Digital multimeter measurement of transistors and MOS tubes

Below is the structure of the transistor and the various identification methods in the circuit diagram

When the multimeter is set to the diode position (buzzer position) to measure the transistor, we must first determine which leg is the b pole. Use the red test lead to touch any one leg without moving, and the black test lead to touch the other two legs. If two sets of numbers that are similar and less than 1 can be measured, it means that the red pen is touching the b pole at this time. If the two sets of numbers measured are not similar, it means that the red pen is not touching the b pole at this time. The red pen should be changed to another leg, and the black pen should be used to measure the other two legs until the b pole is found. If we know which leg is the b pole, how can we determine which of the other two legs is the c pole and the e pole? As shown below:

In the figure, the red pen is at the b pole. The black pen measures two sets of similar data at the other two pins, one of which is slightly larger, and this pin is the e pole, and the smaller pin is the c pole. And we know that this tube is an NPN transistor, because the red pen is at the b pole! The measurement method for PNP transistors is the same, except that the black test pen is at the b pole, and the red pen touches the other two pins to measure two sets of similar data, as shown below:

The following is the measurement method for field effect tubes.

Field effect transistor is abbreviated as FET, which can be divided into junction field effect transistor (JFET) and insulated gate field effect transistor (MOSFET). We usually call it MOS tube for short. MOS tube can be divided into enhancement type and depletion type. The enhancement type MOS tube is commonly used in our motherboard.
The following figure shows the logo of MOS tube:

The three pins GDS in the MOS tube commonly used in our motherboard are fixed, whether it is N-channel or P-channel, put the chip upright and from left to right they are G pole, D pole and S pole respectively! As shown in the figure below:

The measurement sequence is:
1. To measure the MOS tube with the diode range, first short-circuit the three pins to discharge the tube, then connect the red test lead to the S pole and the black test lead to the D pole. If the measured value is more than 500, it means that the tube is N-channel.

2. Keep the black pen still and use the red pen to touch the G pole to measure a value of 1.

3. Move the red pen back to the S pole, and the tube should be turned on.

4. Then use the red pen to measure the D pole and the black pen to measure the S pole, and the measured value should be 1. (Pay attention to this step. Because the voltage of 2.5V multimeter was given to the G pole during the previous measurement, the DS is still connected. However, it will return to normal after about 10 seconds. It is recommended to short-circuit the three pins to discharge the tube when performing this step).

5. Then keep the red pen still and use the black pen to measure the G pole. The value should be 1.

At this point we can determine that this N-channel field transistor is normal. Some people say that the last two steps can be omitted, but I am used to using all five steps, it's a matter of personal habit!!! Of course, the measurement steps for the P-channel are the same, except that the first step is to use the black test lead to measure the S pole and the red test lead to measure the D pole, and a value of more than 500 can be measured.

My understanding of the junction type is that when measuring, the D pole and the S pole are conductive. If the red test lead is connected to the G pole and the black test lead is connected to the DS pole, two sets of similar values ​​should be measured, and this tube is an N channel. If the black test lead is connected to the G pole and the red test lead is connected to the DS pole, two sets of similar values ​​should be measured, and this tube is a P channel.