MATRIX MPS-3010D+ 30V 10A Regulated Linear DC Bench Power Supply with Voltage/Current Preset, Output Button - Precision 100mV 10mA Adjustable for Electronics Testing, Lab Experiments & DIY Projects

I took a bit of a risk buying this power supply with no reviews available, but I figured with free returns what could go wrong? So here is your complete, unbiased review. First of all, the unit is heavy and feels solid, with a metal case and a sturdy carrying handle. There are LOTS of ventilation holes on all three sides, and an opening for the fan in the back. When you first power on the unit, the fan does a quick self test but then turns off again - this is very nice! There is no constant fan noise unless actually needed. When first turned on, the output is off so no voltage is applied to the output terminals. In this state you can set both the desired voltage and maximum current using the two pairs of coarse and fine adjustment knobs. To turn on the output, you just hit the output on/off toggle. Once the output is on, the volt and amp displays show the actual output. You can adjust the voltage while the output is on, and you can also adjust the maximum current but you can't actually see what you're doing since the display is showing the flowing amps not the maximum amps. This is all as I would expect.To test accuracy I used a cheap multimeter and a nicer oscilloscope, which generally agree with each other within ~0.01V. Because the knobs are analog and the display is digital, there is a minimum and maximum knob setting that shows the same display value. I looked at the calibration at these minimum and maximum positions for several voltages (photos 1-3):1.0V:Min setting yields 1.04VMax setting yields 1.13V (~10% off)Output standard deviation <1 mV, actual peak-to-peak <10 mV10.0V:Min setting yields 10.01VMax setting yields 10.11V (~1% off)Output standard deviation <1 mV, actual peak-to-peak <10 mV30.0V:Min setting yields 29.8V (~0.7% off)Max setting yields 29.9VOutput standard deviation <1 mV, actual peak-to-peak <10 mVIn general, the output was always within ~0.1V of the set point. Ripple was negligible and constant across all voltage ranges, with no load and with a small 50 ohm load (0.6 A @ 30V).I also tested current flow, but I'm not sure how much I trust my cheap multimeter. Here's what I measured (photos 4-6):0.10A yields 0.08A (20%)1.00A yields 0.97A (3%)5.00A yields 4.93A (1.4%)I didn't try 10A because I didn't want to burn out my multimeter.When you turn on the output at 10V, there is a transient peak of 10.8V. When you turn off the output at 10V, there is a transient peak of 10.6V.If the output is on when you turn off the main power, it takes 77 ms for the output to start to decay. There is also a 20 us transient of up to 20V (photo 7). This is a little scary, and I would suggest disconnecting your circuit, or turning off the output, before powering down the whole unit. If the output is off when you turn off the main power, there is a 170 us transient of up to 10V. At least this one doesn't peak above the set point. These kinds of transients seem common in modern power supplies, but they're still a little annoying.All in all, for the price (especially for a linear PS), I think this is a very nice unit. It has all the features I've been looking for and no real downsides as long as you're careful with the transients.