Introduction to the method of distinguishing NPN and PNP tubes using the HFE file of a multimeter
On the dial of the multimeter, there is a gear marked with the letters HFE (as shown in the figure below), which is specifically designed for transistors. In the upper right corner of the dial, we can see 8 sockets with numbers and tube types labeled on their surfaces. Therefore, we can use these markings to identify the type of transistor being measured.
How to utilize it? If you don't know anything about this transistor at the beginning, you can try inserting the three pins of the transistor into the socket. If after inserting it, a relatively large and stable number can be displayed on the display screen of the multimeter, then we have inserted it correctly. We can judge based on the information marked at the position of the meter socket. In the previous article, we actually used this method to not only identify the type of transistor, but also the pins of the transistor. The following two pictures are actual measurements of PNP and NPN types.
What if we find that there are no large numbers during measurement? It's okay. We just need to change the insertion hole or the direction of the transistor insertion until the two pictures above appear. This way, we can identify the type of transistor and even measure the magnification factor. In fact, the magnification factor is the number displayed on the multimeter screen.
