This tool is to help mandolin players etc. understand how diatonic scales/modes and basic chords map on to the fretboard of their instrument. It has been tested on Firefox and seems to work on Chrome. It probably won't work very well on IE or Edge. I've tried to make it reasonably usable on touch-screen devices, but you might struggle to use it on smaller phones.
By default, a scale of D major is shown, with the chord of D major highlighted in red (to restore the tool the this state, refresh the browser [F5]). This is reflected in the headers at the top of the screen. There are a few points to note:
The tonic (or ‘keynote’ - in this case “D”) will always appear significantly larger in the diagram than the other notes.
Notes in the selected chord always appear in red.
The root note of the selected chord will always have a black border.
There are three basic functions available in the tool: Transposing, Changing Chord, and Changing Mode.
To see the current configuration in a different key, use the arrow buttons (or the arrow keys on your keyboard) to move the notes on the diagram by string or fret. E.g. the ‘right’ key/button will transpose the default structure to E♭.
Under certain circumstances, an option will be offered as to whether ♭'s or ♯'s are prefered. This only affects scales that can contain either 6 ♭'s or 6 ♯'s. Otherwise the version of the key with the fewest ♭'s/♯'s will always be chosen.
N.B. transposition via the arrow keys is disabled while these instructions are open.
The radio-buttons in rightmost column allow any of the triads within the key to be highlighted in the diagram.
If the current mode is “Major” and chord Ⅴ (in this case the third option from the top) is selected, an option appears which allows the chord to be toggled between the basic triad and the ‘7th’ chord.
The middle column allows you to change the ‘mode‘ represented in the diagram. There are two possible behaviours here:
If “Keep Tonic” is selected, the ‘parallel’ mode is chosen, e.g. selecting “Dorian’ will cause the diagram to display D Dorian. If necessary, the tonic will be swapped for its enharmonic equivalent (e.g. F♯ for G♭).
If “Keep Notes” is selected, the ‘relative’ mode is selected, so the notes stay the same, but the one selected as the root note changes. E.g. selecting “Minor” from the default configuration will cause the diagram to display B Minor.
In either case, the chord displayed will always be reset to Ⅰ (i.e. the one with the same note-name as the scale/mode.)
Other Types of Scale/Mode/Chord
This tool only supports the types of structure described here so, for example, melodic and harmonic minor scales are not supported and neither are Major 6th, ’Suspended‘ 4th chords etc. However, once the relationships between the types of structure with which this tool is concerned are understood, more advanced concepts will be much easier to digest (and probably won't require the aid of an application such as this).