Hi everybody,
I recently bought this power supply, as the specs look quite nice and the comments here looked ok to me. Maybe my two cents are usefull to someone else, as this seems to be the only topic in a forum about this PSU.
First, what convinced me to buy it:
- small footprint
- high voltage and current rating
- mixed-mode meaning low dissipation and still low ripple
- overvoltage and overcurrent protection - this could come in handy when you first power up a circuit. Set overcurrent protection a bit above what you expect the circuit to take. If something is wrong, it will just power off and your circuit might survive.
- dedicated output enable button
- digital control - nice, if you want to set a exact current limit. you don't have to find it with outputs shorted, just enter it!
- save some standard setpoints as preset - not really needed, but i won't complain.
looks cool so far. not the cheapest but seems like a good deal from a known company, so take it!
when it arrived, i did some tests and the disaster started:
Interface:
- when you power it up, but don't enable the output, it doesn't show the set current and voltage but actual values. guess what ... both zero, very helpful -.- only when you turn the wheel to adjust values or press a button, the display is showing the set values, blinking for 3 seconds. after that, zero again. This is pointless and annoying!
- when you then press the enable button, it's NOT showing the actual values, instead again 3 seconds of blinking setpoints. only after that, you see if you draw 10mA or 1000mA. come on! I want to see instantly, what is happening! when i set 50V instead of 5V by accident, it's too late to tell me now. stupid!
- overcurrent / overvoltage protection: i tried setting an overcurrent protection for the purpose, i descibed above. it takes like pressing buttons 10 times to accomplish that -.- ok, i won't need it too often. BUT: this setting is also the top value for the usual current limit. I saw it coming - the PSU will go into current limit before the protection kicks in. yep, I was right, and it comes even worse, see Electrical.
- generally, many other settings are a bit awkward to reach. thats not too severe, but i have seen better.
Electrical:
- a rise time of ~700ms from 0V to 10V at no load seems quite a lot (see screenshot). that's certainly better than overshooting. Still I'm a bit puzzled at that long a time. Not what I expect from a quality PSU.
- but you don't have to search for the overshooting for long - you can't miss it when looking at constant current mode. and here, this unit proves, that it doesn't take half-measures :-P look at the screenshots!
some tests might be unfair (10V/20mA, 30V/100mA), but when I set to e.g. 3V/20mA like for a LED, it produces still an overshoot of factor 6.5!! it takes about 80ms to find back to 20mA. at 1V/20mA it's still factor 3,5 and takes ~180ms to find home! the results for other settings don't look different. unfortunately, I have no capable resistors at home. At work, I also did some tests with higher currents. same thing at 1 or 2 Amps.
Ummm, now I know the reason for the slow voltage rise time. If it had been faster, those figures would have been even worse ^^
- then, the promoted overcurrent protection (dotted line) does exactly ... nothing! more than 100ms limit exceeded in case of 1V/20mA. Doesn't matter, it had lost its use to me already (see Interface) :-P
- finally, there is one single good point: when the unit has decided to settle, current and voltage are quite accurate and ripple is indeed no issue. who cares about some oddities and spikes :-P
Do i have to say anything about my final opinion on this? YES!!! :
FAIL!!!!!!!!
Sorry for the longish rant, I simply had to vent my anger. And maybe it's even useful to the next one to buy this ***. I'm off, browsing for a new PSU
Bye, Alex
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