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Circle of fifths with degrees, modes and chord-finder written in $\LaTeX$ and PGF/TikZ.

You can use the file circle_of_fifths.tex to create three PDF's, print, cut out (, laminate) and join them in the center:

Photo of laminated parts (older version)

Instruction

In the LaTeX document look for the Phase comments and follow the instructions. Print after each phase. The document is set default to the first phase.

Note that in the 'degree'-layer you need to cut out the parts where it says cut out...

If you cannot create the PDF's please download the base.pdf, degree.pdf and chord.pdf.

You can try to join the three pieces in the center with a split pin.

Description

nomenclature:

tonic: the root or home note of a key
key and scale: the order of notes determined by the tonic. For the purpose of this text key and scale are similar. Although: "A scale is musical notes arranged in an order, whereas a key is determined by the tonic note from which we derive the chords of a scale. A mode is an elaboration of a scale." (from https://www.musicianwave.com/key-vs-scale-vs-mode/)
degree: the position of a particular note on a scale relative to the tonic (from https://en.wikipedia.org/wiki/Degree_(music))
mode: a scale of notes within one key starting at a certain note in that key, each mode with its own "characteristic melodic and harmonic behavior" (loosely from https://en.wikipedia.org/wiki/Mode_(music))

The outer ring on the base plate shows the root note (tonic) of the major keys (green ring) in the circle of fifths, below this note is the number of $\flat$ or $\sharp$ in that key (yellow ring) and below that the parallel minor tonic (red ring) (e.g. $\textrm{A-}$ is the parallel minor of $\textrm{C}$ ).

The middle ring shows the seven degrees (scale step) in a key from $\textrm{I}\triangle$ to $\textrm{vii\o}$ (blue ring). These consist of a roman number and a $\triangle$ , a 7 or a $\textrm{\o}$ . An upper case roman number indicates a major chord (major third) and a lower roman number a minor chord (minor third). The $\triangle$ indicates a major seventh chord, the 7 a minor seventh chord and the $\textrm{\o}$ a half-diminished seventh chord (minor third, diminished fifth and minor seventh). Below the degrees in some cases the odd note numbers above the octave are shown: the 9th, 11th and 13th as they are often used as extensions of a chord (orange ring). Below that the names of the modes corresponding with the degree from $\textrm{ionian}$ to $\textrm{locrian}$ (blue text). Below the $\textrm{ionian}$ and $\textrm{aeolian}$ it shows the common names $\textrm{major}$ and $\textrm{natural minor}$ (red text).

The inner disc show the notes in a chord in the holes on the disc together with their note numbers. The chord is selected with the arrow on the disc (see Usage for more information).

Usage

Turn the middle ring (the degrees) with the $\textrm{I}\triangle$ (ionian) pointing to the tonic of your major key in the outer ring (closest to the edge, in the example above pointing to $\textrm{C}$ ).

For the minor key point the $\textrm{vi}7$ ( $\textrm{aeolian}$ ) to the tonic of your minor key in the outer ring (again closest the edge, in the example above pointing to $\textrm{A}$ ).

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Rotate the arrow on the inner disc to point to the desired chord (=degree) on the middle ring.
On the inner disc you find the notes of that chord in the selected key (in the example on top: $\textrm{C}$ - $\textrm{E}$ - $\textrm{G}$ - $\textrm{B}$ ).

Note that for the seventh degree $\textrm{vii\o}$ you will need to add the note in the outer ring indicted in the slice with " $\textrm{add to vii\o (5)}$ ".

Find the scale

Disclaimer: the author of this text is an amateur musician at best and his theoretical knowledge is very basic. The following tips are from his own experience and have not been checked by a professional musician.

There are several steps that might help to figure out the tonic and the key of a piece of music:

how many $\flat$ or $\sharp$ are written at the start of the piece? In the outer ring you can find the corresponding major or minor key
what is the last chord of the piece? More than often a piece of music ends with the root chord (chord starting with the tonic of the key) or tonic
what is the first chord of the piece? Also often a piece of musics starts with the root chord
check the chords in the piece and rotate the middle ring with the degrees until it fits (most) of these chords (pay attention to major/minor and seventh). At the first degree ( $\textrm{I}\triangle$ ) you will find the tonic of the major key in the outer ring and at the sixth degree ( $\textrm{vi}7$ ) you will find the tonic of the minor key in the outer ring

Is the piece major or minor?

listen to the music! Although this being a grave oversimplification a minor song tends more towards a 'sad' emotion whereas a major songs gives you a more 'happy' feeling
again the last chord of the piece. If this is the root chord the chord itself will tell you if the key is major or minor
this will also uphold if the first chord of the piece is the root chord

Read a chord

Chords are typically a combination of three or more notes. Each chord has a name indicating the root note of the chord together with added letters, numbers and symbols to specify all the other notes in the chord. An example of a chord can be $\textrm{C}7$ :

The $\textrm{C}$ indicates the root note of the chord
The $\textrm{C}$ -chord consists of three notes: the tonic, the major third (four semitones from tonic) and the perfect fifth (seven semitones from tonic)
The $\textrm{7}$ indicates the addition of the minor seventh (ten semitones from tonic)

The resulting notes of this chord are:

$\textrm{C}$ tonic
$\textrm{E}$ major third
$\textrm{G}$ perfect fifth
$\textrm{B}\flat$ minor seventh

Sometimes you see the following notation: $\textrm{D}_{\textrm{/}_\textrm{E}}$ . This is called D over E (or slash chord). The chord is $\textrm{D}$ and the bass note is the $\textrm{E}$ and not the tonic of $\textrm{D}$ scale (being $\textrm{D}$ ).

Below is a list of symbols that can be used:

symbol	name	meaning	semitones from tonic
$\textrm{-}$	minor third		3
$\textrm{m}$	minor third		3
$\triangle$	major seventh		11
$\textrm{Maj7}$ or $\textrm{Maj}$ or $\textrm{M7}$ or $\textrm{M}$	major seventh		11
$\flat5$	diminished fifth	also with other notes, e.g. $\flat9$	6
$\textrm{\o}$	half diminished or half dim	tonic - minor third - diminished fifth - minor seventh	0 - 3 - 6 - 10
$\textrm{o}$ or $\textrm{dim}$	diminished	tonic - minor third - diminished fifth - diminished seventh	0 - 3 - 6 - 9
$\textrm{+}$	augmented fifth		8
$\textrm{aug}$	augmented fifth		8
$\sharp5$	augmented fifth	also with other notes, e.g. $\sharp11$	8
$\textrm{sus}$ or $\textrm{sus4}$	perfect fourth	fourth instead of third	5
$\textrm{sus2}$	major second	second instead of third	2
$\textrm{6}$	major sixth	sixth instead of fifth	9
$\textrm{9}$	major ninth	mostly implies seventh	14
$\textrm{11}$	perfect eleventh	mostly implies seventh	17
$\textrm{13}$	major thirteenth	mostly implies seventh	21
$^6/_9$ or $\textrm{6add9}$	six nine	sixth instead of fifth and ninth instead of seventh	0 - 3 - 9 - 14

Acknowledgement

Many thanks to Joel Mabus for his Wheel Of Fifths http://www.joelmabus.com/mabus%20wheel%20of%20fifths.htm and the authors of the code found in https://tex.stackexchange.com/questions/442783/circle-of-fifths-diagram-with-printed-music-in-latex