The Circle of Fifths is an Interesting concept and like Modes overly clouded in mystery. I will try to shed some light on the use-value of the circle of fifths for guitar players and especially those that like to learn the scales in a visual manner. Notice that on my illustration of the Circle of Fifths that I’ve removed the information on how many sharps and flats are found in a scale, you can see that info on the pic that’s under mine which is found on wikipedia.
Now for an explanation. You remember that the cromatic scale has 12 notes right? Well the circle of five describes a harmony relationship of all the 12 notes. Or rather if you start on one note such as C and go to the fifth of C which is G and then the fifth of G which is D and so forth then you will hit all of the 12 notes and reach C again. If you are shaky on what I mean by a fifth you should check out my Major Scale video/text and learn how to count out those intervals. Now this harmony relationship is used very much when songs change keys but as well used within one song. Hey Joe by Hendrix is a Circle of fifths harmony for example.
In the video I will play the Major Scale walking the circle with the Major Scale. Learn this relationship like you would any scale. The outer circle is the circle of fifths if we count out from the Ionian Mode of the Major Scale but the inner circle the black one shows the notes counted out from Aoelian mode or Minor. So each slice describes the relation ship for Major and Minor. For example A is the 6th interval of C thus the Minor Mode of the Major Scale and E is the 6th interval of G etc.
It’s worth mentioning that the Circle of Fifths Backwards equals the Circle of Fourths.