Definition
An electrical device that rapidly opens and closes a set of contacts to interrupt a steady direct current (DC), producing a pulsing or alternating current. In aircraft magneto ignition systems, a vibrator is used during engine starting to supply a stream of high-energy electrical pulses to the magneto primary coil, generating a hot, retarded spark for reliable starting.
Plain English
A small device that quickly switches an electrical current on and off many times a second. In aircraft, it helps create a strong starting spark by chopping up steady battery current into pulses the ignition system can use.
Context Anchor
Seen in piston-engine aircraft ignition systems, especially when discussing engine starting, hard starting, or older magneto starting aids.
Derivation
From the Latin vibrare, meaning to shake or move rapidly back and forth. The name describes what the contacts inside the device physically do — they oscillate open and closed many times per second.
Why Pilots Care
Without a functioning vibrator, many older piston engines become difficult or impossible to start, especially in cold conditions or with low battery voltage.
Analogy
It works a little like an old doorbell buzzer: a contact opens and closes rapidly, creating a fast pulsing action instead of one steady flow.
Intuition Check
Do not read vibrator here as simply “something that shakes the airplane.” In this context, it is an electrical starting-aid device that rapidly switches a circuit on and off.
Example Sentence 1
When the starter switch is held in the START position, the vibrator sends a stream of pulses to the left magneto, producing a hot spark for engine start.
Example Sentence 2
During the annual inspection the mechanic cleaned the vibrator contacts to ensure reliable starting.