Since discovering that inductors are reactive components depending on frequency (their reactance increases with frequency unlike capacitors which do the opposite - an ideal combination for mains RFI/EMI filters), I discovered that where you place AC capacitors before and after a common mode choke can either filter out noise from the load or filter out line noise.
Line - C1 - Choke - C2 - Load
In this example, C1 filters out noise from the load while C2 filters out line noise.
Line - C1 - Choke 1 - C2 - Choke 2 - C3 - Load
C1 filters out noise from the load while C3 filters out noise for the load, but C2 is filtering out noise from the line and load.
Line - C1 - Choke 1 - C2 - Choke 2 - C3 - Choke 3 - C4 - Load
Any capacitors between Choke 1 and Choke 3 will filter out noise from the line and load.
Line - C1 - Choke - C2 - Load
In this example, C1 filters out noise from the load while C2 filters out line noise.
Line - C1 - Choke 1 - C2 - Choke 2 - C3 - Load
C1 filters out noise from the load while C3 filters out noise for the load, but C2 is filtering out noise from the line and load.
Line - C1 - Choke 1 - C2 - Choke 2 - C3 - Choke 3 - C4 - Load
Any capacitors between Choke 1 and Choke 3 will filter out noise from the line and load.
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