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 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.

r1However, 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.

68 thoughts on “Resistance is… There’s an Augmented Reality App for That!

  1. Nowadays everyone wants to make everything without knowing anything. It isn’t such a big deal to learn the color chart with or without memory crutch, or even this became a pain in the ass?

    1. As much as I agree with you this could also just be a hobby project with the goal to learn something else. The person might just have been interested in learning how to work with computer vision while making something that has some relevance to his other fields of interests.
      I highly doubt that somebody would go through the trouble of creating such an app just to get around learning the resistance color chart.
      There’s a big chance that he already knows the color chart himself.

        1. One of my colleagues (a highly skilled electronics engineer) is colour blind. I asked him if it affects his work he said it’s more of a problem when using schematic capture and PCB layout tools on a computer screen, as they are seldom set up to accomodate colourblind users. As for the hands-on aspects, he just uses a multimeter if he needs to be certain of a resistor value.

        2. Well perhaps today it could be due to all the non-spec resistors coming out of China.

          Both the E12 and E24 specification systems (and others) used for resistors have precise specifications of the colors. Although most may not be away of it, those colors fall into a grey scale so that color blind people can read them to.

          I am color blind and I have been reading resistor color codes for 40 years and the only ones I have trouble is the cheap low quality parts that in recent times have started to come from China.

          The same applies for electronics in general like cable/wire color codes etc. Wires color codes also vary the length of the stripe which is totally independent of both color and contrast.

          While this abandonment of specification is a pain to a color blind person, it’s no biggie – I just use a multi-meter, problem solved.

          There is one place where abandonment of specifications has me very concerned though. Newer cars use colored bulbs behind clear covers as opposed to the old system that used clear bulbs behind colored covers. I (as a color blind person) can’t see this new style indicator flash because the have increased the range of color and reduced the range of contrast.

          There are a great number of color blind people in this world so it **should** really bother you that most of these people can no longer see your indicators.

          1. Don’t understand me wrong, please: I never thought that there are that many color blind persons in the world. I always thought that 99% of the color blind people “just” have hard times keeping different shades of the same color apart from each other or something like that. Is the true gray-scale only thing a “common” issue?
            Is that considered to be an illness?

      1. Yes, I can tell what resistor values mean if I can figure out the colors. I’m not color-blind, but resistors are smaller than they used to be, my eyesight’s not what it was 50 years ago, the paint on resistors isn’t always in that good shape, and I usually have to get out a magnifying glass and good light to read it anyway, so hey, if my phone camera can at least do the lighting and magnifying, that’s a really good start (and I need that for the capacitors anyway.)

    2. because menial tasks are what computers are for in the first place

      sure I could learn this and that, but if you are a hobbist and you use it only so often, why bother – you have plenty other things to remember

      BTW: wtf is with these “back in my days” comments? sure you can do something without use of special tool, but just knowing that its enough, you don’t have to be dissing people for using (/coming up with?) it.

    3. I want to be able to take my Jamco big bag of assorted resistors. Dump the bag out on the work bench and take a picture.

      Then type in a arbitrary resistance and have the app highlight all the resistors of that value for me…
      If that value is not found then cycle thru highlighting different parallel / series combinations that get close to the target value.

      And yes, I have the color code memorized.

      1. I certainly cannot get the colour code to stick in my brain, so I just use a little cheatsheet of which integer represents which number, not hard at all, and the algorithm is very simple when run on top of the color recognition of a human brain.

    4. Exactly!!! I don’t know how I couldn’t know the color code. I don’t even remember any of the mnemonic tricks anymore, but hand me a banded resistor and I can tell you right off the bat what value it is!

      But In my time I have seen A LOT of mislabeled resistors, like magnitudes off. Even expensive high precision ones. So even after going to the parts stock and grabbing a resistor, the very first thing I do is check the thing with a calibrated DMM! And maybe that is why I know. After you’ve looked for a resistor for what the bands say, and then reinforce that with looking at the actual value, it sticks. But I don’t think outside of a brain injury that I could forget orange = 3 or violet = 7 or yellow = 4 or white = 9 or green = 5 etc.. <– I just did that right off the top of my brain while typing this. I think ya'll need a little less pot in your diets…

      1. Well, yes we’ve talked about one of the four programs I mentioned before (and I knew that). I had started talking about the one that was very recently released, and it wound up being a rant about augmented reality and so I threw the other programs (including SandScan) in.

        I agree with [Dave1990]. I’ll be interested in augmented reality/vision apps when they are that smart!

      1. The one I learned was far more politically incorrect, but along the same lines. Different times. The trick to learning it is exactly the same, something so out of whack that it would be embedded in your mind of life.

  2. I have remembered the colour code as a teenager without mnemonic. Got lots of practices as I put all of the resistors unsorted in a big bag. These days I recognize the colour patterns for common values. See how your app can do that.
    SMT parts ftw until I start using 0402. :(

  3. I don’t understand what is the hard part in color codes.
    Black is zero and then there is brown which is one. After that it is rainbow.

    White as in color has all other colors blended in so it has to have biggest number. And one stop down from white there is grey.

    And after a while you don’t need to count as you start remembering the numbers.

    1. A great engineer I knew (he’s gone to the great lab in the sky now) was color blind. In fact, I’ve known a few people over the years totally mystified over the color code because THEY CAN’T SEE COLOR. So while I wouldn’t use these apps myself, I bet they would have.

      1. I’m not colour blind, but I still find it difficult to see what colour it is sometimes. You don’t always have perfect lighting where you’re tinkering. I still find it amazing that they haven’t started printing the values in plain text on resistors yet. Surely it can’t be that costly if it can be done for caps, smd parts, transistors etc etc. Resistors are the exception it seems.

        1. They do, for some series. Offhand, I recall that Vishay Dale through-hole resistors typically have printed values.

          I suspect the adherence to the color code for most companies is due to convention. Although it does allow the value to be read no matter what the rotation of the part, something which always annoys me with the printed values on other axial leaded parts such as diodes.

    2. I agree, The middle six colors are the rainbow, which every first-grader already knows.The outer four go in order from dark to light: black, brown, gray, white. You don’t need any mnemonics when you recognize the pattern.

  4. When I was still using color coded resistors, I just memorized the patterns, not the individual colors. With the common E12 range, there’s only 12 different color patterns for the first two rings. And in a lot of cases, you can manage with a very small subset of that.

    Nowadays, I just use SMD. So much easier, and even for shaky people with bad eyesight, there’s 1206 or 0805.

  5. There are already like ten of these apps on the Google play store. IMHO it takes way too much time to use. If it could show me a live readout of the values over top of the resistors laying on a table, then you might have something.

  6. Once when I had access to a full set of enamel colors, I painted the buttons of a cordless phone getting rid of that silly alphabet. The keyboard had all ready been converted to numeric from the Bell handicap inverted that only telephones use. Nobody else could use it, it kept outgoing calls to a minimum. For me it was easier than Bell handicap and no symbols as well.

  7. The Dutch mnemonic is:
    “Zij Brengt Rozen Op Gerrits Graf Bij Vies Grijs Weer”

    Zwart, Bruin, Rood, Oranje, Geel, Groen, Blauw, Violet, Grijs, Wit
    Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray, White

    It means: “She brings flowers to Gerrit’s grave during dirty gray weather”

    Very romantic, and you can teach it to kids without problem. ;)

    1. If only I remembered much of the Dutch by Radio class I took from Radio Nederland when I was a kid. Actually, every time I’m in Noordwijk I think the same thing although honestly, I can’t remember the last time I met someone there who did not speak English perfectly. Still wish I remembered more than “hello everybody”

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