R&D #12 Review: Yihua $50 power supply from Ebay

Test and adjustment of the Yihua power supply found from numerous sellers on Ebay.
Max current draw test, using thermocouples to measure the heat sink under load.


Dzorz's Top's says:

13:46 wtf was that

iwh725 says:

Be aware that these supplys are made REALY cheap with no brains going in!
I have a smaler version 30V / 2Amps. Allmost all screws are lose even the earth on the transformer.
BUT the Big problem is, mine has NO Earth connection going to the metal case, its a suicide Device or attempted murder depending on your views.
If you buy one please check all screws and all connections AND check that earth IS connected to the metal case!

SergIv says:

I myself chose a long time, bought the – and very happy. Therefore, I recommend to all. Very compact and precise adjustment unit 32V/5A power supply. Model Gophert 3205E have 4-digits on display current: http://ali.pub/91wip Price is only 55 dollars.
“Out of the box” it was calibrated to a 1-2 mark last almost the entire range. Excellent stabilization of voltage and current.

Scott Marshall says:

I’ve got a pair of them Branded QW-MS305D. They look to be exactly the same device, but the internals on mine are better laid out and they behave a little better. They have 2 heatsinks aligned front to rear and the fan blows right thru them. Mine are within .2v 0-24v and run at 5a without appreciable heating (more than you’d expect anyway). The fans come on about 150ma and pwms to full speed at about 500ma. I’ve been using them daily for a couple of months and they serve the purpose well. Most days they’re on for 12+ hours. They’re not HP or Agilent, but at 1/10th the price, I don’t expect them to be. I paid about $85 for the pair at Yallstore on ebay (out of New Jersey). I buy a lot of SMPS from them, and figured I’d try a couple of these rather than spend big bucks or gamble on used.
Time will tell, but so far, for a low end solution, they’re not bad.

Thanks for the great review.

Jumbo Egg says:

You seriously tried to calibrate a small mA output on the amp scale using your fluke’s milliamp reading, and didn’t consider using the button to change to the milliamp scale? lol

kael'thas sunstrider says:

my 40$ diy psu is much better than this :c

nodriveknowitall says:

I’d have figured fluke would make a better meter than that. 150 mV off? I mean the power
supply was giving bang on five volts.

Harry Haefner says:

chinglish yup I know 🙁

Scott Campbell says:

You cant be too harsh on a $50 psu.

The Kaveman says:

You may want to wrap the unit in plastic wrap to test the unit under closed conditions as open unit has too much air flow to test .

BCcreativeInnovation says:

I bought a similar looking power supply from a local electronics store, I think paid close to $150 for it, within the 1st year, the power button broke, had to unplug it from the back, not even 3 years later, and didn’t even use it all that often, one day, was testing a circuit I have built, I left it on for a few minutes, went to grab something to drink, came back, and I smelled something burning, and next thing I knew, the power supply was showing 50 volts and cooked my circuit and a VERY expensive automotive hall effect sensor, the unit is only suppose to go to 30 volts, strange…

meagain2222 says:

I was using a supply like this to charge a small lead acid battery.
The power supply didn’t like that and the current readout is now toast.
Can this be fixed?

Maurice Petit says:

I don’t know why you keep testing this power supply, if you know in advance that you will find something wrong with it. If you have enough money to buy a fluke and agilent digital multimeters which cost an arm and a leg???? We’re not all rich enough to be able to afford buying those fancy multimeters.Nevertheless, we still enjoy working in electronics, but have to use cheaper testing gears.

LeiserGeist says:

I always recommend people old HP power supplies from the 80s or 90s – they’re reasonably low in price given their age, but they’re still professional-tier equipment, and reliable as hell.
Only cons are that they’re boat anchors and don’t always have modern features, but hobbyists like myself usually don’t need those. Hell, most of the time we don’t even need more than a little 5 volt wall wart
Oh well, just my two cent ramble

Joe Kuku says:

crappy stuff . make your own using a pc power supply . the best power youl ever have

soupercooper says:

mine out of the box was defective and junk, dont buy

Harry Haefner says:

Twing Twang Chinlish does help at all!

mehmet2247 says:

i stopped wathing the video when i saw the inconsistency of the measured voltages between fluke and psu, anyway i liked the video, thanks.

Pro1er says:

Very good review! I wish I would have bought one of these a few years ago when they were linear PSUs – now they are all switching PSUs. I’m not worried about the noise but rather the durability.

Edgaras V says:

Hey, somebody has to pay for the gloves, arrrgh!

John Conrad says:

the voltmeter was ok before u messed with it. u were reading high without a load and when u loaded it the voltage dropped to what ur Fluke was showing. u needed to adjust the current readout.

Victor Orozco says:

Excelent review, thank you !

TJ's Practical DIY says:

I hope people read the comments.

houstonceng says:

Should have used the current range switch to make the meter read mA

Digger D says:

I would recommend looking around for a good used power supply.  I was lucky enough to pick up a B&K Precision 1660 for $100 Cdn.  There are lots of nice used pieces of professional quality equipment around.

robviolin1 says:

very helpful, thanks

helicrashpro says:

I have this exact power supply and I can only get about 17 watts out of it. For whatever reason the one you have almost put out 100W.

Rossiblypetep says:

He wouldn’t be out of place teaching at Cape Canaveral.

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