When the transistor is in use, the polarity of each pin must not be mistaken, otherwise it will lead to the failure of production and even damage the components. The pin positions of the various common triodes are indicated in the figure. For the commonly used domestic metal external bright package low-power crystal triode (the two tubes on the left side of the figure), the pin identification method is: put the pin up, the isosceles triangle bottom edge (the wider side) to yourself The apex of the triangle is facing outward, then the left pin is the emitter e, the right pin is the collector c, and the middle pin is the base b (the port is: the pin is facing up, the notch is facing itself, the left is "sending", Right "set", middle "base").
Domestic plastic sealed small power crystal triode (the middle tube in the figure), its three lead pins are arranged in a "line shape", facing the side marked with the model, from left to right are the emitter e, the base b and the collector c. The medium- and high-power crystal triodes (the right two tubes in the figure) with plastic seals are different. From left to right are the base b, the collector c and the emitter e, respectively, and the collector and c in the middle The heat release sheets are connected.
Some metal-packaged high-power crystal transistors have only two pins (the rightmost tube in the figure), and its external light is the third pin-collector c. In addition, the high-frequency crystal triode of the metal casing has four lead-out legs. Except for the base b, the collector c and the emitter e, the fourth lead-out leg is connected to the "ground" leg, which is only exposed to the metal of the tube. Pass, it should be connected to the "ground" end of the circuit to avoid high frequency self-excitation.
When encountering other packages and pin types that we are not familiar with, check the relevant information or use the multimeter to check the card before connecting to the circuit. For example, the 9000 series of triodes that we often use, in addition to the order of "e, b, c" from left to right, as shown in the figure, there are also some manufacturers in accordance with "e, The order of b". Therefore, we must first check the pin arrangement when using the body triode to avoid mis-rework.
Japan's plastic low-power crystal three-stage tube, if the model is marked with the letter "R", the pin arrangement is opposite to the ordinary tube. In addition, some common integrated circuits only have three pins, such as fixed three-terminal integrated voltage regulators 78L05, LM7812, etc., their package shape is the same as the crystal three-stage tube, do not mistakenly believe that it is a crystal transistor produced abroad.
The above is the SMT patch processing factory to share the knowledge of commonly used crystal three-stage tube pin identification. For more industry information, please pay attention to us.