How to identify and detect transistors?

How to identify and detect transistors?

pin recognition method

Intuitionistic recognition.Figure shows the pin distribution diagram of common transistors.

Figure 6-3a shows a transistor with a metal shell encapsulated.Its three pins are in an isoscele triangle,the middle one is a base B,the root near the convex key is the emitter E,and one on the top is the collector C.In a glass encapsulated transistor,the pin distribution is also shown as an isosceles triangle,but it has no convex key mark,and the pin distribution rule is the same as above.

Figure 6-3b and Figure 6 3C show two transistors with two pins and metal packages. The power of the transistor is larger. The two pins of the transistor are B and E, they are distributed above the horizontal centerline, the left is B pin, and the right is E pin. The metal shell is the collector C. The transistor has large power and is directly connected to the housing for heat dissipation. On the circuit board, the transistor housing is connected to the circuit board through fixed screws. Figure 6-3d, 6-3e, and figure 6-3f show a plastic encapsulated transistor with the names of pins on the transistor housing. However, there are many kinds of transistors packaged in plastic. Most of them do not mark pins on the shell, and the distribution rules of each pin are different. In use, it is necessary to identify them by measurement.

Figure 6-3g shows the flake transistor,which is characterized by small size and short pins,which can be directly attached to printed circuit boards and suitable for microcircuits.

multimeter identification pin.

The base is determined and the NPN and PNP transistors are distinguished.It is assumed that an extremely polar base is blocked by multimeter RX12~RX1002,the black pen is assumed to be the base,and the red pen is used to measure the other two electrodes.If the needle is swaying,it is assumed that the hypothesis is correct (for example,if one movement is not repeated one time,it is incorrect,and a base should be assumed again).At this point the black pen is connected to the base of the NPN transistor.If the needle is stationary,the assumption is correct,indicating that the black pen is connected to the PNP base.This method can also be used to distinguish PNP and NPN transistors.

A method of distinguishing the collector and the emitter pin.Assuming the NPN transistor,after finding the B pole,we need to distinguish the other two pins.The method is:the red and black pens are separately removed from the two pins of the B pin,and then the base and the black pen are pinched with the hand. At this time,if the needle is deflected to the right one angle (the value is smaller),the pin is the collector and the other red pen holds the pin as the emitter.If you do not swing,you can change the pen again.On the contrary,when measuring PNP,the black pen is E pole,the red pen is C pole, and the pinch is B pole.

Quick identification trick:since most transistors are silicon tubes,RX10kQ can be used (a multimeter battery is 15V or 22V battery),and the voltage is not applicable when the voltage is lower than 9V,and the battery string can be used to raise the voltage.The red and black pen directly measured C and E poles,positive and negative two times,of which there was a swinging of the needle (about a hundred thousand or so),and there was another swing.If the two time is swinging, the swing must be large.The NPN transistor is the C pole of the red pen and the E is the black one.The PNP tube red pen is connected to the E pole,and the black pen is connected to the C pole (Note:this method is only applicable to silicon tube).In addition,this method is also the best way to distinguish C and E in optocoupler.

distinguish germanium tube and silicon tube

The digital multimeter is placed in the diode block,and the red and black forms are connected to BE and BC respectively.When the multimeter is prompted by the positive pressure drop of the tube's emitter,the voltage value is 0.2~0.3V,and the voltage is 0.6~0.8V for the silicon tube.

judging the quality of the pipe

Using the multimeter RX 100 block to measure the positive and negative resistances between poles,we can distinguish transistor from good or bad.

the positive resistance between the C.E and the NPN tube is connected to the B,the red pen is connected to the C,the E poles respectively;the PNP tube should be on the adjustable pen.For the silicon tube,it is about several thousand Europe,and the germanium tube is hundreds of Europe.The resistance is too large,indicating that the transistor is not performing well:the internal circuit of the transistor is infinite, and the internal short circuit of the zero ohm transistor.