Kathy Joseph

The Origin of the Cathode Ray Tube: Physics of the Geissler tube to the Crookes tube

Let’s start in early 1857 in a laboratory in Bonn, Germany.  That is where a physics professor named Julius Plücker was working with an instrument maker named Heinrich Geissler to create odd glass tubes that were, according to Plücker, “incomparably beautiful[i].”  Geissler and Plücker didn’t know it, but these Geissler tubes would change the world.  …

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Howard Armstrong and Frequency Modulation

Frequency modulation or FM radio transformed how we communicate.  It was, as Armstrong’s nemesis David Sarnoff said, “a revolution”.  There are videos, books, and articles about this history but they seem to skim over the science.  In fact, I haven’t seen any videos or articles that simply and accurately describe how Armstrong’s original system actually …

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The Trials of Howard Armstrong

Wait, how can a good invention lead to the inventor’s destruction? Table of Contents Armstrong’s Struggle The Frequency Modulation Sarnoff’s Mistake Armstrong’s Rise The Law Suit Armstrong’s Death References Armstrong’s Struggle However, at the same time Armstrong was dealing with several lawsuits.  The longest of which was with Lee de Forest.  De Forest had invented …

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Howard Armstrong, David Sarnoff And the Influential Superheterodyne Receiver

The superheterodyne method is where two signals are mixed to make a lower frequency signal that is easier to deal with, and, according to Wikipedia, “virtually all modern radio receivers use the superheterodyne principle.” But where did it come from and how does it work and why (and how) did it usher radio broadcasting into …

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Positive Feedback (Regeneration) How a College Student Invented it in 1912!

Table of Contents Edwin Howard Armstrong The Start of Armstrong’s Invention References Edwin Howard Armstrong It all started with an extremely smart and tragically stubborn college student named Edwin Howard Armstrong.   Howard (he went by his middle name) grew up in Manhattan when it was just a relaxed suburb of New York to middle class …

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