This is really good. Very much appreciated. I have a much better understanding now. I listen to a lot of music and have a 2 watt/channel tube amplifier connected to very sensitive speakers (105dB @ 1 watt). I wonder if you could/would do a video on reducing/eliminating hum and noise on RCA cables, and possibly earth loop ground hum. That would be very interesting for me, and perhaps a lot of others. I know there are a lot of TH-cam videos on this but I followed your video - it was so clear.
Hi Dr Min, For example CAT7 ETH cable. Do you Terminate the Foil( which separates each Twisted pair ) and the Braid shielding that covers all foils in the same place? or other arrangement? In addition could you make a video that explains how the Current returns in this case, and in general the return path of shielded ethernet cables? ( there is coaxial structure between the Foil and the braid outer shield) " shield inside shield"? Thank you.
There are many ways of measuring the effectiveness of a shielded cable. Using a current probe is just one of these methods. As I mentioned, when it comes to shielding effectiveness of a screen, the theory often doesn't match with the reality. So a current probe method measures the current on the outer surface of the shield, which should be zero if the shield is really good and terminated properly. if not, you are gonna see significant CM current on the outer shield. I would recommend watching this th-cam.com/video/bKaBWkOyMe8/w-d-xo.htmlsi=ZmWBJIa7sG2z7WPT
@@MachOneDesignEMC Thank you for your reply. But that is actually a question. In that video, you provoke high CM current by attaching an extra piece of wire to the central conductor. In this case, you measure CM current that is just because of extra displacement current from the central conductor to external room ground. But here you measure the effectiveness of the shield using a similar approach but not connecting anything to the central conductor.
I assume here that with a bad cable, the skin depth is relatively high so return path current density is also presented on the outer layer of the cable, and due to finite conductivity and inductance, the is some voltage drop on the outer side of the cable, that causes the CM current... Thank you.
Thank you for this informative video. I did test my cables and the result was the same. But I have a question. Are there any documents about this comparison and the reason behind it? I couldn't understand the math behind it.
It is going to be very tricky to explain this in a TH-cam video, you can find this either on proper text book, or attend an EMC training workshop/seminar. We have a few follow up videos, which we hope to cover some basics. We do a great deal of detailed explanation in our training programme.
Good video again! And nice tshirt! 😀 But there is one question: I was tought that it is very important to ground a shield in both ends. So what is the difference when measuring?
Thanks Tomas, you are very kind. Yes, there are so many myths about terminating the shield, which we hope to answer in future videos, stay tuned. I just need to find/build some circuits to prove the point.
@@MachOneDesignEMC As someone who has to terminate shielded cables daily, I eagerly anticipate your video on this in order to dispel some of those myths and let me know the best way to terminate them. For this reason you have another subscriber.
This is normal in USB A to B cables. Even when they have a braided shield they are rarely connected on both sides. However, USBC did away with that by mandating the shield and GND to be connected on both ends.
indeed. I still remember my first iPod. When I opened up the flat connector, I was curious how a good quality copper tape there could improve the EMI suppression.
Lol, bonus points for Maxwell and Faraday in the back!
And Tesla, not the EV!
This is really good. Very much appreciated. I have a much better understanding now. I listen to a lot of music and have a 2 watt/channel tube amplifier connected to very sensitive speakers (105dB @ 1 watt). I wonder if you could/would do a video on reducing/eliminating hum and noise on RCA cables, and possibly earth loop ground hum. That would be very interesting for me, and perhaps a lot of others. I know there are a lot of TH-cam videos on this but I followed your video - it was so clear.
Great suggestions, David, we will do some video on this subject soon.
Hi Dr Min,
For example CAT7 ETH cable.
Do you Terminate the Foil( which separates each Twisted pair ) and the Braid shielding that covers all foils in the same place?
or other arrangement?
In addition could you make a video that explains how the Current returns in this case, and in general the return path of shielded ethernet cables? ( there is coaxial structure between the Foil and the braid outer shield) " shield inside shield"?
Thank you.
How is the clock demonstrator built? I'd love to see what chip you used to generate the fast rising edges.
It is just some switching MOSFET, you can design the gate drive turn on resistor (make it close to 0 R), so the rise time is sub nanosecond
Thank you for the video. But could you explain why you are measuring CM current to measure shielding effectiveness?
There are many ways of measuring the effectiveness of a shielded cable. Using a current probe is just one of these methods. As I mentioned, when it comes to shielding effectiveness of a screen, the theory often doesn't match with the reality. So a current probe method measures the current on the outer surface of the shield, which should be zero if the shield is really good and terminated properly. if not, you are gonna see significant CM current on the outer shield. I would recommend watching this th-cam.com/video/bKaBWkOyMe8/w-d-xo.htmlsi=ZmWBJIa7sG2z7WPT
@@MachOneDesignEMC Thank you for your reply. But that is actually a question. In that video, you provoke high CM current by attaching an extra piece of wire to the central conductor. In this case, you measure CM current that is just because of extra displacement current from the central conductor to external room ground. But here you measure the effectiveness of the shield using a similar approach but not connecting anything to the central conductor.
I assume here that with a bad cable, the skin depth is relatively high so return path current density is also presented on the outer layer of the cable, and due to finite conductivity and inductance, the is some voltage drop on the outer side of the cable, that causes the CM current... Thank you.
Thank you for this informative video. I did test my cables and the result was the same. But I have a question. Are there any documents about this comparison and the reason behind it? I couldn't understand the math behind it.
It is going to be very tricky to explain this in a TH-cam video, you can find this either on proper text book, or attend an EMC training workshop/seminar. We have a few follow up videos, which we hope to cover some basics. We do a great deal of detailed explanation in our training programme.
Good video again! And nice tshirt! 😀 But there is one question: I was tought that it is very important to ground a shield in both ends. So what is the difference when measuring?
Thanks Tomas, you are very kind. Yes, there are so many myths about terminating the shield, which we hope to answer in future videos, stay tuned. I just need to find/build some circuits to prove the point.
@@MachOneDesignEMC Super!
@@MachOneDesignEMC As someone who has to terminate shielded cables daily, I eagerly anticipate your video on this in order to dispel some of those myths and let me know the best way to terminate them.
For this reason you have another subscriber.
This is normal in USB A to B cables. Even when they have a braided shield they are rarely connected on both sides. However, USBC did away with that by mandating the shield and GND to be connected on both ends.
indeed. I still remember my first iPod. When I opened up the flat connector, I was curious how a good quality copper tape there could improve the EMI suppression.
Niche, but I’m here for it.
👍👌
Glad it is not a 🤌. Lol
Nice shirt.
I think we will start designing some really fun EMC SIPI related shirt and sell them, just for fun or charity.