The circuit is composed of n-channel insulated gate FET Q, bypass resistance RC, energy storage capacitor C and switching diodes D1 and D2. A control pulse is input to the gate of insulated gate FET Q. when the gate of Q is low potential, the gate source voltage difference is zero, FET q is turned off, and the energy storage capacitor C is charged through bypass resistance RC and diode D1. The charging time is determined by the time constant, The time constant also determines that the maximum pulse source voltage is a positive voltage, the FET q is turned on, the energy stored in the energy storage capacitor C is discharged to the sensor TX through the FET Q and diode D2, and ultrasonic waves are excited in the sensor TX. The resistance RD is used to adjust the excitation energy and change the amplitude of the excited ultrasonic wave.

Schematic diagram of capacitor instantaneous discharge

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