ABSTRACT
Since the late 19th century, scientists have researched technologies
that provide an electronic switch and signal amplifier. The vacuum
tube is a triode with a hot cathode, plate anode, and a controlling
grid inside an evacuated glass tube as shown in Fig. 4.1. Since its first
patent in 1906, the vacuum tube was a dominant technology until
the rise of the transistor, around 1960. Yet even today, vacuum tubes
survive in specialized areas, including high-power applications,
audio amplifiers, and in military applications due to their resistance
to electromagnetic pulse. Besides these practical applications, the
vacuum tube is elegant in both structure and operation principle,
and whether the vacuum tube concept can revive in this era of solid-
state electronics, and once again prove its unique advantages, is an
interesting consideration.
