EMI/RFI/Common Mode Filter – assembled and tested PCB

 40.00 43.00

  • USD: 48.15$ - 51.76$
  • GBP: 35.12£ - 37.75£

 48.00 Incl. VAT

Fully assembled and tested EMI/RFI/Common Mode Filter



Nowadays we use an enormous amount of Switched Mode Power Supplies (SMPS) equipped domestic appliances, industrial electrical consumers etc. in our everyday life. These appliances can throw a great deal of RF hash which sneaks and disturbs the precious analogous networks of our audio equipment.

Here is proposed a fully assembled and tested EMI/RFI/Common Mode Filter (CMF).
Schematic of the unit can be seen below:

EMI/RFI/Common Mode Filter (CMF)
EMI/RFI/Common Mode Filter (CMF)


The Common Mode Filter will deal with the high frequency pollution in the AC Mains Network.
It was inspired by the very successful “Felix project” (

In-depth explanation and examples of Common Mode Filters can be found here:

In the process of CMF simulation the following results were outlined:

– The damping resistors lower the spike in frequency response with approx. 20 dB

CMF without damping resistors
CMF without damping resistors
CMF with damping resistors

– Removing the load-side shunt capacitors (as supposed in the Fo-Felix version of the filter) will give us a smoother frequency response but the corner frequency is shifted to the higher frequencies approx. 25 times

CMF without load-side shunt capacitor


PCB specifications:

Dimensions of PCB: 50×115 mm.
PCB thickness: FR4 2 mm. Copper thickness: 70 um (2oz). Surface finish – Nickel Gold (ENIG).

The board is TWO-layer design which allows the PCB traces to be doubled on the TOP and BOTTOM layers thus doubling the current handling capabilities of the board. All current conducting traces are widened as much as possible which additional raise the max. handled current.
PCB has solder mask coating on top and bottom layer for best durability.
Silk screen with parts layout is placed on the top of the PCB.

The unit has following abilities:

It is calculated to have a corner frequency of approx. 20 kHz and max. handled current of 20A with the parts used
– 4 pcs. X2 type safety polypropylene capacitors
– 2 pcs. Y2 type safety polypropylene capacitors
– Triad Magnetics Common Mode Choke, rated at 20A
– AC input/output connectors can be of the following types:
– 3-pins terminal blocks with lead spacing 5 mm.

NOTE: Some parts of the unit (Common Mode Choke, X2/Y2 capacitors, Input/Output terminals) can be replaced with another ones upon customer’s request, as it’s shown on the pictures.

What the buyer will receive:
The package will contain 1 pcs. Fully Assembled and tested PCB for EMI/RFI/Common Mode Filter.

The unit will be shipped with Priority AirMail Registered (or equivalent courier service where applicable). The tracking number will be sent to the customer after shipment.

Additional information

Weight 0.24 kg
IN/OUT Connectors

Standard Terminal Blocks, Barrier Terminal Blocks