This is a very common kit on eBay intended for use with audio amplifiers to filter out mains borne noise. It looks as though it's been copied from another design, but with the usual flaws introduced during the interpretation. Particularly with regard to separation, current carrying path, pad sizing for mechanical strength and a possible swap of MOVs for class Y filter caps.
It's quite easy to build with basic tools but will need mounted in a suitable enclosure (often the amplifier itself) with insulated pillars due to a slight design issue with live to ground clearance.
This module might find applications inside other equipment sensitive to mains borne transients and noise. Keep in mind you can buy fully compliant inline filter modules for equipment from local electronic suppliers for professional applications.
I may have described the common mode choke completely back to front. Let me know your thoughts on that.
Here's a search link for the kits:-
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR0.TRC0.A0.H0.TRS1&_nkw=diy+power+filter+emi&_sacat=0&LH_TitleDesc=0&_sop=15&_osacat=0&_odkw=diy+power+filter+emi
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13 thoughts on “Building an ebay power filter kit with schematic .”
  1. Avataaar/Circle Created with python_avatars Mark Clark says:

    I use Lead-Free solder as a weight for my cheep iron holder

  2. Avataaar/Circle Created with python_avatars Nuts n Proud says:

    I might build one of those kits just to hear the bang when I sort out the caps with pliers.

  3. Avataaar/Circle Created with python_avatars wiedapp says:

    I might be a little late to the party, but for what you do on your channel, I couldn't suppress a little snicker when you said you misidentified the MOVs for some Y-CAPs at first…😂😉

  4. Avataaar/Circle Created with python_avatars carlu bambi says:

    It's getting worse with the quality of our AC Mains supply as we add more electronics on it .The switching power supplies and VFDs and Drives and computers just making a mess of the AC line .

  5. Avataaar/Circle Created with python_avatars Tobias James says:

    A filter circuit board like this really should be a single layer copper design, so you can see and thus know there is correct gaps

  6. Avataaar/Circle Created with python_avatars Roy Tellason says:

    My generic ebay snips somehow ended up with one jaw significantly shorter than the other, I''ve no idea how that happened or where the missing bit went… 🙂

    I have a whole bunch of these sorts of parts, both as whole assemblies and as discrete parts when the filter was a section of a larger power supply board. The values for the capacitors is all over the place, and I've no idea of the current-carrying capacity of any of those coils. I'm not sure where I would want to use one of these, too. Though I suppose power going into an audio amplifier might be a good place.

    I've also seen some that had multiple stages, many capacitors and more than one common mode coil, too. I'm not sure when you'd want to go that far.

    That bit about getting the coil the wrong way around can happen in other situations too. Many years ago I was directing someone as to the assembly of a computer from a pile of parts that we'd bought, and one of the steps was attaching four wires from the power supply to the back of the power switch. When we were done we plugged it in and turned it on and nothing happened, until I noticed that the power cord was getting rather warm. That cord went into the trash and the situation got corrected. With no breaker being tripped and the cord only getting rather warm, I'm wondering what the impedances were in that setup…

  7. Avataaar/Circle Created with python_avatars ethzero says:

    Hate to be the counter to the "leaded solder" argument but it's not largely about the effect it can have any single person but what happens to that lead content when it's inevitably sent to landfill and environment impact long after we're all dust.

    On a personal note I have both some decades-old leaded solder and modern lead-free solder and, I would assume due to lengthy oxidation, I've found the lead-free stuff far easier to work with. Even accounting for the age, I've also found solder with a Sn/Ag/Cu/Rosin mix perfect for small amounts of SMD repairs, something I found absolutely not possible (again probably down to skill rather than materials) a few decades ago.

  8. Avataaar/Circle Created with python_avatars jp says:

    I have one of these filters but it doesn't have any connection to earth on it. It would have been nice if you had explained how important caps are where the movs were. I'm going to guess so if you see a rather red sunset in the East from where you are – it's me.

  9. Avataaar/Circle Created with python_avatars jimmy Ross says:

    lol im 35 turning 36 in two months so yeah im still young but im getting there lol i might not make it till i get old but if i do ill be happy lol

  10. Avataaar/Circle Created with python_avatars fremeaner says:

    Could you not have mounted everything upside down on that board which would have alleviated the concern of solder and plated through holes

  11. Avataaar/Circle Created with python_avatars FCWW says:

    “I shall connect it to the mains, and see if it goes bang!” I know that because the video is posted, it didn’t go bang in too bad of a way. I still love that he has a sense of humor around electricity, all while giving her great respect as well.

  12. Avataaar/Circle Created with python_avatars Mention not Please says:

    Why don't you talk about it?

  13. Avataaar/Circle Created with python_avatars Shane Johns says:

    So even those metalized film capacitors degrade over usage time due to corona discharge. That kinda sucks. How are we supposed to go from one star system to another if we have to wake up from cryosleep and swap out capacitors every decade or so?

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