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A comment on The Magnetic Amplifier – A Lost Technology of the 1950s. Parent comment

Re:The Magnetic Amplifier – A Lost Technology of the 1950s by 082349872349872 on Thursday June 18, 2020 @04:31AM (#23561029)
Now locomotive power engineers can even have fun turning bugs (harmonics in the audio range) into features (solfege):

https://www.youtube.com/watch?v=_iLrXDU31Dg

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Re:The Magnetic Amplifier – A Lost Technology of the 1950s by VBprogrammer on Thursday June 18, 2020 @07:23AM (#23562010)
For anyone else wondering what's going on there, certain types of semiconductors have a minimum off time. They have to work around this by varying the frequency of the PWM. Usually it results in a kind of space age sound as they accelerate. In this case they have chosen something more interesting.
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