X10 noise problem PUBLIC

Do you realy mean 120 khz? Add an in line choke, and small bypass capacitors. Low pass filter (example) http:///d9ugfwm

Noise can come through building power lines. Leave it in the building wiring.

A laminated core isolation transformer

Primary & Secondary coils are independently wound.

And isolated from each other. Only inductive coupled.

Soft iron laminated core is Grounded.

Magnetically shielded, conductive container, also Grounded.

Power cable from isolation transformer

Twisted pair or Ground shielded.

Clip on EMI RFI Noise Ferrite just before Low Pass Filter.

Low Pass Filter

Signal across lines “A” & “B” are shunted by low impedance C1,

in series with high impedance transformer used as an inductor,

and shunted once again by low impedance C2

Signal in common with lines “A” & “B” are

in series with high impedance transformer used as inductor,

and see low impedance shunt of C3 & C4 in parallel.

Your “Electronic xfmr” should now have a fairly clean “X10” signal.

In some sensitive medical electronics, a low impedance amplifier (<1), can be used to feed enough “Common mode” signal to the final stage, to cancel any interfering signal found there.

The circuit simulator may help you find component values.