Giant resistor-shaped Ohmmeter


The fun of having a giant resistor-shaped Ohmmeter is that it reads back the resistance by displaying the color code. If you’re not too hot with decoding those bands there’s a helper band to the right which will display the value numerically.

All of the electronics are housed in the opaque part of the resistor, making for a nice low-profile base. The bent leads are hollow and allow [Sebastian] and his friend to run power and measurement leads through to the power connector on the back and the pair of banana jacks near the front. Each translucent ring houses an RGB LED, except for the one on the right which has four 7-segment display modules embedded in it. An ATmega168 takes the measurements using its Analog to Digital Converter (ADC) to read the value from a voltage divider. You can see a quick demo of the Ohmmeter in the video after the jump.

This would be a fun thing to pair with that giant breadboard.


  1. Paul says:

    Cool idea but I would paint the board green or red to look like a PCB.

  2. theonlycritic says:

    Next they should make a plugin for google glasses that converts digital clock faces in to watch hands.

  3. cde says:

    Ha. That’s adorable.

  4. Dale says:

    For those of you who don’t know or have a hard time remembering the color codes. Remember them by their order in the spectrum. , with each color step add a zero starting from black.

    • Haku says:

      Sadly the only colour codes I have ever managed to remember for any length of time are the ones for snooker, because of that damned Chas & Dave song back in the 80s – I can still remember the sequence to this day :(

      • signal7 says:


        I, unfortunately, can’t repeat the sentence by which I remember that sequence of letters because it’s not politically correct nor family-friendly. On the other hand, it’s very effective. I only ever heard one professor recite it and I’ve never forgotten it since. :-)

        Though – It does give me an idea for an RGB clock since each color represents a number…..

  5. cde says:

    One improvement. They should have two metal plates on the board instead of post jacks (or along with). This way you can just press the resistor into place without needing cables.

  6. Ryan7777 says:

    Great build and a cool idea overall. This thing would be good in a classroom.

    There are resistors lurking out there that have more bands than this though…

    And nice mega-grabbers on that 1/8 watt. Don’t want that guy getting away.

  7. kay says:

    Pretty! :D

  8. kstillin says:

    That is so, so funny! I actually laughed. Hey- based on the size of it, wouldn’t that be, like, a 1KW resistor? Pretty neat.

  9. Sven says:

    One thing, isn’t displaying brown light in RGB a big problem?

  10. vonskippy says:

    With modern manufacturing techniques, there’s no reason not to just laser/screen the value on the part, using ancient color banding in this day and age is ridiculous.

  11. This. Looks. Awesome!

  12. trialex says:

    One of the cleverest ideas I’ve seen in a long time. So obvious when someone else has already done it! Kudos

  13. M4CGYV3R says:

    That’s so much fun. Great practice for learning the bands, too. Kind of pointless to measure actual resistors that already have the bands…but neat for other resistive loads.

    • Tony says:

      Sell it to the scientologists as a new e-meter or hippies as an aura gauge.

      “You’re aura is red… make it green, make it green”.

      An E-meter is just an overprice ohm meter in a crappy case – apparently thetans have resistance or something.

  14. word clock says:

    Haha I really love this giant resistor :-)

  15. Frank Cohen says:

    Beautiful, awesome build!

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