/sci/ - Science & Math

>>9001649
A gain of 20 may look impressive but doesn't change that much and now you have two diodes in series. The main drawback is that the output is no longer ground-referenced, it floats. This configuration can be used to drive a moving coil indicator, but not a meter. The idea behind the precision rectifier is to use the open-loop gain of an opamp to (almost) fully eliminate the diode voltage as shown in the picture. The current through R2 (and the instrument) precisely follows the input signal, even if it is small.