Sure it's "linear," but it has a SMPS output stage with questionable filtering capabilities and high ripple (even though they claim it's 10mV, I highly doubt it
--100mV,
maybe).
It weighs ~3 pounds. The linear series pass stage will attenuate the noise, sure, but it wont be much with the amount of puny little capacitors and inductors they can fit in something that size. Instead of paying $36 on that sort of SMPS garbage, I'd much rather pay double for the GPC-3020.
The GPC-3020 available on eBay for $60-80, 30V, 2A, parallelable or series-able (to 60V, 2A), and
weigh 18 pounds. Look at its
impressive datasheet and you have a clear winner in terms of what the better quality PSU is.
I'm aware it's economically unwise to create a DIY power supply, because, well, it won't quite meet the performance of quality, factory made devices. With $20/hr wages, you can buy a quality PSU for 3-4 hours of work. Besides, building an op-amp based PSU is a good learning experience, and that's my main goal--experience and knowledge.
EDIT: Found a post with a schematic for a lab cc/cv PSU using very common parts:
https://www.eevblog.com/forum/testgear/are-cheap-ebay-power-supply-worth-the-money/msg248693/#msg248693Attached schematic for those curious.
EDIT2: edavid, those are all SMPS based cc/cv lab PSUs you're linking
There's nothing wrong with them, but what is a dead giveaway is the cost. A SMPS based lab PSU will need a lot of proper filtering for decent noise levels. At $36, I know for a fact that I can't find anything decent when buying those, new. A 10kuF, major branded capacitor costs $5 (Mouser), some TO-247 power transistors ($3 each), opamps, precision resistors, etc etc, it'll come out to at least $30 for the base parts if lucky. Much better off buying used linear PSUs for long term guarantee that the thing wont expode or pop the capacitors.