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.

34 thoughts on “Giant Resistor-shaped Ohmmeter

    1. 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 :(


        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…..

  1. 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.

    1. Considering that the color banding machine already exists at the factory, and that a laser would take longer than to run it through the color machine, that would mean significantly more expensive THM resistors.

      1. true, but the bands have a tendency to become discolored, especially with heat, which is a bit of a problem when you’re trying to identify that burnt resistor in your old tube radio.

    2. The most significant advantage, IMHO, of color bands over laser printing is that they can be read from any rotation of the resistor. A laser printed part might be turned such that the numbers aren’t easy to read, or even upside down. Color bands can be “read” from any rotation or orientation.

    1. 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.

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