SWYoon Labs

Series navigation: Episode 1: The Roadmap · Episode 7: Reading Arduino Pin-Current Specifications · Episode 16 The problem: A wire patch makes Revision A work, but the next board may repeat the same mistake. The goal: Convert symptoms and workarounds into traced design changes and regression tests. The result: A Revision B process that preserves evidence instead of hiding failure. AI-generated illustration of hardware iteration. The boards and defect notes are not artifacts from a physical project. The wire patch worked—so was the board fixed? Revision A would not start reliably. A wire was added, one resistor changed, and the board began working. That is a valuable diagnostic result, but it is not yet a controlled design revision. The patch may create a new antenna, bypass protection, depend on assembly skill, or fix only the one unit on the desk. In software, a quick production patch should eventually become a reviewed source change and regression test. Hardware ne...

Series navigation: Episode 1: The Roadmap · Episode 7: Reading Arduino Pin-Current Specifications · Episode 14 The problem: A routed board can look complete while containing a mirrored connector, missing return path, or untestable power rail. The goal: Review electrical intent, physical reality, manufacturing, assembly, and test before ordering. The result: Twelve checks that turn “DRC passes” into a reviewable release decision. AI-generated illustration of a design review, not a manufactured board from this series. The green board on the screen looked like a product The traces were routed, the ground zone was filled, and the 3D view looked convincing. That visual finish created a dangerous feeling: the PCB seemed done. Then a review question changed everything: If the connector is mounted on the real board, which side is pin 1 on? The layout was not a product yet. It was a set of assumptions waiting to meet copper, components, cables, tools, and a manufacturer. ...

Series navigation: Episode 1: The Roadmap · Episode 7: Reading Arduino Pin-Current Specifications · Episode 13 The problem: The prototype works, but its meaning exists only in wire colors and memory. The goal: Convert physical connections into named, reviewable electrical intent. The result: A schematic checklist that becomes the source of truth for PCB design. AI-generated illustration of the documentation transition. It is not a circuit to copy. The prototype failed after I cleaned the desk The breadboard had worked the night before. I disconnected a few wires to organize them, rebuilt the circuit from a photo, and the sensor disappeared. The photo showed where the wires appeared to go. It did not explain which nodes were power, ground, I2C, reset, or an intentionally unused pin. It also did not reveal the breadboard's hidden internal strips. A working breadboard proves that one physical arrangement worked once. A schematic explains the intended electrical rela...