(Last Updated: April 30, 2020)

Wall Warts AC-DC power supplies tested

  • As most electronic systems, home control/automation appliances are DC powered. We power them either with batteries or what we mistakenly call "AC" pointing to the house plug AC power. My recent discovery that some of these wall warts close proximity to my zwave module can cause RF noise, and the proliferation of these constantly plugged AC-DC converters drove my curiosity to go test a large number of them with whatever equipment I have for RF emissions.
    I am using a simple 50-60Hz AC detector from the hardware store which relies on detection of RF emissions induced by AC current to detect ripple in the DC line. I will be using an RF meter for my next test which will be more sensitive but require more isolation (I have not yet received) from the environment for increased accuracy but for this first post, that's all I have.

    I was quite surprised that across a very large variety of wall warts, all of them emit noise an buzz the AC current detector when I plug the exact same USB cable into them or down the line of the wart:
    Apple iPhone 5W
    Apple iPad 10W
    Apple iPad 12W
    Apple MacBook USB-C PD 29W
    Amazon Echo Dot Gen1
    Amazon Echo Dot Gen2
    Amazon Echo
    Amazon Show Gen1
    Amazon Show Gen2
    Vera (Edge/Plus)
    Amcrest & Foscam IP Cams (I have a large variety of them)
    Philips Hue/Friends of Hue (all of them)
    Logitech Harmony
    A very large set of multi port USB chargers from Amazon branded Anker, iClever, RavPower, Vogek, Aukey. All of them get.
    Microsoft Surface Dock power brick
    Lenovo Wall Wart Designed Laptop 45W USB-C charger
    USB port from all CyberPower UPS (I have 6 models)
    USB port from the white colored APC UPS

    The only lines I have found to not ripple are:
    USB ports from the black colored APC UPS
    Power coming out of all my desktop PCs/Macs and laptops (except for that Surface Dock which I think is the same as the one for the Surface laptop). HP, Dell, Lenovo, Apple.
    Oddly the OEM Microsoft Surface Pro 4 travel charger does not ripple neither on its USB-C or its USB-A Port
    All the USB-C powered laptop chargers (except for the MacBook 29W one)
    Ubiquity Unifi line of products from non POE to POE switch including the USB C power USW Mini, POE injectors for APs.

    I am considering replacing everything I can: For ethernet networked devices, using a POE splitter; for all the others, using 45W USB PD laptop chargers off of eBay to plug into a usb-c PD hub to act as a multiport USB charger. (this came to be negligibly more expensive than a dedicated charger).
    If this measure is a gauge of quality of the AC-DC power supplies, a vast majority of them fail the test... Opinions? Are the USB power specs that loose and how about all those 12V devices?


    An interesting read on the topic, though my results on some of them don't quite match and another site with a database of reviews.

  • @rafale77 depressing reading. I'm tempted to test my Anker charger but....


  • Yes, if I were to build a new house it would have a regulated 12/5V distribution system. There don’t seem to be any widespread standards for plugs & sockets, though. Best practice seems to come from the marine industry. The usual car 'cigarette lighter' approach is certainly not adequate... looks worse than a wall wart!

  • Disappointed to say that I got another one fail the test with a Lenovo 45W laptop USB-C "Wall wart" style charger.
    Generally speaking, the laptop chargers with a ground prong seem to be better quality, with the microsoft Surface travel charger being the exception. Pretty sad reality that these send enough ripple down the line to trip a $2 AC voltage sensor even without load.

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