Hi there Miguel,
There is also a sneaky way to do this
That is, build a series resonant circuit and take the output voltage
from across the inductor.
In other words, a cap in series with an inductor to ground, the input
ac voltage is applied between the cap and ground and the output is
taken from the center tap of the cap and inductor to ground.
This forms a 'filter' of sorts.
The esr of the cap shouldnt be exceedingly high, and the series
resistance of the inductor shouldnt be either.
For example, an 80uf cap in series with a 100mH inductor with 10 ohms
series resistance. Input voltage of 1v peak at 60Hz turns into 3v peak
ac. The output load can not be too great either, so 10k might get
you 3v peak but 1k might take that down to only 2v peak or even less.
You'd have to try a few values.
Code:
[FONT=Courier New]Vin(AC) -----cap------+------ Vout(AC)
|
inductor
|
---------------+----- ground
[/FONT]
The circuit works on resonant principles so has to be tuned.