In this example, I'll be using the major scale (Ionian mode) of the key a
tritone interval away from my main key, placed over a III7 chord, to lead to a
dominant IV.
Because I used the key F# in my last example, I'll use it here also.
Key:
F#, G#, A#, B, C#, D#, E#
Now, since we're using the key of F#, our
tritone interval would take us to the key of C.
Related Key:
C, D, E, F, G, A, B, C
We'll take the
related scale and play it over a
dominant III in the original key.
A#-D-G# / C, D, E, F, G, A, B, C
Use this to lead to a
dominant IV.