Schmitt circuit widely used for waveform shaping

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This circuit functions as a zero-cross comparator. If there is no resistor chui, if
the signal is input from the inverting input terminal for zero-cross comparison, the noise in the input signal
will sometimes cause oscillation. In order to obtain positive and negative symmetrical hysteresis voltage ±y, use
a Zener = tube to stabilize the A1 output and obtain a square shield of about ±5v. For example, to
obtain a hysteresis voltage of ±100mV, the voltage dividing ratio must be 1/50. If five. =
lOkQ, R: approximately sookQ.
    The input voltage starts from negative
and crosses zero. When it crosses +100mV
, the Ai output saturates in the negative direction.
On the contrary, when the signal input crosses 1 iOomV from zero to
disk, then