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.
Long ago I took one of these supplies apart and reverse engineered it. I still have that schematic. This design has been around for a very long time, and would appear to be made by the same Chinese factory but with different labels when sold to different retailers. I don't think the design has changed one iota in all of that time. The first thing I did was replace the VOLTS "fine" pot from a 1k one-turn pot to a small 10-turn 1k pot. It barely fit in the old location, but it DID fit. I had to use my own knob for this pot, but that was no big deal. I hated the lash in that old fine control pot, which the change to a 10-turn pot corrected. After that, I could easily set the supply's output voltage to 1mV accuracy. The current sense resistor is nothing more than a short length of some heavy gauge copper wire, perhaps 12 gauge. While it's a cheap way to do it, because copper has a high tempco (about +0.4%/°C), then as the output current gets in the amp region, the wire heats up and the resistance of this current sense "resistor" increases as well. Thus, your meter indicates a higher current than reality. I.e., the supply has a real lousy current sense circuit that is guaranteed to be inaccurate regardless of how you set the current trimpot. The A/D converter for the two LED displays (volts, current) is based on an Intersil ICL7106 3.5-digit LED dual-slope integrator. If memory serves me correct (and it seldom does anymore), the design of the supply only uses about 1/3 of the Intersil's full range. Thus, the two displays end up operating in the lower part of the A/D's range, which further degrades the accuracy of all readings. At one time, I was going to redesign this A/D board and use a better A/D as well as use all-in-one 4-digit LED displays so that I could get more accuracy from my meters. But alas, my day job demanded more time of me that I could apply to my modification, and I had to abandon my plans. It is a very interesting design, particularly the use of the 3 relays to chop up the linear power supply output voltage so that the pass transistors (three 2N3055 NPN transistors in parallel) operate with at most 5V of collector-emitter voltage, which keeps the heat dissipation low (almost like a low-resolution switching power supply).That clank-clank sound you hear as you raise/lower the output voltage is that circuity kicking in and out the 3 relays, chopping the transformer's output voltage into 5V steps. Whoever designed it, as well as the feedback loop, really knew his stuff. Bottom line: for $50, how can you go wrong? Try sending a 15 pound brick to China and the postage alone will cost you over $50. How these guys manage to manufacture and ship this supply to me for $50 demonstrates the magic of free markets in action!
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.
Thank you so much for showing how to correct the meters! I'm a disabled veteran with limited resources. This was the power supply I settled on due to its extremely versatile amperage (mine claims 10 Amps). It's nice to see such a thorough investigation into a piece of budget gear.
I have to say that what I saw in this video was a very inexpensive power supply hold up to a pretty punishing (not to mention imperfect) test far better than I would have expected. I'm a big fan of the notion that you get what you pay for and, as such, I like to buy the higher end, more reputable equipment whenever I can. That said, I also firmly believe that cheap tools and equipment can be extremely useful so long as your expectations and uses for them are reasonable. Would I use this power supply for applications that require its highest outputs of either voltage or amperage for long periods of time? No, I wouldn't. However, for lower current and/or voltage applications, or for applications which may not be ideal for my equipment in general (wherein I'd rather risk a $50 power supply than a more expensive one or one that I built), this Yihua seems like it may be pretty useful.
I think the same. I am using a chinese PSU for all kind of everyday stuff. And it's fine (even though, I don't like it's internals). I also have a high end model for high end applications.
I think you should sign the praises of this little PSU, given you paid next to nothing for it. It is good practice to use calibrated metering equipment to test current and voltage in any lab setup. The meters on any PSU (even a lab-grade one) are meant to be a rough indication. Fine adjustments are done by means of proper meters. If you want a cheap but good PSU, try to 'score' one from a server or a hard-disk-rack . Those can be had for little money are are far superior to anything commercial (that isn't lab grade) Making a regulator for that is an interesting project that actually may teach you a thing or two. Paddy
Your wire connections for testing volts and amps are not correct. The external voltmeter should be connected on the PSU terminals shafts. Then the current load resistor needs to be plugged into the sockets of the terminals. Otherwise the connecting wire resistance and contact resistances are masking the performance of the power supply.
its probably important to retest with the meters at the PS because you made a firm point about the meters being incorrect. I think ( if your aligator connectors are like mine were ) the voltage drop across them was significant under these load tests. I had to upgrade my leads to thicker 14awg and solder crimp the ends . The CHinese leads use super fine wire .
I always solder my alligator leads, this power supply is not worth spending any more time on, but I will use your suggestions on the next one. thanks for commenting. Cheers.
I have one , it is "ok". I found it did not have current controlling setting just a current and power limiting which switches off the Voltage once triggered . So it is a current protection but this cannot be set in advance. I also found some noise being generated on the Mains AC that appeared to go into other devices. The Voltage is fairly accurate but this can always be improved by buyng a small Voltage display from ebay attached in parallel .
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
Exactly. He was at the absolute limit of the A range, and the reading on the power supply was 2-3 counts out - totally within spec of any meter. Then he tweaked it and put it wildly out of calibration at full scale (showing 5.7A when it was actually 4.8A). I bet if he'd used the mA range, as you said, it'd be fine.
I think the heatsink temperature test is misleading as the unit's case will funnel air around the heatsink and cool it more effectively than is possible with the case off
Thank you for the $50 power supply évaluation. I would have been interested to see if your 5A load had been left on & the Amp limiter changed down, if the power supply would have correctly limited the amperage. Is the yellow connector for AC? Arthur.
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.
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.
This thing is linear. You can tell by it getting hot. And the gigantic transformer. But uh... Durability is *better* for switching designs. They don't get hot.
@@JasperJanssen Although Linears are hotter than SMPS and less efficient, Linears used to be more reliable and durable. Also, i guess for audio power testing linear are better, in the college, someday i tested some TDA2040 circuits, some with linear psu and some using an old AT PC psu. The circuits tested on the AT psu exploded, all of them, the ones tested on the linear survived and worked almost perfectly. Despite that, personally i still prefer SMPS due its eficient and lightness
The current meter can be fixed with a few passive parts changed. I have mine now accurate and even modified it to show 2 decimal places. But 10.20A shows as 0.20A, but that is very small price for the higher resolution ...useful now that it is accurate.
WOW, I was just on Ebay and the last thing I looked at was this model power supply. then I come on here and this was in the first spot, so I had to check it out.
Yikes! 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
I have a power supply I built in college in 1986 still in use. normal transformer, based on a 4194 ic. 0 - 30v variable to 1 amp. Bearing in mind that most digital circuits these days are low power the need for 30v 10 amps is limited anyway. For the price and features the type of supply shown here is excellent value
Would something like this work fine using a breadboard to create LED lighting and other train related circuits for our HO Scale model railroad layout that has 15V across the tracks? Thanks!
I had it too. One day, I went away from table while it was running and when I arrived, board connected to it was smoked. Voltage limiter died and it switched from 5V to 30V and keep feeding circuit.
Just finished repairing my 305D. I was testing out a drone motor which operated probably at 3.7V to see how fast it could go. Started at lowest voltage and gradually cranked it up. Voltage was over 20V when the clip to the motor lead came off, so I put it straight back on, blew up the motor and the PS. Display read about 29V and couldn't be adjusted. Searched all over for a schematic, never found one that matched exactly. There are two 2N3773 output transistors (most schematics show 2N3055's). The bases and collectors are connected together (parallel arrangement) and the emitters have 0.33 ohm resistors which then join and go to the positive output. Both transistors and one of the 0.33 ohm resistors blew up. Replaced the blown 0.33 ohm resistor as I found it open first. Display read 49V and couldn't be adjusted. Then test the transistor. Both failed, one as a short base to collector. Main circuit board, display board and control board were ok. Replaced 3 defective parts and it worked again.
Looking for some advice guys. Want a 'Reasonable' quality bench top rather than Lab power supply. Im a beginner so not wanting to overspend on it either. im looking at the £50 - £100 ish range. I might go £120 but thats really my max and i really really dont want to go that high. So what should i get ? Mostly use 5v or 12 v . Ideas ?
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?
Yihua normally makes decent gear for the price. I think the problem here was in part in front of the screen not behind as many have pointed out in the comments. :P Yihua makes a ton of the Chinese soldering stations and they all seem to be decently built.
i like these reviews to see how good this cheap stuff is, worth it for me. i assume when you adjusted the current meter, you adjusted the span pot, this is why it was out at full current. a little more tweaking it'll be sweet. just bought one for hobby use.
I have a similar one, also from eBay. Slightly different labels on it. At 8V it produces 1Vpp noise of 60kHz modulation. So, while any multimeter will show you the same voltage you set (because of averaging) - this kind of supply is pretty useless if you want to design/test any precision analog electronics (something with OpAmps, ADCs or DACs inside, for these cases I still use LiPo batteries as a clean power supply).
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.
Highly depends on what you're going to do with it. I've got an ATX (PC) power supply, to get me +12V, +5V, +3V3, GND and -12V. It can also handle lots of current (driving LED strips and whatnot), has indicator LED's for pwr_on and pwr_ok. Along with a switch in the front to toggle it on and of. But I also have a variable 0-30V 5A CC/CV regulator from ebay. Together they fullfill pretty much all my needs.
"Professional quality power supplies" have remote sensing capabilities, which will do a much better job of delivering a constant voltage at the load when the load current changes. Any power supply with only two output terminals is non-professional, by definition, because the voltage is only regulated only at the supply's two output terminals. Add your cables and anything else to get the voltage to your load, and those wires/connectors add resistance, which creates a voltage drop when current passes through them. Remote sensing (like the very old HP supplies once had) eliminates this issue.
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!
would you recommend this for light work? I'm tempted to getting one for radios and toys nothing big don't need it for heavy loads just repairing toys and radios ect....
I'm asking R&D, or anyone the who has a reasonable product reference. I was trying to reply to R&D's reply, but I guess it doesn't really work that way.
here is an ebay listing, you will have to use your own 24v transformer and convert the ac to dc, but if your learning electronics it's a good starter project. www.ebay.com/itm/Buck-Step-down-LM2596-Power-Converter-Module-DC-4-0-40-to-1-3-37V-LED-Voltmeter-/221970563817?hash=item33ae7a02e9:g:gT8AAOSw5IJWcZxX
if you use current meter to read the current then you are facing with the unknown internal resistance of the current meter . therefore your reading current number may not be accurate. you should use the known resistance as a load then measure the voltage drop then calculate the current using Ohm law formula.
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...
On a circuit design like this, if the pass transistor fails shorted, then yes, you get the full voltage straight from the transformer/rectifier passed right into your DUT.
I had a very similar experience. I had the PS connected to a USB cable and charging a tablet that was being picky about charger and USB cable. I was just topping off my charge before a trip, while I took a shower. I grabbed the tablet as I went out the door, but did not notice any smell. At the airport I realized my tablet was dead. and found it had some fried components in it. Two weeks later when I returned I found my PS was pinned at 50V. Inside a 3W 1K resistor on the board was completely cooked. one of the can caps was blown up. I have not taken the time to repair it, but I would think twice about using this PS unattended or on expensive equipment. I will say that the unit was a very useful tool up to this point.
Three different multimeters double heat sink, wires everywhere. Just set it up, all you need no. Is hooked F350 Cummins diesel engine to it. And your set
I got exactly the same unit (inside and out) under the Sunshine brand. It cost me around 40 bucks, but when I turn it on it just gives me 0.00 on both LEDs. Cannot get a voltage on it. Anyone watching this have a cct diagram for this unit?
They are excellent supplies. The person doing the review does not know how to test it properly, and he really screwed up the metering my trying to calibrate the meters when he had little or no reading on them. He needs to go back to 15 or 20 volts at 4 or 5 amps and recalibrate. But when he recalibrates he needs to take the resistance of those crappy wires provided with the meter into account; OR do his voltage and current measurements right at the power supply output terminals...
My lame joke aside... I bought a Korad and one of the mains wires was pierced by corner of a heat sink. It was fairly accurate after I fixed that. been going for a year now I think.
You got no idea about thermocouple. There is no need for isolation, it can be shorted and the measurement is still the same. The same is abot measurements themselves. 95.6... mA should be calibrated 0.10 A instead of 0.09 A. The device is superior compared to your knwledge. What abot voltage drops in the wires? Whatever you say expose your poor knowledge.
Interesting, I have the same PSU, but the meter board is different. It's much more accurate as well! XD And, it's a little older than yours I think ... heh, weird!..
So many comments here about this power supply being useless, but what is your better eBay alternative to this, or maybe you just like to tell useless opinions?
I have the same model, it has been 5 years since I bought it and still going strong.
Long ago I took one of these supplies apart and reverse engineered it. I still have that schematic. This design has been around for a very long time, and would appear to be made by the same Chinese factory but with different labels when sold to different retailers. I don't think the design has changed one iota in all of that time.
The first thing I did was replace the VOLTS "fine" pot from a 1k one-turn pot to a small 10-turn 1k pot. It barely fit in the old location, but it DID fit. I had to use my own knob for this pot, but that was no big deal. I hated the lash in that old fine control pot, which the change to a 10-turn pot corrected. After that, I could easily set the supply's output voltage to 1mV accuracy.
The current sense resistor is nothing more than a short length of some heavy gauge copper wire, perhaps 12 gauge. While it's a cheap way to do it, because copper has a high tempco (about +0.4%/°C), then as the output current gets in the amp region, the wire heats up and the resistance of this current sense "resistor" increases as well. Thus, your meter indicates a higher current than reality. I.e., the supply has a real lousy current sense circuit that is guaranteed to be inaccurate regardless of how you set the current trimpot.
The A/D converter for the two LED displays (volts, current) is based on an Intersil ICL7106 3.5-digit LED dual-slope integrator. If memory serves me correct (and it seldom does anymore), the design of the supply only uses about 1/3 of the Intersil's full range. Thus, the two displays end up operating in the lower part of the A/D's range, which further degrades the accuracy of all readings.
At one time, I was going to redesign this A/D board and use a better A/D as well as use all-in-one 4-digit LED displays so that I could get more accuracy from my meters. But alas, my day job demanded more time of me that I could apply to my modification, and I had to abandon my plans.
It is a very interesting design, particularly the use of the 3 relays to chop up the linear power supply output voltage so that the pass transistors (three 2N3055 NPN transistors in parallel) operate with at most 5V of collector-emitter voltage, which keeps the heat dissipation low (almost like a low-resolution switching power supply).That clank-clank sound you hear as you raise/lower the output voltage is that circuity kicking in and out the 3 relays, chopping the transformer's output voltage into 5V steps. Whoever designed it, as well as the feedback loop, really knew his stuff.
Bottom line: for $50, how can you go wrong? Try sending a 15 pound brick to China and the postage alone will cost you over $50. How these guys manage to manufacture and ship this supply to me for $50 demonstrates the magic of free markets in action!
Try to say something nice. This power supply works great for 50 bucks!!!
Now they are cheaper. I bought the Yihua 305D for $ 30 from the outlet a week ago.
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.
Thank you so much for showing how to correct the meters! I'm a disabled veteran with limited resources. This was the power supply I settled on due to its extremely versatile amperage (mine claims 10 Amps). It's nice to see such a thorough investigation into a piece of budget gear.
I use mine almost exclusively for 12V automotive electronics. With the volt meter corrected at 14V, I only need ONE multimeter to monitor the current.
I have to say that what I saw in this video was a very inexpensive power supply hold up to a pretty punishing (not to mention imperfect) test far better than I would have expected. I'm a big fan of the notion that you get what you pay for and, as such, I like to buy the higher end, more reputable equipment whenever I can. That said, I also firmly believe that cheap tools and equipment can be extremely useful so long as your expectations and uses for them are reasonable.
Would I use this power supply for applications that require its highest outputs of either voltage or amperage for long periods of time? No, I wouldn't. However, for lower current and/or voltage applications, or for applications which may not be ideal for my equipment in general (wherein I'd rather risk a $50 power supply than a more expensive one or one that I built), this Yihua seems like it may be pretty useful.
I think the same. I am using a chinese PSU for all kind of everyday stuff. And it's fine (even though, I don't like it's internals).
I also have a high end model for high end applications.
I think you should sign the praises of this little PSU, given you paid next to nothing for it.
It is good practice to use calibrated metering equipment to test current and voltage in any lab setup. The meters on any PSU (even a lab-grade one) are meant to be a rough indication. Fine adjustments are done by means of proper meters.
If you want a cheap but good PSU, try to 'score' one from a server or a hard-disk-rack . Those can be had for little money are are far superior to anything commercial (that isn't lab grade)
Making a regulator for that is an interesting project that actually may teach you a thing or two.
Paddy
Your wire connections for testing volts and amps are not correct. The external voltmeter should be connected on the PSU terminals shafts. Then the current load resistor needs to be plugged into the sockets of the terminals. Otherwise the connecting wire resistance and contact resistances are masking the performance of the power supply.
You are correct, I will keep this in mind for future testing.
Thanks- hope you didn't mind me mentioning.
its probably important to retest with the meters at the PS because you made a firm point about the meters being incorrect. I think ( if your aligator connectors are like mine were ) the voltage drop across them was significant under these load tests. I had to upgrade my leads to thicker 14awg and solder crimp the ends . The CHinese leads use super fine wire .
I always solder my alligator leads, this power supply is not worth spending any more time on, but I will use your suggestions on the next one. thanks for commenting. Cheers.
I have one , it is "ok". I found it did not have current controlling setting just a current and power limiting which switches off the Voltage once triggered . So it is a current protection but this cannot be set in advance. I also found some noise being generated on the Mains AC that appeared to go into other devices. The Voltage is fairly accurate but this can always be improved by buyng a small Voltage display from ebay attached in parallel .
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
Exactly. He was at the absolute limit of the A range, and the reading on the power supply was 2-3 counts out - totally within spec of any meter. Then he tweaked it and put it wildly out of calibration at full scale (showing 5.7A when it was actually 4.8A). I bet if he'd used the mA range, as you said, it'd be fine.
OMG Yes! It was driving me CrAzY.
I think the heatsink temperature test is misleading as the unit's case will funnel air around the heatsink and cool it more effectively than is possible with the case off
Thank you for the $50 power supply évaluation.
I would have been interested to see if your 5A load had been left on & the Amp limiter changed down, if the power supply would have correctly limited the amperage.
Is the yellow connector for AC?
Arthur.
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.
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.
This thing is linear. You can tell by it getting hot. And the gigantic transformer.
But uh... Durability is *better* for switching designs. They don't get hot.
@@JasperJanssen Although Linears are hotter than SMPS and less efficient, Linears used to be more reliable and durable. Also, i guess for audio power testing linear are better, in the college, someday i tested some TDA2040 circuits, some with linear psu and some using an old AT PC psu. The circuits tested on the AT psu exploded, all of them, the ones tested on the linear survived and worked almost perfectly. Despite that, personally i still prefer SMPS due its eficient and lightness
The current meter can be fixed with a few passive parts changed.
I have mine now accurate and even modified it to show 2 decimal places.
But 10.20A shows as 0.20A, but that is very small price for the higher resolution ...useful now that it is accurate.
I hope people read the comments.
WOW, I was just on Ebay and the last thing I looked at was this model power supply. then I come on here and this was in the first spot, so I had to check it out.
Yikes!
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
I have a power supply I built in college in 1986 still in use. normal transformer, based on a 4194 ic. 0 - 30v variable to 1 amp. Bearing in mind that most digital circuits these days are low power the need for 30v 10 amps is limited anyway. For the price and features the type of supply shown here is excellent value
Well thought out test and I think fair. Not a bad deal for $50 bucks.
Would something like this work fine using a breadboard to create LED lighting and other train related circuits for our HO Scale model railroad layout that has 15V across the tracks? Thanks!
I had it too. One day, I went away from table while it was running and when I arrived, board connected to it was smoked. Voltage limiter died and it switched from 5V to 30V and keep feeding circuit.
Just finished repairing my 305D. I was testing out a drone motor which operated probably at 3.7V to see how fast it could go. Started at lowest voltage and gradually cranked it up. Voltage was over 20V when the clip to the motor lead came off, so I put it straight back on, blew up the motor and the PS. Display read about 29V and couldn't be adjusted. Searched all over for a schematic, never found one that matched exactly. There are two 2N3773 output transistors (most schematics show 2N3055's). The bases and collectors are connected together (parallel arrangement) and the emitters have 0.33 ohm resistors which then join and go to the positive output. Both transistors and one of the 0.33 ohm resistors blew up. Replaced the blown 0.33 ohm resistor as I found it open first. Display read 49V and couldn't be adjusted. Then test the transistor. Both failed, one as a short base to collector. Main circuit board, display board and control board were ok. Replaced 3 defective parts and it worked again.
This is definitely a great buy for $50 finger prints or not. I also have one and have been using it for years.
Looking for some advice guys. Want a 'Reasonable' quality bench top rather than Lab power supply. Im a beginner so not wanting to overspend on it either. im looking at the £50 - £100 ish range. I might go £120 but thats really my max and i really really dont want to go that high. So what should i get ? Mostly use 5v or 12 v . Ideas ?
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?
Yihua normally makes decent gear for the price. I think the problem here was in part in front of the screen not behind as many have pointed out in the comments. :P Yihua makes a ton of the Chinese soldering stations and they all seem to be decently built.
Should have used the current range switch to make the meter read mA
I've got the same unit and I find that the amperage is way more accurate in milliamp mode.
i like these reviews to see how good this cheap stuff is, worth it for me. i assume when you adjusted the current meter, you adjusted the span pot, this is why it was out at full current. a little more tweaking it'll be sweet. just bought one for hobby use.
Thanks for checking stuff for me before I buy it lol love your channel
I have a similar one, also from eBay. Slightly different labels on it. At 8V it produces 1Vpp noise of 60kHz modulation. So, while any multimeter will show you the same voltage you set (because of averaging) - this kind of supply is pretty useless if you want to design/test any precision analog electronics (something with OpAmps, ADCs or DACs inside, for these cases I still use LiPo batteries as a clean power supply).
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.
Highly depends on what you're going to do with it.
I've got an ATX (PC) power supply, to get me +12V, +5V, +3V3, GND and -12V. It can also handle lots of current (driving LED strips and whatnot), has indicator LED's for pwr_on and pwr_ok. Along with a switch in the front to toggle it on and of.
But I also have a variable 0-30V 5A CC/CV regulator from ebay.
Together they fullfill pretty much all my needs.
"Professional quality power supplies" have remote sensing capabilities, which will do a much better job of delivering a constant voltage at the load when the load current changes. Any power supply with only two output terminals is non-professional, by definition, because the voltage is only regulated only at the supply's two output terminals. Add your cables and anything else to get the voltage to your load, and those wires/connectors add resistance, which creates a voltage drop when current passes through them. Remote sensing (like the very old HP supplies once had) eliminates this issue.
It's worth it for the box ,tran and meters .Rip the rest out and put your own in.
Is it possible to use for discharging lifepo4 cells at 1ah or 4ah?
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 .
What is the switch on the front panel for the current?
Yes choose high or low current.
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!
now, that's really bad. my chinese PSU didn't light up. Turned out that the ribbon cable going to the faceplate wasn't plugged in.
What a sulk! Not yet gone past Fahrenheit?
I just bought one identical to this one but its supposed to be 10amps. I only paid $15 for it from Hong Kong. Hopefully it does ok for the price lol.
would you recommend this for light work? I'm tempted to getting one for radios and toys nothing big don't need it for heavy loads just repairing toys and radios ect....
You can get a small adjustable switching power supply from Ebay for half the price.
Can you show me an example?
Matt Maloney who are you asking me or R&D?
I'm asking R&D, or anyone the who has a reasonable product reference. I was trying to reply to R&D's reply, but I guess it doesn't really work that way.
here is an ebay listing, you will have to use your own 24v transformer and convert the ac to dc, but if your learning electronics it's a good starter project.
www.ebay.com/itm/Buck-Step-down-LM2596-Power-Converter-Module-DC-4-0-40-to-1-3-37V-LED-Voltmeter-/221970563817?hash=item33ae7a02e9:g:gT8AAOSw5IJWcZxX
if you use current meter to read the current then you are facing with the unknown internal resistance of the current meter . therefore your reading current number may not be accurate. you should use the known resistance as a load then measure the voltage drop then calculate the current using Ohm law formula.
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.
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...
On a circuit design like this, if the pass transistor fails shorted, then yes, you get the full voltage straight from the transformer/rectifier passed right into your DUT.
I had a very similar experience. I had the PS connected to a USB cable and charging a tablet that was being picky about charger and USB cable. I was just topping off my charge before a trip, while I took a shower. I grabbed the tablet as I went out the door, but did not notice any smell. At the airport I realized my tablet was dead. and found it had some fried components in it. Two weeks later when I returned I found my PS was pinned at 50V. Inside a 3W 1K resistor on the board was completely cooked. one of the can caps was blown up. I have not taken the time to repair it, but I would think twice about using this PS unattended or on expensive equipment. I will say that the unit was a very useful tool up to this point.
Three different multimeters double heat sink, wires everywhere. Just set it up, all you need no. Is hooked F350 Cummins diesel engine to it. And your set
I got exactly the same unit (inside and out) under the Sunshine brand. It cost me around 40 bucks, but when I turn it on it just gives me 0.00 on both LEDs. Cannot get a voltage on it.
Anyone watching this have a cct diagram for this unit?
Good review. Saved me 50 bucks. Thanks.
They are excellent supplies.
The person doing the review does not know how to test it properly, and he really screwed up the metering my trying to calibrate the meters when he had little or no reading on them.
He needs to go back to 15 or 20 volts at 4 or 5 amps and recalibrate.
But when he recalibrates he needs to take the resistance of those crappy wires provided with the meter into account; OR do his voltage and current measurements right at the power supply output terminals...
he also has the leads to test amps connected wrong and is measuring the resistance of the wires.
the heatsink is only aluminium ?, for the money id expect platinum or at least gold .......
One good trick on those aligator clips is spray them with alcohol inside.
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.
My lame joke aside... I bought a Korad and one of the mains wires was pierced by corner of a heat sink. It was fairly accurate after I fixed that. been going for a year now I think.
Great review. 🤙
You got no idea about thermocouple. There is no need for isolation, it can be shorted and the measurement is still the same. The same is abot measurements themselves. 95.6... mA should be calibrated 0.10 A instead of 0.09 A. The device is superior compared to your knwledge. What abot voltage drops in the wires? Whatever you say expose your poor knowledge.
very helpful, thanks
Interesting, I have the same PSU, but the meter board is different. It's much more accurate as well! XD
And, it's a little older than yours I think ... heh, weird!..
His was accurate until he recalibrated it incorrectly.
50? An electronics store here in Greece sell these the past 10 years for 200 euros!!!
Say something positive geezz for 50 bucks!!
actually, it's not that bad. you are right.
very good video
Fingerprints might mean someones had a go at it and it was repackaged !!! You don't need heatsink for that !!
Excelent review, thank you !
I noticed these fingerprints on start of the video
this thing in local china market only cost about 25 dollars, maybe even include shipment.
for 50 dollars, sorry to let you know you got robbed.
i stopped wathing the video when i saw the inconsistency of the measured voltages between fluke and psu, anyway i liked the video, thanks.
there's nothing more annoying than FINE and COARSE pots on a bench top power supply
You cant be too harsh on a $50 psu.
Not having the case on allows better heat dissipation into the air. You're results may be a bit off...
So many comments here about this power supply being useless, but what is your better eBay alternative to this, or maybe you just like to tell useless opinions?
Hey, somebody has to pay for the gloves, arrrgh!
13:46 wtf was that
chinglish yup I know :(
Twing Twang Chinlish does help at all!
احسنت
mine out of the box was defective and junk, dont buy
50 buk and 150 shipment😲🤣
Castellano hablen
What are you expecting when you're paying cheap?! 👎
my 40$ diy psu is much better than this :c
in other words it is a piece of junk that there is no trust
God this is so boring. It’s like watching paint dry. Sorry!!!!!!