Just finished my first sensor test and found the power draw issue

Had almost the same thing happen with an LDR and a 10k resistor on my Uno last fall. Sensor kept reading 0 no matter how I shaded it, and I spent an evening rewriting the analogRead sketch convinced it was my code. Turned out one of the legs of the resistor had never relly gone into the hole properly, it was just resting against the side of the clip. Multimeter said everthing was fine til I wiggled the wire, then the reading jumped around like crazy.

My zeros turned out to have a completly different cause, so maybe this helps someone. I was reading a photoresistor on A2 of a clone Nano and kept getting flatlined values no matter what I did with the wiring. After an hour of poking around I discovered my breadboard's power rail was split somewhere down the middle. Half the rail got 5V, the other half didn't, and I'd plugged the sensor's supply into the dead end. Test it by measuring the rail at both ends with the board powered, not just at one spot.

Since then I've also gotten pickier about breadboards in general. The cheap one I bought in a multipack had clips so loose that component legs wiggled free with the lightest touch, and that caused weeks of intermittent readings that looked like code problems. I moved that sensor circuit onto a nicer board from my local electronics shop and it's been stable ever since. I still use breadboards for quick experiments, but anything I plan to keep running for more than a day gets transferred to perfboard with soldered joints. Life got alot calmer once I stopped chasing ghost faults in spring clips.

My issue was a little different. I was trying to get a temperature reading and kept getting totally erratic values, even after checking the power supply. I was convinced my library was faulty because the numbers were jumping all over the place. It turns out the wire running from the sensor into the Arduino's analog pin wasn't seated all the way down. It felt okay, but it was just catching the clip and would shift a tiny bit when I touched the breadboard. Now it seems stable.

I recall a frustrating instance where my data was equally inconsistent, though the symptoms were more erratic than simply reading zero. I spent considerable time scrutinizing the sensor parameters, but the actual problem lay in the ground connection itself. It turned out that the specific jumper wire I was utilizing to link the common ground to the Arduino exhibited slightly higher resistance than the power lines, wich caused a measurable ripple in the analog signal reading. This subtle impedance created a ground loop effect that only manifested under certain load conditions.

I remember running into a similar issue with an environmental sensor, but my problem wasn't the wires. It was that the sensor unit itself felt flaky. I spent hours thinking the sensor was broken when in reality, the physical mounting was just bad. I eventually moved the setup off the breadboard entirely and onto a small perf strip to run the final tests. That small change really made the difference because it kept the tiny component from wobbling when I moved the desk.