Oxidation and reduction are best controlled by a potento- or galvanostsat, where you can control the current and potential over a cell. The charge exchanged is a measure of the amount of reaction that has taken place, whereas the voltage usually gives you an idea on what reaction. (used in a 3-electrode cell, with a reference electrode)
But for simple indicators use the links enahs provided. Indicators work as a simple version of the reference electrode in the 3-electrode cell.