Definition
A gas-filled electron tube designed to maintain a constant voltage across its terminals despite variations in the current passing through it. When the tube conducts, the ionized gas inside holds the voltage drop at a fixed value, so any device connected across the tube receives that steady reference voltage.
Plain English
A small glass tube filled with gas that keeps the voltage at a steady level, even when the electrical current going through it changes. It acts like a pressure-relief point that holds the voltage exactly where it needs to be.
Context Anchor
Seen mainly in maintenance information for older aircraft radios, instruments, and electrical equipment.
Derivation
Voltage comes from the name of Italian physicist Alessandro Volta, who invented the first electric battery. Regulator comes from the Latin regula, meaning 'rule' or 'straight stick' -- something that keeps things in line. Together the term describes a tube whose job is to keep voltage in line.
Why Pilots Care
Provides stable power to instruments and radios in pre-solid-state aircraft, preventing voltage swings that could disrupt navigation or communication.
Intuition Check
Do not read tube here as a fluid tube or hose. In this term, tube means an older sealed electronic device used inside a circuit.
Example Sentence 1
The voltage regulator tube in the radio's power supply held the plate voltage at a constant 150 volts.
Example Sentence 2
In the vintage aircraft, the voltage regulator tube glowed steadily once the engine reached operating RPM.