Schmidt trigger has two steady states; The monostable trigger has only one steady state; The multivibrator has steady states.

when the input voltage is higher than the forward threshold voltage, the output is low; When the input voltage is lower than the negative threshold voltage, the output is high, and when the input is between the positive and negative threshold voltages, the output remains unchanged, which is the characteristic of the standard Schmidt trigger.

under the action of external pulse, a stable state turns to a transient state, which is maintained for a period of time and returns to the original steady state due to the RC delay link in the circuit, which is the characteristic of monostable flip-flop.

a self-excited oscillator that can generate rectangular waves. When working, the state of the circuit automatically alternates between these two transient states, thus generating rectangular wave pulse signals, which is the characteristic of a multivibrator.

Extended data

Application of Schmidt trigger:

1) Waveform transformation:

Triangular wave, sine wave and periodic wave can be turned into rectangular wave.

2) pulse wave shaping:

In the digital system, the waveform of rectangular pulse is often distorted during transmission, and the rising edge and falling edge are not ideal. After being shaped by Schmidt trigger, an ideal rectangular pulse can be obtained.

3) Pulse amplitude discrimination:

When pulse signals with different and irregular amplitudes are applied to the input end of Schmidt trigger, pulse signals with amplitudes greater than the preset values can be selected for output.

4) Forming multivibrator:

Signals with different amplitudes will generate rectangular pulses and rectangular wave pulse signals after passing through a Schmidt trigger with a suitable capacitor, which are often used as pulse signal sources and clock signals in sequential circuits. ?

Baidu encyclopedia-Schmidt trigger

Baidu encyclopedia-monostable trigger

Baidu encyclopedia-multivibrator.