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

[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.