This part is a kind of semiconductor called 2N4431.Function of this product has Trans GP BJT NPN 40V 0.002A 4-Pin MT66. Manufacturers : New Jersey Semiconductor Image and pinout : Some of the text within the PDF file : [ ... ] 2N4431 PDF Datasheet Download Metablog 2017/10/29 22:12 2017/10/29 22:12