I have flyback power supply has noise in its output and this noise is common mode noise ,I did try different common mode filter but still noisey, is any suggestion for how to get ride of the common mode noise.

 

I have flyback power supply has noise in its output and this noise is common mode noise ,I did try different common mode filter but still noisey, is any suggestion for how to get ride of the common mode noise.

Do you mean the output is noisy? Isn't the output just a voltage and ground?

 

Do you mean the output is noisy? Isn't the output just a voltage and ground?

The output is noisy and this 15 vdc and current 4A and 15vdc and its return is noisy , the Specification is the return of 15vdc to the chassis of the unit to be very low noisy ,less than 20Uvdb

 

The output is noisy and this 15 vdc and current 4A and 15vdc and its return is noisy , the Specification is the return of 15vdc to the chassis of the unit to be very low noisy ,less than 20Uvdb

Is the return grounded to the chassis?
How about a schematic and a picture of the noise.
The more information you can give us the better.

 

What is the common-mode inductance of the filter you are using?
Try one with a higher common-mode inductance.

 

Is the return grounded to the chassis?
How about a schematic and a picture of the noise.
The more information you can give us the better.

the return is not connected to ground and for schematic I do not have it right now

 

What is the common-mode inductance of the filter you are using?
Try one with a higher common-mode inductance.

Thanks so much, I will try this tomorrow when I get to work

 

Another question:
Is there a switching transistor attached to a grounded heatsink?
That can put noise into the ground.

 

Another question:
Is there a switching transistor attached to a grounded heatsink?
That can put noise into the ground.

No ,i did try the common mode filter, it fix the range from 1mhz and above ,but i still have noise in the range lower than 1Mhz.