RuiDeng Riden RD6006 DC power supply

[blueskull]

One of the forum member did a brief performance check and review -> DC2132A Review , quite decent imo.

Now test cc-cv mode switch over.

[mawyatt]

Hoping this can be placed into a true linear mode (switcher is turned off) for lower power/current levels. Using the linear LDO as a post regulator to the switcher is good but raises the question of how much of the switching "noise" is allowed to feed through to the output. After looking at the PCB is seems the true linear mode isn't likely since this would require heatsinks for the LDO in this mode.

So back to wondering how much noise is on the output??

Best,

Noise is not the biggest problem. If you want clean power, you should put power regulators on your own board. The problem, however, is to get the SMPS to respond fast enough.

If the SMPS is slow, when the load suddenly needs more voltage (in CC mode), the LDO will be starved, and oppositely the LDO will see too much power (which may cause punch through breakdown in BJTs).

Even if you don't consider SOA breakdowns in BJTs, you still have the slow recovery issue, thus you need a larger margin so that by the time the margin voltage is all used up, the SMPS hopefully can respond.

Hence, you have an efficiency vs step response trade off, and that makes most commercial SMPS+LDO CC-CV supplies horribly bad in step response performance, and that's why you don't see big players like Keysight doing this.

I know ITech/B&K does this, and I have a few of their products. In short, they suck in dynamic CC mode, and the user should be aware of that in advance.

Yeah, it will not be perfect with SMPS+LDO combination as pure linear.

But, at least (I wish) it will have "decent" noise, ripple and transient response like these below Linear Technolgy/Analog SMPS+LDO DC2132A kit does, or at least close to it. 

One of the forum member did a brief performance check and review -> DC2132A Review , quite decent imo.

Agree, hopefully this will be just "good enough", but well have to wait for some review. That LT supply is nice, but pretty expensive at ~$200 and you still need an input DC source!

BTW I think what UniSoft has done with these is great, so hat's off 

Best,

[BravoV]

One of the forum member did a brief performance check and review -> DC2132A Review , quite decent imo.

Now test cc-cv mode switch over.

C'mon man, you knew the answer already. 

With your PhD in power electronics, I believe it becomes 2nd to nature to you, that all you need is just briefly within seconds, CMIIW, to take a look at the switcher's freq, it's output cap and then another few seconds look at the LDO datasheet and it's AC performance, and finally the output cap to sort of estimate how this perform when switching over modes CC to CV or vice versa. 

Just curious, what if Ruideng approaches you, say for one off design contract with handsome money that is hard to reject, to improve the linear front end, as humane and "good enough" as possible ? Would you take that challenge ? 

[BravoV]

That LT supply is nice, but pretty expensive at ~$200 and you still need an input DC source!

If you read the sub-sequent post after that review post, there was a post made by Linear Technology's staff (I believed), that the BOM cost was just < $50  , they deliberately put a hefty price tag to wade off PSU hoarder like me  , usually they gave these for free for their big customers for evaluation.

BTW I think what UniSoft has done with these is great, so hat's off 

Yep, UniSoft 's great work made a trickling sensation teasing me to buy this Ruideng bench PS, I'm a bench PSU hoarder btw  , own many quality bench PSUs like HP, Kenwood, Kikusui, Thurlby Thandar, Nemic Lambda, but all of those are beefy big and heavy. 

Just imagining "if" Ruideng made the linear pre-regulating series "good enough" , I'm intrigued what if this tiny little gadget coupled with high power density converter like made by Vicor, as I have plenty in my disposal  , may be the size of computer's optical drive with 500 Watt capable bench PSU ? or even smaller ? 

[blueskull]

Just curious, what if Ruideng approaches you, say for one off design contract with handsome money that is hard to reject, to improve the linear front end, as humane and "good enough" as possible ? Would you take that challenge ? 

I turned that offer down from Rigol. I know it's not gonna work. Fundamentally the buck will retrograded into envelope tracking as transient speed increases, and eventually the LDO may take all voltage drop, so to get an ideal response, the thermal design would be as aggressive as a pure linear solution. It does save energy in most cases, and I'd be happy to implement such in an actual use case, knowing how the load would look like. But not in a test gear where the goal is to be as adaptive as it can be.

[nikitasius]

Since there are no negative reviews and interesting ideas, then I can already release the final versions.
Here are versions for all 3 models.

Hi, last firmware you posted for 6006 is RD6006_Flasher_V1.32.12.zip , there are no the new one?

[UniSoft]

Hi, last firmware you posted for 6006 is RD6006_Flasher_V1.32.12.zip , there are no the new one?

this is latest release version...
New version on the way... now on beta testing...
If anyone want to join a beta testing, beta version(s) can be downloaded here:
https://monitor.net.ru/forum/threads/651114/post-6081567

[nikitasius]

Hi, last firmware you posted for 6006 is RD6006_Flasher_V1.32.12.zip , there are no the new one?

this is latest release version...
New version on the way... now on beta testing...

Cool, my RD6006 is on the way too.

As a powersupply i will use few switch power supply modules (2x24/9 in serial) with 4-5 filters (4 pins inductors + caps) for different freqs.
It's cheap and handy.

[mawyatt]

Back to my original request, could someone provide measurements on the output noise levels of these Ruideng power supplies?

Best & Thanks in Advance,

[BravoV]

Back to my original request, could someone provide measurements on the output noise levels of these Ruideng power supplies?

Best & Thanks in Advance,

Dave did it.

[BravoV]

Also on above Dave's video, he made an addendum in the Youtube comment ...

"UPDATE: I screwed up the noise measurement. It's actually way better at 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...."

[mawyatt]

Back to my original request, could someone provide measurements on the output noise levels of these Ruideng power supplies?

Best & Thanks in Advance,

Dave did it.

Just watched, the switching noise is really high, this is what I was worried about

Like that Dave used a "floating" battery DSO to measure, eliminating any ground induced measurement artifacts.

Everything about this looks encouraging except the noise output, hopefully the new "Hybrid" version will improve on this, but not sure that putting a post LDO will attenuate the switching noise much.

Anyway, looking forward to how well this Hybrid" version behaves, especially from the output noise perspective.

Thanks.

Best,

[mawyatt]

If you read the sub-sequent post after that review post, there was a post made by Linear Technology's staff (I believed), that the BOM cost was just < $50  , they deliberately put a hefty price tag to wade off PSU hoarder like me  , usually they gave these for free for their big customers for evaluation.

When I was working we got all kinds of things "free", from expensive chips, components, boards, space on IC fab runs and so on. However, my time was limited and expensive so I couldn't take full advantage of these "offerings".

Now I'm retired with lots of available "free" time, there are no "offerings" 

Best,

[alex34]

I messed with the noise of RD6006W. I measured about 20mV on a 50 Ohm probe (If I remember correctly). Decoupling with ceramic caps soldered right to the output terms on the PCB does not eliminate the noise. More of that, there is a ceramic cap in RD6006W. I managed to decrease the noise by placing a ceramic cap right on the OUTPUT of the jack (directly to the probe's input). Seems, terminals form a kind of antenna.
I plan to design a PCB with ferrite beads on it + aluminum and ceramic caps. It should attenuate the noise.

PS: I designed a PCB with a 5V standby supply and relays. I can share it as soon as I check it.

[Tatanka1961]

Back to my original request, could someone provide measurements on the output noise levels of these Ruideng power supplies?

Best & Thanks in Advance,

Dave did it.

If you mention this, you should also check the video where he explains what happened:


So the noise is actually quite acceptable...

[mawyatt]

So the noise is actually quite acceptable...

Looks as if Dave actually flubbed up both the standard DSO and the Battery Powered DSO measurements

Agree this is much better noise performance, and getting near acceptable.

Thanks for the update.

Best, 

[mawyatt]

I messed with the noise of RD6006W. I measured about 20mV on a 50 Ohm probe (If I remember correctly). Decoupling with ceramic caps soldered right to the output terms on the PCB does not eliminate the noise. More of that, there is a ceramic cap in RD6006W. I managed to decrease the noise by placing a ceramic cap right on the OUTPUT of the jack (directly to the probe's input). Seems, terminals form a kind of antenna.
I plan to design a PCB with ferrite beads on it + aluminum and ceramic caps. It should attenuate the noise.

PS: I designed a PCB with a 5V standby supply and relays. I can share it as soon as I check it.

Awhile back we tried a similar approach with a cheap eBay 32V 5A supply, result was not much improvement. This supply put out so much noise everywhere, on the AC input, input ground and output, you would have thought it was some sort of Electronic Warfare Jammer

Finally gave up on trying to improve the noise and now only use it for motors and such, pretty much useless for any lab work.

Maybe it would be a good source for EMI susceptibility, if things work when powered with this supply they should work with anything 

Good luck taming those noise spikes.

Best,

[nikitasius]

I messed with the noise of RD6006W. I measured about 20mV on a 50 Ohm probe (If I remember correctly). Decoupling with ceramic caps soldered right to the output terms on the PCB does not eliminate the noise. More of that, there is a ceramic cap in RD6006W. I managed to decrease the noise by placing a ceramic cap right on the OUTPUT of the jack (directly to the probe's input). Seems, terminals form a kind of antenna.
I plan to design a PCB with ferrite beads on it + aluminum and ceramic caps. It should attenuate the noise.

PS: I designed a PCB with a 5V standby supply and relays. I can share it as soon as I check it.

Awhile back we tried a similar approach with a cheap eBay 32V 5A supply, result was not much improvement. This supply put out so much noise everywhere, on the AC input, input ground and output, you would have thought it was some sort of Electronic Warfare Jammer

Finally gave up on trying to improve the noise and now only use it for motors and such, pretty much useless for any lab work.

Maybe it would be a good source for EMI susceptibility, if things work when powered with this supply they should work with anything 

Good luck taming those noise spikes.

Best,

But if you shield switching supply and put électrolytes, it should remove noise upto 10k, then you can place 10kHz, 60kHz and 250kHz filters to remove noise on those freqs (using 4 pin inductors and ceramic caps). Wires from ACDC to rd6006 should be threaded and shielded too. Am i right? Have a good friend who helps me with advices 😁

On the image there are 10mH inductors (4 pins each) and différent caps. For almost 40dB (39.37).

[mawyatt]

But if you shield switching supply and put électrolytes, it should remove noise upto 10k, then you can place 10kHz, 60kHz and 250kHz filters to remove noise on those freqs (using 4 pin inductors and ceramic caps). Wires from ACDC to rd6006 should be threaded and shielded too. Am i right? Have a good friend who helps me with advices 😁

On the image there are 10mH inductors (4 pins each) and différent caps. For almost 40dB (39.37).

One shouldn't have to go to all that trouble just make a supply useable that was advertised as a "Lab Supply"

All the shielding, filtering and what not on the inputs and outputs isn't worth the effort and additional cost IMO, and likely won't achieve a respectable noise level anyway. I'll just get another supply that will support lab use, and hoping maybe this new Ruideng "Hybrid" mentioned just might be acceptable 

Anyway, thanks for the note.

Best,

[Simon_RL]

But if you shield switching supply and put électrolytes, it should remove noise upto 10k, then you can place 10kHz, 60kHz and 250kHz filters to remove noise on those freqs (using 4 pin inductors and ceramic caps). Wires from ACDC to rd6006 should be threaded and shielded too. Am i right? Have a good friend who helps me with advices 😁

On the image there are 10mH inductors (4 pins each) and différent caps. For almost 40dB (39.37).

One shouldn't have to go to all that trouble just make a supply useable that was advertised as a "Lab Supply"

All the shielding, filtering and what not on the inputs and outputs isn't worth the effort and additional cost IMO, and likely won't achieve a respectable noise level anyway. I'll just get another supply that will support lab use, and hoping maybe this new Ruideng "Hybrid" mentioned just might be acceptable 

Anyway, thanks for the note.

Best,

Totally agree.

I found out the other day, the power supply for my RD6006 is putting out a shit tonne of EMI. I hadn't used it for ages, needed 4 amps input (my regular power supply is a DP832). On testing the DUT I got a lot of noise on my scope. I disconnected my probes from the DUT and the noise/EMI was still there (please see below).

After a bit of searching, including powering down my device, the RD6006 was found to be the culprit. When I disconnected the probe from my scope the noise disappears, so I am guessing my probe cables are acting like an antenna.

I haven't had a chance to read through all previous post yet, but I am guessing the problem is the actual power supply and not the actual RD6006. Can somebody please confirm if I confirm if this is correct?

Forgot to mention that the EMI still occurs when the RD6006 is off but the PSU is on. I just answered my question

[alex34]

I think there is a lot of lab tasks which does not require a pure clean PSU. (Unless you powering some preamp or RF circuit).In that case it's better to have a low power pure linear PSU. So, RD6006 is a good choice for all other tasks. In fact. 30V 3A (which most PSUs have)  is not near enough for my lab.
Speaking of RD6006 noise - how about use a ferrite beads on a cable? Cheap and handy

[nikitasius]

hi, i just thinking about improving a little bit the ACDC which will feed the RD6006. Not about placing RD6006 into range of 500€ lab tools.
Filters will cost for me maximum 20€ to do.

hi, but if we place ferrite rings on output contacts and shield front plastic panel with permalloy it should help with EMI or reduce it at least?

As i said, i don't want to place rd6006 in the same range with 500€ lab tools, i just want to get the best from it.

Switching power supply is a temporary, before i will order two toroidal transformers (they will compensate EMI of each other).

And all this will be inside a nice shielded woodbox, rétro style 

[BlueTronic]

Hi Unisoft

I have tested your Beta versions V1.31.6c and V1.31.6d (RD6012) and I found two bugs:

1. Under Menu/Home/Layout 1 -> "SHOW IIME" (it should be "TIME" - the letter "T") - same bug in German and Chinese language.
    I know, you mentioned it before, that at the moment there is no update for German language (you use English words for new settings),
    thats why there is the same bug in different languages.
 
2. I´m not sure if its a bug, maybe you programed this purposely!? 
   When I program Menu/Power Settings -> "OTP (ext)" for example to "40°C" it will affect only in the current session.
   Turning my RD6012 off and on, the "OTP (ext)" will be set to "OFF" again.
   
   If I want to set a value in the "OTP (ext)" forever, I had to set it in MENU/Battery Charger -> "CuttOff temp."
   (changing at "CutOff temp." will automaticly set the same value in "OTP (ext)")

[UniSoft]

1. Under Menu/Home/Layout 1 -> "SHOW IIME"...
2. I´m not sure if its a bug, maybe you programed this purposely!? 
   When I program Menu/Power Settings -> "OTP (ext)" ... will be set to "OFF" again.

1, 2: Yes small BUGs will be fixed in next beta...
Thanks

[mawyatt]

hi, i just thinking about improving a little bit the ACDC which will feed the RD6006. Not about placing RD6006 into range of 500€ lab tools.
Filters will cost for me maximum 20€ to do.

Agree the RD6006 likely will not perform well enough for replacing a proper Lab Supply, but the new "Hybrid" version mentioned might just be good enough for low end Lab Supply use, hopefully soon we'll find out

Best,