Cheap bench power supply? - Page 1
Forum section: electronics / testgear

author: slybunda
author_rank: Regular Contributor
timestamp: January 28, 2024, 01:37:29 pm
content: Looking fora cheapo bench power supply, one of those 0-30v things. Seen a few on AliExpress but not sure which one to go with. I dont want to cheapo out to the point i end up with something dangerous so just need it to be safe and reliable.Any suggestions?

author: Aldo22
author_rank: Super Contributor
timestamp: January 28, 2024, 01:54:49 pm
content: I recently bought the cheapest one and wrote about ithere.

author: nctnico
author_rank: Super Contributor
timestamp: January 28, 2024, 02:12:06 pm
content: Quote from: Aldo22 on January 28, 2024, 01:54:49 pmFor your primary bench power supply, you'll want a linear one. Not a switcher like yours. Way too much noise on the output; you can't make decent measurements in circuits. Korad sells decent linear bench power supplies. I'd go that route when on a budget.

author: Aldo22
author_rank: Super Contributor
timestamp: January 28, 2024, 02:21:22 pm
content: Quote from: nctnico on January 28, 2024, 02:12:06 pmYes, that's right.I still have an old linear one, which is usually sufficient for electronics experiments.But it doesn't deliver more than 10 watts.The new one can deliver up to 300 watts.It just depends on the intended use.

author: madires
author_rank: Super Contributor
timestamp: January 28, 2024, 02:22:33 pm
content: Cheap, AliExpress, safe and reliable in one sentence sounds like an oxymoron. Or in other words, anything with a mains plug you buy from AliExpress requires a safety inspection before plugging in. Back to your question. Are you looking for a linear or switching mode PSU? How many amps?

author: audiotubes
author_rank: Regular Contributor
timestamp: January 28, 2024, 02:51:56 pm
content: The Korad KA3005PS is supposed to be an update on the prior "P model. I just got the new one for 100 euros to use for some radios while I check out my main POS supply I was using. Seems pretty ok, especially for the price.

author: slybunda
author_rank: Regular Contributor
timestamp: January 28, 2024, 03:00:12 pm
content: Doesnt need to be much on amps maybe 5amp. Can use it to charge batteries and inject voltage here and there and pop a few old capacitors now and then lol.

author: bdunham7
author_rank: Super Contributor
timestamp: January 28, 2024, 03:14:42 pm
content: Quote from: slybunda on January 28, 2024, 03:00:12 pmMany otherwise OK power supplies are at risk of blowing up if you charge batteries. You either need one that won't do that (good luck and lots of money, these are typically vintage units) or you can get one with a remote sense feature and use a large diode for battery charging. The Korad KA3005PEA from Eleshop in the UK has the remote sense option, you'd need to read the manual to see if it will perform properly charging a battery through a diode. Some PSUs have significant limitations on the sense voltage differential and won't work with this setup.

author: slybunda
author_rank: Regular Contributor
timestamp: January 28, 2024, 03:29:31 pm
content: Ahh i see. Mostly want to charge up some lead acid batteries like the ones you get in ups 6v and 12v batts. What sort of power supply am i looking at then for this sort of job? Im in the uk so ebay, amazon and mouser etc are available to me. Cheapest power supply at rs components seems to be well over priced.

author: andersthuresson
author_rank: Contributor
timestamp: January 28, 2024, 03:34:26 pm
content: I have 4 power supplies. 2 of them are linear and the other 2 are switching type. Which ones I use depends on what type of work I will do. For audio work I always choose linear supplies because I want to keep the noise low. One of my supplies is a switching power supply from Aliexpress and it's branded "Nice-Power". It outputs 60VDC/5A and so far it's been working fine. They have a bunch of different versions with various outputs.

author: madires
author_rank: Super Contributor
timestamp: January 28, 2024, 03:48:51 pm
content: Quote from: slybunda on January 28, 2024, 03:29:31 pmYou can find good lead acid battery chargers for 50 bucks (supporting 6 and 12V).

author: DaneLaw
author_rank: Frequent Contributor
timestamp: January 28, 2024, 05:57:40 pm
content: A cheap linear bench PSU, here Korad has been the obvious choice for many over the last decade, simply because of the price.Korad KA3005D / 31V / 5.1A is around 70 euros and up from European resellers incl. VAT but the Korad KA300X series control scheme is problematic, as you control the output "on/off" by one of the two main knobs by holding it in for a given time, here the KD300X series is preferred, with its dedicated on/off buttons.. - if you control it from PC then you don't have these issues.Also, the path I went a little over a handful of years back, I purchased one from Europe KA3005P, and one from China KD3003P both with PC control interface (=P).A look inside..http://tinyurl.com/28upwfrehttp://tinyurl.com/5h636f4cWent with linear to circumvent the noise from switching when working with delicate laser diodes but nowadays, I really don't use them a lot, I primarily use these small switching PSUs like below that can run on fx powerbanks - as the diodes don't seem to mind and it is way easier to manage when your setup are based on mobility in lack of a dedicated bench, here these 4½ kg AC PSU's gets quite cumbersome.You can obviously daisy chain them to get a higher voltage or amps than the 5.1A or 31V as most linear PSUs are limited at 3A or 5A.If I were in the market for a linear PSU in 2024, I would pursue one with a graphical interface, as these 7-segmented displays can be a limiting factor, when trying to maintain an overview of your settings etc.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 28, 2024, 06:02:40 pm
content: I have a Tekpower TP3005P I got on Amazon for $100 7 years ago, and it's been great. Seems generally clean and stable.

author: csuhi17
author_rank: Frequent Contributor
timestamp: January 28, 2024, 06:12:03 pm
content: To charge the battery, only use a charger or through a charging circuit, do not use a PSU directly.Even battery chargers can cause problems, I know someone who burned down his shed with a battery charger because he overloaded the charger...Buy two separate units for charging and feeding.For charging, there are a couple of RC battery chargers that can charge several types, and they have a variety of protections and parameters.You have to pay close attention to the setting, because you have to set the number of cells (voltage) separately, not all of them are automatic.I do not recommend the HTRC T400 duo series because they measure inaccurately.

author: bingo600
author_rank: Super Contributor
timestamp: January 28, 2024, 06:19:40 pm
content: Quote from: audiotubes on January 28, 2024, 02:51:56 pmArrghhhhNOT NICE to reveal that (fine) priceOne Korad KA3005PS on the way from eleshop.euEnded up in122€ incl shippingto DK/Bingo

author: slybunda
author_rank: Regular Contributor
timestamp: January 28, 2024, 09:43:05 pm
content: any options for powering small stuff like mosfets and led's and microcontrollers for a little while on a breadboard? usb powerbank and some sort of buck/boost converter possible?

author: shapirus
author_rank: Super Contributor
timestamp: January 28, 2024, 10:30:02 pm
content: Quote from: slybunda on January 28, 2024, 09:43:05 pmI got one of these ~3 years ago:https://www.aliexpress.com/item/1005005145280146.htmland coupled it with an old school transformer+bridge+caps AC/DC PSU (I thought I needed this kind of galvanic isolation at the time).It works fine.I charged batteries with it many times, because nobody told me it was a bad idea. Just as expected, no issues whatsoever (though it does consume a little bit of current, like few mA, when it's off and you apply voltage to its terminals).Voltage regulation is off by ~10 mV. Current regulation struggles to work correctly up to about 25-35 mA, but it glitches on the safe side: sometimes it goes into CC mode and lowers voltage when it's not yet necessary. Higher than that, it works well.One caveat in this configuration: because of the capacitive coupling between the transformer's windings, there is considerable AC voltage between either of the terminals and mains earth or a human. Of course they are in phase, so it's proper DC between the two of them, and it's a very high impedance source, but I did kill a few MOSFETs with this voltage (connect source to one of the PSU terminals, touch gate, bingo). It would make sense to add a PE connection to optionally tie one of the terminals (negative) to mains earth to avoid these issues.The only scenario so far when I needed anything else has been when more than one power rail was required. In these cases a proper multi-channel (2 or better 3) lab PSU would be much more convenient.Noise at 15V output with a 1.2k resistor as load, 5us/div horizontal, 10mV/div vertical:

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 28, 2024, 10:40:20 pm
content: Quote from: shapirus on January 28, 2024, 10:30:02 pmThose are great. I use one of those in my FUtracer curve tracers. I usually get this version:https://www.amazon.com/gp/product/B01LWXAC5E/I haven't tried this one yet, but it looks interesting for people that need more voltage:https://www.amazon.com/dp/B0C89F4XJY/

author: shapirus
author_rank: Super Contributor
timestamp: January 28, 2024, 10:42:32 pm
content: BTW, speaking of noise, you should not necessarily rely on power being clean. If the circuit you develop requires very clean power, then adding filters is on you. If your device will be powered by e.g. a USB port, then you can expect any sort of noise in power input, and you need to filter it anyway.If you need to test some components etc. and make precise measurements that can be affected by the PSU's switching noise, then it's easy to add filtering between the PSU and the circuit, including, if necessary, a linear regulator. I really see no point in requiring that your bench PSU should necessarily be a linear one. Switching converters, even cheap ones, should be fine for most cases.

author: shapirus
author_rank: Super Contributor
timestamp: January 28, 2024, 10:52:04 pm
content: Quote from: KungFuJosh on January 28, 2024, 10:40:20 pmYeah it looks quite good, and it's btw a lot cheaper (about $35) on Ali. I might build a second unit to serve as a second channel, will see. However when you add the price of an AC/DC PSU... it may well be that getting the ready made one (I am sure they make ones already with a case and AC/DC supply) will cost the same, if not less, not to mention that it's easier. Building my first one was fun, but it was just enough of that particular kind of fun for me :).

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 28, 2024, 11:04:50 pm
content: Quote from: shapirus on January 28, 2024, 10:52:04 pmYes, I've seen it on Ali, and they do have readymade versions. There's also the RD6024 you can look for on there that has more power. The assembled version isn't that cheap though.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: January 28, 2024, 11:39:10 pm
content: It is possible to filter switching PS. But I have found it to be very difficult. In a switching PS there is both line noise and radiated noise. It is very hard to get rid of the radiated noise. Putting filters on the output of a PS (line noise) can decrease the volts and amps from that indicated on the PS meters They also inject noise into your house wiring.. Besides that the switching of the PS changes with amp demands of the circuit so the freq of the interference changes. The higher the power of the PS the louder the noise. It is a lot easier to get a quiet PS than to deal with all that.If you are dealing with RF. there is already enough interference caused by your household appliances and computer stuff. The high power switching stuff in electric cars can make AM radio unusable.There are many very good switching PS built for specific equipment. The harmonics or noise from these PS is such that it does not interfere with the intended load. An example would be radios like HAM transceivers. The PS are built so that there is no interference with any freq used in the radio.If you are not going to deal with any radio stuff then I guess this is not as important, but for RF Hobbyist it is very important.

author: Aldo22
author_rank: Super Contributor
timestamp: January 29, 2024, 10:03:48 am
content: What do you think of the measures shown in this video to reduce the noise?He has almost thesame device as me, so I would like to do the same if there are no objections.

author: shapirus
author_rank: Super Contributor
timestamp: January 29, 2024, 10:22:46 am
content: Quote from: Aldo22 on January 29, 2024, 10:03:48 amI loved his way of using the probe as a contactless sensor to find the source of EMI. Sweet! Live and learn.

author: BeBuLamar
author_rank: Super Contributor
timestamp: January 29, 2024, 10:58:28 am
content: I don't know much but I bought the Matrix MPS-3605LP for $129 from Amazon and I am very happy with it. However, now i check the price is up to $250.

author: nctnico
author_rank: Super Contributor
timestamp: January 29, 2024, 12:52:41 pm
content: Quote from: Aldo22 on January 29, 2024, 10:03:48 amHe stole my idea from EEVblog! That is what I thinkI did exactly the same (and more) to a similar PSU and posted the results here.But the noise still is too high for use as a bench supply if you want to make measurements in a circuit

author: Aldo22
author_rank: Super Contributor
timestamp: January 29, 2024, 01:47:08 pm
content: Quote from: nctnico on January 29, 2024, 12:52:41 pmThen it can't be all that wrong.Quote from: nctnico on January 29, 2024, 12:52:41 pmWhere exactly is "here"?Thank you.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: January 29, 2024, 01:51:27 pm
content: You can also use a probe like that with a spectrum analyzer to locate source of a specific frequency that concerns you.. I do it all the time. You can even use a probe that contacts a crystal to see its freq. Just touch the probe to the xtal can. The signal is too small for a scope but a spectrum picks it up.Fix looks pretty good.But here you have how much test equipment and stock of parts to get a switching supply under control?Then you would have to test it with different loads and different power levels.To avoid this problem get a linear supply at first. Even an old one with analog meters. You can always check your voltage with a voltmeter.Now, if you plan on using things that have USB power it would be nice to have these outputs on your PS.

author: Randy222
author_rank: Frequent Contributor
timestamp: January 29, 2024, 03:25:02 pm
content: What about the Matrix line of PSU's? Some appear to look like the Korad'sAnd then, I always wondered what you can get from a kit like this, but you add in some filtering on the output.https://www.aliexpress.us/item/3256801871857454.htmlI am eyeballing this dc-dc set (style) because I might actually place the psu unit under my work desk, then cable to the controller using a shielded cable. I need small footprint on desk workspace.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: January 29, 2024, 04:54:35 pm
content: Quote from: Randy222 on January 29, 2024, 03:25:02 pmYour link is sadly region-restricted.A shame how Aliexpress gone bananas with their listing region-restrictions for certain continents here in 2024.

author: shapirus
author_rank: Super Contributor
timestamp: January 29, 2024, 05:25:05 pm
content: Quote from: DaneLaw on January 29, 2024, 04:54:35 pmThat's really weird, for me it opens, but says "This product can't be shipped to your address. Select another product or address. "Anyway, it's not unique, search for "rd6006 kit" or "rd6006 set"https://www.aliexpress.com/item/1005006144878911.htmlhttps://www.aliexpress.com/item/1005006140421543.htmlhttps://www.aliexpress.com/item/1005005902055333.htmletc.(it's not exactly cheap though, when it includes the case and AC/DC PSU)

author: Randy222
author_rank: Frequent Contributor
timestamp: January 29, 2024, 05:43:20 pm
content: Does this link work ?https://www.aliexpress.com/item/1005002058172206.html?gatewayAdapt=4itemAdaptThey appear to ID a country source and then dump you through a "gateway".

author: DaneLaw
author_rank: Frequent Contributor
timestamp: January 29, 2024, 07:22:24 pm
content: Quote from: Randy222 on January 29, 2024, 05:43:20 pmNo it's the same, I think its an EU thing that got even more extreme here in 2024 and Aliexpress is locking out tons of listings.. though I have tried to log out of my account and then connect to Aliexpress through a VPN so my IP in theory should bounce in another continent, but even then many of these listings will simply not display and gives the screendumps above.Its a shame as some of my saved items are here in 2024 behind this regionwall posted above, which gives no information about the product.Even though a given seller could still ship it, with the purchase of another item at the same price-level, I still need to be able to see the listing.Maybe if one made a new proforma account on Aliexpress, and put in a fake address in a given country, and just used that account solely for searching & looking around in Aliexpress.But I don't know which country has the widest latitude for being able to see listings on Aliexpress, but this region's & censoring restrictions are problematic.But I reckon it's sadly another EU-thing (unless other people in the EU can access links like the one above) weirdly many items on Aliexpress are now in 2024 forbidden to be displayed for people in my location (DK/EU)Same with the seller I purchased the Rigol DG800PRO from in Nov. 2023 - here in the first weeks of 2024 90% of all his listings were suddenly behind this wall "not valid for people in your location"He asked Aliexpress and they explained that there were new certification rules that took effect in 2024 for people in certain regions.. though he would try to counter that..

author: Aldo22
author_rank: Super Contributor
timestamp: January 29, 2024, 07:46:17 pm
content: From Switzerland it is different.I can see the products on all 4 links.I can also order the products of the last 3 links.Only the first one says:Quote

author: orzel
author_rank: Regular Contributor
timestamp: January 29, 2024, 07:57:28 pm
content: Quote from: shapirus on January 29, 2024, 05:25:05 pmDave did few videos about those, starting with this one i think:https://odysee.com/@eevblog:7/eevblog-1265-53-360w-lab-bench-psu:6

author: DaneLaw
author_rank: Frequent Contributor
timestamp: January 29, 2024, 09:02:56 pm
content: Quote from: Aldo22 on January 29, 2024, 07:46:17 pmYep, but neither you  nor Shapirus  ain't based in the EU, and why I wonder if it's an EU restriction? or maybe it's simply country-based as its tragicomic how a quarter of my wishlists on Aliexpress with tech products that suddenly at the year turn is now being restricted to the point you can't see the listing anymore, only a locked-out to your region banner..But in regards to links above, its solely this link from early posts - and if other users in the EU could access it.https://www.aliexpress.com/item/1005002058172206.html?// VPN (Brazil) + incognito mode.. seems to do the job, same as Ukraine VPN + incognito.

author: tautech
author_rank: Super Contributor
timestamp: January 29, 2024, 10:19:01 pm
content: Quote from: Aldo22 on January 29, 2024, 01:47:08 pmProbably this one:https://www.eevblog.com/forum/testgear/cheap-variable-switching-power-supply/

author: thm_w
author_rank: Super Contributor
timestamp: January 29, 2024, 11:43:29 pm
content: Quote from: shapirus on January 28, 2024, 10:52:04 pmOne of the major reasons to get these is if you have a spare PSU laying around. Usually at work or through friends you can find old laptop bricks (20V 10-20A) or server PSUs, etc. that are no longer used. I didn't bother with a case just mounted it on a flat sheet. But you could 3D print a case or just back cover I guess.The Riden are way more expensive but offer proper battery charging relay + custom firmware. Wish some would come out with LXI though instead of dumb stuff like a handheld remote and weather screensaver.https://www.aliexpress.us/item/3256803286017579.html60V 12A Riden $100https://www.aliexpress.com/item/1005003432603471.html60V 12A WEGE $40https://www.aliexpress.com/item/1005004945384897.html60V 14A XY6014 $40

author: Randy222
author_rank: Frequent Contributor
timestamp: January 30, 2024, 12:43:10 am
content: These dc-dc front ends (choppers) are noisy though.Most are buck type, be nice if some could be buck/boost types.

author: thm_w
author_rank: Super Contributor
timestamp: January 30, 2024, 01:41:34 am
content: Quote from: Randy222 on January 30, 2024, 12:43:10 amRiden is Buck->linear reg.. I don't have the other brands handy so not sure, but I assume would be similar.You could get a generic buck/boost and put it before the Riden, but for me there is no point, just series a few scrap supplies together.

author: shapirus
author_rank: Super Contributor
timestamp: January 30, 2024, 09:17:01 am
content: Quote from: thm_w on January 30, 2024, 01:41:34 amAre you sure? Which one? The RD60xx series looks just like a usual adjustable DC/DC switching converter.

author: slybunda
author_rank: Regular Contributor
timestamp: January 30, 2024, 09:36:10 am
content: I do have spare laptop power adapters lying around, some hp 65w ones and dell too

author: Randy222
author_rank: Frequent Contributor
timestamp: January 30, 2024, 02:21:32 pm
content: Quote from: shapirus on January 30, 2024, 09:17:01 amEven if it were, the chopper noise is fairly large, unless RD has made some changes to their ckt's.However, from that Dave vid, the noise appears to be ringing from silicon on/off cycles, which can perhaps be mitigated with a designed snubber. Placing it onto the PCB might however be a challenge.

author: thm_w
author_rank: Super Contributor
timestamp: January 30, 2024, 11:09:38 pm
content: Quote from: shapirus on January 30, 2024, 09:17:01 amYeah you are correct, its just buck, thought there was something else under the heatsink..Quote from: shapirus on January 30, 2024, 09:17:01 amI also recall some of the noise was injected from the source PSU. As people had varying results depending on what was used.You are right the ringing noise is large. I'll see about testing a snubber.

author: Randy222
author_rank: Frequent Contributor
timestamp: January 30, 2024, 11:15:30 pm
content: Quote from: thm_w on January 30, 2024, 11:09:38 pmNot in the Dave vid. Noise from the dc-dc lunchbox PSU showed no additional noise.It however just looked like ringing when the silicon turns off, basic LC ringing which (I think) can be dealt with fairly easy with snubber. I had a similar issue of ringing from a fet that was sinking large inductive load. I managed to squash the ringing with correct snubber.The dandy RD buck chopper is like buying a project even before you get to use it.

author: nctnico
author_rank: Super Contributor
timestamp: January 31, 2024, 12:43:04 am
content: Quote from: tautech on January 29, 2024, 10:19:01 pmIndeed but in the meantime I have decided to retire both power supplies I mentioned in this thread (I never even turned the 10A version on). I got a few Rek and Gophert power supplies for use as adjustable wall-warts:https://www.eevblog.com/forum/testgear/rek-kps6003-and-gophert-nps-1602-60v-3a-psu-hack-review/msg3336994/#msg3336994. The formfactor makes it easier to stack these.But these are switchers as well so I don't recommend these for powering circuits where you are doing measurements on. Besides that the user interface is a bit clunky with the single rotate / select knob.

author: bingo600
author_rank: Super Contributor
timestamp: January 31, 2024, 06:11:05 pm
content: Quote from: bingo600 on January 28, 2024, 06:19:40 pmI got my PSU today ....Super fast (3 days) from NLeleshop.eu

author: shapirus
author_rank: Super Contributor
timestamp: February 07, 2024, 11:22:51 am
content: Another decent lab (switching -- the usual caveats apply) power supply of the 60V/6A category, for which they offer an assembled unit with an AC/DC converter built in:https://www.aliexpress.com/item/1005005771018101.htmlSame manufacturer as the one of the RD series discussed above, but this time it's a smaller and cheaper RK series. A winner in the sub-$100 category?Not sure about how much noise will be added by the AC/DC unit, but the DC/DC converter looks pretty decent in that respect, and it also seems to be good in all that it has to do for its purpose. There's a review of the DC/DC unit in russian (google or whatever translate should make an acceptable translation for those who need it), which, importantly, has scope screenshots showing transient response and noise:https://www.kirich.blog/obzory/preobrazovateli/1165-novaya-model-reguliruemogo-preobrazovatelya-rk6006-ot-ruideng.html