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Can you talk a bit about the tingling sensation from touching the aluminium case of a macbook pro, when using a non-earthed cable with the power supply? With the latest macbook pro M1s, apple no longer include an earthed cable in the box (with the exception of the three pronged adapter in the uk).

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Here are some good answers about it [1], but it's current leakage from the mains voltage making its way onto your chassis.

You end up with upwards of 60V sine wave on your MacBook case, compared to the relatively grounded you (capacitively to your surroundings). This voltage creates some electrostatic force to attract your finger to the surface enough that you can feel a change in friction. The Disney Research Lab made a neat touch display surface that used the same effect (and higher voltage) to modify the friction and "texture" feeling for a haptic touchscreen [2].

1. https://la.disneyresearch.com/publication/teslatouch-electro...

2. https://la.disneyresearch.com/publication/teslatouch-electro...

Insufficient isolation between input and output. Perhaps you should try a medical-grade power supply.

https://www.seacomp.com/resources/medical-vs-commercial-powe...

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