Allow me to present a sample chart of some of the various changes.
Now let's apply 濁点 and watch the the sounds change to this:
With the above exceptions, the rest of the applicable 平仮名 follow the same pattern of addition and change in sound. For all the uses ゛ has, though,゜ only has one known one with the h family of 仮名, changing them from h to p sounds. Kinda strange, but at least it's only one more thing to learn with it, and less is always more, with how much you gotta learn.
If you need a bigger helping to grasp the changes, please turn your attention to this chart