Cheap Bench PSU - What to look for? - Page 1
Forum section: electronics / beginners

author: Distinctly Average
author_rank: Contributor
timestamp: January 08, 2021, 09:58:06 pm
content: This has probably been asked a million times but here goes. I’ve been searching Amazon for a cheap bench PSU. Just for getting back into the game really, mainly playing with STM32, Arduino stuff an the like. Don’t want to spend a mint as I am not sure how much it will get used. Any recommendations and any specific features that would be good to have? Years ago I just used a self modified CB PSU that would go from 3v-15v so I have never really had a proper bench PSU hence the lack of knowledge.

author: ataradov
author_rank: Super Contributor
timestamp: January 08, 2021, 10:10:56 pm
content: Define cheap. KORAD KA3005D is $110 on Amazon and it is an excellent power supply.I personally would avoid anything with analog knobs for control. They are fiddly and unreliable. They are also very easy to bump on accident.

author: Distinctly Average
author_rank: Contributor
timestamp: January 08, 2021, 10:17:32 pm
content: Good call on the knobs. Back when I had my modifies CB PSU I had a pot to adjust with a screwdriver so that is something I never though of.Looking at the pics, the Konrad is currently not available on Amazon but this unit on CPC looks the same going by the pics alone -https://cpc.farnell.com/tenma/72-10480/power-supply-1ch-30v-3a-adjustable/dp/IN06822?mckv=sNNe1WaAF_dt%7Cpcrid%7C426684131255%7Ckword%7C%7Cmatch%7C%7Cplid%7C%7Cslid%7C%7Cproduct%7CIN06822%7Cpgrid%7C100371161478%7Cptaid%7Cpla-311115855977%7C&CMP=KNC-GUK-CPC-SHOPPING&gclid=CjwKCAiAouD_BRBIEiwALhJH6H3TcqzDAgKRAergJSdOVOf339F1rEJE-kBe0O4R-h7oGf_-E2-RvRoCqcYQAvD_BwEAs for price, I would like to stick under £120 GBP.

author: ataradov
author_rank: Super Contributor
timestamp: January 08, 2021, 10:23:36 pm
content: That Tenma appears to be a rebrand of Korad, I bet it has the same guts. But the model you are linking is 30 V, 3 A.But keep in mind that it does not have screw terminals, just the banana plugs. Generally not a huge deal.But also, you need to figure out what characteristics you may need. 30V 3A is plenty for a lot applications, but may become limiting in some. Also number of channels matters. It all depends on what you are planning to do.

author: Distinctly Average
author_rank: Contributor
timestamp: January 08, 2021, 10:56:30 pm
content: Thanks. I was thinking about the 3A. Given I will probably be experimenting with LED strips I should probably go for 5A.Single channel should be fine for me. I also don’t have too much room and most of the dual channel ones begin to get more bulky.

author: Mr. Wizard
author_rank: Unknown
timestamp: January 08, 2021, 11:05:21 pm
content: Do consider something like the RD6012W (search AliExpress:https://www.aliexpress.com/wholesale?SearchText=RD6012W). That’s a 60V 12A power supply with very powerful features for around £115, all inclusive. Dave has done EEVblog videos with teardowns and reviews of a few similar power supplies, which have been generally favorable.

author: ataradov
author_rank: Super Contributor
timestamp: January 08, 2021, 11:07:37 pm
content: Yes, those modules are good too, but as typical for this type of product, their UI is infuriating and confusing. But they do perform well.

author: cdev
author_rank: Super Contributor
timestamp: January 08, 2021, 11:12:01 pm
content: Silence in a power supply is nice.

author: Distinctly Average
author_rank: Contributor
timestamp: January 08, 2021, 11:22:41 pm
content: Never used Ali Express. Given the Brexit mess Coupled with Covid I could see me waiting a couple of months to for delivery which would be annoying. I have the energy and momentum going so having to wait would get me in a tizz. It certainly looks interesting but seems to have a lot of features I will never use so probably I would get infuriated by the UI. I will watch Dave’s video.

author: Mr. Wizard
author_rank: Unknown
timestamp: January 09, 2021, 05:47:03 am
content: Here is the video where Dave’s introduces the Riden RD bench power supplies:EEVblog #1265 - $53 360W Lab Bench PSU!He also did a followup video to correct an error in probing:EEVblog #1266 - PSU Probing Screw Up!There are even cheaper ones, which may require a bit of additional work, which he introduces here:EEVblog #1030 - $20 DIY Bench Power Supply!He has a few other videos on similar supplies, but those will give you a good taste of what this type of supply can do and how easy (or not) they are to use. There’s a wide variety of similar models out there. The Riden models have a fairly straightforward interface compared to the cheaper ones.

author: ledtester
author_rank: Super Contributor
timestamp: January 09, 2021, 07:25:08 am
content: For the RD6012 there is an alternate firmware which a lot of people like -- see this thread:https://www.eevblog.com/forum/testgear/ruideng-riden-rd6006-dc-power-supply/msg3398072/#msg3398072

author: connectTek
author_rank: Regular Contributor
timestamp: January 09, 2021, 08:46:33 am
content: I use 2 X korads 6005D PS.Have been great, although I blew a diode internally by accidentally reverse connection of a 18650 battery.Easily fixed.Still going great and in series I can get upto 120v at 5amps.CC and CV as well as OVP Work great.Highly recommended.

author: Electro Fan
author_rank: Super Contributor
timestamp: January 09, 2021, 11:06:53 am
content: Seems like this might be what the OP is looking for:https://cpc.farnell.com/tenma/72-2540/power-supply-1ch-30v-5a-prog/dp/IN07294?st=tenma%2030v%205%20afwiw, big +1 for Korad KA3005D, and seems like Tenma is pretty similar....Edit: this Tenna model looks more like a version of the KA3005P; the Tenma has both USB and RS232 via DB9 for external monitor and control. Seems to meet the OP’s specs.imo the Korad KA3005D/P (and probably the comparable Tenmas sans the screw terminals) should be the default starting reference point for anyone looking to buy a linear power supply in the vicinity of $100/Euros/Pounds.

author: Distinctly Average
author_rank: Contributor
timestamp: January 09, 2021, 02:50:12 pm
content: Thanks all for the very useful tips and advice. Having watched the video and listened to all your advice I have gone for the 5A Tenma/Korad from CPC as it can be delivered to my door by Monday. I really did consider the Ali Express option but the long lead time put me off.I now look forward to some experimentation and fun with a few projects already in progress.

author: Mr. Wizard
author_rank: Unknown
timestamp: January 09, 2021, 04:21:09 pm
content: It will work well. Enjoy!If you later decide you want some more features, you can then use the Tenma/Korad supply to feed a Riden supply. You can basically save 2/3 the price of the Riden because now that you have a DC supply, you only need to buy the front panel of the Riden and (if you choose) a small enclosure to hold it.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: January 10, 2021, 02:51:27 pm
content: UTP3315TFL-II DC Power Supply, very good.

author: innkeeper
author_rank: Unknown
timestamp: January 12, 2021, 10:24:59 pm
content: Quote from: Distinctly Average on January 08, 2021, 09:58:06 pmI was recently faced with this exact same question and I just bought 2 MATRIX MPS-3206 - should be heretomarrowThursday. - ye ai know who the heck is MATRIX.....well more on that down below but they seem to be the actual manufacturer, not some rebadger. - i know you are in the UK, it does 110/220 a50hz /60hz.So my situation is that I needed either a second dual tracking supply or 2 separate supplies that I could do split rail work (which means floating outputs) and didn't want to plunk down a lot of cash to do it as it's not my primary supply(s). but, not giving up on features or quality.this was my criteria that i used to compare what supplies I was considering in no particular order:needs to be cheap, like around 50usd each delivered or 100 for a dual tracking supply. (this is not my primary supply so not spending a lot on it)The manufacturer/seller needs to be responsive on issues, no companies that rebadge and don't directly support their products I don't wanna get stuck with some flaw.The displays should be at least 4 digit resolution (1ma/1mv below 9.999 or 10ma/10mv at 10.00 and above)needs to have a button to turn the outputs on and off separate from the main power switchneeds to use rotary encoder for the power adjustments and have coarse and fine adjustments(no analog pot adjustments)needs to have CV CC (current limiting)needs to be able to set and see the CC while the load is active. which means no supplies that make you short the output to set the max current.needs to be floating outputs and have separate dedicated earth ground so I can chain them together to make spit rail supplies and set earth ground wherever I want.needs to have a low ripple voltage and current.needs to have good load regulation.needs to have binding posts. (no not just banana jacks, I want to be able to stick a wire in the binding posts)needs to hit at least 15v and 2a (greater is nice, but not at the expense of any other criteria)nice to have but not critical is memory. (not that important many loose memory when powered down but save the current settings, it should save the last settings used.)no modules, or hacked together solutions, it needs to be plug and play (i do not need another project right now)I just ordered 2 matrix MPS-3206why:so they ran me $56.99 usd with free shipping (prime) through amazon. they sell directly through Amazon.in short, it meets all my criteria, so I didn't have to compromise anyplace.the closest dual supply was 149.00 usd and it only had 3 digit resolution so i went with 2 single supplies..ok well, matrix is not a household name, but, 6-7 months ago they had an issue with a bad batch of power switches on this supply and, they stepped up and replaced the bad units or shipped out replacement switches for those that didn't mind changing them themselves. on amazon there active with the buyers.The specs for noise is 10mv rms - i will be checking this, that's very low.load regulation .1mv / .2ma0-32v0-6.1Aadmittedly I went over 50 usd by a little bit but frankly, there was nothing even close to it spec-wise on amazon for the price that I could find and is getting great reviews on amazon.I was able to not compromise on features, according to reviews it delivers on quality. there are even some teardown videos out there. seems well built.in comparison, I have a GW Instek GPD-3303s which is a dual tracking ps 0-32v 0-3.2a and it retails for 399.00 on amazon. and the features I find important are comparable.So there is my 2 cents. i would make a list of what's important for you and then judge what you are going to buy against that.

author: Electro Fan
author_rank: Super Contributor
timestamp: January 13, 2021, 04:27:21 am
content: Looks like Matrix also makes a linear power supply.https://www.amazon.com/dp/B08FC3WGHT/ref=emc_b_5_mob_t

author: radiolistener
author_rank: Super Contributor
timestamp: January 13, 2021, 06:00:00 am
content: KORAD KA3005D cheap and covers most of amateur needs. It has a little noise from LED drivers, so if you planning to work with very sensitive analog circuits, it will be worth to buy also second fully analog linear regulated PSU with low noise. But for most of the cases KORAD KA3005D is good enough.

author: innkeeper
author_rank: Unknown
timestamp: January 13, 2021, 06:02:53 am
content: Quote from: Electro Fan on January 13, 2021, 04:27:21 am75 bucks though... guess if you needed to avoid any switching noise it is a good option, those noise specs look good .. .. personly I was going as cheap as I could get away with lol.think this might be the better deal if you're going linear for 49 yankee buckshttps://www.amazon.com/Kungber-Adjustable-Switching-Regulated-Adjustments/dp/B08DJ1S7J5/ref=sr_1_2?dchild=1&keywords=variable%2Blinear%2Bsupply&qid=1610517548&s=electronics&sr=1-2&th=1i read someplace where those guys burn them in for 72 hours before they package them.

author: innkeeper
author_rank: Unknown
timestamp: January 13, 2021, 06:10:09 am
content: Quote from: radiolistener on January 13, 2021, 06:00:00 amKORAD is pretty popular.its 109.99 USD on amazon though ... at double the price of what I ordered MATRIX MPS-3206 at 56.99 usd with the only additional feature the KORAD has is a lock function, so not as cheap.i'll have to see what kind of bargain my bargain is once i get it, ... i'll check the noise and regulation. and open it up and see how its put together. ... will post

author: Berni
author_rank: Super Contributor
timestamp: January 13, 2021, 06:10:26 am
content: These are pretty decent in terms of cheep PSU:https://si.farnell.com/tenma/72-2690/bench-power-supply-1-ch-30v-5a/dp/2563982They have a simple, no nonsense UI. Except those are digital encoders with push rather than regular potentiometers, so setting the voltage and current is quick and easy, it previews the set current while setting so no need to short the output. It remembers the last settings and powers up instantly so you can just turn it on/off on the big main power switch. Only down side is that the temperature regulated fan can be a bit noisy at low speeds because of the PWM whine.

author: innkeeper
author_rank: Unknown
timestamp: January 13, 2021, 06:16:07 am
content: interesting Berni, it uses PWM.. how is the electrical noise on that, it says it's linear but id didn't think that they might be using pwm. actually makes sense there using PWM i bet the other analog ones do the same.hmm then is there any real advantage if your going linear and is using PWM... night as well go switching. six of one half a dozen of the other id think from a noise standpoint.

author: Berni
author_rank: Super Contributor
timestamp: January 13, 2021, 06:28:39 am
content: Quote from: innkeeper on January 13, 2021, 06:02:53 amI would stay away from these no name brand switching lab PSUs.We got a similar one at work because we just needed a cheep small PSU with a bit more grunt for some non demanding stuff. We ended up with it here as a spare PSU afterwards, but then found out what a pile of crap it really is.It was annoying to use due to the slow updating display and slow response to the knobs. The output was noisy as heck. It emitted so much RF noise that when i was tracing down a EMI problem on a board using a spectrum analyzer, my coworker switched the PSU on in the other side of the room and my spectrum analyzer started beeping about its input being overloaded. It ended up just sitting around until finally someone came in to ask if he can borrow a lab psu, so i gave that to him and told him that he can keep it, no need to bring it back.Not all switching supplies are crap. The reputable manufacturers like TDK Lambda, Keysight, Keithley, BK Precision etc... can make a switching supply that performs well and is pretty low noise too, but those are VERY expensive.My advice is stick with a simple linear lab PSU for any generic work. You don't need more than 3A and that is easy to do linear. If you ever have a need for more power like 200W 500W 1000W or even 3000W then buy a old rack mount PSU from ebay, they can be had fairly cheep if you look around while being built like a brick wall as they are designed to be pushed hard 24/7Quote from: innkeeper on January 13, 2021, 06:16:07 amI had a quick poke at it once with a scope and there was nothing alarming about it. I was not looking at microvolts or anything, i didn't have high expectations for this cheep PSU, i just wanted to check that its as low noise as one would expect for a linear PSU and that it doesn't have any ugly turn on/off transients. It all was fine.As for the whiny PWM fan, I actually created a bodge PCB that takes the PWM signal and turns it into a analog voltage. This makes the fan completely silent on low speeds. This is mostly because we ended up buying like 5 of these PSUs at work and people got annoyed by the whiny fans (some work in completely quiet offices). So i just quickly put together the simple opamp+transistor board and bodge wired it into the PSU.

author: innkeeper
author_rank: Unknown
timestamp: January 13, 2021, 06:34:19 am
content: holy crap brerni, well crossing my fingers on that. .. my main supply, the GW Instek one, is quiet and is parked right next to my spectrum analyzer, in the same power strip.. so no issues with that, but it's not a cheap supply. So ... ok so when I get the matrix, I'll check for that ... that would suck!yea that would have me return that real quick.and ah I took pwm meaning for the control of the output power and voltage, not the fan, so my mistake. .. i was kinda scratching m head because then a liner supply with PWM control is then a switching supply lol. ok all is right with the worldyea I can see where linear is the safer choice noise-wise when your bargain hunting for a supply.

author: radiolistener
author_rank: Super Contributor
timestamp: January 13, 2021, 10:35:16 am
content: Quote from: innkeeper on January 13, 2021, 06:10:09 amI bought my KORDA KA3005D for about 80 USD from local web-store. There is not only lock feature.The main and significant difference is digital setup. It means there is no risk that you will get high voltage pulse due to bad mechanical contact on potentiometer. KORAD doesn't have potentiometer, it uses DAC to setup reference for current and voltage. At the same time it use fast analog regulation.The next significant advantage of KORAD, you can calibrate it and it works pretty well, can be used even as precise voltage source. No analog potentiometers. You're just set required voltage with encoder, press ON and get very precise voltage level. The same for current. You can setup current limit with 1 mA resolution.The next significant advantage of KORAD is that all possible modes are included: OVP, OCP, CV, CC.The next significant advantage is that KORAD display works for setup voltage/current regulation when output is disabled and when you enable output it turns into measurement mode, so you will see actual voltage/current. This is very useful for measurement, because there is no need to connect multimeter in order to measure current consumption and actual voltageAlso, memory for 4 settings and LOCK mode.

author: Electro Fan
author_rank: Super Contributor
timestamp: January 13, 2021, 07:13:59 pm
content: Quote from: radiolistener on January 13, 2021, 10:35:16 am+1... and it’s a linear power supply vs the MPS-3206 switching power supply

author: innkeeper
author_rank: Unknown
timestamp: January 13, 2021, 07:15:22 pm
content: I stand behind what I said in that it has the same operational features as the MATRIX MPS-3206.all-digital uses encoders and not potentiometers.same resolution 1mv / 1ma for precise settings.it has OVP and OCP and is CC ancd CV supply.and yes the current and voltage display and setting work like your korad, displays current voltage and current, and also allows you to set voltage and current on the display too.it has 5 memories. (korad also has 5 but only 4 buttons .. weird quirk)So yes, the only operational difference is it has no lock feature, oh and it has one more memory setting button.the only REAL difference is that the Korad is not switching based, It is a linear supply "heavy iron" as opposed to the Matrix using a switching supply,Is that worth double the price .. well maybe. If the switching is leaking switching noise either out the outputs or down the ac line then definitely yes it's worth the extra money for me.if they were the same price, would I have gotten Korad? definitely yes. I am a linear power supply fan.For the original poster, who is working on mainly playing with STM32, Arduino stuff, he won't notice the difference and might be the perfect cheap solution. I tend to work on a wide range of things including RF and Audio along with digital stuff so for me, it makes a difference. As I posted, it's not a primary supplies, so I can live with some known sins if there not too bad.Remember the goal here is CHEAP but still good/usable. Best bang for the buck.I'm starting to sound like a matrix MPS-3206 fanboy, but truly I am not, I haven't got this thing in my hands yet. Just keeping the specs straight.I have to see what the deal is with switching noise. That could be a deal-breaker for me. but.. seriously .. bang for the buck wise, if you don't care about it being a switching supply then it's an awesome deal.Not sure if you have seen any teardowns of it, but it appears like is well built, but that doesn't mean electrically quiet. ... I'll see when I get it.

author: Electro Fan
author_rank: Super Contributor
timestamp: January 13, 2021, 07:48:00 pm
content: Back on the Korad, one feature that doesn't get much attention but that was mentioned by radiolistener is the ability to calibrate the power supply. This can be done externally with the user interface (no need to open the enclosure). This might not be a widely known feature, and it might not be needed by most users, but it can be pretty useful for dialing in a unit.But it's good to have choices. Maybe the MPS-3206 will provide low enough noise and good enough accuracy at it's price point. It's good to have competition in the market. Let us know what you find when you get a chance to test it out.

author: innkeeper
author_rank: Unknown
timestamp: January 14, 2021, 10:55:35 pm
content: Got my 2 Matrix MPS-3206 suppliesquick measurementsCode:P-P P-PP-P switch noise switch noiseV I ripple (20Mhz limit) (no B/W Limit)5v 0.163A 3.1mv 26mv 73mv5v 1.91A 5.4mv 35mv 86mv15V 1.97A 6.7mv 42mv 106mv15v 5.70a 14.0mv 66mv 167mvall masurements are peak to peakI did some power-on tests to see if there was any overshoot and detected none across the voltage range.I checked the voltage and current against my 6 digit meter and it is accurate across the range.I did have my spectrum analyzer on in the same circuit as the power supply during the tests and there was no interference through the lines that affected the spectrum analyzer.issue:the power cords did not fit the socket. I was able to use another one, but, it looks like there is a burr on both power jacks that prevents the included chords from plugging in. I've contacted them about this.. i could just file the bur, but, really wanna see how they deal with the issue.The included red and white leads are the split solid post plug type, not a spring type banana plug. so don't expect much from those, I will use others I have.other than that, everything functions as you expect with no operational glitches that I see.

author: M0HZH
author_rank: Regular Contributor
timestamp: January 14, 2021, 11:24:53 pm
content: +1 for Korad / Tenma.I use the Tenma 72-10500 which is the dual 30V/3A version. Outputs can be switched to series / parallel mode too, so you can turn it into a single 60V/3A or single 30V/6A PSU.

author: Berni
author_rank: Super Contributor
timestamp: January 15, 2021, 06:42:41 am
content: Oh and i did blow up one of those Korad supplies before.It was actually Tenma branded (Since Farnell sells all of the cheep chinese gear under that store brand name) and it was being used as part of a automated test jig for cycling batteries and collecting data about it. The USB interface on the back of it is buggy, works most of the time but then starts missing/repeating/replacing commands every so often. Turned out the RS232 port with an external USB to RS232 dongle worked way better (So keep that in mind if you want to remote control your Korad, don't use USB)So i set it up the test jig with a large 12V lead acid battery and let it run, worked fine for a while, so i went home after work. Then at about midnight before going to bed i remote connect into the PC running the show to check if everything is running as it should. But there i see the battery voltage is at 16V (This is way overcharged for lead acid) and the power supply was reporting a large current. Oh shit shit shit, something is not right. I'm essentially just putting amps into eletrolyzing water and filling the room with hydrogen. I take over manual control and crank up the electronic load as high as it goes to bring the battery voltage back down while i try to turn off the power supply. Well according to the voltage measured by the electronic load there was still power being output. At this point i was considering calling up a coworker that lives closer to go unplug it. Eventually i found out i can get the power supply to reduce its output by setting its output voltage to 1V rather than telling it to disable the output. So the situation was under control and i could wait til the next day of work to come unplug it and see what went wrong.Looking trough the log files i found out that the PSU was charging the battery in constant current mode for about 30 minutes at 3 or 4A (forgot exactly) but then at some point the current reading started jumping about oddly for a few seconds before shooting up past 5A (And its only a 5A rated PSU) and stayed there. Looks like the log file has recorded the death of the PSUs pass transistors, making it output maximum beans. The reason why setting it to 1V made it better is this switches a transformer tap relay to the smallest tap.Bringing the PSU back to my bench i tested it, and sure enough its outputting max voltage all the time, shorting the outputs would make it push 7 to 8A out of it no matter what the current limit is set to. So yeah indeed failed pass transistors. Made some photos to document it and sent it back under warranty and replaced the PSU in the test jig with a more reputable BK Precision PSU with USB control.This is just a sample size of 1 however. Perhaps i happened to get a dud unit. Then again Dave managed to blow up a Korad in his video too. The thermal solution in these things is kinda wimpy and that heatsink does get rather toasty. So yeah i do not recommend running your Korad flat out for long periods of time, its possible that they overheat and blow up when drawing max current at a particularly unfavorable transformer tap vs output combinations. Its easy to fix if it does happen tho.

author: Electro Fan
author_rank: Super Contributor
timestamp: January 15, 2021, 09:58:37 am
content: As an admitted Korad fanboy I would say this about that.There seems to be a bit of a consenus around here that, for example, an Aneng 8008 is a good meter for the price if you are doing DC and low voltage work but for AC and especially high voltage work Flukes and Brymens are better choices.I think Korad power supplies, like the the Aneng 8008, offer excellent value for the price when used for the appropriate purposes.The Korads are very suitable for powering electronics in the vicinity of 5V and probably to a lesser extent all the way to 30V but the suitability diminishes as you push the power supply higher through the transformer taps and higher in current. To be clear I have no test data to confirm this. My impressions are based largely on listening to the audible sounds the Korad KA3005P makes (and I’ve been listening for several years). My impressions are that you could probably run at 5V and 3A for a long time (days? maybe weeks? maybe longer?) and the power supply will be fine. As you push toward 30V and 5A I’m of the opinion that the reliable life of the power supply might be shortened vs relatively lower voltage and current settings and relatively shorter operating durations.My experience with the remote control is limited but I think it can be described as functional rather than elegant - and as the voltage and current demands go further toward 30V and 5A I would rely on it less. I’m pretty sure connecting the 3005 to a car battery for unattended operation is not one of the best use cases for a 3005.IMO, what is a great use case istestinglow voltage, maybe ~12V DC and typically 5V or less at 3A or less for minutes or hours or maybe days at a time. The power supply is reasonably to very stable and durable in these ranges. In my experience it is also pretty accurate - maybe within 1-2 hundredths of a volt and a milliamp or two throughout the full range of 0-30V and 0-5A.The key point here is that the Korads are very good for enthusiast testing which typically involves powering various DUTs so as to get fairly accurate measurement readings over long enough durations to learn what causes what.Based on my experience I believe the Korad KA3005P and KA3005D are very good choices for measuring, learning, and basic to intermediate testing within the low to middle ranges of the 30/5 power specs for moderate durations (minutes, hours, and maybe days rather than weeks and months). This is in contrast to using the power supply as a24x7xforever powering / charging / load characterization product, especially toward the higher end of it’s specs.I’m not saying a Korad KA3005P/D couldn’t run at 30V and 5A 24x7 but I’ve never tried and that probably isn’t it’s best use case.An analogy is that the Korad is like an affordable, nicely performing, and very enjoyable sports car. Used thoughtfully it could occasionally substitute for a station wagon but it’s not a truck. At approximately $100 for the Korad KA3005D it would be hard to find a better linear power supply for testing.

author: Berni
author_rank: Super Contributor
timestamp: January 15, 2021, 02:17:23 pm
content: That is the reason why i used it around about the 3A ballpark, i avoided using the PSU at the max 5A spec, i didn't really trust it to handle max load for longer periods of time.Not saying that it is a bad PSU. I think it is a great value for money when it comes to an entry level PSU, indeed difficult to get anything better at this price point. But just so that you have its limitations in mind. I have a Aneng 8008 too, great little meter that is amazing value for money, but i also have other DMMs from Keysight,Agilent,HP,Keithley... some bench some portable. I like to keep a mix of both cheep gear and fancy gear, using it as appropriate.The reason this Korad ended up on battery charging duty is that i got the task to throw together this test rig. But all the nice remote controllable PSUs ware used for something so i couldn't take them for a few days, so i just went and bought a cheap remote controllable PSU on Farnell with next day shipping. It was only needed for a few days to run these tests for development use, and it can be used as a simple small general purpose lab PSU afterwards. It worked great in the test rig (once i learned that the RS232 port is more reliable) going trough quite a few charge cycles on the small batteries, but then once the big lead acid battery was hooked up to measure its characteristics then the charge times went up a lot and so the PSU was sitting at the set current limit for a lot longer. The PSU has proven to be reliable for days on end, so i was not too worried about hooking up the big boatanchor of a lead acid battery they asked me to run on it. It still had the appropriate fuse fitted, the PSU had a external diode protecting from any possible back flow. Same fuse also protecting the electronic load in case that failed short, Vsense line on it had a separate smaller fuse etc. The internal construction of the Korad didn't look horrible or anything. i was not pushing it to the limit or anything, i had external protective measures in place, so i assumed its good enough to get the job done. Most test rigs i cobble together in a day to test something out are not perfect anyway, so i didn't think much of using a chinese PSU.The chinese products can be impressively good when you find those hidden gems among the other cheap crap. And this Korad PSU is certainly one of those hidden gems, just be aware of its limitations.

author: wizard69
author_rank: Super Contributor
timestamp: January 15, 2021, 10:50:49 pm
content: Quote from: Distinctly Average on January 08, 2021, 09:58:06 pmYes but there are a million possible answers.[quoteI’ve been searching Amazon for a cheap bench PSU. Just for getting back into the game really, mainly playing with STM32, Arduino stuff an the like. Don’t want to spend a mint as I am not sure how much it will get used.This immediately sent up red flags. Let me put it this way DO NOT BUY A BENCH POWER SUPPLY then. It can be a terrible waste of money for somebody starting out or just getting started in electronics. Yes they are very nice to have but you would know in less than a year if you can justify one and actually make use of the investment.Contrast this with buying a quality DVM. OK so you loose interest in microprocessor projects for a time, even if that happens a multimeter is a good tool to have in ones tool box. I learned this the hard way after finishing tech school and changing jobs thinking that the company would supply the tools I need. What I missed is that it is very handy to have such an instrument at home for projects and repairs. I can't really say that a bench power supply fills that role. So I ended up buying a new one soon after selling the old one.So you may ask how do you power your projects. For miroporcessors you can start out with simple 3 terminal regulators at the right voltage and a few discreet parts. YOu need nothing fancy to power up a microprocessor (at least a modern one). Beyond that there is a lot that can be learned from a power supply build.QuoteWell here is the thing, you will likely end up need more than one if your interest in electronics blossoms. So keeping that thought in mind here i what I would suggest for a first supply, with the thought that you buy it once you are fairly sure it will be used:The supply should support three channels of output.There should be one channel that supports the minimal range of 1 to 6 volts DC for the microprocessor supply. This should be at least 1 amp and it be nice if it went to 3 amps. I wouldn't mind if the voltage here was semi fixed. In the old days you could buy bench supplies with a fixed 5VDC output along side the two variable supplies, that doesn't work with today's various microprocessors and their operating voltages. Thus you want this supply to be variable across the common range of microprocessor operating voltages.There should be two variable, "high voltage" supplies that do 0 to 30 volts DC or so. One amp should be plenty.The two high voltage supplies should have digital displays with both voltage and current possible.The low voltage supply ideally would have its own displays also. However this isn't as big of a deal as you generally would want to set the voltage of this supply and have it be very difficult to adjust.There is an interesting comment about pots and accidental adjustments, that is a real issue but I like pots or encoders to twist. All I can say here is that if the low voltage supply for the microprocessor is hard to adjust you prevent a lot of problems. Meanwhile encoders (preferred) or pots allow you to ramp up a voltage output in a very human way so are preferred in my mind for the high voltage supplies. I seem to remember some manufacture addressing accidental adjustment with a lock out feature. In any event yeah I like knobs!Obviously you need current limiting on all channels.Ideally the supply is protected against reverse voltagesA battery charge mode might not be a bad thing if you are into lithium batteries.Support for communications with a PC. Maybe not important if you are not into programming and data collection but with modern hardware it is hardly expensive to implement.Displays that are easy on the eyes! This is one of those things where modern displays are trumpeted as ideal but they are not so ideal if you can't read them. Old LED displays can be a better choice for readability especially if your supply is not front and center. Since some LCD's are better than others it would be nice if you could take a look before purchase. However that likely isn't possible. You should ask yourself if the display is on the top shelf of the bench or off in some odd location, will you be able to read it sitting at the bench.In any event just some thoughts that come to mind if I was in the market for a bench supply. I'm not even sure if you could find a supply today that has all the features I highlighted above. Knobs seem to be out of style on many supplies these days for example. I really believe a semifixed microprocessor supply (low voltage supply) makes a lot of sense simply to avoid the accidental adjustment of death but most supplies these days make that supply very adjustable.

author: cdev
author_rank: Super Contributor
timestamp: January 16, 2021, 12:15:39 am
content: used equipment is so cheap there is no reason not to get a small power supply with the most important thing being adjustable current and voltage. If you do do experimenting, this will pay for itself by preventing mistakes from destroying your valuable parts.Also, from experience, a totally silent power supply is very preferable to one that makes noise as far as usability even if the voltage/current it delivers is much lower.You can quite possibly also convert a PC power supply to adjustable voltage and current with one of those buck/boost modules.

author: Trader
author_rank: Frequent Contributor
timestamp: September 07, 2021, 01:22:44 am
content: There are some bad reviews on Amazon about the KORAD PSU."Set to 3.5V and was powering a rather expensive board. When turned the supply off, it blew up his board. Hooked up the oscilloscope to measure the voltage when the supply is turned off, appeared spikes that were more than twice the voltage setting.""Scope trace captures an unsafe voltage transient that occurred on the output terminals after the output was disabled, when the power supply power switch was turned off. These transients are 70V peak-to-peak. Tested 4 units in our lab that all do the same thing, (though with inconsistent magnitude) so we are looking for a different model supply that doesn't jeopardize our units that we are testing. When the output is disabled, no voltage applied on the output terminals is acceptable, let alone +/- 35 Volts!"

author: AaronLee
author_rank: Regular Contributor
timestamp: September 07, 2021, 03:13:58 am
content: Quote from: Trader on September 07, 2021, 01:22:44 amI got in the habit long ago of putting a separate switch inline on the leads from my power supplies, and turn on the PSU with the inline switch off, then turn power to the board on/off with the inline switch. When done, turn off the inline switch, then the PSU. Even some of the name brand PSUs seem to have issues with overshoot, and the inline switch gives me more peace of mind. Not sure if it's ever saved me or not though.

author: mawyatt
author_rank: Super Contributor
timestamp: September 07, 2021, 02:17:14 pm
content: Quote from: AaronLee on September 07, 2021, 03:13:58 amWe are working with some very expensive sensitive chips and concerned about PS issues, we ordered the Siglent SPD3303X-E to evaluate. We now have 3, and maybe will be ordering another. One concern was overshoot at PS turn on or turn off and these Siglent PS don't exhibit any bad behavior and well suited for lab use IMO. Long ago had an experience with a name brand PS having overshoot at turn on, this destroyed a couple very expensive custom chips before the overshoot was discoveredBest,

author: MultiMike
author_rank: Contributor
timestamp: September 07, 2021, 11:59:09 pm
content: Quote from: AaronLee on September 07, 2021, 03:13:58 amI recently bought a TopShak LW-3010EC from.. probably Banggood. It was pretty cheap, but it had the important requirement: an 'output' button, so that you don't have to short to leads to set the volts and amps. I realize it's not a perfect test, but if it's jumping the voltage at turn-on or turn-off then my meter can't see it.Mike

author: Berni
author_rank: Super Contributor
timestamp: September 08, 2021, 05:17:58 am
content: Quote from: AaronLee on September 07, 2021, 03:13:58 amNo competent lab PSU should have trouble with overshoots on turn on or turn off. Relegate such a PSU to being used as a battery charger or something.But even if the inline switch saves you from the turn on overshoot it won't save you from a unstable regulation loop. Circuits often have a good deal of capacitance on its power rails, suddenly applying that to a PSU output will cause a very large output current transient. If it's an unstable loop causing overshoots then this current spike might also cause the PSU to overshoot the output voltage. (Especially since the PSU can't sink current and has output capacitance that can take a while to go back down)It's not hard to test for overshoot with a scope, so its worth doing. Mindful of also doing this with a large load resistor or large capacitor across the output.The Chinese can make a pretty decent linear PSU if you look around. Tho one should be careful running them near rated max for long periods as they often lack the required cooling for it. The thing to absolutely stay away from are switchmode bench supplies. They look enticing with the large outputs of say 10A and more while being tiny. But every single one of them i have seen barfs out noise like its designed to be a radio jammer. They are fine for running high power loads like heaters and motors, but they are NOT suitable for powering electronics on your bench.EDIT: Not to say switchmode bench supplies are crap in general. The well made ones from the big well known test equipment manufacturers are actually impressively low noise. Tho they are very expensive, so your best bet on those is to pick up a old rack mount one on ebay.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: September 08, 2021, 12:36:52 pm
content: Trader, I have a Uni-t 0-30v 0-5a Utp3315tfl-ii Dimmable Laboratory Source, which in general terms works well, I reduced the fan noise by lowering the voltage to 12V with a DC-DC source, that way the I regulate, due to the problem of peaks when turning the equipment on and off, I make sure that nothing is connected.in spanishTrader, yo tengo una Fuente Laboratorio Regulable Uni-t 0-30v 0-5a Utp3315tfl-ii, que en terminos generales funciona bien, el ruido del ventilador lo reduje bajando el voltaje a 12V con una fuente DC-DC, de esa manera la regulo, por el problema de los picos al encender y apagar el equipo me aseguro que no haya nada conectado.

author: mawyatt
author_rank: Super Contributor
timestamp: September 08, 2021, 01:30:17 pm
content: Quote from: Berni on September 08, 2021, 05:17:58 amWe stay away from switchers of any kind for general purpose lab use, have never found one that wasn't noisy. We do have a few switch-mode supplies for things like power LED or motors use, and a couple HV switch-mode supplies to provide specific HV needs.The overshoot is caused by an underdamped response, not an unstable response. A good PS should be overdamped in all usages, with all expected loads, real or reactive. Using a scope to verify your PS at turn-on and off is a wise move, since a DMM likely won't show this.We've found the Chinese Siglent SPD3303X-E a decent lab supply, and after evaluation entrusted it with our development project where a single hiccup could destroy well more than the supply cost!!If one is involved with electronics development work, the PS is the most important piece of test equipment on your bench. How are you going to verify the circuits performance without a good, clean and stable supply input as a baselineBTW I think it's funny how we often cheap out on the power supply, or test leads, or scope probes, and I am as guilty as anyone. Something about the "lure" of a bargain set of test leads, or a wide-band scope probe, or a nice new looking power supply, that one just can't resist. This must be some sort of "Engineering Addiction" and the "Rehab Centers" are the established quality suppliersBest,

author: AaronLee
author_rank: Regular Contributor
timestamp: September 09, 2021, 12:06:51 am
content: Just a few months ago, Dave did a teardown of the new R&S power supply which had an overshoot problem:https://www.eevblog.com/forum/blog/eevblog-1402-rohde-schwarz-nga100-psu-teardown-giveaway/That's definitely in no way a cheap power supply, and R&S is a well trusted brand name. I actually was considering buying that power supply, but to spend that kind of money and still have overshoot, I decided to save my money and went with a Siglent PSU instead and spend the remainder on other gear I needed.

author: ua4yhz
author_rank: Regular Contributor
timestamp: August 23, 2025, 10:38:19 am
content: I wrote a program to remotely control these power supplies.

author: armandine2
author_rank: Frequent Contributor
timestamp: August 23, 2025, 07:40:14 pm
content: ...I too am dismayed by the slow pace of hobby electronics