A while ago I looked at the HLK-PM01, and amazingly it turned into a very well read post… (do not even touch the cheaper crap!) with a lot of people asking how to make it work properly.
Hi-Link’s solution for RF emission of a device using a HLK-PM01I also got an email from Tom at smart-sense.hr saying that he had used one of the HLK-PM01 modules, and his emission graphs were similar to the ones I produced in the last post. He had also been in contact with people at Hi-Link, the manufacturer who sent him the following solution.
I don’t have any 10 mH chokes (Well I probably do, I just have no idea which ones they are) however I have some 20 mH chokes, and a Schaffner RN102-0.6/02 which is 2 x 4.4 mH chokes in common mode (Farnell number 2097049).
I don’t use Inductors all that much as a component that I spec by value, but on paper Serial and Parallel Inductors behave nicely, so lets have a look at doing that:
Possible solution for using an HLK-PM01 with 4.4 mH common mode choke
At work we have two LCR meters, a Wayne Kerr B424/N and an Sourcetronic ST2830 (ST2830 LCR Meter Manual), so setting the RN102-0.6-02 up to each of them in a number of configurations I managed to get some values (easer than the maths, and less likely to be wrong):
RN102-0.6/02 – 2 x 4.4 mH
Wayne Kerr B424/N
Wired as per A on Table below
Wired as per B on Table below
Wired as per C on Table below
Wired as per D on Table below
Wired as per E on Table below
Sourcetronic ST2830
Wired as per A on Table below
Wired as per B on Table below
Wired as per C on Table below
Wired as per D on Table below
Wired as per E on Table below
Wayne Kerr Meter B424/N
Sourcetronic ST2830 LCR Meter
A. One Inductor only (Both Inductors give similar results)
5.39 mH
7.59 mH
B. Both inductors at one end
73 μH
50.82 μH
C. Both inductors diagonally
23.9 mH
27.24 mH
D. Both inductors in parallel
6.51 mH
8.75 mH
E. Both inductors in parallel, one reversed.
27 μH
12.78 μH
Well there goes that cunning plan…
It turns out that if you put two inductors in series, that while yes you double the turns, and double the inductance, this only works if you are not doubling the turns on the same core! just doubling the turns on a core quadruples the inductance, as we can see from above.
Lucky for me, I had a Schaffner RN114-1.2-02 2 x 10 mH 1.2 A laying around, so I will use one side of that.
HLK-PM01 Markings
HLK-PM01 Barcode
Schematics for Filter 1
Schaffner RN114-1.2-02 2 x 10 mH 1.2 A
100 nF 400 V X1 rated cap.
Assembled filter with 33 Ω load
Assembled filter with 33 Ω load
Looking back at the original results, which were performed with the following setup. We can see that it is only the conducted emission we have to try and win back:
HLK-PM01 loaded with a 33Ω resistor as per original test
HLK-PM01 – Conducted Emissions – Class B – BS EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments
HLK-PM01 – Conducted Emissions – Class A -BS EN 61000-6-4:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for industrial environments
HLK-PM01 – Radiated Emissions – Class A -BS EN 61000-6-4:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for industrial environments and Class B – BS EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments
So lets look at the results using Filter 1:
HLK-PM01 – Conducted Emissions – Class B – BS EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments – Live Side using Filter One
HLK-PM01 – Conducted Emissions – Class B – BS EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments – Neutral Side using Filter One
As you can see while there is some improvement of the Live conductor however the Neutral conductor still lets the circuit down. unlike last time I am not looking at the Class A limit lines due to BS EN 55022 “Information technology equipment. Radio disturbance characteristics. Limits and methods of measurement” [pdf] no longer being a current standard, and its replacement BS EN 55032:2015 “Electromagnetic compatibility of multimedia equipment. Emission Requirements” further restricts the get out clause for using Class A limits:
BS EN 55032:2015 “Electromagnetic compatibility of multimedia equipment. Emission Requirements” Section 4 BS EN 55032:2015 “Electromagnetic compatibility of multimedia equipment. Emission Requirements” Section 7 Filter twoHowever also in Tom’s email was a solution that he had come up with that has slightly more components (And lucky for me the RN102-0.6-02 is the correct component):
Building it up out of components and wire I had laying around, I think it goes without saying that I can do daft things because I know what I am doing, but here it goes anyway. Please don’t use this size of wire when you do anything like this!
This is a common mode filter, any common mode noise should be removed by the choke, the additional capacitance (and ground wiring) should help to take out differential mode noise. lets see how it goes…
Schematics for Filter 2
330nF cap
330nF cap
two 2.2nF caps
The common mode choke
Filter Components
Assembled filter with 33 Ω load
HLK-PM01 – Plugged into LISN with Filter Two
Ok so the results from testing:
HLK-PM01 – Conducted Emissions – Class B – BS EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments – Live Side with Filter Two
HLK-PM01 – Conducted Emissions – Class B – BS EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments – Neutral Side with Filter Two
Some how I have managed to kill the HLK-PM01, as I don’t trust the results I have got from the Neutral line scan, however the live side scan does show a close pass to Class B limits.
While I would not be happy using this Switched mode PSU to make anything I was going to place on the market, I may consider it!
If you are making a product that users are required to plug in, Please, please send CASS Industries an email to ask about testing!
The test results on this page are indicative, and in no way constitute evidence of a pass! and as the Irish or Welsh would say “Well sir, if I were you, I wouldn’t start from here” I would go with something like a VIGORTRONIX VTX-214-005-105 AC/DC PCB Mount Power Supply (Farnell #2401040 ), as for only a few quid more you win a switch mode PSU that stands a chance of not requiring external components to pass Class B!
We haven’t tried the first solution, with one inductor and one capacitor, but now that I see your results, I will not bother trying. At the end, it is kind of logical that the neutral wire will not benefit much from it since it doesn’t have a choke inline.
We have big price pressure on our product, and that is why we are stuck with HLK-PM01 which we get at $1.70.
Anyway, while I was exploring how power supplies should be designed, I took apart few modern mobile phone chargers – Samsung, Nokia, HTC, and Apple.
Some of them share similar design which is not much different from HLK-PM01, but with capacitors and other components of a higher quality. But Apple iPhone 6 charger was something completely different.
Tightly packed design on 4 orthogonal PCB-s, integrated switcher, common mode choke at the AC side, high quality capacitors, additional insulation – really worth the price.
Hi Tomislav. I was wondering why you didn’t go with the idea of using a mobile phone charger that your customers could supply. Everybody has lots of USB chargers giving out 5v and some even supply up to 2 Amps. You save money and it’s good for the environment. It also relieves you of the responsibility if something goes wrong with the 5v supply. The chargers would also probably have been in use by the customer for some time and are therefore probably safe.
It does not limit your liability; if a random USB supply destroys the device the customer is going to be upset with you as the manufacturer, not the USB supply supplier.
7 thoughts on “Revisiting the HLK-PM01”
We haven’t tried the first solution, with one inductor and one capacitor, but now that I see your results, I will not bother trying. At the end, it is kind of logical that the neutral wire will not benefit much from it since it doesn’t have a choke inline.
We have big price pressure on our product, and that is why we are stuck with HLK-PM01 which we get at $1.70.
Anyway, while I was exploring how power supplies should be designed, I took apart few modern mobile phone chargers – Samsung, Nokia, HTC, and Apple.
Some of them share similar design which is not much different from HLK-PM01, but with capacitors and other components of a higher quality. But Apple iPhone 6 charger was something completely different.
Tightly packed design on 4 orthogonal PCB-s, integrated switcher, common mode choke at the AC side, high quality capacitors, additional insulation – really worth the price.
I will try and get another unit, however now I have killed this one I will try to get inside it to see what is in it.
Hi Tomislav. I was wondering why you didn’t go with the idea of using a mobile phone charger that your customers could supply. Everybody has lots of USB chargers giving out 5v and some even supply up to 2 Amps. You save money and it’s good for the environment. It also relieves you of the responsibility if something goes wrong with the 5v supply. The chargers would also probably have been in use by the customer for some time and are therefore probably safe.
It does not limit your liability; if a random USB supply destroys the device the customer is going to be upset with you as the manufacturer, not the USB supply supplier.
A long time ago I read the review linked bellow, about the same unit. It may help you as he has opened it and show the PCB.
http://lygte-info.dk/review/Power%20Mains%20to%205V%200.6A%20Hi-Link%20HLK-PM01%20UK.html
Thank you for the link, I have also seen that review, and I linked to it in the original post abut the HLK-PM01.
Thanks for taking the time to revisit this! Much anticipated!! 🙂