Definition
An electronic circuit that uses two amplifying devices (such as transistors or vacuum tubes) cross-coupled so that each one switches the other on and off, producing a repeating square-wave output. Multivibrators come in three forms: astable (free-running, generating a continuous pulse train), monostable (producing one pulse of a set length when triggered), and bistable (holding either of two stable states until triggered, also called a flip-flop).
Plain English
A small electronic circuit that flips back and forth between two states to produce on-off pulses. Depending on how it's wired, it can run on its own as a pulse generator, fire off a single timed pulse when triggered, or sit quietly in one of two states until told to switch.
Context Anchor
Seen in aircraft electrical and avionics maintenance descriptions, especially in timing, pulse, warning, and older radio circuits.
Derivation
From Latin 'multi' (many) and 'vibrare' (to vibrate or oscillate). The name reflects the circuit's output, which contains many harmonic frequencies rather than a single clean tone — a 'many-vibration' signal.
Why Pilots Care
Pilots normally do not operate a multivibrator directly, but one may be part of equipment that drives timing, flashing, signaling, or warning functions. Understanding the word helps when reading maintenance information or troubleshooting descriptions.
Grounding Statement
Picture a hidden circuit inside a panel unit creating regular electrical beats that another part of the system uses for timing.
Intuition Check
Do not read “vibrator” as a part that physically vibrates. In this term, it means an electrical circuit that changes between states.
Example Sentence 1
The transponder's timing section uses a multivibrator to generate the precise pulse intervals required for its reply code.
Example Sentence 2
A faulty multivibrator in the instrument amplifier caused the indicator needle to flicker at regular intervals.