Transistor method for judging polarity

Before the method of judging the transistor is used by the memory method, that is, as long as the three-level tube series Let it have a face of their own words, from left to right in turn is E-Class B class C. Until one time in the process of using the transistor circuit in a mistake, found that the pipe is always inexplicable conduction, find a good reason for a long time, finally found that the NPN tube has a sequence of e-Class C-Class B. In order to prevent further errors, and then found a variety of data to determine the transistor polarity method, summarized here.

1: In general, instruments that measure the polarity of transistors typically use a multimeter. (except, of course, if you have time to switch tests on the hardware circuit)

2: First of all to declare a point of view, if the multimeter as a power source, the pointer multimeter black pen is positive, the red pen is the negative. The digital multimeter is opposite to the pointer multimeter.

3: Measured with a pointer multimeter (red negative black positive):

(1): Adjust the position of the pointer multimeter to the R x 1K gear, first the Red watch pen to any one pin, with a black pen to connect the remaining two pins in turn, if the two are on, then the red table is the level of the pen to class B. The transistor is a PNP type transistor. Observe the two-level resistance of the black table pen, the resistance is slightly lower than the C-class. (If there is no conduction, the red pen is changed to the remaining two pins in turn, repeating the above actions)

(2): If the above three times the order of the Red pen is not the result, the Black table pen to any one pin, with a red pen to connect the remaining two pins in turn, if the two are on, then the Black table pen to the level of B. The transistor is an NPN type transistor. Observe the Red watch pen to the two-level resistance size, the resistance slightly smaller for the C-class. (If there is no conduction, the black pen is changed to the remaining two pins in turn, repeat the above actions)

The transistor polarity can be measured by means of a pointer multimeter.

4: Using digital multimeter measurement (red Positive black negative):

(1): First of all, a simple way to measure, now the digital multimeter generally with HFE gear. The function of this gear is to measure the current magnification of the transistor. Usage: Dial the multimeter's gear to the hFE file, insert the three pins of the transistor into the measuring hole in different order, then record the insertion sequence if there is a number. (The measured 8050 plug-in transistor's magnification is 250, 8550 the plug-in transistor's magnification is 304).

(2): The second measure: the multimeter to the measurement diode, the red pen to any one pin, with a black pen to connect the remaining two pins in turn, if the two are on, then the Red table pen to the level of B. The transistor is an NPN type transistor. The measured value of the two levels of the black table pen is observed, with a slightly smaller value of C-class. (If there is no conduction, the red pen is changed to the remaining two pins in turn, repeating the above actions)

If the above three conversion of the Red pen is not the order of the results, the Black table pen to any one pin, with a red pen to connect the remaining two pins in turn, if the two are conduction, then the black table is the level of the pen to class B. The transistor is a PNP type transistor. Observe the magnitude of the measured value of the two levels of the Red watch pen, with a slightly smaller value of level C. (If there is no conduction, the black pen is changed to the remaining two pins in turn, repeat the above actions)

The transistor polarity can be measured with a digital multimeter using the above method.

Welcome reprint: Reprint Please indicate source: http://blog.csdn.net/zbb564833642/article/details/17002521