Fixing Faulty But Genuine Apple Power Adapters

apple The standard power adapter for Apple laptops is a work of art. The Magsafe connector has saved more than one laptop owned by the Hackaday crew, and the power brick with interchangeable plugs for different countries is a work of genius. Being a miracle of modern manufacturing doesn’t mean Apple gets it right all the time; the UK adapter doesn’t use the ground plug, leading to the power supplies singing at 50 Hz when plugged in. [Gareth] had had enough of the poor design of his charger and decided to fix it.

The Apple power adapter has two obvious connections, and another shiny metal disk meant for a connection to Earth. In most of the Apple charger ‘extension cords’, this earth connection is provided by the cord. In the smaller plug adapters – even ones where space is not an issue, like the UK plug – this connection is absent.

To fix this glaring oversight, [Gareth] shoved some aluminum foil where the earth terminal on the plug should go. A hole was drilled through the plug to connect this foil to the Earth socket terminal, and everything was covered up with kneadable epoxy.

No, aluminum foil probably won’t do its actual job of preventing horribleness in the event of an insulation failure or short. It will, however, silence the 50 cycle hum emanating from the power adapter, and that’s good enough for [Gareth].

Tube preamp with a dazzling wood case

It’s been a while since we’ve looked in on the world of vacuum tube audio equipment. [Bruce] just finished documenting a tube preamp he built. He actually made a couple of these with slightly different cases but they use the same circuit design. We found his discussion of common errors made when tying into ground quite interesting. It seems that many folks struggle with noise in their circuits because of ground loops. There’s some details about isolating the signal ground from a metal chassis, and also an admonition about not connecting the input or output jacks directly the chassis.
If you like this, don’t miss on of our favorite tube projects, [Bruce’s] Poddwatt.

USB Isolation

[Oleg] over at Circuits@Home has made a USB isolator for his hacking needs. This isolator separates the signal, ground, and power lines of a USB host device, such as a PC, from a USB device like a USB oscilloscope or logic analyzer. This might be useful for Keyboard sniffing, ECG, EEG or diagnosing the control system on the positive ground of your autonomous Ford 8N. What other applications can you come up with for this tool?