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The Music of the Protons

Paul Horowitz performing the nuclear procession experiment.

I just stumbled across this gem of an old video from MIT. It was made between 1983 and 1984, and stars Sidney Coleman, Ed Purcell, Paul Horowitz, and Isaac Silvera.

I’m a huge fan of Paul Horowitz, his Art of Electronics books have taught me much of what I know about electrical engineering. There isn’t a lot of info about him online, he seems to mainly keep to himself despite being a celebrity among electronics nerds.

The experiment they are performing is described in more detail at the bottom of this page: http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/nmr.html

A large magnetic field is applied to a sample of hexane (a straight chain hydrocarbon with 6 carbon atoms and 14 hydrogen atoms) which causes 1 in $latex 10^{7}$ of the protons to align with this strong magnetic field. Once the field is turned off, the protons precess around the earth’s magnetic field. They do this at the Larmor frequency of approximately 2-3kHz (https://en.wikipedia.org/wiki/Earth%27s_field_NMR).

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Bob Wildar’s Introduction to Semiconductor Devices

I recently came across the PDFs of Bob Wildar’s Introduction to Semiconductor Devices in the Computer History Museum’s digital archive. I haven’t read them yet, but from glancing through chapters 1 and 2 I’m really excited. I’ve been looking for a text that explains how transistors work, not just how to use a model to predict their behavior. While having a model is important for designing circuits, I really want to have an intuitive understanding of what happens inside of a transistor that allows it to act as an amplifier. I love “The Art of Electronics”, and while it tells you pretty much everything you need to use a transistor, it doesn’t really get into what is happening inside of a transistor (other than the famous transistor man).

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