I wrote an article in IEEE Spectrum about the history of the magnetic amplifier. Magnetic amplifiers were popular in the 1950s, even used as logic elements in computers, but became mostly obsolete as transistors improved.
https://spectrum.ieee.org/the-vacuum-tubes-forgotten-rival 7/13
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@kenshirriff Yeah, I first learned about mag amps in the 1970s. I thought it was a really cool idea. In the 1990s I repaired a couple of old industrial grade battery chargers for large banks of lead acid batteries on a ship. They used a bipolar power transistor to control the mag amp that handled the big power. Pretty neat. They worked. I patted myself on the back for knowing what I was looking at. Hah.
