Posted by casper on
URL: https://www.es-forum.com/where-to-go-any-ideas-tp4034304p4034333.html

Karl I want to say I really appreciate your replies. Your posts are extremely helpful. You gave me so many new ideas. I'm sorry I didn't reply earlier, but I was not feeling well and I have to wait to have the energy to type again.

You really have some nice McGyver-type solutions. Especially the steel pipes for the power supplies. Where can you find such pipes? Just your average hardware store?

Anyway, after reading your posts I started looking more into filtering my laptop supply, and I found this page:    
http://ka7oei.blogspot.com/2014/08/completely-containing-switching-power.html

That guy managed to completely eliminate his SMPS noise. His approach seem similar to yours; to filter and put stuff into steel boxes.

What I did next was order two filters:

For the AC side I ordered this:  
https://www.ebay.com/itm/10A-EMI-filter-Power-Purifier-Finished-board-AC0V-220V-DC0V-400V-40-100mm/253039768211

And for the DC side this one:  
https://www.ebay.com/itm/DC-Power-Filter-Board-Power-Amplifier-Car-Power-EMI-Interference-Suppression-5A/323505215668

I'm only thinking the chokes on the DC side might be too small. Perhaps I have to try and find suitable toroids for 5A (my supply is 18V 4.9A) and build another one myself, if this eBay setup is not good enough.

If I manage to build something that works I will report here later.

I have an AC line noise meter, and I find that my laptop supply is polluting the whole apartment. Without the supply the reading is 200mV noise, with the supply it goes up to 1000mV in the same socket, and 600-800mV in remote sockets. Hopefully the eBay AC filter will cut out must of that.

Btw. the Bourns inductor you used on the AC socket, does that help with anything? Did you put any other components there?