Andrey,
I read your post and it sounds chinese to me. When you use terms like "basically", "I am pretty sure you can build one yourself," and "easy soldering," I feel stumped. I have built motors, swapped an M20 in a 2002, installed an M52 into my 318ti, including some pretty nasty wiring, I must have removed and installed over 20 cylinder heads. My mechanical abilties and understanding are above average. A VR frequency to voltage converter, an amplifier... not exactly typical for a shade tree mechanic. Or am I the only one who does have a clue what a DIP is?
It's like that friend of mine who told me how simple it was to replace this guy's heart valve. Slice the chest open, cut a couple of hoses, replace the tricuspid or perform a ring annuloplasty and saw it back together. Piece of cake.
Now, if it really is a simple operation that an semi-intelligent person can actually understand without a master degree in electrical engineering, do share more intricate details so that the rest of us can build one. It would be a huge service to a lot of us who enjoy the challenge and lack the funds to fork over bg bucks to have somone else do it. Thanks.