Definition
A small evacuated electron tube used in older aircraft electrical and electronic equipment to maintain a constant voltage at its output despite variations in supply voltage or load. It contains a gas that ionizes at a specific voltage, holding the voltage across the tube steady within that range.
Plain English
An old-style vacuum tube that holds a steady voltage in a circuit, even when the input voltage moves around.
Context Anchor
Seen in aircraft engine and carburetor system descriptions, especially when studying how a float-type carburetor meters fuel.
Derivation
Regulator comes from the Latin regula, meaning a rule or straight stick used as a measuring standard. A regulator keeps something within set limits. Tube refers to the glass envelope that holds the gas and electrodes. Together: a tube that keeps voltage within set limits.
Why Pilots Care
Correct pressure delivered through the regulator tube is essential for consistent engine power and to prevent lean or rich conditions that could lead to power loss or damage.
Intuition Check
Do not think of the regulator tube as an adjustable valve the pilot controls. It is a fixed passage that helps regulate fuel flow by changing pressure inside the carburetor.
Example Sentence 1
The technician traced the unstable radio output to a worn regulator tube in the power supply.
Example Sentence 2
During the engine run-up, fluctuating manifold pressure traced back to a loose fitting on the regulator tube.