50Hz4 PoleChebyshevFilter

My F-Scan2 equipped with a 4-pole Chebyshev filter with a cut-off frequency of 50 Hz. The two chips are Burr Brown UAF 42. This filter suppresses spurious peaks, such as the periodic occuring peaks with multiples of ~1360 Hz. The red lead of the finger electrode receptacle located in the upper right in this picture has been removed and the filter has been looped into the the input of the F-Scan2 circuitry. The filter's gain has been increased to 5X, so that smaller DIRP signals can be picked up. Therefore the F-Scan2 shows CV values of about 60-50% instead about 10% before the filter installation.

The slow-varying DC can pass the filter and, as stated above, is amplified by a factor 5X.