New Bench Power Supply - Chinese - Page 1
Forum section: electronics / testgear

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 04:29:13 am
content: Well, I received a 30V 10A power supply back a while ago, and posted up here. A couple of days ago, I received another Chinese bench power supply operating at 30 5A. I requested it because it was a LOT smaller than the 10A unit, and since I will infrequently use 10A, I thought I would replace the 10A unit with the smaller 5A unit, and save some space on my bench.Anyway, I wanted to toss up some images and see what the community thinks. One thing I would like to ask is that this unit has a 120/240 switch on the back. How does that switch work? If I leave it at 240, will it work on 120V power mains? I've just never thought about it before, and most modern supplies convert automatically (if they convert at all).Link:https://www.amazon.com/dp/B09CGWG4GP[ Specified attachment is not available ]For some reason I had to limit my images to 5000kb, which is about 3 images per post. Sorry for the multiple replies, but it was the only way to get the images uploaded.

author: MarkF
author_rank: Super Contributor
timestamp: October 25, 2021, 07:09:27 am
content: Quote from: DW1961 on October 25, 2021, 04:29:13 amThere is absolutely NO REASON to upload a 5 MB image to the forum!I don't need to watch fleas running underneath SMD resistors.There is a thread somewhere about how big images should be. I haven't followed it to its end.But, images that size SHOULD be scaled down before posting. IMHO.My 'dark' theme for the forum limits the display of images to my screen size (i.e. 1080p).The best thing I ever wrote.

author: tautech
author_rank: Super Contributor
timestamp: October 25, 2021, 07:13:44 am
content: Quote from: MarkF on October 25, 2021, 07:09:27 amI very much agree. 200-500KB images are plenty large enough excepting when the finest detail is required.Clearly listed on the posting page in the Attachments and other options section:Restrictions: 10 per post, maximum total size 5000KB, maximum individual size 4000KB

author: radiolistener
author_rank: Super Contributor
timestamp: October 25, 2021, 07:38:46 am
content: There is no reason to buy such PSU. First of all, this is switching power supply, and this means that it's output is very noisy, it produces high EM interference for nearby equipment. And it's max current is just 10 Amps which is almost the same as for popular linear PSU with 5-10 Amps. In addition this is a cheap Chinese switching mode PSU, which means that it is even more noisy than branded PSU, it produce more EM interferences, has unstable output and is not reliable. This is just a noisy kids toy.And after all, such cheap switching mode PSU may be unsafe for your life and equipment. Because it uses cheap components on a "hot" (high voltage) part of circuit.So, it's better to buy 10 Amps linear PSU, likeKORAD KA3010D.Switching mode PSU makes sense to buy if you're needs very high current (about 20-100 Amps) for powerful equipment and you are not worried about the level of interference and noise. So, in order to buy switching mode PSU, it needs at least 20-30 Amps output. Otherwise it can be easily replaced with linear PSU which has low noise and don't produce EM interferences.Quote from: DW1961 on October 25, 2021, 04:29:13 amThere is no sense to upload tens of images with 5 MB each. 600 kB limit is well enough. So large image may have sense if you upload a single image with a high resolution which is needed to see all details. But it have no sense for a usual teardown pictures.There is no sense to see the dust particles shape on the table near PSU

author: J-R
author_rank: Super Contributor
timestamp: October 25, 2021, 08:52:22 am
content: - Sure, no need for such large photos. But also no need for the attitude from the forum veterans. Just ask the OP to please replace the photos with smaller ones?- I can't remember the last time I saw a consumer device with a linear power supply, they are all switching. So it might be of use for some purposes. (But yes, linear is still better for the electronics bench.)- That Korad might be a linear supply, but other than some credibility it has earned here on the forums is still just a cheap PSU that could also be dangerous. It had many faults when it first came out.- I would be pretty confident in saying the switch on the back should be set to 120V if that is what you're feeding it.- Can't tell exactly from the photos but the power switch wiring and the grounding looks a little suspect. Better check it out.- What is "programmable" about this? Do you plug in to the USB port on the front or something?

author: Gyro
author_rank: Super Contributor
timestamp: October 25, 2021, 09:05:31 am
content: If you're posting a thread like this, then you should be posting traces of output performance - turn on / off and load change transient behaviour, ripple and noise etc.A few oversized internal photos really don't tell you anything much (apart from grounding) about the desirability of the supply for actual use.

author: radiolistener
author_rank: Super Contributor
timestamp: October 25, 2021, 10:22:06 am
content: Quote from: J-R on October 25, 2021, 08:52:22 amLab power supply is not usual consumer device, it should produce clean and stable voltage for different purposes. You're needs to believe that it has clean output with no issues. With no needs to guess a riddle what is the source of that noise and why there a strange pulses... So, switching PSU is a bad choice. And if it's cheap Chinese switching PSU it is even worse..

author: RoGeorge
author_rank: Super Contributor
timestamp: October 25, 2021, 10:34:24 am
content: Quote from: DW1961 on October 25, 2021, 04:29:13 amIf your power supply has a switch to choose between 110 or 220Vac for mains, then you must put it in the correct position. Read the manual to double check which position is for each mains voltage level. Most of the switching power supplies can work on either voltage, but not all of them. If there is a switch, it means itmustbe set according to the mains voltage.- If your mains is 240Vac and the switch is set for 120Vac, the source will get damaged, or even start a fire.- If your mains is 120Vac and the switch is set for 240Vac, it won't work correctly

author: Yansi
author_rank: Super Contributor
timestamp: October 25, 2021, 12:09:53 pm
content: the switch bridges half of the mains bridge rectifier with the midpoint of the two filtering caps, to form a voltage doubler.For 230V input, it works as a normal bridge rectifier, obtaining about 330Vdc at the capacitors.At 115V position, it makes it a voltage doubler, providing the same 330Vdc at the cap outputs.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 04:40:34 pm
content: Quote from: tautech on October 25, 2021, 07:13:44 amAnd there you go! The problem is that if you compress down past about 50% for a JPG, you start to get bad artifacts and pixeling. I set it to 65% and the files recompressed to 1.4MB each.

author: Gyro
author_rank: Super Contributor
timestamp: October 25, 2021, 04:51:42 pm
content: It sounds as if you're using the wrong tool - try Resize. It's as old as the hills and standalone, but I use it to do major image compressions (~6MB down to a couple of hundred kB) with very little perceptible quality reduction...https://resize.en.uptodown.com/windowsEdit: Eg, This one... 6MB down to 116kB.https://www.eevblog.com/forum/projects/resistor-extreme-pulse-overload-experiments/?action=dlattach;attach=372530;image

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:02:38 pm
content: Quote from: radiolistener on October 25, 2021, 07:38:46 amI don't buy them. I receive them for free for doing a basic review of the products.You mean all switching power supplies are necessarily RF noisy, like my computer power supply (that isn't at all)?

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:06:01 pm
content: Quote from: J-R on October 25, 2021, 08:52:22 amHey JR thanks for your comment. As already stated, i did reduce the files to 1.4MB but I was unaware that total files cannot exceed 5MB.Anyway, on one of the PSU, not this one, you can plug it into your computer and do some stuff with it using software.I will retake some pictures of the power switch so you can better comment on it.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:10:15 pm
content: Quote from: Gyro on October 25, 2021, 09:05:31 amIt can tell you how well they have use RFI and other filters and capacitors, grounding, etc. though. Of course, the end result is a scope. I don't have a scope so I can't measure the output power cleanliness and efficiency of the unit. I was just wondering if even the unit is electronically or mechanically sound. I only saw one coil choke on it, for instance.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:12:47 pm
content: Quote from: Yansi on October 25, 2021, 12:09:53 pmWhy would you need to double 120V with a 30V power supply?

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:16:44 pm
content: Quote from: radiolistener on October 25, 2021, 10:22:06 amRadio, have you ever seen the output on a scope for a higher end computer power supply? They are far from dirty and unstable and their RFI is near zero.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:24:22 pm
content: Quote from: Gyro on October 25, 2021, 04:51:42 pmMy error. Just tested it and my compression program will compress it way down past 62% with good results. I got it down to 432KB and can probably go even lower. Completely acceptable quality for the forum. Thanks.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 25, 2021, 05:26:56 pm
content: Just wanted to say this isn't a thread for switching vs linear arguments.I was just simply looking for opinions on the hardware they used, wiring, filters, etc.

author: Gyro
author_rank: Super Contributor
timestamp: October 25, 2021, 05:33:55 pm
content: Quote from: DW1961 on October 25, 2021, 05:10:15 pmUnfortunately not. Areallydetailed analysis of the PCB layout (and schematic) might give a clue, but the effort would be considerable, for an experienced designer, and you wouldn't really have confidence in this without actual measurements. It depends on things like the internal construction quality of the magnetics etc, which are invisible.

author: radiolistener
author_rank: Super Contributor
timestamp: October 25, 2021, 05:39:05 pm
content: Quote from: DW1961 on October 25, 2021, 05:02:38 pmYes, all switching mode PSU have noise on the output and produce EM interference. Good branded switching mode PSU has a good filters, shielding, bypass-capacitors through shielding for enter and exit wires and is designed in such way to minimize these issues. Cheap Chinese PSU don't have it at all and is noisy like hell.Quote from: DW1961 on October 25, 2021, 05:16:44 pmyes, it's output is very-very noisy. As I remember it has noise with up to 0.5 V peak pulses. And it has RFI, you can listen it on a short wave receiver

author: AVGresponding
author_rank: Super Contributor
timestamp: October 25, 2021, 06:27:29 pm
content: It's a good idea to check the security of all the connections in these, particularly the mains ones, they are not infrequently dangerously loose. Also the one I have (but never use, since it destroys its own display, faulty LED driver IC probably) had not only loosely terminated mains cabling, but some of the semis weren't screwed back tightly to their heatsinks. Remedying this cured a certain amount of audible noise at higher loads...Now, this isn't from the same manufacturer as mine, or the self-igniting one that Big Clive looked at, but it's worth bearing in mind it'll be designed and built with much the same philosophy and methodology; pare back the costs by using the cheapest possible components (both electrical and mechanical) and assembled by horribly underpaid and overworked unskilled labour.TLDR; I wouldn't leave it running unsupervised, or powering anything I would be upset to lose.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 26, 2021, 01:54:22 am
content: Quote from: radiolistener on October 25, 2021, 05:39:05 pmWell, ok, so you would call this power supply noisy?https://www.tomshardware.com/reviews/corsair-rm850x-2021-power-supply-review/4

author: radiolistener
author_rank: Super Contributor
timestamp: October 26, 2021, 03:58:57 am
content: Quote from: DW1961 on October 26, 2021, 01:54:22 amYes, they all are noisy.I don't have exactly this model for testing, but I have Corsair HX620W. Just measured it, here is it's output noise:For comparison, here is linear lab PSU KORAD KA3005D:

author: DW1961
author_rank: Frequent Contributor
timestamp: October 26, 2021, 04:27:16 am
content: Quote from: AVGresponding on October 25, 2021, 06:27:29 pmI'll get back to you after I do that. Chinese electronics and products overall are getting better, or I should say, can be better than in the past (UNI-T DMM, for example). Some of the speakers I've had for review sound quite good for $100 speakers. Some, not so good at all. Will they stand test of time, I wouldn't bet on it, but you never know. I have a Chinese class D amp that uses the Texas Instruments class D 3116D2 amp chip and a Qualcomm Bluetooth chip, and I have had zero problems with it over the last two years, running 16 hours a day (low volume).

author: DW1961
author_rank: Frequent Contributor
timestamp: October 26, 2021, 04:41:53 am
content: Quote from: Gyro on October 25, 2021, 05:33:55 pmJust wondering because when I read computer power supply reviews, where they do fully test the units using a scope, hot boxes, and at various loads, they always do a run down about what the board looks like, separation of mains , rectifier usage, filters, what brand caps they use and how many , soldering job, OCP protections, etc. ex:COMPONENT ANALYSISGeneral Data -Manufacturer (OEM) CWTPCB Type Double SidedPrimary Side- Transient Filter: 4x Y caps, 2x X caps, 2x CM chokes, 1x MOVInrush Protection: NTC Thermistor SCK-037 (3 Ohm) & RelayBridge Rectifier(s): 2x GBU1506 (600V, 15A @ 100°C)APFC MOSFETs: 2x Vishay SiHF30N60E (650V, 18A @ 100°C, Rds(on): 0.125Ohm)APFC Boost Diode: 1x On Semiconductor FFSP0865A (650V, 8A @ 155°C)Bulk Cap(s): 2x Nippon Chemi-Con (400V, 470uF each or 940uF combined, 2,000h @ 105°C, KMW)Main Switchers: 2x On Semiconductor FCPF190N60E (600V, 13.1A @ 100°C, Rds(on): 0.19Ohm)APFC Controller: Champion CM6500UNX & Champion CM03XResonant Controller: Champion CU6901VACTopologyPrimary side: APFC, Half-Bridge & LLC converterSecondary side: Synchronous Rectification & DC-DC convertersSecondary Side: +12V MOSFETs 6x On Semiconductor NTMFS5C430N (40V, 131A @ 100°C, Rds(on): 1.7mOhm)5V & 3.3V: DC-DC Converters: 2x UBIQ QM3054M6 (30V, 61A @ 100°C, Rds(on): 4.8mOhm) & 2x UBIQ QN3107M6N (30V, 70A @ 100°C, Rds(on): 2.6mOhm)PWM Controllers: UPI Semi uP3861PFiltering Capacitors: Electrolytic: 7x Nippon Chemi-Con (1-5,000h @ 105°C, KZE), 7x Nippon Chemi-Con (4-10,000h @ 105°C, KY), 1x Rubycon (4-10,000h @ @ 105°C, YXJ)Polymer: 37x FPCAPChange Over Switch: 1x Sync Power SPN3006 MOSFET (30V, 57A @ 100°C, Rds(on): 5.5mOhm)Supervisor IC: Weltrend WT7502R (OVP, UVP, SCP, PG)The transient/EMI filter has all necessary parts and it does a good job, in restricting EMI emissions.The main switching FETs, provided by Infineon, are installed into a half-bridge topology. An LLC resonant converter is also used to boost efficiency.The APFC converter uses two Vishay FETs and a single boost diode, by On Semiconductor. These are high-quality parts.The two powerful bridge rectifiers are more than enough to handle the max power that this platform can deliver.Link:https://www.tomshardware.com/uk/reviews/corsair-rm850x-2021-power-supply-review

author: DW1961
author_rank: Frequent Contributor
timestamp: October 26, 2021, 04:54:24 am
content: Quote from: radiolistener on October 26, 2021, 03:58:57 amThat power supply is 16 years old. Maybe check this one out?https://www.tomshardware.com/reviews/corsair-hx850-psu,5257-10.html(2017 model and I linked to the EMI test page)The ripply was:80% Load: 10.2mVBTW, a line overlay would be more useful so we can see exactly how much difference there is between the perfect linear scope and the SPS. By their very nature, they will never be flat like a linear, but they may be "flat enough." In fact, everything I own runs off of a switching power supply, including my lamps (All 24V+ switching power supplies). Then I have chargers, amp power supplies, TV, monitors, routers, modems, all running 16 hours a day, and I dunno man. There must be something right with them.As far as safety goes, China puts out millions of these $60-100 dollar power supplies, and they are in use all over the world. Believe me, I'm no fan of crap electronics. However, if they were catching fire or otherwise harming people, I think you'd know about it. Millions of bench supplies all over the world is a pretty damn good statistical safety test. The exception proves the rule.

author: radiolistener
author_rank: Super Contributor
timestamp: October 26, 2021, 05:19:28 am
content: Quote from: DW1961 on October 26, 2021, 04:54:24 amThe issue is not it's age, the issue is that this isswitching mode power supply. Any switching mode power supply use pulses for voltage regulation. And you can see these pulses on the output.Very expensive elite branded SMPS has expensive filters, shielding and other measures to suppress these noise. They also have noise, but that noise is lower than for cheap Chinese SMPS.The better switching mode power supply use MHz band working frequency and have frequency knob, which allows user to shift noise from the working bandwidth.If you're needs noise free power supply, you're needs to look for linear power supply.For ultra low noise applications it's better to use battery powered devices with no switching mode converters. And if it needs mains voltage you're needs to use pure sine wave generator with power amplifier, because connecting to mains may lead to RF leakage (from mains to device).Quote from: DW1961 on October 26, 2021, 04:54:24 amYes, all these things with SMPS produce RFI. Some Chinese chargers have so high RFI noise that it is better to just put it into garbage bin.You can listen all these RFI noise on a short wave receiver with LW and MW band.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 26, 2021, 05:58:35 pm
content: Quote from: radiolistener on October 26, 2021, 05:19:28 amWhat I meant about the PSU being 16 years old is that they get better with each iteration.Of course I agree with you that is you need an extra quite power supply, then go linear. Ok. Sure. No argument there . I don't need that. My computer power supply will work to power my computer and other devices must fine, and I don't listen for RFI on a short wave radio. We're talking bout consumer electronics here, testing hobby things like LED lights, etc.My original post was just tossing up the internal of this thing to see if anyone wanted to look inside to see if it was just garbage, from an external point of view, capacitors, soldering, filter use, etc., like so many other people do on the internet.For example:Kiss Analog did a review on a Kaiweets (Chinese) bench power supply, and he started by scoping it, then looking at the electronics inside of it, then put it on a scope. Overshoot was almost perfect. He got some ripple on it (about 1.5V peak to peak) but then just added a 1mfd poly capacitor. See below:Video time stamp 28:35The post wasn't about linear vs switching.It was about how the electronics look inside of the machine, something like tearing down a DMM to inspect it visually.This isn't necessarily directed to you, but generally to anyone:My point in posting was to just have people get a look at it and see what they think (Like Eddie does in the above video, minus scoping it). It seems some people are more interested in simply shutting me down, instead of offering any constructive feedback. Like one poster said, what's with all of the attitude? Geeze.**radiolistener, I don't take your comments as attitude at all. It's interesting where you are coming from. It's just not really on topic, but I appreciate your explanations because I'm learning from them (I already knew SPS were noisy vs linear, but the conversation is still productive based on your explanations. I appreciate it).

author: Gyro
author_rank: Super Contributor
timestamp: October 26, 2021, 06:51:42 pm
content: Quote from: DW1961 on October 25, 2021, 05:02:38 pmQuote from: DW1961 on October 26, 2021, 05:58:35 pmAnyone feel that they're doing the work while somebody else is getting the free stuff?

author: Hamelec
author_rank: Regular Contributor
timestamp: October 26, 2021, 09:28:04 pm
content: Quote from: DW1961 on October 26, 2021, 05:58:35 pmfully agreed !

author: narkeleptk
author_rank: Contributor
timestamp: October 27, 2021, 12:33:51 am
content: Radio makes a great point. These cheap power supplies can be useful but I will never go back to them as a main unit on the bench after using a linear supply. I used to wrongly blame my picoscope and pc for being so noisy when testing stuff. Had no idea and never thought to think about it just being the cheap power supply I was powering up the devices with it causing all the noise. Not just that but both of the cheap units I have went bad and I had to repair with better quality components. 1 of which was barley used before it failed.

author: rsjsouza
author_rank: Super Contributor
timestamp: October 27, 2021, 12:56:56 am
content: The power supply looks a typical standard issue from China, thus it does not seem to have anything terribly special about it. If the power supply can sustain a load for long periods, it can still be very useful to power beefier loads such as automotive lamps, for example. Also, not every circuit requires ultra low noise and I can also count a large number of development kits (Arduino, launchpads, etc) that could benefit from such power supply powering auxiliary circuits, for example. Just be sure to measure any voltage differences in the ground between the power supply and a laptop where the board is connected (Dave has a good video about this) and you should be alright.I have one (not this exact model) that has been working quite well for a number of years.

author: dophuc
author_rank: Contributor
timestamp: October 27, 2021, 01:01:40 am
content: Quote from: radiolistener on October 26, 2021, 03:58:57 amYou have a cheap, very old and bad PSU so you think all switching PSUs are the same as yours? Totally wrong, try to buy a new good one, for example Corsair RMX series, maybe it will change your mind.

author: Trader
author_rank: Frequent Contributor
timestamp: October 27, 2021, 01:20:51 am
content: Quote from: radiolistener on October 26, 2021, 03:58:57 amTo measure the PSU noise, I need to setup the scope to:Coupling ACBandwith of 20MHzProbe in 1X (why not 10X?)And the PSU must have a load to Max Current (10A) and Max Voltage (30V)? (or 90% of max?)Any other setup? Thank you for your measures.

author: Someone
author_rank: Super Contributor
timestamp: October 27, 2021, 01:27:37 am
content: Quote from: Gyro on October 26, 2021, 06:51:42 pmNot hating on the big pictures like some posters (most of them justify the file szie being in tight focus and showing lots of detail) which add some nice archival material for the forum, but the general vibe is farming out generation of content and editing for their external use/promotion.P.S. the mains earthing arrangement looks "interesting" and soldered? to the PCB mounting tabs. That would fail most international safety standards.

author: tautech
author_rank: Super Contributor
timestamp: October 27, 2021, 01:34:00 am
content: Quote from: Trader on October 27, 2021, 01:20:51 amWhen ripple is well down in the mV's most scopes have insufficient sensitivity to display such ripple with a 10x probe.Further down into uV's of ripple it's even harder to measure even with a 1x probe............

author: Trader
author_rank: Frequent Contributor
timestamp: October 27, 2021, 01:39:12 am
content: Quote from: radiolistener on October 26, 2021, 03:58:57 amI was thinking about buying the KORAD PSU, but I gave up after reading these reviews:https://www.amazon.com/gp/customer-reviews/R1QZ2T4NK0SU60/https://www.amazon.com/gp/customer-reviews/R3PQK6U1SYZTL1/Since you have the same model (KA3005D), please, could you check if your KORAD also has this Issue/Bug? Is this a real problem or maybe just a factory defect of that PSUs in the reviews? Thanks

author: Electro Fan
author_rank: Super Contributor
timestamp: October 27, 2021, 03:12:56 am
content: These are somewhat old reviews and any model from any manufacturer can have a failure. I have two Korad power supplies including one from ~2013 that continues to run fine. I periodically check for overshoot with an oscilloscope - so far so good, and ripple is very low too, fwiw. If you have a normal unit which you likely will I think you will be impressed with the performance, ease of use, and reliability. If you buy it from SRA Soldering (which I think is possible direct from SRA or via Amazon) they will provide a good price and good support. The Korad power supplies might be the best bang for the buck on my bench which includes gear from Rigol, Tektronix, HP/Agilent/Keysight, Brymen, and Fluke - all of which I am happy with but the point is $ for $ the Korad KA3005 (D and P) hold their own.

author: J-R
author_rank: Super Contributor
timestamp: October 27, 2021, 03:16:23 am
content: Switching power supplies run our current electronics. They are everywhere. If you want a switching or linear supply on your bench, then buy what you want. Each have their place. I have one switching supply on my bench in order to get 15V 40A, but rarely ever use it, preferring my linear supplies otherwise. Bashing one or the other endlessly is silly.My Korad supply does not have that voltage spike issue, but it did have a very loud fan that I had to replace with a temperature controlled one for my sanity.But there is always perhaps some heightened risk with the budget brands and random sellers. You may get some old stock with issues for example.I have a couple of the Keysight power supplies and have been happy enough with their performance. This has been sitting on ebay for quite some time:https://www.ebay.com/itm/194385942444Cute little supply with USB and ethernet. Maybe it is what someone is looking for. Ignore the 100V option if you're in the US, there are simply two switches on the bottom you can change. An internal fuse change is only required when going between 100/120 and 230.Back to the original power supply being discussed, yes, it has me concerned somewhat.I have moved past such equipment in general. But a tinkerer on a budget might go for it.

author: Electro Fan
author_rank: Super Contributor
timestamp: October 27, 2021, 03:36:26 am
content: Korad spike and ripple measurements in this thread:https://www.eevblog.com/forum/testgear/korad-kd3005d-bench-supply-power-on-spike/msg3509200/#msg3509200

author: Monkeh
author_rank: Super Contributor
timestamp: October 27, 2021, 04:52:20 am
content: Quote from: Someone on October 27, 2021, 01:27:37 amHe's been doing this for a while.. receiving piles of free stuff from Amazon sellers and using the forum to help him create glowing 'reviews' of tools he doesn't really know how to use.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 27, 2021, 05:09:58 am
content: Quote from: narkeleptk on October 27, 2021, 12:33:51 amYeah no problem with that logic. I'm just using it to test stuff like LED lighting and things like that. Nothing that requires s super quite supply. I mean, I'm mainly testing DC stuff that is powered by a computer power supply, so, yeah, it's ok. haha.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 27, 2021, 05:18:24 am
content: Quote from: rsjsouza on October 27, 2021, 12:56:56 amYeah that, and I will only have it on to test devices and not be powering anything from it for any period of time at all. I like to build computers and so I want to test specific runs of fans or LEDs for amps before adding more power to a circuit. Since most everything is powered from an SATA connector, and they SATA connectors are only my good for 4.5A, lest they melt, a 5A supply will work fine for me.My latest build is below. You can't see the work that went into this by looking at it, but all of the 12V RGB runs were cut and soldered to size for their specific location. Then neodymium magnets were attached to the strings to hold them in place. The 140mm fans were dark gray, and the ARGB fan covers were also dark gray. Since the build is a white theme, I meticulously painted each fan and fan ARGB cover using a makeshift paint booth. Then re-sanded any imperfections, repainted, re-sanded. All of the screws were painted white in the same manner. The top grill cover over the radiator was an aluminum vent cut to size, sanded, and then also painted white in the same manner. The radiator and radiator fans were already white, so I didn't need to do those. However, I wanted 140mm Noctua fans, and they only come in dark gray and doctor office brown/tan. (I didn't paint the fan blades in order to maintain their balance.) The bottom pedestal is a repurposed acrylic monitor stand that I added a custom soldered and sized RGB lighting strip to the edge after sanding and diffusing the edges. I then found shorter legs for it, turned it upside down, and used it like it is in the pictures. In short, a lot of hours went into it.My latest iteration:

author: DW1961
author_rank: Frequent Contributor
timestamp: October 27, 2021, 05:23:56 am
content: Quote from: dophuc on October 27, 2021, 01:01:40 amThat PSU he has was a VERY high end unit when it came out. Also, any ripple might be noisy to him for his applications. I see what he is saying, but there are many other uses for a switching bench supply, for noncritical testing purposes, right?

author: DW1961
author_rank: Frequent Contributor
timestamp: October 27, 2021, 05:31:59 am
content: Quote from: J-R on October 27, 2021, 03:16:23 amJ-R, very interested what you see that is concerning you. Please elaborate? I can post more pictures if you need. Just let me now what you need to see.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 27, 2021, 05:47:41 am
content: Quote from: Monkeh on October 27, 2021, 04:52:20 amWhy the personal attack?

author: DW1961
author_rank: Frequent Contributor
timestamp: October 27, 2021, 05:50:33 am
content: Quote from: Someone on October 27, 2021, 01:27:37 amGood information and I'll check that out again. I did see that too when I opened it. I think someone else said that they didn't like the other one I posted because it had the mains screwed down on the board instead of soldered-lol. Interesting though, so soldering the mains to the board is a no go?

author: radiolistener
author_rank: Super Contributor
timestamp: October 27, 2021, 09:13:43 am
content: Quote from: Trader on October 27, 2021, 01:39:12 amI think this is not PSU issue, but RF interference from power-on switch due to high current sparks in the mains switch. This interference has high amplitude because your scope has high impedance.Here is KORAD KA3005D 12 V / 5 Amps transition on the output when you press ON button:

author: DW1961
author_rank: Frequent Contributor
timestamp: October 29, 2021, 05:06:32 am
content: Quote from: Someone on October 27, 2021, 01:27:37 amHere are more pictures. It looks like the ground once had a spade connector on it, then got cut off and soldered. I'm going to send the image to the vendor and see what they say.

author: Someone
author_rank: Super Contributor
timestamp: October 29, 2021, 11:16:42 am
content: Quote from: DW1961 on October 29, 2021, 05:06:32 amha ha ha, and in the bin it goes with the rubbish where it belongs.

author: Gyro
author_rank: Super Contributor
timestamp: October 29, 2021, 11:27:10 am
content: It's fairly common to use a soldered connection rather than a spade for the earth connection, less likely to become detached (or mis-connected). The chassis earth connection should directly to a dedicated mechanical connection though, to an unpainted area with a tag with shakeproof washers to ensure solid connection, rather than an indirect connection via the PCB.I've seen worse though - at least it's immediately adjacent to a mechanical PCB mounting bracket.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 29, 2021, 05:13:02 pm
content: Quote from: Gyro on October 29, 2021, 11:27:10 amIt's strange because the way they did it is much more labor intensive than simply soldering it to the bracket that is solde4red to the PCB. The bracket has 4 really nice solder points connecting it to the PCB. Then that "U" bracket is screwed to the chassis. There is another "U" and solder joints just like the one in the image that comes back up through the PCB connecting the front panel posts.I mean, that's a lot more work than screwing it to the chassis and then running a wire directly to the front panel post. I doubt the ground will ever come loose, since the "U" bracket has 4 really nice large joints connecting it to the PCB and the ground solder joint is very robust and nice looking too, but still, just seems like more expense and work than screwing it down.

author: niner_007
author_rank: Frequent Contributor
timestamp: October 31, 2021, 08:20:23 pm
content: Quote from: radiolistener on October 25, 2021, 07:38:46 amYou shouldn’t be throwing around 5 or 10A so causally, that is very significant amount of power for a linear supply. Korad is not a high quality manufacturer, I’d be concerned for my life or DUT, I’d never use one, but if budget is a concern, you inspect the product and are careful, it’s understandable, that might the only option for lots of folks.

author: nctnico
author_rank: Super Contributor
timestamp: October 31, 2021, 08:33:34 pm
content: Quote from: DW1961 on October 26, 2021, 05:58:35 pmNobody is shutting you down. It is just that the power supply you have there has been brought up several times already with various brands & model numbers. It isn't new. Whether a switching PSU is usefull or not depends on your use. If you are going to use it for developing circuitry (and it is very likely you need to make measurements) then a switching PSU is a horrible choice. The electric noise will show up on all your measurements. OTOH, if you need a beefy power supply to power a circuit just to have it powered on (like during burn-in testing) then a switching PSU is fine for use as an adjustable wall-wart / lump in chord PSU.I have a similar model PSU like you have but I no longer use it due to the noise of the fan. I bought a bunch of fanless Gophert and Rek power supplies (https://www.eevblog.com/forum/testgear/rek-kps6003-and-gophert-nps-1602-60v-3a-psu-hack-review/msg3336994/which can deliver 60V @3A. Other voltages / currents are also available but I deal with 48V DC equipment regulary so 60V is more convenient for me.

author: DW1961
author_rank: Frequent Contributor
timestamp: October 31, 2021, 10:26:28 pm
content: Quote from: nctnico on October 31, 2021, 08:33:34 pmThis one's fan only comes on during a heavy load. Why can't you just swap out the fan with a different less noisy fan, and or run it without the cover on it, or a modified mesh cover that lets it breath better?Absolutely would need a no noise source for developing circuitry. I do understand. People were making personal attacks instead of product comments, and that's what I mean by shutting me down.I'm only using it to power things for testing, to see if they come on, how much amps they use, things like LED srtrips, fan controllers, things that are already powered by switching power supplies.It would be nice to see it's actual noise and voltage performance on a scope, like Eddie above did on that Kaiweets model (Ripple test a cap application at video 28:06):He simply used a cheap 1uF poly capacitor to really reduce the noise. I wonder why the manufacturer didn't just install something like that in the first place?

author: nctnico
author_rank: Super Contributor
timestamp: November 01, 2021, 12:34:49 am
content: Quote from: DW1961 on October 31, 2021, 10:26:28 pmNo fan is better than a low noise fan. The fan going on & off is just irritating and a decent fan costs as much as a significant part of the price of the alternative, fanless PSUs I bought.QuoteThere is a bit more to it because a lot of noise is being pushed into the ground. I tried to improve the EMC/noise performance of the PSU I have (https://www.eevblog.com/forum/testgear/cheap-variable-switching-power-supply/msg676967/#msg676967) and it still isn't particulary good.

author: wizard69
author_rank: Super Contributor
timestamp: November 02, 2021, 02:55:00 am
content: What the forum owners want is one thing (with respect to file size). However high resolution images actually have value in this thread when the posters is looking for comments on the new power supply. 1080P is not high resolution, not even close really. Of course high resolution is only useful when there is quality in the photography. So what the forum wants to support resolution wise is one thing, having the full resolution pics available in general, someplace, is a good idea.Quote from: MarkF on October 25, 2021, 07:09:27 amWhich does little for people running 4k screens. 1080P is sort of like watching old TV videos from the 1960's. The video may be a funny comedy but actually watching the video can be a joke all on its own.

author: electr_peter
author_rank: Unknown
timestamp: November 23, 2021, 02:26:30 pm
content: Gophert released new series of PSUs. GophertPPS-3202/1610/6003 is very similar to NPS-3205/1610/6003 (same power, output jacks on the front) with some changes:vertical form factor- it will use less space on the bench, can be bolted down3rd LED display for power20 presets for V/A settingsCurrently costs slightly more than "horizontal" NPS/CPS series, maybe will be interesting due to form factor.

author: nctnico
author_rank: Super Contributor
timestamp: November 23, 2021, 05:50:20 pm
content: Quote from: electr_peter on November 23, 2021, 02:26:30 pmPersonally I strongly prefer the horizontal form factor because it is easier to stack. It is one of the reasons I bought a whole bunch of Gophert (-ish) NPS series PSUs.

author: electr_peter
author_rank: Unknown
timestamp: November 23, 2021, 06:15:03 pm
content: Vertical form factor maybe interesting to lab setups consisting of one small table without any stacking options where every square cm2 is valuable. Not space efficient otherwise.I use few horizontal Gophert PSUs, they stack fine or fit well in low height gaps. Still running fine, but supplied banana cables (too high resistance, not suitable for "high" currents of 3-5A), IEC7 mains cables (far too high resistance, questionable materials, get something decent instead) and banana sockets (just look at them) are a joke. Easily fixable to a better standard though.

author: DW1961
author_rank: Frequent Contributor
timestamp: November 23, 2021, 06:37:00 pm
content: Quote from: electr_peter on November 23, 2021, 06:15:03 pmIncidentally, this is exactly why I requested another switcher: The previous one I received was horizontal and took up more space on my small bench. It's really small, like L7.5" x W3.4" x H5".