Decent little AC adapter for under $5

RDL2004

I saw these "New at Mouser" PSM03 series AC adapters made by Phihong and added one to my last Mouser order. I got it today and it's really not very big at all. They come in several voltages and all are 2.75 watts. That's not a lot, but plenty enough for most small projects.




I bought the 7.5 volt version which should work well for supplying both 5 volt and 3.3 volt regulators. They come with 2.1 mm center positive plugs, which is fairly standard these days, and the cord is about 1 meter long. They also have a couple of 5 volt versions with USB jacks.

With no load, the output voltage was 7.48 volts. I ran it at 275 mA for about 30 minutes and it didn't even get warm (max is about 365 mA). Voltage regulation is pretty good at low current, but gets kind of noisy at higher current draw. Voltage drop at 275 mA was about 35 mV. That's nowhere near as bad as some I've seen. It is UL listed and Mouser says they're 90-264 volt input, but mine is marked 100-240 volts.



Anyway, not too bad at all for under $5 from a fairly reputable supplier.

LoopyByteloose

Wall warts have benefited greatly from the latest generation of switching regulator chips. I even have some that cleanly provide 5.0VDC. I see a lot that are specifically labeled for powering digital devices and claim better stability.

What I really should do, is go through my junk and throw out all those older wall warts have much wider voltage swings and are much heavier.

User Name

These look great, Rick. Cute, cool, quiet, classy! Thanks for the head's up.

RDL2004

AC adapters have definitely come a long way in the last five years or so. It seems like almost any of the the newer switch mode type will far out perform the old style linear kind, and use less electricity at the same time. You still have to be kind of careful and not take everything at face value.

Each one I buy gets a little bit of basic testing done on it before I plug it into anything expensive. I have a 9 volt switcher I bought for about the same price as the Phihong from, well, a popular supplier in NYC. It sags by more than a volt at less than 80% of it's rated full current load of 1 amp. I have another that came from the big W that's intended as a cell phone charger. Rated at 5 volts and 800 mA, it actually meets those specs pretty well, but it's noisier than the Phihong and cost about twice as much. Both are still usable, it's just good to know their limitations.