这是一个计数器原理图，主要是用protel dxp设计的，希望对大家有用-This is a counter schematics, it is mainly used Protel Pitch design, we hope to useful

书中详细的描述了protel dsp各种元器件的使用，并附有大量的电路设计例子，为精通protel打下基础。-The book describes in detail the various components of the use protel dsp, together with a large number of circuit design example, lay the foundation for the master protel.