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Jun 04, 2024

Resistance Is… There’s An Augmented Reality App For That!

Like many engineers of a certain age I learned the resistor color code using a mnemonic device that is so politically incorrect, only Tosh might venture to utter it in public today. When teaching

Like many engineers of a certain age I learned the resistor color code using a mnemonic device that is so politically incorrect, only Tosh might venture to utter it in public today. When teaching kids, I have to resort to the old Radio Shack standby: Big Boys Race Our Young Girls But Violet Generally Wins. Doesn’t really roll off the tongue or beg to be remembered. Maybe: Bad Beer Rots Our Young Guts But Vodka Goes Well. But again, when teaching kids that’s probably not ideal either.

Maybe you can forget all those old memory crutches. For one thing, the world’s going surface mount and color coded resistors are becoming a thing of the past. However, if you really need to read the color code, there’s at least three apps on the Google Play Store that try to do the job. The latest one is ScanR, although there is also Resistor Scanner and Resistor Scan. If you use an iPhone, you might try this app, although not being an Apple guy, I can’t give you my feedback on that one.

The Android apps, though, are a little spotty. The idea is great, and Resistor Scanner seems to be the one that works most like I’d expect. However, none of them could get a decent image of a few 1/4 watt carbon film resistors I had handy. My Nexus 5’s camera was simply useless at the range it would take to get a good picture of the little resistor. A borrowed LG phone’s much better camera worked a little better even though the image was fuzzy. However, no app correctly identified all the colors. Granted, I know what the bands mean and you could even double check the color. But if I have to type in the color or check it against the value I know it is, that sort of defeats the purpose.

I also tested an Asus Zen Pad which didn’t show any better results. Then I popped on my toy cellphone to microscope converter (bought at a dollar store) but that made the resistors too large and none of the programs could handle it. I feel like the main limitation is the phone camera. When in focus, the image is too small. When large enough, the camera is too close to the resistor making it illegible.

However, the Zen Pad’s camera could focus and it still didn’t get good results. Look at the image to the left. Can you read the resistance value? I can. None of the programs could. In some cases, white bands didn’t look different from the resistor body. In some cases like this one, it wasn’t clear why the program couldn’t figure out the bands (or worse, got them wrong). It could be I needed to experiment with the background or the lighting or maybe I just need larger resistors.

These apps are far from ready for prime time. Even if the camera was sufficient, you have to line the colors up and you have to know which way to read the resistor and which band is the tolerance band. If you know that, I’d be surprised you didn’t know the color code.

Another attempt at augmented reality for electronics people is SandScan, also for Android. In theory, you can use the camera to take a picture of a chip, it will read the text and do a search on the part number. I couldn’t get any of that to work either. Laser markings on chips are generally pretty faint and only the largest chips would give me any workable image. Even then, I couldn’t get the program to search. Judging by the comments on this program (and the resistance ones) in the Google Play store, I’m not alone.

In the future, maybe you’ll pop your Google Glass (or equivalent) and look at a circuit board to get all the component values. A right wink might call up the data sheet while a left wink highlights the traces that connect to the part. Maybe. Or perhaps that’s not enough. What would it be like to look at a circuit and be able to visualize the voltages and currents going through it? Far fetched? Perhaps not. Electron beam stroboscopy can show bits going down the bus of a CPU chip (although that CPU better be in a loop and you better synchronize to the exact same spot over and over).

On the other hand, just because the present state of the art in cameras and image software isn’t quite up to the task doesn’t mean people should stop working at it. Early cell phones were comical when you look back on them. Early PCs were not really practical by any modern definition. Yet they formed the building blocks of what we do have today. That stuff will probably look pretty dumb, too, in only a few years.

Of course, if you want to build a dedicated machine, you might have better luck. Or you could just make your own official Hackaday reference card.