of the first 74XX90)
- **Display**:
- 2-digit 7-segment display (expandable)
- Driven by chained 74XX90 decade counters and 74XX47 BCD-to-7-segment drivers
- A D flip-flop latches the output from the counters to the display drivers
- **Modularity**:
- RC timing is easily adjustable for frequency testing
- Logic chips can be swapped to experiment with propagation delays, power consumption, or chip families