Looking at a schematic is always how I decide of I want to build a circuit or not so I will present it first. I found the one I based my design off of here:
Although mine isn't exactly like that one it is essentially the same topography. It sure looks simple enough doesn't it? That is why I choose to build it myself. I made my schematic because I did not have a TLE2141C Op-Amp. If you do then you can build the original and it should be easier than building mine.
IC1 and IC2 on my schematic are 15 volt regulators I used 12 volt ones. SL4 from the power supply section should power the lower voltage dual op-amp of course.