Digital multimeter to measure the polarity of transistors and the methods of NPN and PnP

How to use the digital Universal meter to measure the polarity of transistors and the method of NPN, PNP .

First of all, say the pointer of the multimeter and the digital multimeter of the red-black pen and the internal battery connection difference;

So there are some differences between the two types of tables. Next, just talk about how to use the digital measurements.

Use a digital multimeter buzzer gear.
①, fixed base pole (b)
Select the transistor of the two pins, with a red and black pen to connect two pins, and then the red and black pen Exchange connection, if the two connections are not shown on (can be conduction, but the buzzer does not make a noise), the remaining pin is the base (b).

This is the internal structure of the transistor NPN and PNP, which is actually two diodes. Seeing this, you can understand why the first step of the judgment, and why it can only lead, but the buzzer will not ring.

②, Stereotypes (PNP, NPN)
The base has been determined, with a digital multimeter of the red pen to connect the B-pole, with a black pen to connect the other two pins, if the multimeter display can be conductive, the NPN type; Conversely, with a black pen to connect the B pole, with a red pen to connect the other two pins, if the multimeter display can be conductive, then the PNP type The principle is as follows, the Diode Single wizard pass. "Note: It's basically an NPN transistor."

③, fixed C-Poles (collector) and E-Poles (emitter) "For NPN"
Connect two pins except B with the red and black pens, respectively. Then with the tongue, lick the B-pole and one of the pins, if the multimeter is shown on, then the red pen is connected to the pin C (collector); If two pins are not connected, the red and black pens are exchanged, then the tongue, the B-pole and one of the pins, if the multimeter displays conduction , the pin for the Red Pen connection is C (collector), and the remaining pin is E (emitter). The principle is as follows:

Tongue licking, equivalent to between B and C acting as a resistor R. According to the schematic diagram can be seen, r is equivalent to conduction (can be said to be "short-circuit" b, the reverse diode between c) circuit, B, E is a forward diode can be conduction. Thus, the C and e Poles are judged.

The three polarity of the transistor can be judged by the above, but you can also measure it with the HFE gear of a digital multimeter. I think the internet is a lot of use of the pointer multimeter, the multimeter is not very common. wrote a digital multimeter blog. But the method and the truth are the same. At the same time, I hope that the great God to give me suggestions and questions, thank you.