This is a 4 band Mechanical Color Code Resistor Calculator, The idea of making this Mechanical Resistor came when I accidentally dropped my box of resistors and all resistors (1300 of them) got mixed up. ooops! . Thank god there's an APP  for that, So while picking them up (the resistors) and soaring them out I was thinking, how cool would it be to have a big resistor that you can actually manually rotate the bands and get the resistor value right away.  If you are into electronics and you are really passionate about it like me, you're always looking for projects and challenges to take on all the time. So, with that idea and a vision in mind I started working  on my new project, of course  with the help of Arduino UNO microcontroller.
There are 4 small stepper motors , 4 stepper motor drivers, 4 10K potentiometers and 2 Arduino UNO on a breadboard. As you turn the potentiometer,  the motors rotate displaying a color and a value at the same time.

Step 1: Material List

SP = www.sparkfun.com ,  YD = www.yourduino.com , J = www.jameco.com , HP = Home Depot
                                                                                                                                                                                                                                                                                                                                                                                                                                                                      ARDUINO UNO  ON A BREADBOARD COMPONENTS LIST                ( J )
At Mega 328p with arduino UNO boot loader                    
5v Voltage Regulator 7805-T   
LED  (2 red ) and (2 green)   
resistor 1/4 w, 10k and 180 ohms  
Radial Capacitor 10uf 50v   
Ceramic Capacitor disc 22pf 50v  
ceramic Capacitor disc 0.1uf 50v  
Tantalum Capacitor 10uf 25v   
16Mhz Crystal low-profile   
Pushbutton switch, off/on   
Stepper Motor with driver board                                        (YD)
Blue LED light                                                                   (YD)
Panel mount LED holder 5mm                                          (YD)
DPDT On /OFF switch                                                      (YD)
10k small Potentiometer                                                    (YD)
10k Potentiometer chicken head Knob                              (SP)
9v Battery holder (Pack of two)                                         (YD)
9v Battery                                                                          (YD)
6v, AA Battery case                                                          (YD)   
AA Battery (pack of 4)                                                       (YD)
40pin flat cable female ends                                             (YD)  
Breadboard jumper kit                                                       (YD)
Breadboard 16cm with power and Grd busses                 (YD)
Breadboard 8cm with power and Grd busses                  (YD)
Mini Digital Voltmeter 0-30v dc (red)                                (YD)
Hook-up wire, solid (black, Red & Green)                        (SP)
solder tube .031 Inch Dia.                                                 (SP)
Liquid Tape 4FL. OZ                                                        (HD)
Servo Mounts                                                                   (SP)
Screw-Phillips head (1/2", 4-40, 10-pack)                       (SP)
Nut metal (4-40, 10-pack)                                               (SP)
wood screws #6 x 3/4" pan head Phillips                 (HD)
11/32", 2' x 2' Plywood sheet                                    (HD)
MINWAX wood finish stain (provincial 211)             (HD)  
Primer spray paint                                                    (HD)
Gold spray paint                                                       (HD)
1/8" Plexiglas 11" x 14"                                             (HD)    
Compressed wood                                                   (HD)
Narrow utility hinges 1"                                            (HD)
1/2" x 2' PVC pipe                                                     (HD)
1/2" PVC 90* elbow                                                  (HD)
1/2" PVC coupling                                                      (HD)
2" PVC pipe Blocker                                                  (HD)
2" x 2' PVC pipe                                                        (HD)
3" PVC pipe Blocker                                                   (HD)
3" x 2' PVC pipe                                                         (HD)
Nailed metal bridging                                                  (HD)
4" (10cm) Cable Ties                                                   (HD)

<p>How about a row colored buttons for each band?</p>
i think i'd go in a slightly different direction, which would be a complete redo, terminals to put a resistor across, the wheels would rotate to the value it reads, with a segmented led backup. 10% resistors could be an increment or two out, a faster way of verifying the values, or perhaps relabelling would be really nice.
This is really cool. Can't tell you how many times I've done that. It took me two days one time to reorganize. Thanks for the tip.
I'd like it better if you could just point the beak of the chickenhead knob on each pot to the applicable color and have it output the value from there. Kind of a different approach, but I'm sure you could have done it just as easy.
Great project, I was thinking of doing something similar to help my son learn resistors (he's autistic so he learns differently) & I was thinking of rotary dip switches w/ the colors & servos instead of stepper motors 'cause it would take less power & it would be allot faster.<br/><br/>All in all great work though.
... *facepalm
But this misses the point entirely of having a mechanical resistor! you should have leads sticking out the ends of the resistor, and actually have the indicated resistance across them. Otherwise, you'd be just as well off (if not better) by just having a hunk of PVC pipe with some rings around it that you turn by hand.
I see your point. I'd been talking with some friends about making this project practical and easy to use.
hello its near to be the more useless machine ever build, it expensive to be build, take too much time, and the more important too slow to resolve the resistors value, but, no doubt, it is an excelent project, and well done. <br>otherwise, the idea of numbers inside the appropiate color, is a good idea to build a simple cilinder with all the rings operated manually, thanks a lot, good luck
I could change the code so it would rotate faster to resolve the resistor value. I want to get a LCD and numeric key pad to replace the pots, that will make it practical.
excelent plan, you give me the idea of a touch screen, with bars for each figure, where you can touch the colours of the bars, and get the value, but i know it could turn in another project, because there will be no electronics and mechanical parts in place, but could be interesting too, good luck!
It's really cool but....<br> <br> .... I'm guessing you could have learnt the colour code in the time it took to build :p<br> <br> http://wiki.answers.com/Q/Is_there_a_rhyme_for_remembering_colour_bands_on_a_resistor<br> <br> I learnt them with a variation of one of the above :)
I learnt them long time ago, but I though of having a mechanical resistor will be kind of cool.
nice job! upload a video shows how works!!!
I'm working on it, I'll upload it next week.
Nice work! It;s just the way I like my projects, overly complicated electronics to do a simple task :)
There is something about complicated projects that I like. The challenge probably.
* It's *
WOW! You must have a lot of spare time on your hands! :-) Nice job though!
I wish, I started this project back in December, 2012 and finished it on May, 2013.
It was an on and off project. You know full time job, full time school.
coudn't it be like, you out the resistor then the arduino run 5v through it, the arduino reads the output and calculate the ohms value ? (display in the big one you made)
Good idea, that sounds great. I'm going to start planning on making this project better. Better means practical and probably making it a kit where you lift up the top cover and display small compartments to store you resistors.
It would be better if it mesured the value of the resistor as well
I thought about it but that was after I finished the project.
That is the most ridiculously entertaining thing I've seen here in a long time! Nice job.
Thank you
Nice project, thanks. <br>Next time you could save time making your video without moving the picture left and right or zooming it bigger or smaller. It also would be much more enjoyable to watch. ;-)
Thanks, yes I'll probably make a second video.
This is so super cool! everyone needs a robot to tell them what their resistors mean! <br> <br>It'd be pretty funny if each value triggered fortune-cookie like messages to be played back.
Thank you, I'm thinking of adding a LCD and replace the potentiometers with a numeric key pad from www.sparkfun.com
nice project
Thank you
A really complicated build but really neat and professional! Great job!
Thank you, yes it is complicated. I walked away from this project so many times but I was determine to get it done.

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