monostabile

Monostabile, in electronics, refers to a monostable multivibrator, or one-shot, a circuit that has one stable state and one quasi-stable state. When a trigger input occurs, the circuit temporarily switches to its unstable state and then automatically returns to the stable state after a predetermined interval, producing a single output pulse.

The pulse width is set by external components, commonly an RC network; durations range from microseconds to seconds in typical circuits. In a typical 555 timer monostable, the pulse width is approximately t ≈ 1.1 R C.

There are retriggerable and non-retriggerable variants, depending on whether a subsequent trigger during the timing interval should extend the pulse. The choice depends on the intended behavior of the circuit in a given application.

Common implementations include the 555 timer in monostable mode, as well as discrete transistor- or op-amp-based designs. Monostable circuits are used to generate precise timing pulses, implement debouncing, perform edge detection, stretch short signals, or condition slow or noisy inputs for further processing.

Monostable circuits contrast with astable circuits (which continuously oscillate) and bistable circuits (which maintain one of two stable states until switched).