It's better to have the rectifier and storage cap in the remote supply and to have a pi-filter at the input of switcher providing an excellent dampening of switching frequency. Then, usually, an additional filtering is not necessary. In the case, that your device produces a lot of common mode noise, you should have a common mode choke at the input of pi-filter of switcher. This can also be snap-on ferrite, for instance.


Without knowing more about your circuit, I can only say, that the traces to the rectifier can be extremely noisy and should not form any loop! Route them in parallel and as close as possible. Reduce their length to the absolute minimum. Also, this AC voltage should not power other parts like the door opener. Everything connected to the rectifier inputs is contaminated by the switching noise from the acting rectifier.

Kai