Definition
An electronic circuit that has two stable output states and remains in whichever state it was last switched to until an input signal causes it to change. The most common form is the flip-flop, widely used in digital logic, memory storage, and counting circuits in aircraft avionics.
Plain English
A circuit that can sit in one of two settings — call them on and off — and stays there until something tells it to flip to the other one. It does not drift back on its own.
Context Anchor
Seen in aircraft electrical and avionics discussions, especially where electronic switching, stored states, or control logic are explained.
Derivation
From Latin 'bi-' meaning two, and 'stable' meaning steady or unchanging. So 'bistable' literally means having two steady states — a useful hint that the circuit has two resting positions, not one.
Why Pilots Care
A pilot does not usually operate a bistable circuit directly, but this idea helps explain how some electronic systems remember a selected condition or hold a switch position electronically.
Analogy
Think of a wall light switch. It rests in either up or down, and it stays there until someone moves it. It does not slowly fall back to the middle.
Intuition Check
Bistable does not mean slightly stable or unstable. It means the circuit has two separate states that are both stable.
Example Sentence 1
The aircraft's digital display uses bistable circuits to remember the pilot's selected mode until a new input is made.
Example Sentence 2
Bistable circuits allow the warning system to remain active until the pilot resets the condition.