To make a spot welding machine, two MOS tubes are needed, one is a high-pressure MOS tube, and the other is a drive MOS tube. The power of the driving MOS tube is smaller than that of the high-voltage MOS tube, and common MOS tubes such as 2N7000 or IRFZ44N are usually used, while the power of the high-voltage MOS tube is larger, and high-power MOS tubes such as IRFP460 are generally used. What kind of MOS tube should be selected also needs to consider the specific situation of the application, different MOS tubes have different voltage, current, power and other parameters, need to be selected according to needs.