单片机电子制作文章，打包合集，包括：40kHZ超声波收发电路，ＦＭ调频发射，红外线自动门控制器电路，指纹识别系统，省电实用的电话灯等-SCM electronics manufacturing articles, packaged Collection, including: 40kHZ ultrasound transceiver circuit, FM FM transmitter, infrared automatic door control circuit, fingerprint identification system, energy-saving lamps and other useful telephone