Custom PCB for 7-segment display

Creating custom PCBs for 7-segment displays comes with its challenges:

1. Pin Requirements: Driving all pins requires many Arduino outputs.
2. Current Control: LEDs need current regulation and more power than the Arduino board can supply.

The go-to solution combines hift registers with transistors for current control. Alternatively, integrated power shift registers provide an efficient and compact solution for this application.

As a first test, I designed a simple PCB that fits onto the 7-segment display and can be easily daisy-chained.

Circuit and PCB Design

The circuit design is straightforward but was an excellent exercise to practice designing and creating a custom PCB for the first time.

This circuit was fabricated into a PCB and printed by PCBWay. The shift registers, sourced from eBay, appeared to have been desoldered roughly but offered significant cost savings compared to new ICs.

Improvements to Be Made

After testing, the following improvements have been identified:

• Support for More Variants: Add compatibility for a wider range of 7-segment displays.
• Flexible Assembly: Position headers to allow 180° rotation, enabling the creation of symbols like :.
• Wider PCB Traces: Increase path width for better current handling.
• Base PCB Addition: Add a “base” PCB with:
  • Power regulation to power the entire display using a USB-C power supply.
  • A DCF77 antenna for time synchronization.
  • An integrated Arduino module.
• Switch to SMD Components: Optimize space and improve assembly quality by transitioning to surface-mount components.

First Test of Custom PCB

The first test of the custom PCB was a success. The system performed as expected and showcased the feasibility of the design.

Key Capabilities and Achievements

Here’s a summary of the capabilities and achievements from this project:

This project reflects hands-on experience with PCB design, circuit optimization, and iterative improvements to hardware solutions.