Bench Power Supply - Page 1
Forum section: electronics / beginners

author: DW1961
author_rank: Frequent Contributor
timestamp: May 17, 2021, 04:53:59 am
content: I belong to a program n Amazon where you can get free items for doing reviews. I've been waiting a long time for a bench power supply to come along, and finally, after 8 months of waiting, they have one. I wanted to know if any of you think this is a decent unit, not specifically if it is the cleanest power around, but if the options on it are okay, such as voltage, amperage and adjustments/connections.it's 10A 30V.Thanks!Link:https://www.amazon.com/dp/B0923PPJ3W?th=1

author: ataradov
author_rank: Super Contributor
timestamp: May 17, 2021, 05:07:04 am
content: Looks like a bog standard switching power supply. There are a ton of similar units on aliexpress. Buying one from amazon is just a waste of money. They are about two times cheaper from ali. Edit: although that specific model seems to go for about $65 on ali vs $90 here.Cleanless of the output and reaction to the load change is something I would like to see.

author: ledtester
author_rank: Super Contributor
timestamp: May 17, 2021, 05:32:01 am
content: QuoteI think he can get it for free as a reward for doing product reviews.Everyone should have at least one good linear power supply. They are heavier, so you'll find them mainly in 3 amp and 5 amp versions. Even though this one has "Switching" and "Linear" in its title it's clear from the cut-away picture that it's a switching supply. Another giveaway is that it's described as "This DC power supply is less than 3 lb".Here's a reputable linear supply you can get on Amazon:https://www.amazon.com/KORAD-KA3005P-Programmable-Precision-Adjustable/dp/B0085QLNFMNote that the weight of the Korad is 4.8 kg -- around 11 lbs -- and that's just the 5 amp version. The 30V 10A Korad KA3010P weighs in at 7.8 kg.

author: ataradov
author_rank: Super Contributor
timestamp: May 17, 2021, 06:09:39 am
content: Yeah, I get it. For free it is fine. I was speaking more to the options and if they are ok. They are fine, typical of that style of power supply. It is a nice and compact unit, and with 7 segments displays there is not a lot that can go wrong in terms of typical Chinese UI design.I would be interested in a review of that unit, but only the performance part. I can see all the options it has to offer from the front planel.It also has a very annoying - GND + layout, which makes it incompatible with fixed plugs.

author: DW1961
author_rank: Frequent Contributor
timestamp: May 17, 2021, 06:32:45 am
content: Quote from: ataradov on May 17, 2021, 06:09:39 amCan you elaborate on the GND incompatibility?The reason asked is because we still have to pay US IRS taxes on those "free" items. So, I try to limit requesting garbage - although we can have it removed from our tax report for deficiencies. I have a lot of shit taken off, though. I don't want to push it too far.So, is this power supply going to be ok for things like running fans for testing, LEDs, stuff like that?

author: DW1961
author_rank: Frequent Contributor
timestamp: May 17, 2021, 06:34:08 am
content: Quote from: ataradov on May 17, 2021, 05:07:04 amI have no way to test that, though. If someone wanted to test it, I could possibly send it to them for testing. I'd also be interested in cleanliness of the power.

author: ataradov
author_rank: Super Contributor
timestamp: May 17, 2021, 06:44:04 am
content: Quote from: DW1961 on May 17, 2021, 06:32:45 amBinding posts are "-" "GND" "+". If you look at any other power supply designed by people with brains, it would be "+" "-" "GND". You want to have + and - close to each other because some of the cables and adapters have fixed plugs, so it is impossible to use them with this supply.Thing like this:But that also assumes standard spacing between the binding posts, which is not given.Quote from: DW1961 on May 17, 2021, 06:32:45 amPlenty ok for that. Don't rely on the current limiter for testing the LEDs though, use external current limiting.

author: DW1961
author_rank: Frequent Contributor
timestamp: May 17, 2021, 07:09:02 am
content: Quote from: ataradov on May 17, 2021, 06:44:04 amWhat about using shorts leads?

author: ataradov
author_rank: Super Contributor
timestamp: May 17, 2021, 07:11:03 am
content: Why not just use a better power supply then?I mean this one will work, and if you want it, then get it. Especially if you can get it for the price of tax.

author: DW1961
author_rank: Frequent Contributor
timestamp: May 17, 2021, 07:18:55 am
content: Quote from: ataradov on May 17, 2021, 07:11:03 amThat's what I was getting at. If it can still do those connectors using leads, then I'm good for the price of tax.

author: exe
author_rank: Unknown
timestamp: May 17, 2021, 08:19:56 am
content: I had issues with the noise from an SMPS (incl. radiated noise), I'd suggest get a linear power supply first. Note that at least some of linear power supplies don't have good filtering from mains noise, but at least they don't produce much of own noise. Also aim at least for two channels or more.So, I'd suggest write down your needs first, then come from requirements. Right now I feel like it's an emotional purchase -- you found something that you like, and now trying to justify it. That's no problem as long as you conscious about it. This power supply looks very niche for (rare?) occasions when one needs a lot of current.

author: beanflying
author_rank: Super Contributor
timestamp: May 17, 2021, 08:51:45 am
content: Just do it IMONot every application NEEDS a linear ripple free supply sometimes you just need a lump of near enough.There is a very reasonable 'guess' (no testing or evidence on this model - so far) that cheap and nasty Chinese origin supplies are noisy. They are BUT those same supply styles fed into things like chargers for R/C, CNC, 3D printers work great or even fed into linear regs with a few caps can very happily supply Micros or other bench projects with low ripple.There is as some have suggested above some issues with radiated noise onto other devices, can be an issue if you are trying to do other really accurate measurements on the bench but while you are getting going likely won't be an issue. The last SMPS that was causing me an issue on the bench was driving an overhead LED light and it was causing a reading to flick a couple of Parts Per Million on a Calibrator, when you get to that then worryGiven the Tax only grab it then have a look at it find its short comings and then look for a Linear of some sort or TWO or THREE(6632B HP in the USA are affordable among others)

author: DW1961
author_rank: Frequent Contributor
timestamp: May 17, 2021, 06:15:03 pm
content: Quote from: exe on May 17, 2021, 08:19:56 amNot really emotional. I found something I need from the "free" program and this is the first one offered since I joined the program over 8 months ago. I could die of old age waiting for another - lol. Also, a linear PSU was not offered. It was either this one, or zero. Adding to the deal is that sometimes the program doesn't have a large stock of these "free" items. if you sit around thinking about it too much, you miss the opportunity. Then you cry.If this one didn't pass the community smell test, I'd just pass over it. It would be nice if it had two channels(Forgot about that), but I would probably rarely need that anyway.If there is a way to test it for noise, I'm game. I can always request that it be taken off my tax report for deficiencies (they always take items off and never question it).As posted in another reply, I'm just going to use to to test computer stuff, like fans, leds lights, and things like that for amperage draw, mainly. I'm not using it for anything permanent.They also have a 5A version that is $20.00 less. I figured the 10A version wold be a better choice for the extra overhead if I ever needed it.I think if no one really has anything bad to say about it, I'll pull the trigger on it.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 18, 2021, 11:38:14 am
content: I found that almost all of the power supplies with a ground connection has it between the negative and positive terminals.

author: rdl
author_rank: Super Contributor
timestamp: May 18, 2021, 03:49:46 pm
content: It seemed to start with the lower tier Chinese manufacturers and since they frequently just copy from each other it has become common. For most people it's probably a non-issue.Rigol doesn't do it on their DP800 series. Siglent doesn't appear to do it either. And of course HP, Agilent, Tektronix generally don't (or maybe never) do itAs for this particular unit, I'd go for it. Can't beat the price and power supplies are something you always need multiples of.

author: ataradov
author_rank: Super Contributor
timestamp: May 18, 2021, 03:54:09 pm
content: All the supplies I have use + and - together. Can you show some examples of reputable brands with a different placement?There are some weird placements in some supplies with 2 channels and ability to configure for serial/parallel using external jumpers. In that case layout can get a bit strange to accommodate for that configuration.

author: bdunham7
author_rank: Super Contributor
timestamp: May 18, 2021, 04:02:07 pm
content: Tektronix PS280 has -/G/+https://w140.com/tekwiki/wiki/PS280#/media/File:Tek_ps280_11.jpgIt's OEMed by GW Instek, but other than the not-so-rugged plastic and the terminal arrangement it is actually a decent PSU that doesn't blow up when you connect batteries--even backwards!

author: boffin
author_rank: Unknown
timestamp: May 18, 2021, 04:51:35 pm
content: My protek 3033 is - / G / +

author: DW1961
author_rank: Frequent Contributor
timestamp: May 18, 2021, 06:28:32 pm
content: Well, after reading all of your comments, I requested it. It should be here today. I got the 30V 10A model.Is there anything any of you would want me to test on the unit, as long as I can do it with a DMM. I don't have a scope. Or, is there anything you want met o specifically look at or try?

author: ataradov
author_rank: Super Contributor
timestamp: May 18, 2021, 06:37:49 pm
content: DMM alone is not sufficient to do any interesting testing.

author: beanflying
author_rank: Super Contributor
timestamp: May 18, 2021, 10:00:52 pm
content: Quote from: DW1961 on May 18, 2021, 06:28:32 pmStart a new topic with the model and or brand in the title so others can find it.Take a few photos front back and sides then "don't turn it on, take it apart"Good reason to do this you want to check the mains wiring is 'safe' so no loose bits and make sure the chassis and enclosure is well connected to ground.Then re assemble it and find a few different things to apply to it as loads. Remember you can pull up to 10A so make sure you use appropriate wire. While its not exiting a 12V car headlamp will work ok as a dummy load.just some random pre coffee thoughts for your new toy.

author: Gregg
author_rank: Super Contributor
timestamp: May 18, 2021, 10:30:56 pm
content: When you take it apart, check the mains input and power switch to see if the neutral is switched and/or fused instead of the line. I’ve noticed a number of Chinese mains powered devices that have the neutral switched. I’ve also seen power cords that have the line and neutral swapped.

author: DW1961
author_rank: Frequent Contributor
timestamp: May 19, 2021, 01:35:26 am
content: Quote from: ataradov on May 18, 2021, 06:37:49 pmYeah, I figured that

author: DW1961
author_rank: Frequent Contributor
timestamp: May 19, 2021, 01:38:15 am
content: Sounds like fun. I'll take it part ASAP and take pictures too. I'll have to try to find something that has some amperage to it to hook up.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 19, 2021, 02:04:16 am
content: Quote from: ataradov on May 18, 2021, 03:54:09 pmPretty much all HP 62xx power supplies, as well as several Power Designs models.

author: GodIsRealUnless DefinedInt
author_rank: Contributor
timestamp: May 19, 2021, 02:52:24 am
content: I just use data center power supplies, USA engineered and Chinese manufactured.Then I get one of a million bucking converter power supply units on Amazon or AliExpress.Unless you want a Chinese engineered and Chinese manufactured switching power supply in your bench top supply you could always do similar. IIRC it was $20 for my data center power supply on eBay.Just another option.I miss my linear supply I built many moons ago in uni, I will be building a new one soon.

author: ledtester
author_rank: Super Contributor
timestamp: May 19, 2021, 04:00:22 am
content: Quote from: DW1961 on May 18, 2021, 06:28:32 pmFor educational purposes you can make the measurements I described in this post:https://www.eevblog.com/forum/beginners/bizarre-behavior-from-24v-dc-power-brick/msg3568432/#msg3568432Some people have gotten a tingling sensation from ungrounded switching power supplies when they've touched exposed metal. As an experimenter the presence of this AC voltage is good to know about.

author: DW1961
author_rank: Frequent Contributor
timestamp: May 19, 2021, 04:50:46 am
content: The images or posted here:https://www.eevblog.com/forum/testgear/kungber-bench-ps-tear-down-images-as-requested/

author: exe
author_rank: Unknown
timestamp: May 19, 2021, 07:22:44 am
content: Quote from: Gregg on May 18, 2021, 10:30:56 pmShouldn't the switch be on both wires because live and neutral are sorta interchangeable? I mean, I can put a EU plug in two different ways, swapping live and neutral. Or am I confusing something? May be it's a EU problem

author: Zero999
author_rank: Super Contributor
timestamp: May 19, 2021, 07:55:30 am
content: Quote from: exe on May 19, 2021, 07:22:44 amThe subject has been discussed at length before. If it's just a power switch and isn't intended to protect against electric shock, then it doesn't matter whether it's in the live, or neutral, but as a general rule, in areas with polarised plugs, it's normally put on the live side.

author: beanflying
author_rank: Super Contributor
timestamp: May 19, 2021, 07:58:45 am
content: Quote from: exe on May 19, 2021, 07:22:44 amIn the case of this Power supply if you follow the link to the new thread the OP opened it is an IEC plug so 'in theory' it is polarised and earthed but the polarity of course relies on the Elecrician or anyone 'playing' with being one wired the outlets correctly.The simple rule is if it is plugged in and switched on at the wall ASSUME it is live to Earth.

author: Old Printer
author_rank: Frequent Contributor
timestamp: May 19, 2021, 04:56:39 pm
content: Quote from: rdl on May 18, 2021, 03:49:46 pmThe Tek CP250 is a great hobby level supply. A few years back one of the big tech schools went bust and dumped pallets of them on the surplus market under the BK Precision badge. I managed to get a few for $20 ea on evilbay. They go for some serious money under the Tek badge. Best part of that is that Tek produced a great service manual for it with their usual detailed troubleshooting guide and clear schematics and parts list. The manual can be had on ebay for $10 on CD. If you are looking for affordable power supply's don't overlook the used market. Many of the older units were built very well, have service manuals available online and you can learn a bunch by fixing up an old one.