There should be no mercy in cases like this. It's like the car mechanic removing the engine to replace the air filter for better performance.
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OFF-TOPIC WARNING:
"It's like the car mechanic removing the engine to replace the air filter."
Sometimes that's how one is supposed to do it: I once had an MG Midget. Factory procedure to replace one particular water hose required pulling the cylinder head. Needless to say I 'short-hosed' it instead.
"It's like the car mechanic removing the engine to replace the air filter."
Sometimes that's how one is supposed to do it: I once had an MG Midget. Factory procedure to replace one particular water hose required pulling the cylinder head. Needless to say I 'short-hosed' it instead.
Aha from air filter to water hose. Please don't tell me you also remove "unnecessary cable pairs" from perfectly fine good working standardized industrial CATx patch cables or I start to scream 
A tube guy I know told me my BMW motorcycle would have way less resistance if I would remove the front wheel. He said it would be more economic, make less noise and have better manoeuvrability. He had read this on the internet and said all BMW owners did this and reported it to be much better. He was absolutely right on all aspects, way less friction but boy it is not easy to ride it now. Does anyone of you know a good way to keep balance?
A tube guy I know told me my BMW motorcycle would have way less resistance if I would remove the front wheel. He said it would be more economic, make less noise and have better manoeuvrability. He had read this on the internet and said all BMW owners did this and reported it to be much better. He was absolutely right on all aspects, way less friction but boy it is not easy to ride it now. Does anyone of you know a good way to keep balance?
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OK- I see - this thread seems to get useless.
For your information:
These industrial switches, which are designed for critical infrastructures with special recuirements for low EMI, only have a connection for 2 pairs. They work verry well and are absolutly robust.
Should I let the 2 other pairs act as an antenna?
Also ProfiNet with real time recuirement uses the Ethernet physical layer with only 4 wire.
For your information:
These industrial switches, which are designed for critical infrastructures with special recuirements for low EMI, only have a connection for 2 pairs. They work verry well and are absolutly robust.
Should I let the 2 other pairs act as an antenna?
Also ProfiNet with real time recuirement uses the Ethernet physical layer with only 4 wire.
Once again no input regarding my question of termination the center taps.
Forget all about the switch and my network setup
Here my initial question:
How should the center taps of an transformer be handled in a 100BaseT network, when used as an isolator (which is an established use case)?
Any thoughts about this problem are welcome, but I am sick of discussions arount my network setup.
The point being that there should be no isolator in between as both sides are already equipped with isolators. The device you want to use in between is meant for isolation of possible high voltage surges till even 6 kV. It is NOT meant to filter out noise. In normal situations it could be called a superfluous device.
https://cdn-reichelt.de/documents/datenblatt/E910/DELOCK_62619_DB_EN.pdf
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Your network devices are already isolated adding another isolator is redundant.
If you want total isolation then your solution is wireless or optical fibre.
You don't need railway standard voltage isolation in your home network.
I feel with you TomJones but make a drawing of both sides and the device in between and you will see the answer.
Yes they are commercial goods, so are heroin and meth. Since the audio branch has discovered network audio is a growing market there are a lot of commercial goods that will give the buyers an extreme improvement.
Ok I will make an end to the misery. Beware and pay attention... the Ethernet Isolator made by Delock should just be inserted by the way of 2 standard UTP CAT6 cables or the like. I know, it is shocking. There is no need to even think of center taps as it are ready made devices that work. With standard cables. In the normal situation there will be a PHY/isolation transformer at both sides.
You spoke of using them in the middle of the cables which will always be the case with stuff that is designed to be inserted In such a case network techs always sigh and use "coupler" blocks. It means they made a mistake by using too short cables. They will need to crimp RJ45 connectors themselves which is (sorry) often worse than automated production cables. They won't be proud and their colleagues will not be happy. Best is to have one uninterrupted cable and then test and measure it. This is why the coupler blocks have a different name amongst them which is somewhat pejorative.
*please note that the overvoltage protection of the Delock Ethernet isolator (that is NOT a filter) only works when you connect the screw to PE. It is not even mentioned in the data sheet which is worrying as the sole purpose is to protect equipment from high voltage surges.
https://www.delock.de/produkt/62619/pdf.html?sprache=en
Yes they are commercial goods, so are heroin and meth. Since the audio branch has discovered network audio is a growing market there are a lot of commercial goods that will give the buyers an extreme improvement.
Ok I will make an end to the misery. Beware and pay attention... the Ethernet Isolator made by Delock should just be inserted by the way of 2 standard UTP CAT6 cables or the like. I know, it is shocking. There is no need to even think of center taps as it are ready made devices that work. With standard cables. In the normal situation there will be a PHY/isolation transformer at both sides.
You spoke of using them in the middle of the cables which will always be the case with stuff that is designed to be inserted
In such a case network techs always sigh and use "coupler" blocks. It means they made a mistake by using too short cables. They will need to crimp RJ45 connectors themselves which is (sorry) often worse than automated production cables. They won't be proud and their colleagues will not be happy. Best is to have one uninterrupted cable and then test and measure it. This is why the coupler blocks have a different name amongst them which is somewhat pejorative.*please note that the overvoltage protection of the Delock Ethernet isolator (that is NOT a filter) only works when you connect the screw to PE. It is not even mentioned in the data sheet which is worrying as the sole purpose is to protect equipment from high voltage surges.
https://www.delock.de/produkt/62619/pdf.html?sprache=en
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OK -just found a possible anwer on Ebay: Lnf-c7: LAN Noise Filter fur Netzwerk-Player, Eliminate Getriebe Gerausche | eBay
They seem to terminate the center tap on the cable side with Bob Smith and the "PHY" just with capacitors.
Unused pairs are also terminated with Bob Smith termination.
They seem to terminate the center tap on the cable side with Bob Smith and the "PHY" just with capacitors.
Unused pairs are also terminated with Bob Smith termination.
Engineering is a social construct as we all know but anyway:
https://www.eetimes.com/updating-the-bob-smith-termination-technique/#
Did you by any chance try out linear PSU's to fight noise? If there is a direct source straying out noise close to the audio band (which noise are you fighting BTW?) it is the SMPS in a switch. Worse are the external adapters. VERY thin ice but there seems to be a correlation of sorts between the voltage and the voltage needed for the switch. Not exact engineering (who cares?) but I found the switches that have 5V adapters to be quieter than the ones that have 12V adapters. After all they often use the same low voltages internally like 3.3V, 1.8V etc. Now I stick my neck out for redemption but decoupling and using beads do make a cleaner voltage in such devices just like replacing the SMPS for a good LPS.
If people think LPS are not useful I always say the linear PSU's are there because they don't whine as SMPS do. End of discussion
https://www.eetimes.com/updating-the-bob-smith-termination-technique/#
Did you by any chance try out linear PSU's to fight noise? If there is a direct source straying out noise close to the audio band (which noise are you fighting BTW?) it is the SMPS in a switch. Worse are the external adapters. VERY thin ice but there seems to be a correlation of sorts between the voltage and the voltage needed for the switch. Not exact engineering (who cares?) but I found the switches that have 5V adapters to be quieter than the ones that have 12V adapters. After all they often use the same low voltages internally like 3.3V, 1.8V etc. Now I stick my neck out for redemption but decoupling and using beads do make a cleaner voltage in such devices just like replacing the SMPS for a good LPS.
If people think LPS are not useful I always say the linear PSU's are there because they don't whine as SMPS do. End of discussion
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In the past I did EMC-measurements with LAN xformers as well and all I can say is that the internal CM-chokes with inductances in the ballpark of 500uH were of little help in reducing CM-noise. Interwinding coupling capacity of these xformers is not neglible and contributes to CM-noise coupling. And I talk of CM-noise with frequencies above 10MHz. In other words, irrelevant for audio,
I have already a LPS driving the switch and Squeezebox Touch ist battery powered.Engineering is a social construct as we all know but anyway:
https://www.eetimes.com/updating-the-bob-smith-termination-technique/#
Did you by any chance try out linear PSU's to fight noise? If there is a direct source straying out noise close to the audio band (which noise are you fighting BTW?) it is the SMPS in a switch. Worse are the external adapters. VERY thin ice but there seems to be a correlation of sorts between the voltage and the voltage needed for the switch. Not exact engineering (who cares?) but I found the switches that have 5V adapters to be quieter than the ones that have 12V adapters. After all they often use the same low voltages internally like 3.3V, 1.8V etc. Now I stick my neck out for redemption but decoupling and using beads do make a cleaner voltage in such devices just like replacing the SMPS for a good LPS.
If people think LPS are not useful I always say the linear PSU's are there because they don't whine as SMPS do. End of discussion
The frequencies are of course not in the audio range, but can have a negative influence on the conversion from D to A.
There are also common mode chokes (CMCs) in these xformers.
Assuming the transformer (incl. CMC) has positive effects, it may be that this is mainly due to the CMCs.
Would it then make sense to use only CMCs instead of an isolator (transformer + CMCs)?