AC DC Power Adapter, AC- DC Power Module 12V 250mA Switching Power Module Input AC 110-240V Output DC 12V 3W, Used in Consumer Electronics, Instrumentation, and Smart Home, Etc. (2PCS)

Good little 12VDC power supplies with a few minor flaws
Tested at both 120VAC and 240VAC.Internally, it is designed for L and N input. So I was worried that USA 240VAC (L and L) was going to cause line leakage on the output.Since the label or case was not marked as UL listed, I performed my own “hobby” level testing as follows:1) I took a lighter and set one of the tabs on fire, confirming it would self-extinguish. It did immediately upon flame removal. — Pass2) Applied both 120VAC and 240VAC and compared output. Same. — Pass3) Attached to 120VAC. Then turned it on and off 20 times, varying the off time. Repeated for 240VAC. No output surges, no explosions. — Pass4) Floating no-load output does read high (15V). With a 1K resistor, it settles down to 12.5V and stays steady. Very light loads of just 1ma or less or light pulsing loads are poorly regulated between 12.5-15V. — Marginal result5) Applied a 90% load test for 10 minutes. The case runs warm to the touch. Does not run hot. — Pass6) Applied a small load test (15%) for over 24 hours. The case is slightly warm to the touch. Voltage remained steady. — Pass7) I attempted to test ripple (voltage and current) by setting my meter for VAC, and using it across the DC output through a 1K load. No gross ripple detected. But this is not the proper way to test it. I also used my frequency counter and noted some higher frequency noise but nothing surprising than what would be beyond ambient/HF noise from the regulation circuit which is to be expected. I was searching for 60Hz ripple at rated current and could not detect it. No audible noise is detected from the unit either. I do not have the proper equipment or scope to do this properly. — Pass (with caveats)8) Using 120VAC, no leakage to ground through the output (no load) when neutral is removed. — Pass9) Using 240VAC, I noted 22VAC leakage to ground during no-load output if either hot line is removed. This is fairly common with these types of power supplies designed for L+N and used on L+L USA circuits. The leakage current to ground must be too low for my meter to register (mA). After confirming no current, I could not feel any “tingles” when touching the output and ground with my fingers. Therefore I don’t think it’s of much concern, though I am not an expert in understanding leakage current and overall safety. — Pass (with caveats)10) Disassembled unit and noticed poor solder joints on the input and output leads. There are nice “through holes” for the leads (with good isolation) on the PCB, yet they were skipped and the leads just soldered straight to the pads. Unsure why they chose not to use the holes. Also noted no strain relief on the leads. — Marginal result11) Fit and finish is OK for what it is. But the circuit board does rattle in the case when moving the wires or shaking. — Marginal result12) I did not perform an overload test as I was in a hurry to finish a project and didn’t want to risk blowing up the power supplies. — SkippedSummary:Good product. No tests “failed”. Just a few “marginal” results. Most tests passed, and the unit does what it’s supposed to do. It has better regulation under load. No (or very low) load causes poor regulation (output above 12V). For very low loads, I recommend using a 1K resistor wired permanently across the output to clamp it down to 12V. A 1/2W resistor is fine. I also suggest disassembly and resoldering the input and output leads to use the through-holes on the PCB. And add small zip ties around the wires internally for strain relief.Overall I am happy with these little power supplies. Both have been in service for about a month now, working well so far.I hope this review helps someone.

Works
Works as advertised. Have been in continuous use for 12 weeks now.