Based in Oxford, Mach One Design is an Engineering consulting firm that is specialised in the field of EMC. We provide EMC pre-compliance, troubleshooting and design consultancy service to customers all over the world.
My issue is as a engineer is the ferrite core of any power transformer is inductance no matter how tight I wound the turns in phase the capacitance always end up to be there in 8 or 9 nf even commercial transformer has the same capacitance and ringing is always there when current is drawing pass 20 amp and this is my issue I even use copper trip to cover the transformer and connect to ground the ringing still there I have to use a iron powder core and 450uf capacitor to remove the oscillation from the current sensor transformer to stop the ringing of the transformer when over current pass
The parasitic capacitance is always there, sometimes, you can place some broadband ferrite sleeves on the co-axial cables to block possible E-field coupling between the DUT and the metallic case of an RF current probe.
Thank you, interesting video. Can we use a TBPCP1-20100 probe to visualise EMI in the frequency domain on a spectrum analizer or does it only work for time domain on an osciloscope?
Yes, absolutely. But most spectrum analysers start working from 9kHz, so you better check if yours is the same. I used Tekbox receiver which works from 0.1Hz. You should have no problem connecting it to an oscilloscope.
@@MachOneDesignEMC Thamk you Mr. Zhang. They used to sell the Spectran NF-5030 at Aaronia but it has been discontinud for some reason. Maybe I can find a second hand one
Hi, I wonder what setup would you use for monitoring the EMI frequencies between DC and 30 MHz. present in a 240V electrical installation: Can you please comment on that?
Hi Torito, check this probe, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RrVsoWCMyH0.htmlsi=Z_19B5qMecjSPVSf. But bear in mind, the senstivity is not as good as other RF current probes, so you may miss small signals. So perhaps just a good quality Hall effect current probe is better.
@@MachOneDesignEMC Thank you, I watched the video but I'd like to use a spectrum analyzer to see the frequency domain and then somehow filter out the dirty electricity. I know you are running a business and I'm sure i can't afford your services but pease help me out with some free advice. I suffer from EHS and I'm trying to get rid of the dirty electricity from my electrical installation. God bless you Sir
I wonder if that company has that technology patented. Seems like it would be pretty easy to replicate those seals. Even if the seal itself couldn't be copied I think it would be easy to add a small pass through adapter pcb that grounds to the connector metal.
In the past, I have crammed a couple of 10nF capacitors into a 9-pin D connector housing, wasn't particularly fiddly - but I guess the point of the seal is that is quick and easy to install...
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.
Thanks for a video on this so important yet mostly ignored part of electronics. I've seen far worse cables. I'd call the two cables and plugs you are demonstrating typical standard qualiities. And sure, as long as a plastic plug is only used for something like RS-232 everything is fine. My two lowlights were RG58 variants. The one had “shielding” which was made from exactly one thin wire - the wire a mesh would normally be made of. This was probably made to just about the use as a network cable - but I was feeding RF through it. It came as it had to, the shielding wire burn up on first trie. The other RG58 had a foam dielectric, double shielding made from one layer of aluminium foil covered by another layer of dense mesh. It did look like a really good cable. Except it was the worse performing cable I ever held in my hands.
Hi Ralfbaechle, that's really good feedback. To be honest, as you can see, our videos are mainly focused on EMI, EMC and high-speed measurement, I have been very surprised to see so much interest in this particular video, which is not even one of my personal favourites. But it does highlight the issues we face in our job and life, we have some more videos coming on co-aixal cables, in which I used two different methods measuring the performance of co-axial cables, which are scheduled for November 21st and 28th. It will be interesting to hear your feedback by then!
As a system field technician i find lots of poorly cheaply terminated cables being used in fleet tracking gps units upon inspecting them. i stumbled on your channel by accident and this is the best channel i have seen close to what i do in the field. i would like to know which is better aluminium or copper foil? Subscribed and thumbs up.i will definitely be watching your other videos.🎉🎉🎉🎉
I used to study the possiblity of using Aluminium wire to replace copper wire in EV charging cables, because aluminium is a lot cheaper and lighter, but at least at the time i studied it, there were big challenges.
Many thanks Rubhern, we will try to make more on this subject for sure. As i mentioned to the other viewer, this video took me by a massive surprise. I was not expecting so much interests, but we have more videos schedueld on cables and connectors in the following weeks and months. Typically, our vidoes address different issues related to EMI, not just cables and connectors, but we do take great advice from our viewers and we often make videos according to your need. Thanks
@@MachOneDesignEMC The "lighter" property would be appreciated. I was surprised when I fond out an extension cord for a 12V batteri charger had aluminium conductors. The problem is you can't solder it and if you clamp it there needs to be a spring in the clamp because aluminium deforms with time.
Subscribed to your wonderful channel. If your antenna was connected with a coax cable, should you place the ferrite at the feed as you told or at 1/4 wl from the feed on the coax as well? I see some VGA cables with ferrites at some distance from the connector on both ends. Thank you
Hi David, i guess that is related to radios, it would then depend, here is a better resource for you incompliancemag.com/cable-antennas-and-ferrite-cores/
@@MachOneDesignEMC Wow. Very interesting. Thank you very much for your time. Yes, it was about common mode currents on a coax cable of an HF antenna, amateur ham radio. I always use multiples of 1/2 WL coax cable to see the same impedance of the antenna at the end of the line and I wonder if the line being resonant is good or bad, or if resonance can be avoided using ferrite chokes, and where to put them on the cable. I will study your videos and the document of your link. Thanks again.
Indeed! It’s the little things like this that people overlook when questioning why they’re not seeing top performance at the edges of performance envelopes. This is going to get increasingly important for data exchange/infrastructure.
Ive seen this often where a cable has adequate shielding but it is not adequately grounded at the entry point. In many cases where the cable/conductors continue into the shielded compartment, the cable shield and drain wire enter the shielded compartment as well, essentially providing a path for undesired signals...
Exactly, and if you want to buy a really good quality one, then you have to pay incredibly high price. I think there should be a standard in the industry to regulate this.
Wow. All that money and effort using a "descent" shielded cable and all metal connector, only to go completely amateur hour when connecting the metal connector to the cable. 🤦♂ Great video showing the results of a good termination!
Thanks, indeed, I was shocked when I opened the clamp shell. But I shouldn't be surprised! Perhaps you can get much better ones from trusted distributors such as Digikey, mouser, etc, but I bet the price will be four times more than this one. I spent 15 GBP on this one.
Indeed, this is especially concerning for everyday use. I often receive emails from people who are into sound systems, music, and gaming, sharing horror stories about their experiences with EMI.
I believe that one of the issues is that most of the consumers aren't qualified to have an opinion on the EMC side of things. Therefore, manufacturers focus on easily visible things such as the feeling the cable gives when touched, or how good connectors look, but the invisible things, such as if the shield is properly connected, are the good RF gaskets inside and so on, all of that is not visible to average consumers, and therefore gets cut to save on costs, or to increase profits. It's very similar for Ethernet cables, for computer video cables and so on.
Nice video, ahnk you. This dirty electricity is the root of all my suffering. I am severely EHS person and I'm trying to understand how to get rid of this kind of noise in my electrical wiring. Do you think using shielded cables would fix my problem?
Hi Torito, I think it should be a combination of good grounding and shielding work together to reduce ambient EM noise. The problem we found in the industry is that electricians are not taught about grounding for EMI, they are familiar with the HV safety aspect, but not EMI. Shielding wise, unless you shield the whole house/office, otherwise, I would focus on improving the grounding of the system and use good filters on the mains.
@@MachOneDesignEMC Thank you Mr Zhang. I have shielded the whole house with conductive graphite paint from Yshield. All that shielding is grounded. I also installed some Graham-Stetzer capacitive filters. I want to try some inductive filters connected in series on the main circuit baut I have this weird electrical installation with two phases and no neutral. I measure 133V between each of them and the ground and 230V between the two phases. So all those inductive filters are supposed to work in series with both phase and neutral. What do you think the approach would be in this case please? I would like to measure the frequencies present in my wiring but most spectrum analyzers only go as los as 9 KHz and I need something to cover everything between 1 Hz- 500 MHz. Also i'm not sure haw to connect it to be able to visualize the noise present.
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 RU-vid 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.
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 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bKaBWkOyMe8.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.
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.
And Now I finally understand how A common mode choke works. I have A Question.... Why do some put the CHOKE at the end of the antenna cable by the Radio ??
Hi, the point is to demonstrate that a ferrite works the best when it is placed in the low impedance point, in this case, it is the radio side. As you can see from the video, close to the tip of the antenna, we have almost zero current, that means at the tip side, it is high impedance (because of low current), therefore, if you place the ferrite on the tip end, it will do nothing. Also see ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bflbmTCVKk0.htmlsi=z8PSYyEhk9kjGXAO
Dr. Zhang - Great learning video. I have worked in the energy, utility and power quality industry for over 30 years and make this topic easier to understand. The biggest challenge is compelling end use customers to install PQ monitoring equipment to capture and characterize the power that is so valuable to their business. If you are ever in the Silicon Valley, please let me know! Thank you.
Nice, easy to understand. In your opinion is it reasonable to try to convert a narrow band noise source to broadband by intentionally causing frequency variation? For example if you had a sin oscillator that constantly varied its frequency by 20% all the time to avoid a single narrow band peak and instead have either a sweeping or noisy plateau?
@@Xsiondu lol no. I was thinking if would actually be better to have a poor clock frequency for a micro( lots of variation ) if that would improve emc noise levels by not having a peek be so high, or if it would make it worse by essentially having your peek move around.
@@Cydget This sounds like poor mans spread spectrum clocking, which purposefully spreads clocking instead of relying on (essentially defective) behaviour. Spread spectrum clocking allows multiple devices to communicate while also maintaining the benefits.
What you described is spread spectrum, we have made a video, but recently when I attended the EMC Europe, I attended Prof Bernd Deutschmann's presentation, it was so good, now I think the one I made is not good.... But I think it serves some basics, which we hope to release the video soon.
Jamming and RF weapons are hot topic, when I was in this year's UK, US and European conference, such subjects were really popular. I will try to do some videos in the future. Well, thanks for suggesting all these, because it keeps giving us good video ideas.
Hi, no problem, it is www.mouser.co.uk/new/texas-instruments/ti-ucc28780evm-002-eval-module/?srsltid=AfmBOopoODwIxL2kVqKsavr8RTruF6-oP9KR8A8FtQuaTwDbkJf5utpT
So am I right if I say that the part of the waveform that is present on both sides of the transformer is conducting through the stray capacitance between primary and secondary winding in the transformer?
Correct Tomas, but I failed to find a way of finding the rest of the CM current. You know, I thought the CM on the primary side and the secondary side should be more or less the same level, but, as shown in this video, the primary side of the current is a lot less. I suspect it is due to the CM filtering on the AC side. But how can we prove this without taking all the filters out? If our assumption is correct, then there must be another path returning the CM current back to its source, just before the filter. Difficult to measure in this case!
@@MachOneDesignEMC Hi again, if the CM-current was exactly the same on primary and secondary side, wouldn't that mean that there is no radiation at all from the primary side? The radiation that is common between the primary and secondary side consist of what the stray-capacitance is able to transfer. Ideally, without stray-capacitance, the radiation from the primary- and secondary side may look totally different I suppose?
Hello, I cannot view the details of your oscilloscope for the green trace (mV scale, time scale) but I think the issue you show with Pico Test TA189 can be avoided. In my test lab with radio engineering and EMC pre-compliance, I use quality old tektronix probes with oscilloscope. For instance, I have TCP202 with TDS794D which will show flat response so perfect shielding. Of course, I do use specific probes fantastic made by tekbox but in your video, either the TA189 is badly shielded or there is a phantom EM loop in your setup (probe, display unit...). Note that using a DC-AC probe hence hybrid of Hall effect and CT effect is tricky engineering design plus with your EMC testing, you really look for AC and RF so why focus on DC part... for small cable, I really prefer legacy TCP202 which goes from DC to 50 MHz otherwise really tekbox is the way to go
Hi, you really know your stuff! I am not fortunate enough to have the Tektronix probes, I know they must be well constructed. The issue I found, even when using top class Hall effect probes, is the random noise pick up in the ambient. About 10 years ago, when I was working for a big company, we used to clamp a probe on the body of a handheld product and left it there overnight for measuring the CM current. The following morning, we noticed lots of random noise pick-up due to the E field noise. I guess, when it comes to very high frequency event, such as an ESD event, it is always tricky to shield the E field. I remembered D Smith used to do lots of experiments on this subject.
Wow, this is exactly what I was expecting. Thanks for the new video! One more question: inside the toroid, what was the cutout area for? Will it achieve better E-field shielding capability if we close the gap?
Ok, we may need to create a path for the magnetic field for inductive coupling. The copper shield is increasing the 'overlap area' and 'parasitic capacitance', so that the voltage built up on it is reduced. So we don't need a closed surface. Is this correct?
First of all it was a pleasure meeting you in person at the 2024 EMC SIPI in Phoenix. I learn a great deal from your videos. Thank you for your expertise on the EMC subject.
Well spotted, 6p and 20p are not so much difference for the results (for Low frequency), I think I may have two sim models there and I chose different values when I was building the models. I should have used the same value for consistency. Many thanks
Hey , thanks again for the amazing content! Please keep it coming ^^ Can you maybe also do a video on cdns and or using current injection probes for immunity testing ?
