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Added vacuum tube diodes section
They are used in many different technologies including fiber optic data reception, daylight sensors in automatic lights, IR Beam intrusion alarms, and even in CMOS and CCD image sensors where each pixel is actually a small photodiode.
They are used in many different technologies including fiber optic data reception, daylight sensors in automatic lights, IR Beam intrusion alarms, and even in CMOS and CCD image sensors where each pixel is actually a small photodiode.
== Vacuum tube diode ==
A vacuum tube diode is constructed with a glass envelope sort of like a light bulb, and it has a filament like a light bulb which heats up the cathode which in turns emits electrons. It also has a metal conductor inside called a plate, and when the cathode is more negative than the plate, electrons flow from the cathode through the vacuum to the plate where they then continue on through the rest of the circuit. If, however, the plate is more negative than the cathode, then the electrons are repelled by the plate and stay near the cathode and no current flows, generally speaking.
High voltage vacuum tube diodes can produce x-rays because the high voltage can accelerate the electrons toward the plate with such velocity that they emit x-ray particles when the electrons strike the plate.
Vacuum tube diodes were used of course before solid state diodes were invented, but continued to be used in high voltage applications even into the early days of solid state because it was still cheaper to build electron tubes then high voltage solid state diodes.
Modern x-ray tubes operate on the very same principle as a vacuum tube diode, however they usually have mechanisms to keep the plate from getting too hot and melting.
[[Category:Electronics]]
[[Category:Electronics]]