Hi, I am going to build an RFI mains filter and am using X and Y rated capacitors, and wanted to check 100% that I am not missing any information on the +/- orientation of them before I make the installation.
This is probably a stupid question but I sort of expected to find some guidance on where the + would be when installing but both of the products I have selected, but they seem to be with out any orientation requirement or guidance.
Here they are.
https://docs.rs-online.com/4e61/0900766b8162aeae.pdfhttps://docs.rs-online.com/2181/0900766b8171cbeb.pdf
This is the circuit layout, it's an old design and well established approach.
Any experience or help much appreciated!
This is probably a stupid question but I sort of expected to find some guidance on where the + would be when installing but both of the products I have selected, but they seem to be with out any orientation requirement or guidance.
Here they are.
https://docs.rs-online.com/4e61/0900766b8162aeae.pdfhttps://docs.rs-online.com/2181/0900766b8171cbeb.pdf
This is the circuit layout, it's an old design and well established approach.
Any experience or help much appreciated!
Attachments
Maybe it is a wise choice to buy a ready made filter and just connect that. Mains voltage rated caps like X and Y caps are used on AC circuits and have no polarity.
Yeah I was intrigued by this product and the 'story' of not loosing dynamics, which was my previous experience with mains filters/conditioners.... so for a small sum and a few hours I thought I would make one for 1 channel as a test and see if there is an audible advantage 🙂
http://www.lampizator.eu/AC FILTER/SILK/FILTER.HTML
Experimented a lot with both DIY and industrial filters and always use one in combination with an isolation transformer so a 1:1 version. The transformer makes the largest difference. Effective flters that need to do something useful generally need PE to get rid of the filtered stuff. Considering the required ratings a mains filter is best not built DIY when one has no knowledge of the required parts like X/Y rated caps , fuses, PE etc. Tube pilots in general are the best in adding stuff exactly the way it was not intended to and avoid PE and safety like the Black Plague. So it makes sense not to copy that and to setup a grounding scheme of sorts and which devices you have that need filtering. PE will be needed. My solution was a DIY power distributor with mains switch, mains filter and enough outlets to the now filtered devices one of them being the isolation transformer that feeds the sources.
Just a dynamic 🙂 technical view, it is needed in many areas to remove noise from mains cabling and also to prevent noise created by the device itself creeping back into mains voltage (more an issue when CPU's and SMPS are used in the device).
Just a dynamic 🙂 technical view, it is needed in many areas to remove noise from mains cabling and also to prevent noise created by the device itself creeping back into mains voltage (more an issue when CPU's and SMPS are used in the device).
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X,Y caps are necessarily AC rated so both ends are equivalent. Only electrolytic and tantalum caps have a polarity.
Further, both L1 and L2 (and L3) are filtered with a common mode choke and Y caps because no assumption is made about which side is hot and which is neutral, and the distance to the electrical panel means that the RF frequency voltage on hot and neutral is essentially the same. When powered by a typical hot + neutral connection, there will be essentially no 50/60Hz voltage on the neutral side. Neutral is grounded at the power panel. For connection to 240VAC in North America, L1 and L2 are out of phase and 120VAC each, ie ground is the center tap of the power company power distribution transformer, on the pole or curb. Your circuit shows the AC power floating, which it never is. Line filters are sold in a shielded module because any mains wiring inside a chassis is a RF antenna that couples noise between the inside and the outside of the metal box, a recipe for failing RF emissions compliance.
Further, both L1 and L2 (and L3) are filtered with a common mode choke and Y caps because no assumption is made about which side is hot and which is neutral, and the distance to the electrical panel means that the RF frequency voltage on hot and neutral is essentially the same. When powered by a typical hot + neutral connection, there will be essentially no 50/60Hz voltage on the neutral side. Neutral is grounded at the power panel. For connection to 240VAC in North America, L1 and L2 are out of phase and 120VAC each, ie ground is the center tap of the power company power distribution transformer, on the pole or curb. Your circuit shows the AC power floating, which it never is. Line filters are sold in a shielded module because any mains wiring inside a chassis is a RF antenna that couples noise between the inside and the outside of the metal box, a recipe for failing RF emissions compliance.
Buy a ready EMI filter, not expensive at all.
And like Jean-Paul said above, pay attention to the wiring, that is also a noise source.
And like Jean-Paul said above, pay attention to the wiring, that is also a noise source.
If you dont know what your doing please dont try to build this. Is R5 really 3ohms ? Also 10nf is a little high for Y type cap values if used on 220/240V mains. As they are line to ground caps there
will be leakage current which is subject to government regulation.
will be leakage current which is subject to government regulation.
I have seen this comment about losing dynamics and I have yet to figure any way within the laws of physics it is possible with maybe an exception of HF noise making the result seem brighter, so when reduced, it seems dull. But that should not make it through the DC supply. So I am puzzled. I can't tell you what you can and can not hear, but it does not make sense to me. Actual dynamic compression is more often power supply cap bank too small or not enough voltage overhead for the VAS.
I built a breadboard and tried it - actually very impressed, so I will do the job properly/permanently. I only tried it on the pre-amp so far.
I can supply details of what I did if anyone is interested
I can supply details of what I did if anyone is interested
If the job should be done to filter EMI adequately then the combined IEC socket + EMI filter in one casing are a blessing. A good filter works with PE and shielding. Corcom 6EGG1-2 gives nice results. Saves wiring and drilling and it has fuses in both L and N.
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That Corcom socket looks great, well engineered and cheaper than you could build an inferior version.
The shielding is also important. Strongly recommend that you do not attempt to build one, just buy that.
The shielding is also important. Strongly recommend that you do not attempt to build one, just buy that.