I was loading mine with 12 V and 4 A for about 3 hours and the fan was turning on from time to time for around half a minute. You can definitely hear the fan. The ambient temperature was 25°C.
Can I have a continuously variable output, perhaps to connect a zero volt fan and increase the voltage to see how much it accelerates and when its noise starts to become annoying? Or can I vary the voltage only if the output is disabled?
Thanks for the video, and I will buy the 30v with 10a output unit through the link on this youtube description, and changing to a 10a unit instead of 5a unit you are reviewing, and hope you will get a credit from Amazon. 🙂. I would like to have 2 questions for you: 1)are the USB voltage and USB current displayed on the screen as well? 2)Have you tested the maximum USB current output, i.e 3.6 amp at 5v, because somewhere on the Amazon page, the description indicated the USB output is 5v at 2amp not 18w.
I appreciate the support of the channel. The USB-output voltage and current are not displayed on the screen, just the voltage and current output through the banana plugs. I did not test to see how much current could be pulled from the USB. I saw the USB charging port as more of a bonus, not something I was specifically shopping for, so I did not rigorously test it.
@@reedpetersen I keep my word, I placed the order thru the Amazon link as shown in the description of this RU-vid. "Order placed, thanks! Confirmation will be sent to your email."
Help!! Just got an oscilloscope and learned the importance isolating power supply from the same ground as the oscilloscope. What is the correct way to use a probe on this, the alligator clip on neg and probe in pos? How would this work in circuitly would i always keep the clip on the neg side of the circuit?
I have the same unit. You are correct, I don't think you could find another unit at this price point that has these features that all work so well. I used my dmm and it was ever so slightly more accurate than yours, which is more than enough for me. I am just a bumbling electronics hobbyist. I look forward to the day when I know enough and have progressed far enough to need something better!
The square hole behind was meant for a USB connector, enabling the PSU to be connected to PC for remote control, that’s what I heard. I’m planning to get one that is 120V 3A for my work though. Btw, the brand i meant was Wanptek, which has a very similar design to what you have there.
9.978v vs 10v is just over 0.2% not 3%, thats really good, and at 30v it's 0.17%, I'm not sure how you could get much better than, I would say its very accurate. 2v noise seems huge though, is that definatly correct? I guess its just a peak at the very high frequency? Might be nice to give a noise figure in dB at say audio frequencies as that would be quite useful to know for a lot of uses. Also its a shame you didnt give us the ripple voltage as I can see you had it plugged into a scope. I like the look of these things but I would be concerned they would be noisier than a traditional psu with wound transformers and voltage regulators. They do seem very good value though.
Yes, it is plenty noisy, especially at high frequency, compared to its beefy linear counterparts. My main reason for measuring this range (MHz) was because this is where the power supply is the noisiest. This is also the basic operating principle of a switching power supply, it uses high frequency switching to give a stable voltage so this is to be expected unless they do a good job filtering the output. And correct, I must have misspoke. 0.2% would be the difference. Quite good for a cheap power supply, yes.
Thanks for the reply, yes that makes sense to test the HF noise. I was wondering how good these would be as a power supply for breadboarding audio circuits, so I was thinking about noise further down the spectrum. Ive realised these are probably overkill though for that sort of thing though as most circuits for audio use way less than an amp. @@reedpetersen
Great Review! Would you be able to test the protective contact of the power supply, i.e. whether there is no voltage on the housing in an emergency? According to my information, this can be a problem with cheap power supplies.
No, I don't think it directly cuts off connection because it oftentimes takes a little bit (half a second or so) to settle down to 0 current from whatever voltage you are supplying. I think it is more of a command to the switching circuit to stop supplying current.
@@reedpetersen Thanks! I understand that is a "soft" button. Question was more about its working function. I want to upgrade my old linear 305d power supply with this function, and may be with a SC button for adjusting amps. Direct on front panel.
The noise on he output voltage would concern me for the widest use. A liner power supply with fixed 3.3volt and 5 volt Terminas and an adjustable 0 to 30 volt output channel at even one amp would cover most work in the electronics lab, obviously adjustable current limiting on all channels is escentual. One of the things to look at on any bench supply is the output capacitance and how quickly the current limits, how quickly the voltage recovers and with what overshoot. Smps tend to have large output capacitance to reduce the fluctuations. Those big capacitors are just waiting to dump into your delicate masterpiece. Why not check out the above with your scope and compare with one of your linear supplies. I bet the peak output current of a given setting, say 100mA has a spike more like 3 times that and the voltage recovering overshoots by more than you would like, it would be interesting to see. I agree we are talking a budget psu here, but, two digits after the decimal point that are meaningless due to the output fluctuations may lead you to think it looks better than it is especially if the current limit is for all intense and purposes nothing more than protecting the psu itself.
Yes, you can charge batteries. CC mode works well for this. No reverse voltage protection, as it is a general use power supply not specifically meant for charging batteries. It is up to the user to add some application-specific protection where needed.
This power supply does not operate in constant current mode.. It does, however, demonstrate the ability to set an upper current threshold limit. Were this able to operate in a constant current mode, for example, shorting the leads and adjusting the current to 0.001A ie; (1 milliamp)- and thereafter connecting a load of 1000 ohms across the (+) and (-) output terminals SHOULD indicate 1 volt. It does not. I own this same power supply, albeit it is the 60V/5A model. Let's say the load is actually 1234 ohms rather than 1000 ohms, therefore this DC power supply supply should (and this equipment does not) slew the voltage across the load to 1.234 Volts. In my experience this manufacturer supplies (no pun intended) a solid product meeting the OEM's specification. The constant current foible I examined seems honest and attributable to the vagaries of the Chinese (Mandarin?) languages translation to English. This OEM even included a very nicely attempted explanation of how to set the power supply upper current limit threshold.. I believe many technicians and technologists are not typically exposed to 'Constant Current' functionality in higher-end bench power supplies (Agilent, Lambda, etc) while the verbiage 'constant current' has been heqar bandied about by more senior staff. Another term for 'constant current' is a 'force-and-measure' type circuit which seems more common in the EU and large corporate development labs. Mr. Peterson provided a very professional presentation here and should be commended.
I'm not sure this is the case. I have seen that when I put it into constant current mode to, say, charge a battery, the current hits its upper threshold, and the voltage "floats" based on the resistance of the load attached. You can also see this in the video when I connect the light bar: the voltage doesn't make it to the set voltage, but instead the power supply outputs as much voltage as needed to push through about 5 Amps of current. I am not sure it is good at this at low currents (to your example, 1 mA might not work well) simply due to the imprecision of this supply, but I do believe CC mode works based on my understanding. I read NI's manual on power supplies (located at download.ni.com/evaluation/pxi/Power_Supply_Fundmentals.pdf ) and it seems that this power supply behaves properly in constant-current mode based on their description.
CC mode works just fine. I set V=30V and A=150mA on mine. As soon as I connected a 43R 3W resistor, the voltage adjusts down to 6.53V and the current stays fixed at 150mA. If yours isn't behaving like this there's something wrong with it.
