Debugging Circuits and Code

Circuits and Code: Notes From My Debugging Journey

I’ve always loved the story of Admiral Grace Hopper and the Mark II computer at Harvard. Her team literally found a moth in a relay, taped it in the logbook, and joked about the “first actual bug being found.” Even if the story is half-legend, it speaks to me because debugging really is about finding what’s hidden. I love tracking down issues, so it's no surprise my favorite genre is mystery thriller.

When I’m stuck on a problem, whether it’s hardware or software, I notice the tools have changed, but the mindset hasn’t.

Hardware Debugging Tools

When I’m working with electronics, I’m constantly reminded that I can’t see electrons flow. That’s why tools like multimeters and oscilloscopes feel almost magical; they give me what seems like “x-ray vision” into a circuit.

Multimeter

It’s the first step for diagnosing dead components or breaks in a circuit. You are basically checking voltage, current and continuity in that circuit.

Oscilloscope

If a signal is missing or distorted, an oscilloscope can pinpoint the section of the circuit where things go wrong. It looks like watching a heartbeat on a heart rate monitor.

These tools don’t fix problems on their own, but they show you where to look.

Software Debugging Tools

In code, the “current” isn’t electrons it’s the data you pass through. You need a different kind of visibility:

IDE Debuggers

Depending on the IDE you use, you can pause execution and step line by line, which feels like probing test points on a PCB, only that the traces are variables and loops.

Logging

This usually refers to recording events and the system state so you can diagnose and monitor systems. They let me reconstruct the path data takes, just like measuring voltage along a circuit.

These tools work like the hardware tools; they reveal hidden processes so you can find the fault.

A Debugging Mindset is Hypothesize → Test → Fix

Whether hardware or software, the same mental loop applies:

Hypothesize - You ponder where the failure might occur based on evidence or error logs.

Test - Measure a voltage, step through a function, or check logs.

Fix - Cross off one possible cause at a time until you get to the real problem.

This works like the scientific method applied to engineering: build a theory, run an experiment, refine your theory, and then repeat over and over.

Two Debugging Moments That Stuck With Me

1. Broken LED Circuit (Hardware)

I once wired up a simple LED circuit, and nothing happened. My first thought: no power or reversed polarity. With a multimeter I confirmed voltage at the supply but not across the LED classic reversed install. I flipped it around, and bam, instant light.

2. Broken Login Function (Software)

Years later, working on a web app, users suddenly couldn’t log in. Logs showed authentication wasn’t even being called. With the debugger I stepped through line by line, feeling like I was tracing a signal on a board. Found the culprit: a single typo in a conditional. Fixed it, redeployed, and users were back in.

What I Took Away

Both times, the solution didn’t come from luck; It came from methodically testing assumptions and making the invisible visible.

Debugging, to me, isn’t just a technical skill. It’s a way of thinking. Whether I’m troubleshooting a circuit, a program, or even a stubborn appliance at home, or figuring out a criminal on a TV show, Debugging is a universal reasoning skill.