The transistor acts as the main component of any electrical circuit. It is a kind of amplification key. At the heart of this semiconductor device is a silicon or germanium crystal. Transistors are unipolar and bipolar and, accordingly, field and bipolar. According to the type of conductivity, they are found in two types - direct and reverse. For beginner hams, the main problem is the recognition and decoding of the encoding of these elements. In our article, we will consider the main types of recording of both domestic and foreign products, as well as analyze what transistor labeling means.
Types of Recording
Transistor manufacturers use two main types of encryption - these are color and code markings. However, neither one nor the other have uniform standards. Each plant that produces semiconductor devices (transistors, diodes, zener diodes, etc.) accepts its own code and color designations. You can find transistors of the same group and type, manufactured by different factories, and they will be labeled in different ways. Or vice versa: the elements will be different, and the designations on them will be identical. In such cases, they can only be distinguished by additional features. For example, by the length of the terminals of the emitter and collector or by the color of the opposite (or end) surface. The marking of field effect transistors is no different from the labels on other devices. The same situation is with semiconductor elements of foreign manufacture: each manufacturer uses their own types of designations.
Transistors in the housing of the type KT-26
Consider what the labeling of domestic transistors means. This type of housing is most popular among manufacturers of semiconductor devices. It has the shape of a cylinder with one beveled side, three pins emerge from the lower base. In this case, the principle of mixed marking is used, which contains both code symbols and color symbols. A colored dot denoting a transistor group is applied to the upper base, and a code symbol or colored dot corresponding to the type of device is applied to the beveled side. In addition to the type, the year and month of release can be applied.
To indicate the group, the following color marking of transistors is used: group A corresponds to a dark red dot, B - yellow, C - dark green, G - blue, D - blue, E - white, F - dark brown, And - silver, K - orange, L - light tobacco, M - gray.
Type is indicated by the following symbols and colors.
- KT203 corresponds to a right triangle (legs down and to the right) or a dark red dot.
- KT208 is a small circle (there is no color mark for this type).
- K209 - rhombus (gray dot).
- K313 - a symbol resembling an inverted letter T (orange dot).
- KT326 is an inverted equilateral triangle (brown dot).
- KT339 - an equilateral triangle (blue dot).
- KT342 - a quarter of the circle (blue dot).
- KT502 - half a circle (yellow dot); KT503 - circle (white dot).
- KT3102 is a right-angled triangle with legs up and to the left (dark green dot).
- KT3157 - a right triangle with legs to the left and down (there is no color designation).
- K366 - letter T (no color).
- KT6127 - inverted letter P.
- KT632 - there is no symbolic designation (silver dot).
- KT638 - without a symbol (orange dot).
- KT680 - letter G.
- KT681 - a vertical stick.
- KT698 - The letter P.
Marking the year and month of manufacture
In accordance with GOST 25486-82, two letters or a letter and a number are used to indicate the date. The first character corresponds to the year, and the second to the month. This type of coding is used not only for transistors, but also for other domestic semiconductor elements. On foreign instruments, the date is indicated by four digits, the first two of which correspond to the year, and the last to the week number. Let's consider what the code marking of transistors corresponding to the manufacturing date means. Year of manufacture / symbol: 1986 - U, 1987 - V, 1988 - W, 1989 - X, 1990 - A, 1991 - B, 1992 - C, 1993 - D, 1994 - E, 1995 - F, 1996 - H, 1997 - I, 1998 - K, 1999 - L, 2000 - M, etc. Release month: the first nine months correspond to numbers from 1 to 9 (January - 1, February - 2), and the last to the initial letters of the word: October - Oh, November - N, December - D.
Transistors in the case of the KT-27 type
It is customary to apply either an alphanumeric code or a cipher consisting of geometric shapes to these semiconductor elements. Let's consider what graphic marking of transistors means.
- KT972A - one “lying” rectangle.
- KT972B - two rectangles: the left one lies, the right one stands.
- KT973A - one square.
- KT973B - two squares.
- KT646A - one triangle.
- KT646B - left circle, right triangle.
In addition, there is an additional color marking of the end of the case, which is opposite to the findings:
- KT 814 - gray-beige;
- KT 815 - lilac-violet or gray;
- CT 816 - rose red;
- CT 817 - gray-green;
- CT 683 - purple;
- KT9115 - blue.
Transistors of the KT814-817 series of group B can be marked only by coloring the end, without applying a character code.
European PRO-ELECTRON system
The marking of transistors and other semiconductor devices from European manufacturers is as follows. The code is a character entry. The first letter means the material of the semiconductor: silicon, germanium, etc. The most common silicon, it corresponds to letter B. The next symbol is the type of device. Next is the series number of the product. This number has several ranges. For example, if numbers from 100 to 999 are indicated, then these elements relate to general-purpose products, and if they are preceded by a letter (Z10 - A99), then these semiconductors are considered to be parts of special or industrial purpose. In addition, an additional instrument modification symbol may be added to the general coding. It is determined directly by the manufacturer of semiconductor elements.
The first symbol (material): A - germanium, B - silicon, C - gallium arsenide, R - cadmium sulfide. The second element means the type of transistor: C - low-power low-frequency; D - powerful low-frequency; F - low-power high-frequency; G - several devices in one housing; L - powerful high-frequency; S - low power switching; U is a powerful switch.
American JEDEC System
US semiconductor manufacturers use a four-character character encoding. The first digit means the number of pn junctions: 1 - diode; 2 - transistor; 3 - thyristor; 4 - optocoupler. The second letter denotes a group. The third character is the serial number of the item (range from 100 to 9999). The fourth character is the letter corresponding to the modification of the device.
Japanese JIS system
This system consists of symbols and contains five elements. The first digit corresponds to the type of semiconductor device: 0 - photodiode or phototransistor; 1 - diode; 2 - transistor. The second element is the letter S, it is placed on all elements. The following letter corresponds to the type of transistor: A - high-frequency PNP; B - low frequency PNP; C is a high-frequency NPN; D is a low frequency NPN; H - single junction; J - field with an N-channel; K - field with a P-channel. The following is the product serial number (10 - 9999). The last, fifth, element is a modification of the device (often it may be absent). Sometimes the sixth character is applied - this is an additional index (letters N, M or S), indicating the requirement of compliance with special standards. In the Japanese system, color coding of transistors is not used.
SMD elements
The marking of SMD transistors is only symbolic. Due to the miniature size of these elements, color coding is not used. There is no single encryption standard for them. Each manufacturing plant uses its own symbols. The alphanumeric code in this case may contain from one to three letters or numbers. Each plant produces its own semiconductor labeling tables.