LM 193 voltage double comparator, with 8 pins positive and 4 pins negative. The single power supply voltage range is 2-36V DC, and the dual power supply voltage range is +- 1V to +- 18VDC. Pin 2 = inverting input A, pin 3 = noninverting input A, pin 1 = output A.

The output is in the form of open collector. LM 193 is used as comparator, with square wave as input and triangular wave as output.

U2 and U3 TLP 18 1 are optocouplers. When the 1 pin is high, the resistance between 3 and 4 is equivalent to a small conduction. On the contrary, it is equivalent to breaking the circuit.

Q 1 HAL8 15s is a hall sensor, which outputs a square wave.