I built one, took a while because I first wired it up backwards (~_~;) and then decided to redo all the resistors with a lower value, but it works OK now. I kind of want to make an active one but it was tedious enough building it passive so I'll just try and actually figure out a good way to use this one first. Promising attempts so far but not ready for live use yet, need to find a solid setup. things get COMPLICATED.
