Resistor reading apps

If you are a long time hacker, you might remember all resistor color codes so well that you have no problem in reading them without thinking to much. For other there are those resistor color code tables and calculators.

But could this task be automated? Maybe with mobile phone? Reading Resistors With OpenCV posting mentions a new open source Android app to do that: Resistor Scanner. This app uses OpenCV Open Source Computer Vision Library to scan resistor colour bands and determines resistor values (source available at Take a look at the operation of this app with this video:

The app looks really interesting. So I had to try it. I installed it to my Android smart phone, but I has disappointed with the performance. The reading of the resistors did not seem to be very reliable and it did not read many resistors at all. The problems seem to be centered with the fact that I could not get goo big enough picture of the resistor on the smart phone screen (not enough zoom and smart phone does not focus well to very near objects). The app worked with some larger power resistors, but not with normal 1/4W resistors. Maybe I have to make second test with some smart phone macro lens or something some day.  It also seemed to have some issues on detecting the correct colors. According to Hackaday discussion this app has things to improve “it is a naive implementation that will read the codes in the ideal conditions “.

If you can’t use this this Android app, because you have Apple device, then Hackaday tips that there is iOS app called called ResistorVision (plans to release an Android version of ResistorVision in the near future).




  1. Tomi Engdahl says:

    Another OpenCV application:

    Googly Eyes Follow You Around the Room

    If you’re looking to build the next creepy Halloween decoration or simply thinking about trying out OpenCV for the first time, this next project will have you covered. [Glen] made a pair of giant googly eyes that follow you around the room using some servos and some very powerful software.

    Tracking People with the Googly Eyes and OpenCV

  2. Tomi Engdahl says:

    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.

    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.


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