Watch the Changing Major to Minor online guitar lesson by Matthieu Brandt from Songwriting on Guitar
Secondary dominant chords will often contain a major third instead of a minor third that the key originally contains. We've changed the minor or minor-seventh chords to major or dominant-seventh. Other alterations that can be made within the original key are changing the IV and V chord (both major) to their minor counterparts.You do this by lowering the major third of these chords. The chord you end up with give your composition a very distinctive twist. In some cases you'll create an incredibilly sad chord. The IVm chord can also be used to create a smooth harmonic progression back from the IV to the I chord.