EEVblog #1265 - $53 360W Lab Bench PSU!

[EEVblog]

Review of the $53 Riden (RD Tech / Rui Deng) RD6006 360W bench lab power supply module with WiFi connection.
http://s.click.aliexpress.com/e/DlHrJpFS

[thm_w]

Test gear thread: https://www.eevblog.com/forum/testgear/ruideng-riden-rd6006-dc-power-supply/

$53 not including a case or AC-DC PSU. But in my case neither of those were needed, so the price was valid.

[Bud]

Horrible noise. Would only be good for basic digital circuits or a coffee warmer.

[thm_w]

Horrible noise. Would only be good for basic digital circuits or a coffee warmer.

I haven't watched it yet but he is measuring the pulse height at:
24:54 ~500mV p-p with no load
25:34 ~550mV p-p with 5V and 1A load

I didn't measure anything close to that, it could be coming from a bad source PSU or related to the rigol load and external EMI.

I'm seeing pulse heights of:
<100mV p-p no load 5V
75mV p-p no load 25V
160mV p-p 5V 6A

My source PSU = 30V meanwell so not directly comparable to his setup. I'm sure another owner with 60V source can comment. Or you can measure it fed with a linear PSU to eliminate source PSU issues.

[floobydust]

What is the relationship between RD6006 PSU input(-) and PSU output (-) and digital ground? All connected together? In other words, how is USB-ground related to the PSU output (-)? I wondered if it all is floating, including the Meanwell.

The DPS modules have an N-ch MOSFET switch at the (-) output (to allow battery charging, no backfeed) which can cause a lot of confusion or a ground fault if the USB port/Serial is earth-grounded to a PC, and you switch off the module you still get current flow.
I've added chokes + Y-caps to lower (DPS) noise but without remote-sense, you get sag under load so it  was not a great idea.

edit: the RDENG USB boards have isolation.

[amspire]

I have had a power supply die when charging 12V lead acid batteries and the mains fails. The current from the battery goes back into the power supply to release the magic smoke. It could be that the Battery charging mode has a series diode or mosfet with sense leads after the diode.

[thm_w]

What is the relationship between RD6006 PSU input(-) and PSU output (-) and digital ground? All connected together? In other words, how is USB-ground related to the PSU output (-)? I wondered if it all is floating, including the Meanwell.

When its off I'm not measuring a connection, you'd have to look at the PCB to see whats connected. Earth ground shouldn't be connected, meanwell PSU is floating.
I did not measure any resistance between USB ground and (-) output terminal.
You can see in SDG's video at 12:23, the USB is isolated from the rest of the board. They use a CH340 (U11) then some isolator chip (U13)?

The DPS modules have an N-ch MOSFET switch at the (-) output (to allow battery charging, no backfeed) which can cause a lot of confusion or a ground fault if the USB port/Serial is earth-grounded to a PC, and you switch off the module you still get current flow.
I've added chokes + Y-caps to lower (DPS) noise but without remote-sense, you get sag under load so it  was not a great idea.

This PSU has a dedicated battery output and a relay on the +, so it should not be an issue.
As for the noise, you might be better off adding filtering on the input.

[NiHaoMike]

A 20V, 18A version would probably be more useful for use with general purpose electronics - just enough to cover powering laptops and mini desktop PCs. Of the hobbyist uses for voltages between 20V and 60V, audio is the only one I can think of that's very common.

[EEVblog]

Oops, I goofed the noise measurement 
It's actually about 60mVp-p no load and about 100mVp-p at 6A using a proper scope probe in X10. I was using a BNC cable with banana plugs and forgot the 50ohm series matcher. Oops. Will have to do another video showing this. Good excuse for a video on this topic anyway.

[EEVblog]

What is the relationship between RD6006 PSU input(-) and PSU output (-) and digital ground? All connected together? In other words, how is USB-ground related to the PSU output (-)? I wondered if it all is floating, including the Meanwell.

USB seems isolated from the front panel ground.

[johnlsenchak]

Dave

Be  extremely  careful with downloading files    from China, they are notoriously for  containing  malware  and  other malicious    garbage

Anyway,  another video  on  measuring  ripple , load  , and line  regulation over   the voltage   range  would be great.  Even  putting the   DC-DC converter
under  full load for a  period of time  would   be awesome.   

 Or doing a HI-Pot test  on  the DC-DC converter   from   the input to output  to see of  their is  good isolation   would be good test

[sibeen]

Is there a chance that when in battery charging mode the unit starts off in constant current mode, 0.5 amp in the video, and then when it hits the set voltage, 1.5 volts, it then switches to a constant voltage mode?

It should do.

[EEVblog]

Is there a chance that when in battery charging mode the unit starts off in constant current mode, 0.5 amp in the video, and then when it hits the set voltage, 1.5 volts, it then switches to a constant voltage mode?

It does change modes, buy any PSU will do that with a set voltage. There is a  discrepancy between the charge display value and the read display value too, not a good vibe.
Apparently it cuts off at 10% current level.

[thm_w]

Anyway,  another video  on  measuring  ripple , load  , and line  regulation over   the voltage   range  would be great.  Even  putting the   DC-DC converter
under  full load for a  period of time  would   be awesome.   

 Or doing a HI-Pot test  on  the DC-DC converter   from   the input to output  to see of  their is  good isolation   would be good test

It seemed to overheat in the vid. Even 90% efficiency at 360W, I don't think that little fan can deal with anything close to 36W. 360W is more of a peak rating presumably.

There is no DC-DC input to output isolation. You are relying on the source PSU isolation, which in the case of Meanwell is going to be very good (3kVAC): https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/RSP-320/RSP-320-spec.pdf

[BravoV]

I wish the next/future variant, they will come out with linear pre-regulator (good designed one of course), and even with 20 bucks price increase, definitely I will instantly jump on it.

[james_s]

A 20V, 18A version would probably be more useful for use with general purpose electronics - just enough to cover powering laptops and mini desktop PCs. Of the hobbyist uses for voltages between 20V and 60V, audio is the only one I can think of that's very common.

Lots of 24/28V gear out there, large trucks and aircraft are 24V. I have quite a few different 24V devices kicking around.

[BravoV]

A 20V, 18A version would probably be more useful for use with general purpose electronics - just enough to cover powering laptops and mini desktop PCs. Of the hobbyist uses for voltages between 20V and 60V, audio is the only one I can think of that's very common.

Lots of 24/28V gear out there, large trucks and aircraft are 24V. I have quite a few different 24V devices kicking around.

+1 , and if you look hard enough, especially in big cities where the cellular network gets upgraded often, think of GSM/AMPS era up to current 4G or even 5G, here what I scored few years ago from local contractors that were constantly working/upgrading cellular base station towers.

Still have 6 of these gathering dust in my closet scored cheaply from them. 

[Black Phoenix]

Dave, not related with the product in question, but what kind of stackable leads are you using?

I said that because they are close to what I find for sale in the Huaqiangbei Electronics Market in Shenzhen, and wanted to know if you build themselves, if you bought them from Aliexpress or from another shop like RS Electronics or Farnell.

[johnlsenchak]

Many  years ago  , I worked  for a company  that was dedicated to making  switch  mode and linear  power supplies  for the telecommunication  market mainly  for companies like  "Tie  Communication" that   who  made  PBX  phone  systems.   Doing  Hi-Pot  testing  across  the primary to  secondary  and also  primary  to ground  was a  real  important  test  after  hours of  burn in testing .   It was something to see  those power supplies  take  thousands  of volts  of  short pules of  abuse  to verify that the   switch mode transformer  would  not short  over  and fail   Now  in days you see isolation    slots in the PC board  between the  primary  to secondary, back then when you hit the test button  you risked a nasty shock  if you didn't  pay  attention to what you where doing .    I  strongly  believe  that  this  type of testing  is  a good indicator  of the quality of the power supply  since it proves  isolation and therefore the  safety of    device when  under load  conditions

[Kleinstein]

.....
It seemed to overheat in the vid. Even 90% efficiency at 360W, I don't think that little fan can deal with anything close to 36W. 360W is more of a peak rating presumably.

There is no DC-DC input to output isolation. You are relying on the source PSU isolation, which in the case of Meanwell is going to be very good (3kVAC): https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/RSP-320/RSP-320-spec.pdf

The efficiency depends on the output voltage. With high output voltage the losses won't be so high, as the efficiency will be much higher. So at 360 W out and thus some 60 V a d 6 A efficiency would be more like 98%, as most of the power just goes though. The worst case is more like 60 V in and 25 V out.


The switching ringing at the output looks pretty bad. It is kind of odd to have so infrequent pulse and the main ripply looks like faster in between.
The use interface on the other side looks pretty good.

[SparkyFX]

Now the burning question:
will the µSupply beat it and in which points?

I kind of search for some mobile power supply for stuff like Startrackers or Timelapse cameras and such.

[tmf]

$44 on banggood now...

https://www.banggood.com/custlink/3vKGbv6WUq

just ordering one now...

I do a lot of car electronics, so might just get the small case and add jacks so I can apply the 13.8V car battery, this gives me enough current and power to do my work.

Hope uSupply (is that what it is going to be called?) works better.

RichardS

[TurboTom]

...

The efficiency depends on the output voltage. With high output voltage the losses won't be so high, as the efficiency will be much higher. So at 360 W out and thus some 60 V a d 6 A efficiency would be more like 98%, as most of the power just goes though. The worst case is more like 60 V in and 25 V out.

...

The worst scenatio of a basic buck converter which -- as it seems -- the RD6006 contains in its power section, will be maximum input voltage and minimum output voltage at maximum current.

This means full inductor losses (due to the high current and high frequency components in the signal involved), highest free-wheeling diode conduction losses (it seems the RD6006 doesn't utilize synchronous rectification but a schottky diode instead) since it's almost all the time carrying the current, and highest switching losses in the MOSFET. The latter is probably the smallest contribution factor of all this dissipation. Conduction losses in the MOSFET are usually also rather small in comparison, regardless of the duty cycle.

At an output voltage of half the input voltage, the situation is much more benign regarding diode losses since it's got to conduct the current only 50% of the time.

[dcac]

I'm not very impressed by the fuse installment on that Mean Well PS.

[capt bullshot]

Oops, I goofed the noise measurement 
It's actually about 60mVp-p no load and about 100mVp-p at 6A using a proper scope probe in X10. I was using a BNC cable with banana plugs and forgot the 50ohm series matcher. Oops. Will have to do another video showing this. Good excuse for a video on this topic anyway.

Still in the ballpark of "horrible noise", no good for analog stuff. But you're right, the noise visible on the scope way way above the expected 100mVpp (as shown somewhere within the manual). From my experience, there're many people around not knowing how to measure the ripple correctly, so go on with the topic in a video.

[JohnnyBerg]

Just ordered one. I work mostly on Li-ion based projects, so the noise does not matter (much).

I find the case very interesting, could be the base for some other projects

[Xenoamor]

Just ordered one. I work mostly on Li-ion based projects, so the noise does not matter (much).

I find the case very interesting, could be the base for some other projects

Indeed. I'm half tempted to buy one just to gut to put my own DIY supply in, seems kind of wasteful though

[buzzybee191@gmail.com]

Before aliexpress runs out, here is another supplier

https://www.banggood.com/RD6006RD6006-W-Digital-Control-Switch-Adjustable-Power-Supply-DC-Stabilized-Power-Adapter-Buck-Module-Monitoring-Power-Supply-p-1587151.html?rmmds=mywishlist&ID=6279943&cur_warehouse=CN&p=K6282137007969201907&custlinkid=706783

[Marco]

On the RD Tech channel he shows how to take it apart BTW. Just need to desolder the front panel jacks, the solder being the only thing holding them in place ...

Brave desoldering technique by the way.

[firewalker]

For the other modules (DPS5005c), there is documentation for the serial protocol. I designed a controller interface with rotary encoder for setting the voltage and current. It was slow to processes the serial commands though.

https://github.com/firew4lker/DPS5005-control/blob/master/Software/DPS5005%20communication%20protocol%20-english%20google%20translate%20version%20%20V1.2.pdf

Alexander.

[relax79]

Looks like more powerfull models coming later.

[thm_w]

The efficiency depends on the output voltage. With high output voltage the losses won't be so high, as the efficiency will be much higher. So at 360 W out and thus some 60 V a d 6 A efficiency would be more like 98%, as most of the power just goes though. The worst case is more like 60 V in and 25 V out.


The switching ringing at the output looks pretty bad. It is kind of odd to have so infrequent pulse and the main ripply looks like faster in between.
The use interface on the other side looks pretty good.

You are right, although total efficiency is not quite that good here. We have some inductor resistance, FET resistance, fuse resistance, etc. that will contribute to losses. Although only a few of those go directly to the heatsink.

I tried:
- 29.25Vin 0.459A (13.4W)
- 28.25Vo 0.411A (11.6W)
- 0.61W quiescent from daves vid, ~0.2R lead loss.

Which gives efficiency of around 92%
 
In SDGs video we can see:
- SE100P60A 25mOhm
- MBRF20100CT

Ideally, at 6A output Vin = Vout, we'd only see about 1W going into the heatsink due to FET losses.

[nixfu]

Does this really need a 60V supply? Or can I use one of the 300-400w 24V or 48V meanwell's I already have laying around from my 3d printer builds?

[Xenoamor]

Does this really need a 60V supply? Or can I use one of the 300-400w 24V or 48V meanwell's I already have laying around from my 3d printer builds?

You can use any power supply between 7 - 70V but it's a buck only regulator so you'll only get less than what you put in out

[Cliff Matthews]

RD Tech appear to take Dave's Kudos, test's and comments seriously. They launched a video about the virus issue but the link to the new file (on Google drive) still has an issue with "RidenPowerSupply.exe" according to VirusTotal.com


These guys really need to do videos with computers configured in English.. Sometimes I think they have no idea how bad they look to the world outside of their little Chinese echo chambers. The choice of using background music designed for children was also another marketing failure... 

[Cliff Matthews]

Under the video listed above, I decided to check the whole RAR file from the backup site. The results are not good..
https://www.virustotal.com/gui/file/18d821570731285fd276d62e5cd5a929a15ea066a9e85401db25ef43982fe71a/detection

[nixxon]

Nice review and follow-up regarding the high frequency noise. Just like any other legacy fundamentials Friday.

This guy made a nice effort to reuse the case and 60V 5A power supply of a badly functioning lab power supply to make a new and improved one using the RD6006/RD6006-W as a front end:

[sixtimesseven]

RD Tech appear to take Dave's Kudos, test's and comments seriously. They launched a video about the virus issue but the link to the new file (on Google drive) still has an issue with "RidenPowerSupply.exe" according to VirusTotal.com


These guys really need to do videos with computers configured in English.. Sometimes I think they have no idea how bad they look to the world outside of their little Chinese echo chambers. The choice of using background music designed for children was also another marketing failure... 

I wonder generally why these companies do not get a native speaker to either do the presentation or at the very least get them to proof read the stuff before posting it.

[Monkeh]

Under the video listed above, I decided to check the whole RAR file from the backup site. The results are not good..
https://www.virustotal.com/gui/file/18d821570731285fd276d62e5cd5a929a15ea066a9e85401db25ef43982fe71a/detection

Looks like generic heuristic hits rather than positive malicious code. Probably false positives.

Still, there's about zero chance I'd go anywhere near the software anyway.

[buzzybee191@gmail.com]

Before aliexpress runs out, here is another supplier

https://www.banggood.com/RD6006RD6006-W-Digital-Control-Switch-Adjustable-Power-Supply-DC-Stabilized-Power-Adapter-Buck-Module-Monitoring-Power-Supply-p-1587151.html?rmmds=mywishlist&ID=6279943&cur_warehouse=CN&p=K6282137007969201907&custlinkid=706783

[fandemos]

I would like to know if someone has made any changes in this source to reduce the ripple and noise, beyond putting some capacitor, since its connectors are soldered directly to the board. Thank you. 

[james_s]

I wonder generally why these companies do not get a native speaker to either do the presentation or at the very least get them to proof read the stuff before posting it.

Beats me, there is no shortage of native English speakers. For many kinds of product that interests me, I'd be willing to proof read and edit the English documentation in exchange for one of the devices to play with. Seems like they could do a lot worse with their marketing budget than that. I haven't made a serious attempt to contact any companies with that offer but the thought has crossed my mind.

[Andrew McNamara]

I wonder generally why these companies do not get a native speaker to either do the presentation or at the very least get them to proof read the stuff before posting it.

Having watched a few of their videos, I think RDTech is very small - maybe just a couple of engineers, and a production dept. I would suspect they just don't have the resources, or time. I'm prepared to cut them some slack - they're making interesting products, give good value, and they do try hard to support them, which is more than many western companies do. Frankly, I'd take their best-effort English over the Sweet Nothings from the average corporation.

[Kleinstein]

The output ripple is exaggerated by the probing technique, but it is still strong and odd, that there is not just the regular ripple, but some extra strong pulse at a rather low rate. This looks a little like a superimposed burst mode or some extra pulses added to the set point signal of the switched mode supply. 

So there is chance that the really bad strong pulses could be avoided, possibly with filtering the control signal from the front board to the power board. I would not be surprised if they use PWM plus filtering instead of high resolution DACs.

[thm_w]

The output ripple is exaggerated by the probing technique, but it is still strong and odd, that there is not just the regular ripple, but some extra strong pulse at a rather low rate. This looks a little like a superimposed burst mode or some extra pulses added to the set point signal of the switched mode supply. 

So there is chance that the really bad strong pulses could be avoided, possibly with filtering the control signal from the front board to the power board. I would not be surprised if they use PWM plus filtering instead of high resolution DACs.

STM32F103RCT6 has two 12-bit DACs, but thats not quite enough for the set resolution (14mV/1.5mA vs 10mV/1mA), so they may be using the PWM outputs as you say.

The other parts I see:
- RC04V FRAM U6
- Winbond flash memory U8
- GS8332 350kHz single supply opamp U12
- XL7015 buck, fixed frequency 150kHz so noise shouldn't be related to that.
- AOD2810 FET (dpak not heatsinked)

Most of the pulses are at 100kHz repetition, surely this is the fixed switching frequency of the TL594 right?
As Dave stated, filtering the FET gate drive with a ferrite or resistor is probably going to be beneficial here. The ringing of the pulse is ~10MHz.

I do see some 1kHz and 240kHz spaced pulses as well, which will be something else.


edit: gate of PFET goes to via to top then R34 (10R resistor) so thats already a fair bit of gate resistance. TL594 switching frequency is 64kHz with no load.
edit2: slightly improvement with 600R@100MHz bead but not massive, might need another approach or a lower frequency material. Gate capacitance = 4nF = ~4MHz RC?

[pepelevamp]

whats powering the display? can we get in there with an FFT on a stick and probe some points? Maybe we can find some relevant switching frequencies elsewhere in the box.

[thm_w]

whats powering the display? can we get in there with an FFT on a stick and probe some points? Maybe we can find some relevant switching frequencies elsewhere in the box.

Probably the 5V from XL semi buck chip then LDO, but I think thats not too bad. The "big" pulse is seen on the output when probing for mag field right beside the main inductor.
I'll try adding a gate ferrite and update in a bit.

There is a snubber (R34 (2.2R), C27) to the left of the heatsink.

[montyx]

Does anyone knows about any linux compatible software for the RD6006? I use linux, so it's not an option to use the official sw.

[Mr.B]

Following this thread. I am interested to see the outcome of research into reducing the output noise.
I purchased one from the RDTech store about a week before Dave put the video up.
I will leave it in its respective boxes and wait to see how the noise research goes.
Thanks to those actively pursuing this.

[ironcurtain]

Resurrecting this thread. I was testing a buffered clock distribution board powering it with the RD6006 and then went down the rabbithole of locating the noise/spurious signals.

Can we put together a list of mods to lower the noise/ripple and weird pulses?