The 2N3906 Is 40V 200mA 625mW PNP Bipolar Transistor is designed for use in linear and switching applications. The device is housed in the TO-92 package, which is designed for medium power applications
The PL2303HX is a USB to UART TTL (Transistor-Transistor Logic) converter module that allows communication between a computer or other USB-equipped device and a UART device through a USB port.