BF819 PDF datasheet can download.
This product has NPN high-voltage transistor functions.
This is one of the semiconductor types. This part name is BF819.
Manufacturers of the transistor is Philips Semiconductor.
Some of the text files within the PDF file
NPN high-voltage transistor in a TO-202; SOT128B plastic package.
· Driver for a line output transistor in colour television receivers.
[ … ]
· Low current (max. 100 mA)
· High voltage (max. 250 V).
Please refer to the file for details.