piano scale
A diminished (half–whole)
A1B♭♭2C♭3C♯3D♯♯4E5F♯6G♭7
The same eight notes started a half step earlier: the scale that spells a dominant seventh with a flat ninth and a sharp ninth at once.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
AHB♭WCHC♯WD♯HEWF♯HGWA
What is true of it
A diminished (half–whole) is A, B♭, C, C♯, D♯, E, F♯ and G, and back to A.
Its steps are H – W – H – W – H – W – H – W, where W is a whole step and H a half.
Chords made only of these notes
CmajorCmminorCdimdiminishedC7dominant seventhCm7minor seventhCm7♭5half-diminished seventhC♯dimdiminishedD♯major
Found by testing every chord in the catalogue against these 8 sounds, not chosen.
Other scales on A
A whole tonesymmetricA diminished (whole–half)symmetricA majormajorA natural minorminorA harmonic minorminor
C dim H-WC♯ dim H-WD♭ dim H-WD dim H-WD♯ dim H-WE♭ dim H-WE dim H-WF dim H-Wall 374