What I'm essentially trying to do is to add an amplifier to a simple passive radio receiver:
XFMR2 consists of two inductors 0.4 uH and 730 uH. C3 varies between 35 and 235 pF (or something like this). Numbers and the whole left part is taken from here.
The idea is to demodulate negative part of a signal via D1, R1, C5 and pass it to an inverting amplifier based on OA1.
If this circuit is going to work: I'm interested in receiving medium frequencies. It is said they're quite tough to receive in a city due to industrial and home EM noise, especially during days. Am I going to need something more sophisticated instead of this circuit? (not going into antenna discussion here)
Also, why germanium diode OA47? Can I replace it with a Schottky diode?