mains filters attenuation range.
Well, I didn`t get any sparks in easter, had to make do with Jacob
ladders, 12" long at 8 amps in. :-)
But I have to put some affort into aquiring a RF trap, to keep the
neighbours happy, and the telly working.
Since I am running between two phases, to get 380 volts in, I would have
to get a 3-phase filter = expensive.
Looking at EMC filters in the farnell catalogue, one thing that struck
me was, that the attenuation at 100 KHz is typically only 20 dB, not
rising to 60-90 dB before well into the megahertz range.
Is this really not a "bad" way to use a filter.?
Then there are motor drive filters, they come in 100 and 150 and 300
KHz, and attenuate better than 85 dB common mode, but they are equally
Since I really like to wind coils, I have no doubt that I could make one
up myself, and even make it multi-stage, but filter design is over my
Is there not by chance an EMC-engineer around here that can help me out
with some values for coils and caps. I would prefer to use air cored
coils, as that would make it easier to measure the inductance.
Part of the exersice is to make it all oneself, and 3-phase EMC filters
don`t just lay around, here.