介绍了几种40kHZ 超声波发射电路的原理图和说明，了解内部原理和电路。

介绍了几种40kHZ 超声波发射电路的原理图和说明，了解内部原理和电路。-Introduction fired several 40kHz ultrasonic circuit schematic diagram and descr iption to understand the internal principles and circuitry.