Charger humming?

jjk454ss

macrumors 601
Original poster
Jul 10, 2008
4,340
446
I have a charger/surge protector with 2 USB ports and 3 outlets. I just put it near my bed, so maybe it's always hummed and I never heard it till now, but when I plug in my iPhone or ipad it starts making a humming sound. Is this normal? Any reason not to use it?
 

westom

macrumors regular
Nov 8, 2009
229
23
... but when I plug in my iPhone or ipad it starts making a humming sound. Is this normal?
Coils are wound and then sealed with a varnish (or equivalent). So that winding do not vibrate. Sometimes the winding is not tight and varnish fails to seal that wire. You are hearing the wire vibrate. That vibration typically causes no threat to human life or electronics. And would become more obvious due to how some reactive appliances consume power.
 

jjk454ss

macrumors 601
Original poster
Jul 10, 2008
4,340
446
Coils are wound and then sealed with a varnish (or equivalent). So that winding do not vibrate. Sometimes the winding is not tight and varnish fails to seal that wire. You are hearing the wire vibrate. That vibration typically causes no threat to human life or electronics. And would become more obvious due to how some reactive appliances consume power.
Thanks. I thought it was fine, but I didn't want to take a chance so etching was wrong with it and it would do something to my devices plugged in to it. Wrong voltage or something strange:confused:.
 

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