Armstrong and the Superheterodyne: A Historical Look at the Mixer

It is difficult to pinpoint the invention of the mixer. Although the superheterodyne receiver was invented by Edwin Howard Armstrong around 1918, the use of heterodyne techniques began much earlier, and a crude modulator, arguably a sort of mixer, existed in 1906. Thus, we are currently at a soft 100-year anniversary of the mixer, so it seems like a good time to look back at that technology to see how it arose. It's a good story.