Mercury arc rectifier

[ppppenguin]

The "singing arc" phenomenon was a concern for William Duddell: https://en.wikipedia.org/wiki/William_Du...ing_arc%22

Important work on the subject was done by Hertha Ayrton. She was the first prominent female electrical engineer.
https://www.theiet.org/membership/librar...tha-ayrton
https://en.wikipedia.org/wiki/Hertha_Ayrton

I've no idea how much noise the arc in my MAR makes. Drowned out by the hum from the wound components and the cooling fan.