{"id":15660,"date":"2026-01-06T18:05:33","date_gmt":"2026-01-06T10:05:33","guid":{"rendered":"http:\/\/www.erun-tech.com\/?post_type=dt_portfolio&p=15660"},"modified":"2026-01-06T18:05:33","modified_gmt":"2026-01-06T10:05:33","slug":"diangongjichushicaojingtiguandeshibieyuceliang","status":"publish","type":"dt_portfolio","link":"http:\/\/www.erun-tech.com\/en\/project\/diangongjichushicaojingtiguandeshibieyuceliang","title":{"rendered":"Basic electrician practice: identification and measurement of transistors"},"content":{"rendered":"
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Basic electrician practice: identification and measurement of transistors<\/h1>\n
Fundamental Skills Training in Marine Electronics and Electrical Systems<\/div>\n<\/div>\n
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I. Basic Concepts of Transistors<\/h2>\n
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A transistor is one of the most fundamental semiconductor devices in electronic circuits, capable of amplifying signals, switching control, and modulating signals. It is a core component of modern electronic devices, having replaced early vacuum tubes, and offers advantages such as small size, low power consumption, and high reliability.<\/p>\n

Transistors are divided into two main categories:Bipolar Junction Transistor (BJT)<\/strong> \u548cField-Effect Transistor (FET)<\/strong>. A bipolar transistor consists of three layers of semiconductor material (NPN or PNP) and is classified intoEmitter (E)<\/strong>\u3001Base (B)<\/strong> \u548cCollector (C)<\/strong>\u3002<\/p>\n

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Figure 12-6 Symbol for a BJT<\/p><\/div>\n<\/div>\n<\/div>\n<\/section>\n

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II. Practical Transistor Measurement (Analog Multimeter Method)<\/h2>\n
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1. Tube Type and Base Identification Process<\/div>\n
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(1) Gear:<\/strong>Resistor Range Selection R\u00d71k<\/strong> Block.<\/p>\n

(2) Test A:<\/strong>Touch the red probe to one pin and the black probe to each of the other two pins to obtain three sets of readings (two readings per set).<\/p>\n

(3) Test B:<\/strong>Touch the black probe to one pin, and touch the red probe to each of the other two pins, obtaining three sets of readings (two readings per set).<\/p>\n

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Determining the Type of an NPN Transistor<\/strong><\/p>\n

When one of the groups has two readings that are both low (with a large needle deflection), ifThe common pin is the black test lead.<\/strong>, then it is an NPN transistor; in this case, the pin touched by the black probe isBase (B)<\/strong>\u3002<\/p>\n<\/div>\n

PNP Tube Type Identification<\/strong><\/p>\n

When one of the groups has two readings that are both low (with a large needle deflection), ifThe common pin is the red probe.<\/strong>, then it is a PNP transistor, and in this case, the pin touched by the red probe isBase (B)<\/strong>\u3002<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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2. Distinguishing Between the Emitter (E) and Collector (C) (Finger-Through Method)<\/div>\n
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Discrimination Principle:<\/strong>Determine this based on the principle that the gain is high when the transistor is used in the forward direction and low when used in the reverse direction.<\/p>\n

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Operating procedures using an NPN transistor as an example:<\/strong><\/p>\n

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  1. Of the remaining two pins, let\u2019s assume that one of them is the collector (C) and the other is the emitter (E).<\/li>\n
  2. \u7528Connect the black probe to C, and the red probe to E.<\/strong>\u3002<\/li>\n
  3. Key Moves:<\/strong>Using two dampened fingers, simultaneously touch the C and E terminals (be careful not to short-circuit the terminals directly; the goal is to use the body\u2019s resistance to provide a bias current to the base), and note the angle of the meter needle\u2019s deflection.<\/li>\n
  4. Assume that another pin is the collector (C), and repeat the measurement using the same method.<\/li>\n<\/ol>\n

    Conclusion: Comparing the results of the two measurements, the one with the larger needle deflection angle indicates that the transistor has a higher current gain. This confirms the original hypothesis, namely, that the black probe corresponds to the collector (C).<\/p>\n<\/div>\n

    <\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n
    \ud83d\udca1 Summary of Tips and Tricks:<\/strong><\/p>\n

    When identifying transistors, remember: \u201cThree inversions\u2014find the base; two correspondences\u2014find the collector.\u201d When using an analog multimeter, the black probe is connected to the positive terminal of the internal battery; this is crucial for determining whether a transistor is NPN or PNP.<\/p>\n<\/div>\n