一款靠3977驱动的驱动器原理图和PCB图纸，适合一般42、57型步进电机的控制。-A by 3977 driven drive schematic and PCB drawings suitable for general the 42,57-type stepping motor control.

1602液晶屏的pcb原理图，设计电子时钟。附有C51单片机开发程序等。-Schematic diagram of PCB 1602 LCD screen, electronic clock design. With C51 MCU development program.