EEVblog 1402 - Rohde & Schwarz NGA100 PSU Teardown + GIVEAWAY - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: June 24, 2021, 11:26:47 pm
content: Teardown of the new NGA100 100V 2A NGA142/NGA102 Power Supply, and a look at a few issues found.PLUS a GIVEAWAY of two units!

author: nctnico
author_rank: Super Contributor
timestamp: June 24, 2021, 11:38:20 pm
content: Those constant current mode overshoots are a major fail!

author: Omar Mekkawy
author_rank: Contributor
timestamp: June 24, 2021, 11:53:32 pm
content: I need that Power supply plz. Bueller, Bueller, Bueller, Bueller

author: con-f-use
author_rank: Unknown
timestamp: June 24, 2021, 11:54:01 pm
content: It's been a long while since I posted something, but I wouldn't mind winning one of those.

author: timbailey99
author_rank: Newbie
timestamp: June 24, 2021, 11:59:29 pm
content: Just joined so I cant win, but love the quality. Hopefully they will fix the weird behaviour with a firmware update.

author: mspec
author_rank: Contributor
timestamp: June 24, 2021, 11:59:48 pm
content: Looks like a good supply but then again I do like Rohde & Schwarz gear

author: rupr19
author_rank: Newbie
timestamp: June 25, 2021, 12:10:21 am
content: The 200V serial range on this power supply looks really interesting and useful for some experiments.

author: gdnichols31
author_rank: Regular Contributor
timestamp: June 25, 2021, 12:11:40 am
content: Count me in!ThanksGary

author: dew
author_rank: Contributor
timestamp: June 25, 2021, 12:12:33 am
content: Hopefully this OC/OV overshoot is caused by an algorithm in the P/S controller and can be fixed in the next firmware release. Not that they know there is a glitch

author: stmcore
author_rank: Newbie
timestamp: June 25, 2021, 12:16:39 am
content: I'm in, Nice PSU I would love to own one , Thanks for the teardown video.

author: etnel
author_rank: Contributor
timestamp: June 25, 2021, 12:17:48 am
content: Would love one as a replacement for my 50$ aliexpress power supply.

author: Silveruser
author_rank: Regular Contributor
timestamp: June 25, 2021, 12:26:07 am
content: You can never have enough power (supplies) so yes count me in. Thanks for the tear down.

author: MiDi
author_rank: Frequent Contributor
timestamp: June 25, 2021, 12:28:59 am
content: If I got one, I would make a shootout with myHP 6632A from the late 80s.Would be interesting to see how they compare and how SPSUs have evolved.

author: legrady
author_rank: Contributor
timestamp: June 25, 2021, 12:32:13 am
content: I'd love a beautiful R&S power supply to develop eurorack modules. Winner, Winner, Chicken Dinner?Tom

author: 8bit
author_rank: Newbie
timestamp: June 25, 2021, 12:35:47 am
content: I would be happy to win a free slightly used bench power supply!

author: andymouse
author_rank: Contributor
timestamp: June 25, 2021, 12:36:40 am
content: Cor Blimey guv, would love to win one, a decent PSU !

author: amindavid11
author_rank: Contributor
timestamp: June 25, 2021, 12:39:41 am
content: The overshoot problem should not be in a $1000+ equipment, but I will gladly take it for free

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: June 25, 2021, 12:39:57 am
content: I'm in.

author: russan
author_rank: Newbie
timestamp: June 25, 2021, 12:40:52 am
content: Ah man, I just bought a Siglent power supply for my home lab. A second, better power supply couldn't hurt, right?

author: nardev
author_rank: Unknown
timestamp: June 25, 2021, 12:48:37 am
content: Is this enough?

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: June 25, 2021, 12:50:02 am
content: I'd love to score one of these, here's the homemade one made ages ago and killed somewhat recently:(ah, BBCode tags bring back memories!)It doesn't output anything anymore, the diodes are fine, I'm thinking the switching IC died.Excuse the crudity of the construction, I didn't have time to build it to scale or to paint it!Some wires and things (like screws) are missing since I've stolen some parts out of it. There's a fan under the mainboard to push cool air into the unit and the case had vents on the sides of the top and bottomFingers crossed I'll get selected, thanks Dave!

author: Rabid Badger
author_rank: Contributor
timestamp: June 25, 2021, 12:53:27 am
content: I could use one of those on my new workbench.

author: Peeps
author_rank: Contributor
timestamp: June 25, 2021, 12:57:15 am
content: That would be amazing to have, I'm seriously lacking decent test equipment.

author: graybeard
author_rank: Frequent Contributor
timestamp: June 25, 2021, 12:59:20 am
content: I would love to have a power supply I can control over eithernet!

author: KaneTW
author_rank: Frequent Contributor
timestamp: June 25, 2021, 01:05:07 am
content: Wouldn't mind one, although that CC overshoot is nasty.

author: Han2k21
author_rank: Newbie
timestamp: June 25, 2021, 01:26:35 am
content: I would be very happy to win PSU for my work.

author: TheGoyNextDoor
author_rank: Newbie
timestamp: June 25, 2021, 01:52:31 am
content: A massive upgrade from my garbage eBay PSU. Gib.

author: Scott Holmes
author_rank: Newbie
timestamp: June 25, 2021, 02:11:30 am
content: That's a sweet power supply. I'd love to have one.I'm nearly at the point of building my own. While R&S have a proper knob and settings buttons, I always liked the old hand crafted metal adjustment dials. Changing the voltage on a DC supply should feel like cracking a safe.

author: dentaku
author_rank: Frequent Contributor
timestamp: June 25, 2021, 02:11:45 am
content: It would be nice to finally have a power supply that lets me control the current.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 25, 2021, 02:18:46 am
content: If it's got blinky lights and stuff, I'd love to have it on my bench.

author: rmaranhao
author_rank: Newbie
timestamp: June 25, 2021, 02:23:22 am
content: Everyone loves a giveaway!

author: dodge bullets
author_rank: Newbie
timestamp: June 25, 2021, 02:26:31 am
content: those power supplies are awesome.I would have liked to see how the CC mode reacts when the voltage is on the cusp of triggering it to activate.

author: plurn
author_rank: Regular Contributor
timestamp: June 25, 2021, 02:32:10 am
content: Hi Dave,I know this was not a full review, but any chance you can test current overshoot too when doing power supply reviews?Cheers,Anthony

author: bdunham7
author_rank: Super Contributor
timestamp: June 25, 2021, 02:36:52 am
content: Quote from: nctnico on June 24, 2021, 11:38:20 pmOy. I wonder how it reacts to load impedance changes when in CC mode.......

author: 172pilot
author_rank: Newbie
timestamp: June 25, 2021, 02:40:04 am
content: I'd LOVE to have one of these!! The videos are always great! The power supply would help in my troubleshooting and fixing of classic arcade stuff.. PacMan boards and the like!

author: tchicago
author_rank: Regular Contributor
timestamp: June 25, 2021, 02:51:26 am
content: What is this brown adhesive tape used to attach transistors to the heatsinks instead of fastening them with a screws?I've seen that before, seems like some new technology. How is it called?If this is a permanent thermal conducting adhesive tape, then how do you unglue it to replace a transistor?

author: sir1963
author_rank: Newbie
timestamp: June 25, 2021, 02:53:58 am
content: Oooo pretty, Shinny , would go great in my home workshop

author: tchicago
author_rank: Regular Contributor
timestamp: June 25, 2021, 03:01:14 am
content: The fan starting at high RPM is by design. It is used to reliably start it up, because if you try to start it at low power, the degraded lubrication or degraded bearings may hold the fan and it won't rotate unless maximum torque is applied. Once it started rotating at full speed, the RPM could be safely reduced.The same algorithm is being used in servers and workstations.

author: fivesixzero
author_rank: Contributor
timestamp: June 25, 2021, 03:08:03 am
content: Been teaching myself analog design while fixing up some old HP supplies, starting with a 721A, on to a 723A, then to an E3610A. The leap from those to this R&S is pretty nuts in some ways but in others it’s obvious that linear design hasn’t changed a ton since the 721A came around in 1958.Also, seeing some basic characterization processes was helpful. I’ve mostly been focused on setting up a good PARD test environment so this was a good reminder to look at overshoot too. I recently picked up a 6060B DC load to replace my home-made loads and I’d love to put an R&S supply through its paces once it’s all set up…

author: MRiddickW
author_rank: Contributor
timestamp: June 25, 2021, 03:36:06 am
content: This would have been handy to have before I bought my HP 6626 to put in series for 200 V total! Smaller and not to mention quieter. Of course it's just a tad more expensive.

author: mariush
author_rank: Super Contributor
timestamp: June 25, 2021, 03:53:32 am
content: sure, why not... could use a 2nd linear psu.can work around those overshoots... quality components inside, nice transformer... looks good to me.

author: icinose
author_rank: Newbie
timestamp: June 25, 2021, 03:55:12 am
content: count me please, need PSU for my hobby

author: petters
author_rank: Newbie
timestamp: June 25, 2021, 04:00:11 am
content: Winner winner

author: HoBoPanda
author_rank: Unknown
timestamp: June 25, 2021, 04:25:26 am
content: It's been a long while since I posted something, but I wouldn't mind winning one of those.

author: brob
author_rank: Newbie
timestamp: June 25, 2021, 04:47:54 am
content: I'm InBrent

author: thm_w
author_rank: Super Contributor
timestamp: June 25, 2021, 04:56:51 am
content: Dual bridge rectifiers on a massive heatsink:1.4V * 2A * 2, maybe 6W maxMust share design with the 6A version.Quote from: tchicago on June 25, 2021, 02:51:26 amIts just thermal tape no? Good thermal tape I'm sure, but I question its long term reliability.If you need to replace a transistor you'd pull it off.https://www.parker.com/static_content/parkerimages/chomerics/Articles/ThermallyConductiveTapes_EN_AdvancedPackagingArticle.pdfhttps://multimedia.3m.com/mws/media/122119O/3m-thermally-conductive-adhesive-transfer-tapes-8800-series.pdf

author: boffin
author_rank: Unknown
timestamp: June 25, 2021, 05:23:51 am
content: Can always use a new power supply...

author: torquil
author_rank: Regular Contributor
timestamp: June 25, 2021, 05:47:30 am
content: I'm in!

author: neko
author_rank: Newbie
timestamp: June 25, 2021, 05:50:00 am
content: I'm in!

author: tchicago
author_rank: Regular Contributor
timestamp: June 25, 2021, 05:56:48 am
content: Quote from: thm_w on June 25, 2021, 04:56:51 amYes, that tape from your screenshot. It is very strange how it is applied. If it is just a sticky tape, then the exposed surface will probably collect dust over time, from the air moved by the fan. They also say there is nothing special about separating part from the tape for reword: pry or twist. That means mechanically the contact is not very strong, and can probably come off via vibration? Another strange thing is that they say it will soften if heated or immersed in warm water. This is a heatsink, which gets warm/hot by definition, so it will increase chance of separation even more...

author: yektaakdag
author_rank: Newbie
timestamp: June 25, 2021, 06:00:00 am
content: I am in

author: HKJ
author_rank: Super Contributor
timestamp: June 25, 2021, 06:16:23 am
content: With that kind of overshot it may not be possible to directly (i.e. without a series resistor) test small leds with it. A test with 10-20mA constant current, instead of 1A would ave been interesting.

author: jusaca
author_rank: Unknown
timestamp: June 25, 2021, 06:17:22 am
content: I just realized two days ago that my DIY supply has serious problems with overshoot when loaded by PWM impulses. So yes, I would be really glad to have a decent supply that just works. Nevertheless, I have to figure out the problem with my own PSU...

author: kripton2035
author_rank: Super Contributor
timestamp: June 25, 2021, 06:18:20 am
content: not sure if the giveaway is on the other thread may be so I post here too. thanks Dave (and R&S) !

author: piranha32
author_rank: Unknown
timestamp: June 25, 2021, 06:24:20 am
content: This 100v power supply is sweeet

author: s8548a
author_rank: Regular Contributor
timestamp: June 25, 2021, 07:05:49 am
content: Nice power supply and thanks for the tear-down.why r&s selected the $8 wifi module when there are popular low cost modules available? due to the Atmel eco system?

author: Custom
author_rank: Newbie
timestamp: June 25, 2021, 07:07:07 am
content: I definitely need this power supply in my small but growing electronics lab. Its a beautifully designed PSU and has decent specs as well. Moving from my current computer PSU hack job to a proper benchtop PSU would make doing anything with power sooo much easier, and safer for my little circuits. The supply would be well used and certainly be greatly appreciated here. Thanks for doing this giveaway!!!!

author: Brexei
author_rank: Contributor
timestamp: June 25, 2021, 07:08:43 am
content: I would love to have one of these PSUs. I am building my own home lab and currently lack any proper power supply.

author: HattedSquirrel
author_rank: Newbie
timestamp: June 25, 2021, 07:51:28 am
content: How are the power tarnsistors connected to the heatsink? Do they solely reley on the springyness of the component leads? I see no screw and no clamp. And heat conductive glue doesn't relly work with silcone sheets...On the constant current issue: Yeah, thats a big problem. It always has been. In my last workplace we destroyed several 10th of tousands of dollars of chips just because some Hameg/R&S power supply was overshooting or otherwise misbehaving. Extremly annoying!Also, at least for the HMP4040, from time to time it misses SCPI commands, so you always have to read them back and check. The virtual com port those things provide for communication disappears on every major windows update and you have to reenable it in the driver settings... (Try explaining to the IT staff why you need admin rights on that computer because of some power supply you want to use.)Yeah... those things are nice spec wise but the usability is just such a pain. I found myself biting the table out of frustration many times. It's really sad and it has been so for years. The R&S RF gear is really nice and spot on, but what they bought in from Hameg - no improvement whatsoever since they aquired the company. Really doesn't add to well to their reputation.PS: I would still take it for my home lab. Now that I know all their bugs and can circumvent them... ;-)

author: _michael_
author_rank: Newbie
timestamp: June 25, 2021, 09:08:43 am
content: Wow this is amazing, as a student I would like to have one of theseFor a student these amazing utilities would be to expensive, so I hope I would win one of these. although I haven't been a member for a long time, I follow you on YouTube for a while🙏

author: rbleth51
author_rank: Contributor
timestamp: June 25, 2021, 09:14:44 am
content: One of these would really help in my lab!

author: tubularnut
author_rank: Regular Contributor
timestamp: June 25, 2021, 09:51:03 am
content: I'm in

author: vfxsoup
author_rank: Newbie
timestamp: June 25, 2021, 10:05:29 am
content: Yes please! I'd love one of these bad boys if there's even a 0.001% chance! I need a 2 channel PSU for audio amplifier testing (my Riden is only single channel so I'm relying on an unregulated audio PSU of my own design). Thanks.

author: pstimpel
author_rank: Contributor
timestamp: June 25, 2021, 10:22:33 am
content: Oh, yes please. Could use one of those, and it -probably- wants to travel back to Germany, back home. I'm in!

author: plantgrower
author_rank: Contributor
timestamp: June 25, 2021, 10:32:42 am
content: I could do with a higher voltage power supply!

author: ArnoldJRimmer
author_rank: Newbie
timestamp: June 25, 2021, 10:53:45 am
content: I'm in.

author: info
author_rank: Contributor
timestamp: June 25, 2021, 12:19:31 pm
content: I'd love to have one. I'm in

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: June 25, 2021, 12:20:52 pm
content: Please sign me up.Thank you.

author: Taviman
author_rank: Contributor
timestamp: June 25, 2021, 12:26:04 pm
content: This is my chance! I couldn't afford to buy R&S but I know you will choose wisely the poor guy 🙂.What is that EasyRamp thing? I was expecting that to regulate how sharp the ramp time. Didn't expect it to overshoot like that

author: Marsman1
author_rank: Newbie
timestamp: June 25, 2021, 12:26:32 pm
content: Not a big poster but always a fan. I'm in.

author: Muessigb
author_rank: Contributor
timestamp: June 25, 2021, 01:02:10 pm
content: Quote from: s8548a on June 25, 2021, 07:05:49 amFirst, I'm glad they're using quality components and second, this WiFi module is also developed and manufactured by Microchip (formerly Atmel).This makes them a good match. Their website also claims it works well with Microchip's high performance ARM series.They also claim that it works well with an RTOS, and R&S is known to like using FreeRTOS in their oscilloscopes also running on Atmel processors.

author: h3ndr1k
author_rank: Newbie
timestamp: June 25, 2021, 02:17:05 pm
content: although i'mnot a very active member i do love your video's.would love to finaly have a powersupply!

author: Smith
author_rank: Frequent Contributor
timestamp: June 25, 2021, 02:59:21 pm
content: Would be awesome to win such a power supply. The dual 100V output would be great for testing amplifier outputs without continuously blowing fuses

author: rghisi
author_rank: Newbie
timestamp: June 25, 2021, 03:00:22 pm
content: I've been watching eevblog for a thousand years now and already learned tons from it.Having a PS like that one would be awesome, even with its quirks. Sign me in, please

author: dwd2112
author_rank: Newbie
timestamp: June 25, 2021, 04:12:11 pm
content: Thanks for this, Dave! I hope this qualifies as an entry. Good luck, all!

author: e-nighthawk
author_rank: Newbie
timestamp: June 25, 2021, 04:17:00 pm
content: Does anyone know how that works with import taxes? Do you have to pay 20% or something on that 1000+ USD value?

author: Refrigerator
author_rank: Super Contributor
timestamp: June 25, 2021, 05:07:13 pm
content: Quote from: e-nighthawk on June 25, 2021, 04:17:00 pmPretty sure you can google it, it's not like we're supposed to know German import laws.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 25, 2021, 05:17:37 pm
content: The design with 2 large filter caps and 2 output transistors is likely with an electronik switch over between 2 transformer taps. Makes absolutely sense, as it saves on the heat sink and works without glitches and wear of relay switching.The current measuring shunts look a bit disappointing - I had expected higher power version to get a really good dynamik range.The overshoot on the current limit looks a bit strange, a bit like disabling the current limit just after changing the set votlage voltage. This may be with the idea to faster get to the new voltage. There is a slight chance to it could be fixed with a software update, as this looks like under software control.With the rear ouput and seprate rear sense terminals / cables, I am slightly missing a way to switch between front and rear. The drive terminals may be in parallel, but the sense part would need some switching (front, rear with 2 wires and rear with 4 wires).The regulations on import/sales taxes likely depend on the country - chances are you may have to pay in some countries. In the US you are even supposed to pay income tax for this, at least this is what KS tells you in there giveaways.

author: Refrigerator
author_rank: Super Contributor
timestamp: June 25, 2021, 05:40:34 pm
content: Guys FIY there's a separate thread for the giveaway here:https://www.eevblog.com/forum/contests/giveaway-rohde-schwarz-nga102-psu/So stop posting "i'm in" in this thread.Quote from: EEVblog on June 25, 2021, 12:04:03 amDrive-by posters, you know where the door is.Like 80% posts here are giveaway "entries".Getting back on topic, that overshoot is quite a shame, really. Especially considering the price and the brand name behind the PSU you would really expect something better.How easily would the overshoot in this R&S PSU blow an LED? (max output voltage with 20mA CC on an indicator LED)Also is the voltage and current controlled via a SW loop? What benefits does that have over a regular op-amp based control?Personally i don't find this PSU worthy of 1000+ bucks, especially with that overshoot. Putting expensive components into a product is like putting marble into an expensive NYC apartment, but that alone will not make it good. I have no attachment to R&S because I've never used any R&S equipment and my view point is not that "It's R&S so it's going be good" but rather "let's see how good it is". And so far the impression is not good.I want to see how R&S handles this overshoot situation and if it can be fixed.I think this warrants further testing of not only the R&S, but also other lab bench PSUs for comparison reasons.

author: TheD312
author_rank: Contributor
timestamp: June 25, 2021, 06:33:43 pm
content: I`m in too!

author: e-nighthawk
author_rank: Newbie
timestamp: June 25, 2021, 06:51:41 pm
content: Quote from: iamdarkyoshi on June 25, 2021, 12:50:02 amI like the idea of showing what the R&S would replace.Here's what I put together actually not even that long ago:It's based on a RD DPS5005 I had picked up about two years ago. I used it here and there, but while being quite okay, it never made it to be my preferred piece of equipment. I didn't like the hassle of always having to find a PSU that supplies enough DC for the DPS first before I'm able to power my actual project.So this year I added an AC power supply to it which makes it much easier to use for me. While at it, I also upgraded the fan and made it temperature controlled. I'm not so sure yet, if it'll be able to keep the unit cool when it's running at full power. That's to be tested once I find something that draws enough energy.

author: HattedSquirrel
author_rank: Newbie
timestamp: June 25, 2021, 07:01:26 pm
content: Quote from: Refrigerator on June 25, 2021, 05:40:34 pmIt already has been that way many years back when it still was Hameg. R&S used to be reputeable for extremly high end RF gear (and still is). Then they bought Hameg to extend their portfolio with PSUs and scopes. Like many, I hoped it would make the PSUs better... but... well, they didn't.They did some work on the scopes, though. User interface is now completely different and more in line with their RF stuff. (Showing the current frontend configuration as a block diagram for example.)Quote from: Refrigerator on June 25, 2021, 05:40:34 pmBetter control and more complex control loops. One of the first steps in getting a good and fast control loop is linearizing the hardware's system response. That is easily done in software by applying the inverse (non-linear) transfer function. Creating the same inverse transfer function in HW is much harder. Another point is the ability to fine tune the loop control parameters via firmware updates or even during run time for different operational modes. Some PSUs have special settings for inductive loads or high / low capacitive loads. Numerous four-quadrant power supplies can be switched between current or voltage compliance mode. I have heared that it might be common to tune the speed of both control loops according to the mode in order to give you the best output response once you run into compliance. While there isn't much run-time tuning in the PSU in the video, the ability to retune via firmware updates is considered de-risking and also saves time during development.And last but not least, it is easier & cheaper to get low drift / drift compensated DACs and ADCs, than to build the complete analog control loop in hardware with similarly low drift. You wouldn't think how important 0.1$ saved in a 1000+$ product is. Don't ask how I know.

author: motorev16
author_rank: Newbie
timestamp: June 25, 2021, 07:39:50 pm
content: I would have preferred 2 sensing bananas on the front panel

author: Refrigerator
author_rank: Super Contributor
timestamp: June 25, 2021, 08:36:15 pm
content: Quote from: motorev16 on June 25, 2021, 07:39:50 pmBut there's still connections for external sensing on the back side of the unit, no?

author: Refrigerator
author_rank: Super Contributor
timestamp: June 25, 2021, 08:55:40 pm
content: Quote from: HattedSquirrel on June 25, 2021, 07:01:26 pmThanks for the response, and i have to agree that tuning a circuit in software is quite advantageous, as i've found out with FIR filters in my projects.But it makes me wonder why does it take the NGA100 some 10ms to correct the output. Surely the MCU should be plenty fast enough to do this in microseconds, especially with that slow ramp-up.Are they spending too much resource driving that LCD? Also how does the PSU regulate a changing load, does the control loop lag behind in that case also, or is it just during output enable?I wonder if that Keysight in Dave's video also uses a SW control loop, it seemed to behave a lot better. And the little spike (not an OV) in the output seemed like the control loop "catching" itself before an overshoot happened.I really want to see how a Rigol and other brand PSU's perform on this test, i think Dave also had some ebay cheapies in his storage somewhere.

author: taiteki
author_rank: Contributor
timestamp: June 25, 2021, 08:56:27 pm
content: i need one!!and this is a big one!!

author: Kleinstein
author_rank: Super Contributor
timestamp: June 25, 2021, 09:07:49 pm
content: I don't think the normal control loop would be in software. The demands on the ADC / DAC would be quite high. Digital control starts to become popular with SMPS - these have lower requirements and usually don't need a DAC. They also tend to like getting closer to the limited with the control loop. A point that is relatively difficult to implement analog is anti windup.For this lab supply it looks more like digital control on the set values. The linear ramp part is likely from the set voltage DAC going up in steps to get a controlled ramp when the output is enabled. There is nothing wrong with this an I would not mind the little ripple seen.The other point seems to be an increased current limit when the output voltage is changing (maybe only up) - this is likely controlled by software by adjusting the set point to the analog current limit. It looks like good intentions, but not really though to the end.Best case there may be an option to turn off this feature.It is a bit like the computer to solve problems that you would not have without a computer.Separate sense terminals are not that often used with the 4 mm plugs. It absolutely makes sense to have 2 terminals at the front and 4 wires on the extra connector in the back. With only some 2 A the voltage drop on the wires is not such a big issue.

author: nctnico
author_rank: Super Contributor
timestamp: June 25, 2021, 10:15:11 pm
content: Quote from: Refrigerator on June 25, 2021, 05:40:34 pmActually the power-on behaviour and crossover between constant voltage / constant current is often tested when people do a review of lab PSU.BTW: Keysight had to do a recall of their E36300 series lab PSUs because a spike appeared on the output when you plugged it in. But with power applied it already behaved way better than this R&S NGA100 PSU. Heads are going to roll in the main R&S office this Monday!

author: kcozens
author_rank: Contributor
timestamp: June 25, 2021, 11:49:36 pm
content: That NGA unit is quite the beast in terms of size. I bet it must weigh a lot. As is often the case Dave quickly finds some questionable behaviour of a new piece of test gear. It would take up a fair amount of the space on my small workbench but it would be a nice upgrade to my existing power supply.

author: splin
author_rank: Frequent Contributor
timestamp: June 26, 2021, 03:15:52 am
content: : To make it clear the following is is an (obviously poor) attempt at satire - please don't take it seriously!Why all the whinging about a mere 10ms or so to get the output under control? No doubt you're all hardware engineers who don't understand the extreme complexity and difficulties the firmware system has to deal with!Integrating a unique new, state of the art, high-reliabilty RTOS, engineered for optimised PSU functionality, developed using a cutting-edge customised Agile based methodology helps manage the complexity of the large software development to minimise the distractions of constant inter-team interactive incompatibility disagreements, such as memory and CPU resource allocations, which plague traditional homogenous software developments.For example, this allowed the Wuppertal team to develop the overcurrent detection module, largely decoupled from the Stuttgart team developing the event management and distribution module, the Taipei team responsible for output current control functionality (with 1uV resolution), the event logging object oriented distributed database team etc, and the somewhat undervalued 'Output Fusion' team. (Oddly, nobody seems to be able to recall where they are based).With round-robin 1ms scheduling, 10ms response is actually world class leading especially given the need for triple checking the over current event is not a false noise abberation. And whilst the 550MHz processor might appear to be overkill, consider that as the PSU could be used in safety crtical situations it needs to be fully MISRA compliant - appreciate how long it takes to do a full memory test of the hardware (including 256MB of Flash and 128MB DRAM) to be certain the overcurrent event wasn't due to a mains glitch or similar.Personally I'd have included a speech processor:"Dave. The output current seems to in excess of your expectational parameter tolerances... would you like me to attempt to constrain it?"..."I'm sorry, Dave. I'm afraid I can't do that."..."Dave, please put down the crowbar - it may invalidate your (limited) R&S warranty".

author: gardner
author_rank: Regular Contributor
timestamp: June 26, 2021, 03:41:22 am
content: I would love to have one of those. It would look so nice next to my crappy Yihua 30V/10A one.With all those winding leads coming off the transformer, I was expecting to see some sort of switching between various windings to minimize the voltage drop on the pass transistors. But you'd need 3 or 4 relays per channel to switch them and I don't see any of that. Are there a raft of triacs hiding on one of those heatsinks to do the switching?

author: Kleinstein
author_rank: Super Contributor
timestamp: June 26, 2021, 09:15:04 am
content: With 2 main filter caps that are rated lower than the maximum output voltage, it is quite clear the fitler caps are in seires and very likely with a transformer tap in between. One can that use electronic switch over between the 2 raw DC voltages. This would be only 2 transformer taps, but much faster (e.g. µs instead of seconds). The 2 voltages with a fast corss over may be about as effective as 3 conventional AC swtiched transformer taps, as there is no need for much hysteresis and reserve for ripple and less estra headroom needed. The "switch" over could be by the 2 power transistors seen on the heat sink and a diode (maybe the little extra heat sink ?).In addition to 3 wires for the dual main supply one may need another 2 or 3 wires to power the actual regulator circuit. Like most lab supplies they very likely use the floating regulator principle. Especially for such a high voltage this is the obvious choice.Switching with relays also has some trouble - the relays usually work on the AC side and would see quite some current spike from charging the filter cap. This resuslts in quite some wear to the contacts and the possibility of sticking contacts which can result in failure. The swtiching can also cause some glitch reaching the ouput. Because of the time it takes for switching, it needs extra reserve in the voltage and thus more loss. To limit the wear it needs quite some hysteresis. So switching to a lower transformer tap would be only if the voltage is way higher than actually needed.The overshoot on turn on is only with the current limit, likely not much with the voltage. One has to compare this to the charge stored in the output cap. Some 2 A for 5 ms are 10 mC, which would be equivalent to 10 V in a 1000 µF capacitor, like found with some lower grade lab supplies. It is not great and I have hope it would be improved / fixed, but it also is not a desaster. If in the low current range, the extra current is likely also lower.

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2021, 10:14:54 am
content: Quote from: splin on June 26, 2021, 03:15:52 amA 10ms spike is enough to kill your circuit which is why decent power supplies don't show this behaviour! It doesn't matter how difficult it is to get right, it simply must be right. You have to be able to rely on a power supply to do what you want and not push random voltages/currents into your circuit.Dave should send it this PSU to me and I'll bring it where it belongs: at the recycling station. That will save other people the misfortune of having a circuit that suddenly doesn't work or lets the magic smoke out for no obvious reason. There is nothing worse than a PSU you can't rely on (been there, done that).

author: Refrigerator
author_rank: Super Contributor
timestamp: June 26, 2021, 10:45:22 am
content: Quote from: nctnico on June 26, 2021, 10:14:54 amI thought that post was sarcasm.Also don't be so hasty, that PSU could make a pretty ok car battery charger

author: igorstep
author_rank: Newbie
timestamp: June 26, 2021, 01:48:20 pm
content: I'm in, Nice PSU!!!

author: Mick
author_rank: Unknown
timestamp: June 26, 2021, 01:56:10 pm
content: I'm in100v supply would be super useful.

author: andybrandi
author_rank: Contributor
timestamp: June 26, 2021, 03:51:25 pm
content: Still lacking a nice PSU for my lab, those would make a nice addition for sure.

author: blackdog
author_rank: Frequent Contributor
timestamp: June 26, 2021, 06:30:27 pm
content: HiI often explain it this way:The power supply must first be kind to itself.And second, he must be very caring of his connected load.Even though it seems that way, a linear power supply is not simple.There are very many mistakes made by amateurs (me too in the past) and professionals, especially regarding the current limitng as Dave showed with the R&S power supply, among others.Just because R&S designed this power supply does not mean it is good.The same goes for a number of HP models. I have one here that has a low power rating, below 50Watt, nice and low noise and an output capacitor of 1000u! for less than 2 Amps.1000uF is way to mutch in this HP Power Supply, to be very caring of his connected load.For now, I don't know how the voltage loop and current loop are arranged in the R&S power supplies.But digital is really a NoNo for a linear power supply for now.If you design an Analog/Linear power supply you should in my opinion make sure that both loops are always stable without switching effects from voltage to current and vice versa.It's nice that you have lots of options in the menus but loop stability is #1 for a linear power supply.Also notice the noise or PARD when Dave puts the scope over the output of the power supply, you can sawing wood at the pulses the scope shows, now that's not exactly neat.Those pulses may be a commonmode problem in Dave's measurement setup, but I have a sneaking suspicion that they are not.Some opinions from me:Good linear power supplies do not have digital loop control.To solve this properly in the digital domain, you need very fast and good ADC/DAC and a processor just for this function with a very good "Watch Dog" setup.This is I think, rather expensive.The Power section will have been implemented with medium speed transistors of around 5Mhz Ft. (Faster is possible with modern audio power transistors, but it is harder to keep stable.)If the compensation of your voltage and current loop is set up properly, with good opamps with large phase margin(AD4625), you will achieve 40uF capacitor per Ampere across the output with very good dymamic behavior.Those were my two cents.Kind regards,Bram

author: Kleinstein
author_rank: Super Contributor
timestamp: June 26, 2021, 06:58:06 pm
content: The ouput cap is shown to be 22 µF electrolyic plus a little ceramic (more like <= 1 µF at 100 V max voltage) so it is some 12 µF per amp of output current.I still expect the control loop to be analog, it only looks like there is some software action going in effecting the set points. The easy part to implement is a defined "slow" (some 5 ms) ramp up of the voltage on output enable. This is easy to implement and I see no problem with this.The problematic part is the current limiting not working as expected when the voltage is changed (possibly just some changes, like up). My guess on this is a kind of extra "feature" to make the output faster following a changing set point and the current limit may be disabled / set up for a short time. This may be nice in some cases, but it kind of defeats the current limit idea. So it's a bad idea, at least as the default setting - maybe useful as an option.There is no really fast connection from the high powered µC at the from to the ouput stages. The that µC / CPU is mainly for the UI, not the regulation loops (other than the fan).

author: blackdog
author_rank: Frequent Contributor
timestamp: June 26, 2021, 07:05:55 pm
content: Hi Kleinstein,I'm not sure the electrolitic 22uF are the only capacitors across the output, I saw on the circuit board more electrolitic capacitors near the output wiring.So it's possible they split the capacitance across the output.And I'm not talking about ceramic capacitors at the output terminals.But of course it remains speculation when I don't have the power supply in my hands.Kind regards,Bram

author: Kleinstein
author_rank: Super Contributor
timestamp: June 26, 2021, 07:41:45 pm
content: There are 2 equal electrolytic caps at the rear output. So depending on how the switching is done there could indeed be 2 such caps in parallel for each output.I just had a look at the power transistors and was surprised that the DC SOA is a bit weak: only some 2 A at 50 V. So for the simple series connection this would be a bit underrated.. There are a few more transformer wires - so maybe there is some additional tap swtching at the bottom and using the transistors in parallel.

author: rf-design
author_rank: Regular Contributor
timestamp: June 26, 2021, 08:48:43 pm
content: Quote from: splin on June 26, 2021, 03:15:52 amWOW.... I am shocked by this management speak. Did not expect this here.To give you a little entertainment. All classic voltage regulator circuits which have an emitter-follower or source-follower with a output capacitance could not adjust faster than the current measurement intrinsic delays. It seems to be clever to do this digital and combine low cost high resolution current measurement with the limiting but you give up the reaction time which could kill your DUT. Using a classic analog overtake circuit with analog current setting is the 50y old appoach. You could anyway measure digital in parallel. There is no reason other than to give up reputationFor much better dynamics you use collector or drain outputs with current source operation. The voltage mode is then by closing the voltage feedback mode. Current limiting is by clipping the internal drive current source. So there is no direct current measurment but clipping the drive current source. These technique is used for 30y in SMUs.

author: KaneTW
author_rank: Frequent Contributor
timestamp: June 26, 2021, 11:17:00 pm
content: Quote from: splin on June 26, 2021, 03:15:52 amHonestly, I agree. With all PSUs I'm always considerate of where I set my CV setting is, and some PSUs are not suitable for powering sensitive circuits. BUT:Here's a quote from your website: "Confidently power sensitive circuits" "Supplying extremely stable output voltage and current is crucial when powering sensitive components."At this point you're putting your foot in your mouth somewhat fierce.QuoteProblem in search of a solution. In any case, this is an implementation detail.QuoteI don't think anybody is complaining about the hardware. But again, implementation detail. You're advertising a PSU for sensitive circuits. Do better.

author: solarmax1
author_rank: Newbie
timestamp: June 26, 2021, 11:39:06 pm
content: I don't own and R&S equipment. Would love to give one of these a new home.

author: KaneTW
author_rank: Frequent Contributor
timestamp: June 27, 2021, 01:11:07 am
content: I've looked at some other power supplies and none that I found spec overshoot on turn-on. Keithley in particular suggested reducing rise times in a menu option to prevent overshoot, so this seems to be something a user could do with this PSU (using EasyRamp iirc).

author: thm_w
author_rank: Super Contributor
timestamp: June 27, 2021, 02:53:20 am
content: I checked an old R&S NGMO PSU and it has similar overshoot issues. It will shoot up to the setpoint voltage no matter the current, for 2ms.So if setpoint is say 15V, current is 0.1A, it will shoot to 15V for 2ms, 10x excess over your desired current limit...Quote from: KaneTW on June 27, 2021, 01:11:07 amYeah, they are within their given specs, from what Dave measured, worst case was ~8ms of overshoot. The relevant spec might be: Rise time 10% to 90% of rated output voltage, resistive load R&S®NGA101, R&S®NGA102 < 50 ms. Some PSUs will state a settling time, this does not list anything. Another reason not to trust banner specs, as they can simply omit any that aren't good.You could do it with a custom easyramp setup, but, your Keithley option makes more sense. Just have a rise time setting "slow" "fast" whatever, where slow would guarantee no significant overshoot (say ramp output up 500mV/10ms and let CC have time to react, instead of slamming it).Quote from Keithley 2308 manual:Quote

author: commodore64
author_rank: Newbie
timestamp: June 27, 2021, 03:12:12 am
content: I have never had anything so nice, PLEASE enter me in your drawing!

author: splin
author_rank: Frequent Contributor
timestamp: June 27, 2021, 03:56:27 am
content: Quote from: nctnico on June 26, 2021, 10:14:54 amApologies I should have made it clear that I was trying to be satirical. You're absolutely right - this behaviour is not acceptable at this price point.Quote from: Refrigerator on June 26, 2021, 10:45:22 amQuote from: rf-design on June 26, 2021, 08:48:43 pmOh god did that seem remotely plausible? I hate such buzz-word marketing w**kery word soup! "Output Fusion"? Beam us out of here Scottie please!I was musing on a possible scenario on what went wrong with this design whereby there was too much design at too high a level - design by committee perhaps - rather than having an experienced PSU engineer having tight control of the critical performance and behaviour aspects of the design who would dictate and micro-mange the implementation (if necessary) of the control algorithms whether in hardware or software and would specify the detailed test process to verify the design. The fact that Dave uncovered this failure so readily (after, what only 3 tests?) shows that this didn't happen properly.Perhaps the seperation of the HW and FW/SW teams was too complete, possibly even done at different sites or even in different countries. Big problems can arise if there is no clear engineering expert lead in overall charge of both groups, but only a product manager, possibly more concerned with the marketing issues trying to co-ordinate the two groups who may have differing aims and drivers.For example, a new SW lead is hired because of their expertise in the latest SW development fad of the day which has seduced senior management as being the siver bullet they're hoping for. The old dinosaur engineers in the team who cut their teeth in assembler language who have hard real-time in their DNA get overuled by brash young programmers who don't have a clue what a PSU actually is but do know all the latest buzz words and want the flavour of the month programming languages, SW architectures and paradigms to populate their CVs - regardless of how well suited it is to the current project.The project complexity rapidly spirals upwards until nobody can be absolutely certain of the low level hard real time behaviour - especially when layer upon layers of third party binary libraries are included whose memory and timing behaviour are poorly understood - hence the bizarre sight of a 550MHz processor with 256MB of Flash and 128MB DRAM being used to control a two channel PSU! Yes I know those parts aren't expensive and it's likely about having a core processing solution for a wide range of products, but if they'd only had a 64KB STM32 with 32K of RAM, the SW architecture would likely have been simple enough that it's critical pathways could be easily understood to guarantee they meet the specs, unlike the Java based garbage-collecting monstrosity (or whatever) they actually produced because, well because they could!And yes I also fully understand that underspecifying the processor/memory can also lead to failure due to excessive complexities due to the resulting extreme optimizations needed. And that some engineers get called dinosaurs because they pretty much are.-------I'm not saying any of the above is remotely connected to this PSU's problem. I think Kleinstein could well be right that the main control loops are analog , although the processor is plenty fast enough and fast ADCs and DACs are fairly cheap now. What bandwidth would the control loop need for a typical PSU of this class need? 2 or 3MHz?However the output enable overcurrent behaviour is so bizarre and slow that it has to be SW issue surely? Which means it's probably fixable. I'm guessing this overcurrent problem is related only to the rather odd output enable behaviour. I'm assuming 'EasyRamp' was disabled and that someone decided that a default slow ramp up was desirable despite the fact that traditionally the enable switch provides instant on. As such the over current control behaviour likely relates only to this transitory mode after which a properly functioning overcurrent control is enabled. We won't know until someone does some dynamic load testing. The spikes in CC mode when changing voltage may be something different again.The interesting question is how did this problem survive into delivered product when Dave found it so easily and as several have stated here that they consider it such a serious defect that they would not consider buying it. We'll probably never know of course, but here are a few thoughts:1) The CC mode behaviour at output enable time was not tested because CC mode testing was comprehensively done by dynamic load testing after startup and nobody involved in that testing were aware that the control strategy was different for a short period after the output is enabled. Perhaps being experts in the analog domain it simply didn't occur to them that the SW team would choose to override the normal O/C control when enabling the output and didn't think to check.2) Much worse, they knew about this but didn't consider it important for some reason - which could arise where the subject domain experts don't have sufficient clout with non-technical management (much like various governments' responses to 'expert recommendation' in the covid crisis).3) They discovered it late in the development but decided to release anyway gambling that most users would never find out or even care, which might be true for customers using them in industrial test situations who only the remote control interfaces.4) Farming out the development to a team or subsidary without specific PSU design expertise, providing PSU expertise in a consultancy role, but not being in full control of the project. This could arise from mangement considering that SW is becoming an increasingly dominant part of the total development budgets and thus the focus is changed to being a primarily SW based company with specialized HW/domain support for each product class. The SW teams then call the shots and the HW/subject experts don't get sufficient access to find the problems early enough.Or many more possible reasons.Quote from: KaneTW on June 26, 2021, 11:17:00 pmOnce again my sincere apologies for not making it clear in my original post that it was a mixture of satire and sarcasm. The fact that someone appears to have mistook my post for an official R&S company communication shocked me and shows how low our expectations have sunk that we can't easily differentiate between company marketing speak and the total drivel, buzz word soup I posted - believing it was obviously so. Lesson humbly learned.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 27, 2021, 04:44:38 am
content: I would expect a loop bandwidth of some 50 kHz - 500 kHz, though the behaviour at higher frequencies (e.g. to some 5 MHz) could also matter.Fast ADCs and DACs are available. Higher resolution (24 bit) is available too, but they still cost a pretty penny if one needs both at the same time. The DSP would also need a pretty fast data path to the DAC/ADC. That Dave called ADC near the shunts, too me looks suspiciusly like an TL082 (chip marked as T082).Exceeding the current limit during short periods for turn on would not damage many circuits. The CC mode is never meant to directly drive a sensitive part / circuit. The more important point is no to exceed the set voltage on turn on. This is where some of the cheaper ones already fail.Ideally I would like to have a slow and a fast current limit, so that for a short time the current can be higher, though not by so much (maybe 50%).

author: Refrigerator
author_rank: Super Contributor
timestamp: June 27, 2021, 07:17:29 am
content: Quote from: Kleinstein on June 27, 2021, 04:44:38 amProbably to amplify the shunt voltage, as those aren't at ADC friendly levels most of the time.

author: rf-design
author_rank: Regular Contributor
timestamp: June 27, 2021, 07:24:34 am
content: Quote from: Kleinstein on June 27, 2021, 04:44:38 amIt depend on the application how much "As" is tolerated if Imax is exceeded. For instance a high frequency PA which could be destroyed with time constant of the internal transistors. These depend on the size but could range between 10us-1ms. 3/5 material have higher thermal resistance but similar capacity to silicon. So the thermal time constant is very short. I would guess that the 20uF for a lower power PA could get critical. So reaction times in the us range is a practical advantage for protection.But you have to get rid of the classic regulator with the output filter cap. And digital loops are too expensive for a similar performance. To me there is no clear advantage of having a code option with branches in the regulation loop. This would be the only definite argument for a digital loop.

author: ERIC1123
author_rank: Newbie
timestamp: June 27, 2021, 08:16:32 am
content: can you give me oneThe power supply is too expensive for me to buy

author: alouko
author_rank: Unknown
timestamp: June 27, 2021, 09:20:55 am
content: Please consider me for a giveaway!!!!

author: glx
author_rank: Newbie
timestamp: June 27, 2021, 10:33:08 am
content: Oh, entry-level and around 1000 bucks somehow don’t go together in my headBut I totally wouldn’t say no to one of these

author: AVGresponding
author_rank: Super Contributor
timestamp: June 27, 2021, 01:12:01 pm
content: Yes... I need one of these!I need it because I haven't yet acquired any R&S gear, and also I need to test its performance against my HP 66311B, my HP 6633B, my TTi TSX3510P, EX354D, PL320QMD, and brace of Manson EP-613's. I also need to test it against my VWR300 electrophoresis supply. In general, I need more power supplies. I need more power!

author: kilobyte
author_rank: Regular Contributor
timestamp: June 27, 2021, 01:51:58 pm
content: I'm curios about the power off behavior. My HMP4040 (maybe only on older revisions?) for example does generate an overshot with round about 10Volt if you switch it off via the main power switch when you forgot to disable the outputs beforehand.Luckily it didn't kill any components so far.Test:Set Output to 3,3V or 5VMaybe connect a small load with ~100mA

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2021, 02:37:01 pm
content: Quote from: kilobyte on June 27, 2021, 01:51:58 pmYou are lucky indeed. At one of my former employers someone used an overshooting PSU to test a whole batch of boards. The boards where tested OK but after they where built into the casing none worked. Turned out all the boards where fried and needed all chips replaced. I learned 2 things from that: have overvoltage protection on every circuit board and throw PSUs which overshoot in the bin. Actually some co-workers objected to throwing the power supply in the bin even after it caused a lot more damage than it's purchase price. Needless to say it did dissapear...

author: manu
author_rank: Regular Contributor
timestamp: June 27, 2021, 03:21:15 pm
content: I can't say no to Rhode & Schwarz

author: billrule
author_rank: Newbie
timestamp: June 27, 2021, 03:44:08 pm
content: "fraid I have never been in a position to contribute among this august company, but that doesn't stop me lusting after a little R&S goodness

author: DEV001
author_rank: Contributor
timestamp: June 27, 2021, 04:19:00 pm
content: I am interested as well as it looks like a very precise power supply.

author: Dagobert1
author_rank: Contributor
timestamp: June 27, 2021, 04:41:36 pm
content: I would also like to get one of the power supplys. I am currently setting up my workshop and do not have a power supply unit yet.

author: MBY
author_rank: Regular Contributor
timestamp: June 27, 2021, 08:56:48 pm
content: I'm in! I'm actually looking for some lab supply that can give a high voltage. Saw one on banggood that gives 120V, but it didn't instill confidence. High voltage is useful for a number of things, such as desulfating really old SLA-batteries that can have many kOhms of initial internal resistance (and sensitive current measurements is also nice in this regard), and electrophoresis and testing components such as capacitors for rating (and needed derating).

author: kosmonooit
author_rank: Contributor
timestamp: June 27, 2021, 09:40:24 pm
content: I think I could live with the glitchesPlease include me in the draw, thank you.

author: Deepwinter
author_rank: Newbie
timestamp: June 28, 2021, 05:25:51 am
content: I'm in

author: ascomm
author_rank: Contributor
timestamp: June 28, 2021, 07:25:36 am
content: That CC overshoot is not that bad compared my BangGood El Cheapo lab power supply.

author: Astrodev
author_rank: Regular Contributor
timestamp: June 28, 2021, 05:59:19 pm
content: The overshoot is definitely a potential problem but it would be interesting to see how the CV vs CC affects any transients on the output when used at the upper end of the power envelope, as this has a lot of potential to really do some damage to the circuit being powered. I have also seen some bench power supplies get damaged under these conditions at the edge of the envelope.It would be interesting to know how these power supplies cope under these heavy load conditions.

author: timgiles
author_rank: Regular Contributor
timestamp: June 28, 2021, 06:03:48 pm
content: I could do with a decent power supply - so would be great to be part of the giveaway :-)

author: Stuart Coyle
author_rank: Contributor
timestamp: June 28, 2021, 09:28:19 pm
content: How many power supplies do I need? The answer is, of course, always one more than I already have.

author: Kean
author_rank: Unknown
timestamp: June 29, 2021, 05:17:40 am
content: Quote from: Kleinstein on June 25, 2021, 05:17:37 pmMaybe the relay at 12:25 in the video is for switching between front/back sensing? It does look a bit beefy for that requirement, but wouldn't you need two relays to select between isolated, series, and parallel modes?Was there any other relays for series/parallel mode switching? With isolated channels and 250V DC max to chassis on both channels, I guess they could be using transistors for switching into series and parallel modes.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 29, 2021, 06:37:28 am
content: The large relay is likely for the series / parallel switching. It should need 2 relays for this. Switching with transistors is tricky and would be odd.Switching the sense lines would be more practical to do with with electronic switches or maybe reed relays. One side (usually the positive side with the usual floating regulator) could use a simple CMOS switch.

author: ElectricGuy
author_rank: Regular Contributor
timestamp: June 29, 2021, 09:04:36 am
content: I'm in... like flin!!!

author: f4eru
author_rank: Super Contributor
timestamp: June 29, 2021, 11:10:18 am
content: I have a good old linear 1kW R&S NGRE "STROMVERSORGUNGSGERÄT" like this one but in 10A 100V version, so i'll pass on the giveawayHere you even can select if you want current overshoot or not, there's a button for it and that's really usefulR&S cannot pretend they did not know about current overshoot... if they do it switchable since 40 yearsNice and reliable stuff.When I opened it up, I saw that the voltage ref. is a neon tubeNone of this digital panel with non selectable overshoot rubbish

author: rf-design
author_rank: Regular Contributor
timestamp: June 29, 2021, 02:08:55 pm
content: Now you can see that an agile code developed over distributed sites for a target RTOS samples a grey frontend knob and allow two different ramp functions

author: mrprecision
author_rank: Regular Contributor
timestamp: June 29, 2021, 08:25:54 pm
content: I would like to win that power supply to make a review and a comparison to the siglent power supply.

author: nctnico
author_rank: Super Contributor
timestamp: June 29, 2021, 08:39:30 pm
content: Quote from: f4eru on June 29, 2021, 11:10:18 amNo. It is to select control loop behaviour for loads with a large or small capacitance. It is not uncommon on high-end / high-precission power supplies.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 30, 2021, 02:00:55 am
content: That overshoot is simply unacceptable for a power supply in that price range.Especially the voltage spikes when it is in constant current mode and the set voltage is adjusted.It's also very big for a 2x 40W power supply.I do wonder a bit about all those secondary transformer taps, and how they are switched and there seems to be a black relay stuffed in a corner.All together I'm not impressed.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 01, 2021, 04:55:46 am
content: The 40 W (per channel) power limit is odd for a linear power supply. I would normally expect more like a stepped function like 2 A up to 40 V and 1 A when higher, depending on the transformer taps used. There may be some regulations that make is easier if only specified to 40 W.The transformer wires seem to come in colored pairs, so no split coils with 3 wires. Still there are quite a few wires. The expected votlages would be something like +-10 V (so 2x2 wires) for the regulator and 50/120 V (4 wires) for the main ouput, the 2 large filter caps. There may be an addition 5 V for the regulator / ADC/DAC part, though this may also start from the higher supply rail.With 2 darlingtons on the heat sink I would expect them to be in "series" with a diode to bypass the upper one if the lower tap is sufficient. So the cross over between 2 voltage rails can be electronic. The Keithley SMUs and some audio amplifiers use a similar configuration, though with push pull.There is also some smaller power transitor / FET, that may be used for some switching, maybe limiting the voltage charging the fitler caps. Without this the worst case heat dissipation would still be in the 100 W range (2 A into a short), which would be quite a bit of powert for s single 150 W rated darlington.

author: Bouteille
author_rank: Contributor
timestamp: July 01, 2021, 08:40:55 am
content: Hi there,yet another greedy message to win a power supply with high resolution metering...Would love to reproduce the "self mixing interferometry" experiment with laser diode (from this other great guy on YT)See you and thanks for all you do !!

author: SoiioS
author_rank: Newbie
timestamp: July 01, 2021, 08:57:53 am
content: I’m inNice power supply

author: mrcole
author_rank: Newbie
timestamp: July 01, 2021, 08:23:06 pm
content: Count me in!

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: July 02, 2021, 11:53:02 pm
content: Thanks Dave, nice video!Concerning the front panel connector type: this NGA device can get to quite high voltages - especially with 100V channels in series - which may explain the choice for this safety connector. Maybe less convenient than regular banana sockets, but safe.I suspect that one of the reasons R&S upgraded their older NGE100 (with smaller grey binding posts with black and red rings) series to the NGE100 B series was also to offer safer connectors (large blue and red binding posts). Not many other changes were implemented, if any.(And I’d like to be in for the draw ;-)

author: cortex_m0
author_rank: Regular Contributor
timestamp: July 05, 2021, 03:42:17 am
content: This would not be one of my top choices for a power supply. My first WTF moment was when Dave powered it on and it took 20 seconds to start. It really didn't get better from there.I appreciate the min/max function, but it's useless if it includes the charging of the output caps at power-up, or at least needs an easy to access clear key.The absolute accuracy on the current readout doesn't seem good enough to justify all those digits on the display. IOW, I can't claim to replace a bench ammeter with the internal current readout on this thing. The extra effort R&S went to to produce "10uA/1uA" resolution was wasted, compared to a model that shows 1mA resolution.It looks like a good electrical/mechanical design, but poor software carries the day again.

author: radioing
author_rank: Newbie
timestamp: July 08, 2021, 09:22:57 pm
content: As for the CC overshoot:I'm pretty sure that the problem of this PS with voltage overshooting in CC mode occurs due to the fact that the voltage feedback loop is faster than current feedback loop plus the transformer winding switching (or some pre-regulator?; it's 100 V PS). Therefore, after the PS starts, the transformer winding switch is set according to by user adjusted voltage (e.g. 15 V) and voltage feedback loop is pushing the PS to required 15 V. But, with some delay, the current feedback loop starts to decrease voltage to reach the adjusted current limit 2 amps. As the voltage is going down, the control logic switches transformer winding to lower voltage and then current feedback does the final job. It is visible at Dave's osci screen that after the winding switch the current feedback must increase the voltage to reach required current.With 3.3 V adjusted, the winding switching does not happen and only the slower current loop is the reason that the PS goes to 3.3 volts first and then down to 2.x volts (due to the delayed current feedback) to reach 2 A current.The pulse train generated by Dave is the winding switching effect also.It could be interesting to adjust 100 V and see how many times the winding is switched (how many section is there) to reach 2.x volts for 2 amps at the output (but it is out of the PS power limit so the adjusted current must be probably decreased to PS accepted value for this test).

author: MBY
author_rank: Regular Contributor
timestamp: July 09, 2021, 11:12:00 am
content: Quote from: kosmonooit on June 27, 2021, 09:40:24 pmQuote from: Deepwinter on June 28, 2021, 05:25:51 amQuote from: timgiles on June 28, 2021, 06:03:48 pmQuote from: ElectricGuy on June 29, 2021, 09:04:36 amIt occurred to me that this is the wrong thread for the giveaway! Post your "I'm in" once in this thread instead:https://www.eevblog.com/forum/contests/giveaway-rohde-schwarz-nga102-psu/msg3602896/

author: madsbinger
author_rank: Newbie
timestamp: July 22, 2021, 02:37:03 pm
content: Thanks for the tear down and always good videos to learn from. I have learned a lot from you and keep learning. I would like to win, so I have something to use home in my private hobby lab.

author: Prithul0218
author_rank: Contributor
timestamp: July 24, 2021, 06:47:25 am
content: Count me in please! My Ruideng supply isn't good enoughThanks.

author: Brumby
author_rank: Unknown
timestamp: July 24, 2021, 09:02:09 am
content: GIVEAWAY IS OVER.Draw was made 19th July(Besides, this was the wrong thread for the giveaway.)

author: greencardigan
author_rank: Contributor
timestamp: July 27, 2021, 10:13:17 am
content: There was firmware released a few days after the video was released.V02.006 -https://www.rohde-schwarz.com/au/firmware/nga100/The first improvement listed in the documentation is current overshoot.Dave do you still have the other unit to test the new firmware?

author: Pinkus
author_rank: Frequent Contributor
timestamp: July 27, 2021, 11:36:36 am
content: I am in too.

author: Refrigerator
author_rank: Super Contributor
timestamp: July 27, 2021, 01:23:54 pm
content: Quote from: Pinkus on July 27, 2021, 11:36:36 amNo you're not