A papercraft resistor calculator from Adafruit

The Adafruit blog just posted a neat papercraft resistor calculator. If you haven’t yet learned the horribly offensive mnemonic for resistor color codes, now’s your chance to have a cheap and portable resistor value reference.

This papercraft resistor calculator is the latest in the family of Circuit Playground tools that include a fabulous electronic reference app we reviewed some months ago. Instead of an Android or iOS device, the papercraft resistor calculator runs on its own mechanical computer; a series of four printed disks and some paper fasteners.

If you’d like to print out your own resistor calculator, Adafruit put up the PDF on GitHub and posted the Illustrator file on Thingiverse for easy editing. It’s not the old-school cool of a slide rule, but we could easily see this resistor calculator being useful if you’re ever lucky enough to teach electronics to children. At least then you won’t have to share that offensive mnemonic.


  1. Anonymous says:

    Black Beer Rots Our Young Guts, But Vodka Goes Well, Good Sir!

    I see nothing offensive here.

  2. fartface says:

    radio shack used to sell these. I still have a couple on my parts bench.

  3. jc says:

    hahaha that mnemonic is awesome ! Didn’t know until now. Thanks :D

  4. barryronaldo says:

    I love these things :) I find them at flea markets and such from time to time. Makes me yen for the old days of tube testers in shops and those cacrds on the counter :)
    Now we just need to ISO the paint used for the markings. As I have noted on HaD before, one manufacturer’s red is another’s orange, etc lol.
    Maybe my eyesight is getting bad from screens too. Good to see these lil paper calcs are not lost :)

  5. Jay says:

    I was taught the ‘offensive’ version by the Navy. And I taught it to my girlfriend. But since there were two b’s in it, she changed the first b to make it even more offensive, but easier for her to remember. Too bad I can’t share it.

  6. rue_mohr says:

    I thought someone else was drawing resistors http://eds.dyndns.org/~ircjunk/images/156_drawnresistor.jpg
    I wrote a program for learning resistor colour codes by repitition:
    rue_house: What is the colour for the value 6?
    rue_house: No, the answer was blue. What is the colour for the value 9?
    rue_house: Correct. Your score was: 50%

  7. Aud1073cH says:

    I wrote a program for the TI-83 calculator to translate resistor codes when I was in high school.

    anyone know if there is a TI calculator programming utility that will run in Linux? I’d like to share it.

  8. R says:

    For anyone looking for the mnemonic, I believe it to be the 2nd one here:


    (linking is acceptable, right?)

  9. humble reader says:

    A slightly more compact variant,


  10. gnomad says:

    I have trouble discerning the color bands on 1/4 watt resistors even with the help of a 20x loop. However, I have no trouble reading them when I take a megapixel+ photograph. What’d love to see is an app that will identify all resistors in a photograph and display their values.

    • JohnBailey says:

      I know what you mean. I’m at the age where a pair of glasses with a set of magnifying lenses clipped on is essential. The shades of colour the manufacturers often use don’t help either. Especially with the blue resistors.
      A daylight balanced bulb can help a little. Failing that, use a multimeter. It will at least get you into the right area.

  11. CLC says:

    I feel compeled to create a truly horribly offensive mnemonic.

  12. PI says:

    A 60’s era Popular Science mag suggested this memory aid:

    Bachelor Boys Rush Our Young Girls, But Veronica’s Wild for Silver and Gold

    As I recall, it was accompanied by a classic sketch/cartoon by Roy Doty.

  13. DjKiDD says:

    Are you kidding me? I want to know what it is now!

  14. Galane says:

    I never knew there was an offensive one, so of course I had to go and look.

    Curse you, Hackaday. ;P

  15. Rawdust says:

    All you need to know is the rainbow ROY G BIV. The only colors that aren’t in the rainbow are Black and Brown. Black has no color so it is 0 and Brown is number 1.

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