Hydrogen HP-45B hydrogen thyratron
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3D3DHP-45B hydrogen thyratron.
A thyratron is a vacuum tube used to switch on high voltages. They act like a switch that can be turned on by applying a small voltage to a control terminal. They can only switch on, not off: They turn back off only when the voltage being controlled drops to zero on its own. The modern equivalent is the SCR (silicon controlled rectifier) and triac.
This one contains a small (less than atmospheric pressure) amount of hydrogen gas instead of a pure vacuum. Various different gases are used in thyratrons, and apparently the hydrogen variety is used when particularly fast switching times are required.
Source: eBay seller tapent
Contributor: Theodore Gray
Acquired: 24 February, 2007
Text Updated: 29 April, 2007
Price: $5
Size: 5"
Purity: <1%