Hi everyone. I send this message for everyone new to electronics as a warning to be careful and aware of how do you read a transistor datasheet. Never rely only on datasheets. Some transistor pinouts differ from manufacturer to manufacturer although they have the same model. Ignoring that, you can easily damage your transistor, without knowing the reason. Some semiconductor manufacturers are indicating their specific transistor model in their datasheets, and indicating their pinout numbers in different way, so not all of them are the same. For the example of the same model BF199, there are some different types of datasheets. Some of them may be old, some of them are new. Especially for the unbranded transistors. There you should be extra careful! Always use a multimeter that supports hFE reading. If you don't have that, use diode testing mode, but hFE is a must to easily get the correct pinout.