Any electronic circuit, regardless of its purpose, contains a large number of elements that regulate and control the flow of electric current through the wires. It is voltage regulation that plays an important role in the operation of most modules, because stable and long-term operation of the circuit depends on this parameter.
To stabilize the input voltage to the circuits, a special module was developed, which is literally the most important part of many devices. Imported and domestic zener diodes are used in circuits with different parameters, therefore there are different markings of diodes on the case, which helps to determine and select the desired option.
A little more about the module and how it works
This is a semiconductor diode that has the property of producing a certain voltage value regardless of the current supplied to it. This statement is not completely true for absolutely all options, because different models have different characteristics. If you apply a very strong current to an SMD module (or any other type) that is not designed for this purpose, it will simply burn out. Therefore, the connection is made after installing a current-limiting resistor as a fuse, the value of the output current of which is equal to the maximum possible value of the input current to the stabilizer.
It is very similar to an ordinary semiconductor diode, but has a distinctive feature - its connection is done in reverse. That is, the minus from the power source is supplied to the anode of the zener diode, and the plus to the cathode. Thus, a reverse branch effect is created, which provides its properties.
A similar module is a stabistor - it is connected directly, without a fuse. It is used in cases where the parameters of the input electricity are precisely known and do not fluctuate, and the output also produces an exact value.
Indication of passport characteristics
They are also the main indicators of domestic and imported zener diodes, which must be used as a guide when selecting a zener diode for a specific electronic circuit.
- UCT – indicates what nominal value the module is capable of stabilizing.
- ΔUCT – used to indicate the range of possible incoming current deviation as a safe damping.
- ICT – parameters of the current that can flow when the rated voltage is applied to the module.
- ICT.MIN – shows the smallest value that can flow through the stabilizer. In this case, the voltage flowing through the diode will be in the range UCT ± ΔUCT.
- ICT.MAX – the module is not able to withstand a voltage higher than this value.
The photo below shows the classic version. Please note that right on the body it is shown where the anode and cathode are. A black stripe is drawn in a circle (more rarely, a gray stripe is found), which is located on the cathode side. The opposite side is the anode. This method is used for both domestic and imported diodes.
Additional markings for glass models
Diodes in glass cases have their own designations, which we will consider below. They are so simple (unlike options with plastic cases) that they are almost immediately memorized by heart; there is no need to use a reference book every time.
Color coding is used for plastic diodes, such as SOT-23. The solid body of the module has two flexible leads. On the case itself, next to the stripe described above, several numbers are written in the same color, separated by a Latin letter. Usually the record looks like 1V3, 9V0, and so on, the variety allows you to select any parameters according to the designation, as in SMD.
What does this code marking mean? It shows the stabilization voltage for which this element is designed. For example, 1V3 shows us that this value is 1.3 V, while the second option is 9 volts. Typically, the larger the body itself, the greater the stabilizing property it has. The photo below shows a zener diode in a glass case with a 5.1 V cathode marking
Conclusion
Correct selection of the zener diode parameters will allow you to obtain a stable current, which is supplied from it to the circuit. Be sure to select such fuse parameters using the appropriate reference book so that the input voltage does not damage the part; it is advisable for it to be approximately in the middle of the UCT ± ΔUCT range.
Diodes are considered "valves" in an electrical circuit. This is a two-terminal semiconductor element with two active electrodes, an anode and a cathode, between which current can only flow unidirectionally. They are used in various electrical circuits where a one-way diode effect is required. Silicon and germanium are most often used for the manufacture of devices.
Types of diodes
Diodes based on the same principle of operation are not the same in their mode of operation. There are several types of devices, which differ in designations on the diagram, as well as in appearance:
- Light emitting diodes (LED). When this element allows current to pass between the electrodes, light is generated. The color spectrum depends on the energy gap of the semiconductor;
- Avalanche diode. Operates in reverse bias and uses the avalanche effect. Since the avalanche process achieves a high degree of sensitivity, it is used for photodetection in other schemes;
- Laser diode. It differs from an LED in that it generates coherent light. Used in laser pointers, CD and DVD players;
- Schottky diodes. Have a low forward voltage drop compared to silicon diodes (0.15-0.4 V compared to 0.6 V for silicon diodes). They are built on metal-semiconductor contact;
- Zener diode. Provides a stable reference voltage;
- Photodiode. Used to detect light. It is also used in photometry and in generating electricity in solar cells;
- Varicap. Acts as a capacitor whose capacitance changes depending on the applied reverse voltage;
- Rectifier diodes;
- Gunn diodes. Made from GaAs or InP materials and have a negative differential resistance range;
- Thyristors, or controlled diodes. They have three output contacts.
There are other types of diode elements: point, signal, tunnel, gold-doped, etc.
Structurally, diodes are made in metal, glass, plastic or ceramic cases. Each diode has its own technical parameters for current, voltage, temperatures, etc. Special designations are used to identify the elements.
Marking refers to colored symbols applied to the body of the diode element, providing direct or encoded information about its characteristics.
Marking of domestic diodes
Russian and Soviet devices have a coded color inscription consisting of stripes and dots, the decoding of which can be found in reference books. From it you can understand the material of manufacture, the purpose of the element and its performance characteristics.
In turn, each combination of color symbols corresponds to a code of letters and numbers (GOST 20859.1-89). The color coding of the diodes along with the letter code is included in the table. Partially the code of letters and numbers can be understood immediately, the remaining parameters are grouped in other tables.
For example, the table indicates that the purple stripe on the cathode side indicates KD243A:
- the letter “K” means that the element is made from silicon; instead of the letter for silicon there may be the number 1;
- D – indicates a rectifier diode, maybe a zener diode (C), varicap (V), tunnel diode (I), etc.;
- 2 – operational characteristics (in this case it is intended for a current of 0.3-10 A);
- 43 – number under which the device was developed;
- A – class of a group of elements produced using a common technology.
Diodes from foreign manufacturers
Marking of a diode produced outside of Russia is also done using a certain color marking, indicating alphabetic and digital codes, which can be read from a table. Two main standards apply:
- JEDEC (American);
- PRO-ELECTRON (European).
In the European standard, like the Russian one, the first symbol indicates the material used, then the type and purpose of the element and then the series number are reported. By this number you can understand whether the diode is used in commonly used devices (from 100 to 999) or is produced for installation in a special circuit, then an alphabetic symbol and a two-digit number are used (for example, A96).
Everything is tabulated, and identifying any diode is not difficult.
Important! The location of the cathode terminal should always be looked for where wide stripes are applied.
The American JEDEC standard is less informative than the European standard, but the main characteristics of the device are easy to read.
SMD diodes
SMDs are surface mount devices, microscopic electronic components soldered to the copper side of the board and without long connecting leads. Often it is impossible to apply markings on it, since there is no space for this. If the size is slightly larger, numbers or letters are applied to the element. Some reference data can be found in various tables, but they are incomplete and it is not always possible to find the required element.
SMD diode polarity
Radio amateurs sometimes have difficulty correctly determining the poles of an SMD element.
Polarity designation options:
- Often there is a triangle, the vertex of which points to the cathode. Simplified, the same symbol is represented by a horizontal line with a protrusion facing the cathode;
- If only one bar is designated, it is on the negative pole;
- PLLC devices (white plastic coated) have a slot on the cathode side.
Of the SMD diodes shown in the figure, the one on the far right does not fit any description. In this case, only viewing in the data sheet helps.
LED markings
LED is used in semiconductor optoelectronic devices that emit radiation in the range of visible, infrared and ultraviolet rays.
Most common varietiesSMD LED:
- RGB-LED. A multicolor diode with structures that allow it to generate three primary colors (R - red, G - green, B - blue). By mixing these colors, you can get any spectrum;
- Warm White LED – warm white. Color temperature is below 3300 K;
- Neutral white with a color temperature in the range of 3300-5300 K;
- Cool white diode with a color temperature above 5300 K.
Numerical symbols indicate the size of the diode element:
- 3528. Dimensions 3.5 x 2.8 mm. This is a first generation LED;
- 5050. Dimensions 5.0 x 5.0 mm. Gained high popularity due to good parameters;
- 5630/5730. Size – 5.6 x 3.0 mm. Successor to the 5050 LED. Generates a large luminous flux. Used for devices with increased power and brightness;
- 3014. Dimensions 3.0 x 1.4 mm. It appeared on the market not long ago. Small size and high brightness guarantee growth in its use;
- 2835. Size – 2.8 x 3.5 mm. Also recently sold. Brighter than LED 3014. Increasingly used in lamps with E27, E14 socket;
- OWL diode (chip on board). A large element consisting of small ones. Reaches power up to 200 W with a luminous flux of up to 10,000 lm. It has a long service life and is used in floodlights.
The designation 30 SMD, 60 SMD indicates how many LEDs are located on a 1 m segment of LED strip. There are 150, 300 or 600 SMD in 5 meter rolls, also with bulbs. The inscription 16 SMD 5730 indicates that the lamp contains 16 LEDs 5.7 x 3.0 mm.
LEDs manufactured using DIP technology have a glass or plastic body and long leads, and are marked in the Russian Federation using a developed color code system.
Color rendering index CRI
This is an important parameter that determines color accuracy. The example here is the sun, which has a CRI of 100. Artificial light sources range from 0-100. The higher the CRI, the more natural the lighting looks.
Important! It is worth looking for LED lamps with CRI > 80.
Different LED manufacturers use their own coding system, which is not standardized. Therefore, you need to look for decoding in special reference books.
Video
Diode marking is a short graphic symbol for the element. The elemental base is currently so diverse that the abbreviations differ quite noticeably. It is difficult to identify the diode: zener diode, tunnel diode, Gunn diode. Varieties have been released that resemble a gas-discharge light bulb. The LEDs light up, adding to the confusion.
Semiconductor diodes
Perhaps the section is called somewhat trivially, when you simply need to distinguish typical diodes from obsolete electronic tubes and modern SMD modifications. Ordinary semiconductor diodes are an easily solvable problem for a radio amateur. The side of the cylindrical body with a disk base and legs contains an easily visible inscription painted with paint.
Semiconductor resistors. Can you tell the difference with the naked eye?
The color of the case does not matter; the size indirectly indicates the power dissipation. Powerful diodes often have a thread for the radiator mounting nut. The result of calculating the thermal regime shows the lack of the body’s own capabilities; the cooling system is supplemented by an external element. Today, power consumption is falling, reducing the linear dimensions of device housings. This allowed the use of glass. The new housing material is cheaper, more durable, and safer.
- The first place is occupied by a letter or number that briefly characterizes the material of the element:
- G (1) – germanium compounds.
- K (2) – silicon compounds.
- A (3) – gallium arsenide.
- And (4) – indium compounds.
- The second letter in our case is D. Rectifier or pulse diode.
- The third place was chosen by the figure characterizing the applicability of the diode:
- Low frequency, current below 0.3 A.
- Low frequency, current 0.3 - 10 A.
- Not used.
- Pulse, recovery time over 500 ns.
- Pulse, recovery time 150 – 500 ns.
- The same, recovery time 30 – 150 ns.
- The same, recovery time 5 – 30 ns.
- The same, recovery time 1 – 5 ns.
- Pulsed, minority carrier lifetime below 1 ns.
- The development number is composed of two digits and may be absent altogether. Denominations below 10 are padded on the left with a zero. For example, 07.
- The group number is indicated by a letter and determines the differences in properties and parameters. The letter often becomes a key letter, indicating the operating voltage, direct current, etc.
In addition to the markings, the reference books provide graphs by which the problems of choosing the operating point of a radio element are solved. Information about production technology, body material, and weight is indicated. The information helps the equipment designer, but has no practical meaning for amateurs.
Imported designation systems differ from domestic ones and are well standardized. Therefore, using special tables it is not difficult to find suitable analogues.
Color coding
Every radio amateur knows the difficulty of identifying diodes surrounded by a glass housing. One person. Sometimes the manufacturer bothers to apply clear marks and multi-colored rings. According to the notation system, three characteristics are introduced:
- Markers of cathode and anode areas.
- Body color, replaced by a colored dot.
According to the state of affairs, at first glance we can distinguish the types of diodes:
- The D9 family is marked with one or two colored rings in the anode area.
- KD102 diodes in the anode area are indicated by a colored dot. The case is transparent.
- KD103 have a color body that complements the dot, with the exception of 2D103A, which is indicated by a white dot in the anode area.
- The KD226, 243 families are marked with a cathode region ring. No other marks are provided.
- Two colored rings in the cathode area can be seen in the KD247 family.
- KD410 diodes are indicated by a dot in the anode area.
Other visible marks are present. You will find a more detailed classification by studying the publication of A.P. Kashkarov. On the labeling of radioelements. Beginners are concerned about the issue of determining the location of the cathode and anode.
- You see: one side of the cylinder is equipped with a dark stripe - a cathode has been found. Colored may be part of the labeling discussed today.
- If you know how to operate a multimeter, the anode is easy to find. An electrode where we will apply the red probe to open the valve (we will hear a bell).
- The new diode is equipped with an anode antenna that is longer than the cathode.
- Let's look through the glass body of the LED with a magnifying glass: the metal anode resembles the tip of a spear, smaller in size than the cathode.
- Old diodes contained arrow markings. The tip is the cathode. Allows you to determine the direction of activation visually. Modern radio installers have to train their intelligence, visual acuity, and precision of manipulation.
Foreign products received a different designation system. When choosing an analogue, use special correspondence tables. For the rest, the import base differs little from the domestic one. Marking is carried out according to JEDEC standards (USA), European system (PRO ELECTRON). Colorful color code decoding tables are massively provided by online sources.
Color coding
SMD diodes
In the SMD version, the diode body is sometimes so small that there are no markings at all. The characteristics of the devices depend little on the dimensions. The latter greatly influence the dissipated power. A larger current flows through the circuit; a diode must be larger in size to remove the resulting heat (Joule-Lenz law). As written, the marking of an SMD diode can be:
- Full.
- Abbreviated.
- Lack of markings.
SMD elements in the total volume of electronics occupy approximately 80% of the volume. Surface mounting. The invented method of electrical connection is as convenient as possible for automated assembly lines. The SMD diode marking may not match the contents of the case. With a large volume of production, manufacturers begin to cheat, putting inside something that is not at all what is marked with the symbol. A large number of inconsistent standards causes confusion in the use of microcircuit pins (for diodes - microassemblies).
Frame
The marking may include 4 digits indicating the housing size. They do not directly correspond to the dimensions, take a closer look at the question in GOST R1-12-0.062, GOST R1-12-0.125. For hobbyists who cannot afford to obtain regulations, it is easier to use reference tables. Let's keep in mind the fact: SMD cases can differ in small things from company to company, because each manufacturer tailors the element base to its own products. Samsung has one distance from the motherboard of the washing machine, LG has another. The dimensions of SMD housings will require different conditions, heat dissipation conditions, and other requirements will be met.
Therefore, when purchasing an element according to the numbers in the reference book, take additional measurements if this is important. For example, when repairing household appliances. Otherwise, the purchased diodes may not fit at their destination. Amateurs do not bother with SMD due to the apparent complexity of installation, but for craftsmen this is a common thing, since microelectronics is impossible without such a successful technology.
When choosing a diode, it is worth keeping in mind the fact: many cases are the same, but are marked differently. Some designations do not have numbers. Convenient to use search engines. The cross table of size correspondence shown is taken from the site selixgroup.spb.ru.
SMD diodes are often available in SOD123 package. If one end has a stripe of some color or embossing, then this is the cathode (the place where negative polarity needs to be applied to open the pn junction). If only the case has inscriptions, then this is the designation of the case. If there is more than one line, the one characterizing the shell is larger.
Item type and manufacturer
It is clear that the type of case is a secondary thing for the designer. Some heat is dissipated through the surface of the element. It is from this point of view that the diode should be considered. Other important characteristics are:
- Operating and reverse voltage.
- The maximum permissible current through the p-n junction.
- Power dissipation, etc.
These parameters for semiconductor diodes are indicated in reference books. Labeling helps you find what you need among mountains of waste paper. In the case of an SMD element, the situation is much more complicated. There is no unified notation system. At the same time it is easier - the parameters from one diode to another do not change too much. The power dissipation and operating voltage differ by and large. Each SMD element is marked with a sequence of 8 letters and numbers, and some of the acquaintances may not be used at all. This is the case with industry veterans, giants of the electronics industry:
- Motorola (2).
- Texas Instruments.
- Now converted and partially sold to Siemens (2).
- Maxim Integrated Product.
The mentioned manufacturers are sometimes marked with two letters MO, TI, SI, MX. In addition, a couple of letters address:
- AD – Analog Devices;
- HP – Hewlett-Packard;
- NS – National Semiconductors;
- PC, PS – Philips Components, Semiconductors, respectively;
- SE – Seiko Instruments.
Of course, the appearance of the case does not always make it possible to determine the manufacturer, then you need to immediately type the alphanumeric sequence into a search engine. Other examples have been noticed: the NXP diode assembly in the SOD123W package does not carry any information other than the line indicated above. The manufacturer considers the information provided sufficient. Because SOD itself stands for small outline diode. We’ll find more on the company’s official website (nxp.com/documents/outline_drawing/SOD123W.pdf).
Printing space is limited, which explains these simplifications. The manufacturer tries to make the marking process as minimal as possible. Laser or screen printing is often used. This will allow you to fit 8 characters in an area of only 4 square millimeters (Kashkarov A.P. “Marking of radio elements”). In addition to those indicated for diodes, the following types of housings are used:
- Cylindrical glass MELF (Mini MELF).
- SMA, SMB, SMC.
- MB-S.
To top it off, the same alphanumeric code sometimes corresponds to different elements. In this case, you will have to analyze the electrical circuit. Depending on the purpose of the diode, operating current, voltage, and some other parameters are assumed. According to the catalogs, it is recommended to try to determine the manufacturer, since the parameters have an insignificant scatter, making it difficult to correctly identify the product.
other information
In addition to those indicated, other information is sometimes provided. Batch number, release date. Such measures are taken to make it possible to track new product modifications. The design department issues corrective documentation with a number and date. And if the assembly shop needs to take a feature into account when working on the changes made, the craftsmen should read the markings.
If you assemble equipment according to new drawings (electrical diagrams), using old parts, the result will not be what was expected. Simply put, the product will fail; it is gratifying if the process turns out to be reversible. Nothing will burn. But the shop manager will probably get hit in the head; the product will have to be remade in terms of the unaccounted factor.
Except for diodes
A billion modifications of diodes have been created based on p-n junctions. This includes varicaps, zener diodes and even thyristors. Each family has its own characteristics; there are many similarities with diodes. We see three global views:
- today's outdated element base is relatively large in size, clearly visible markings formed by standard letters and numbers;
- glass cases equipped with color symbols;
- SMD elements.
Analogues are selected based on the conditions specified above: power dissipation, maximum voltage, current flow.
The marking of modern diodes takes into account the technical properties and features of the semiconductor. The material from which the semiconductor is made is also designated by corresponding letters. This marking is affixed along with the type, purpose, properties of the semiconductor device and sometimes its symbol. This helps to correctly connect the diode to the circuit. The cathode and anode terminals are indicated by an arrow or minus or plus signs. Color and code markings in the form of stripes or dots are applied near the positive terminal. All these designations and the color coding of the diode allow you to quickly determine the type of semiconductor and its correct use in amateur radio circuits.
Marking of foreign diodes |
The designation of foreign diodes by color code occurs according to two popular standards JEDEC (USA) and the European system (PRO ELECTRON).
In Europe, the European Pro-Electron association system is widely used for color designation of semiconductor devices. It is much more informative and allows you to determine the subclass and purpose of the semiconductor.
The basis for diode marking in accordance with the PRO ELECTRON system are 5 characters. Devices for special equipment are designated by 3 letters, followed by a development serial number of 2 digits. Semiconductor radio components for consumer equipment are marked with two letters followed by a three-digit serial number.
Only the first 2 letters are of particular importance, and the rest only indicate the serial number or special designation of the diode. First character- indicates the source material from which it is made.
A- germanium;
IN- silicon;
WITH- hapium arsenide;
D-indium antimonide;
R- cadmium sulfite
Second Latin letter defines a subclass of semiconductor.
Third character in PRO ELECTRON - numbers and letters: 100-999 - semiconductors for wide application, Z10-A99 - devices for special equipment.
4th and 5th character- letters and numbers marking - for - permissible change in the rated stabilization voltage (letter) and stabilization voltage in volts (number):
A = 1%;
B = 2%;
C = 5%;
D = 10%;
E = 15%.
For rectifier diodes in which the anode is connected to the body (R) - the maximum amplitude of the reverse voltage, in Volts (number). For, the anode of which is connected together with the housing (R) - the smallest of the values of the maximum turn-on voltage or the maximum amplitude of the reverse voltage.
Color coding of diodes in the PRO ELECTRON system| Color stripes |
Diode type | |||
| 1st wide band |
2nd wide band |
3rd narrow band |
4th narrow band |
|
| A.A. | X | 0 | 0 | |
| 1 | 1 | |||
| B.A. | 2 | 2 | ||
| S | 3 | 3 | ||
| T | 4 | 4 | ||
| V | 5 | 5 | ||
| W | 6 | 6 | ||
| 7 | 7 | |||
| Y | 8 | 8 | ||
| Z | 9 | 9 | ||
PS: The negative electrode of the diode - the cathode - is always located near the wide stripes.
American diode marking system JEDEC (Joint Electron Device Engineering Council)The most common in the world is the American JEDEC diode designation system. In accordance with it, diodes are designated by a certain index (code, marking), in which the 1st digit corresponds to the number of p-n junctions (a diode usually has one), followed by the English letter N and a serial number, which is registered by the Electronics Industry Association (EIA ). The number may be followed by one or more letters, indicating the breakdown of devices of the same type into standard ratings according to various technical characteristics. But the serial number numbers do not determine the type of material from which the diode is made, frequency range, dissipation power, etc.
Example: 2N2221A, 2N904Color marking of semiconductor diodes according to the JEDEC system
| Stripe color | ||||||||||
| Number | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Letter | - | A | B | C | D | E | F | G | H | J |
Addition:
The first digit 1 and the second letter N in the color marking are omitted;
2-digit numbers are marked with one black stripe and two colored ones; additional fourth stripe - letter
3-digit numbers - three colored stripes; additional fourth stripe - letter
numbers of 4 digits - four colored stripes and a fifth black or colored one, indicating the letter
the colored stripes are closer to the cathode or the first from the cathode is wide
The type of diode must be deciphered from the cathode.
Diode marking according to the Japanese JIS system (Japanese Industrial Standard)
In accordance with this system, you can find out the class of the device, the type of conductivity and its purpose. The type of semiconductor material is not reflected. The symbol consists of five elements:
| 1 element | 2 element | 3 element | 4 element | 5th element |
| Number:
0 - photodiode, phototransistor 1 - diode 2 - transistor 3 - thyristor |
Letter:
S |
Letter - device type:
A - high-frequency PNP transistor B - low frequency PNP transistor C - high-frequency NPN transistor D - low frequency NPN transistor E - Esaki diode (four-layer PNPN diode) F - thyristor G - Gunn diode (quad-layer NPNP diode) N - unijunction transistor J - field effect transistor with N-channel K - field-effect transistor with P-channel M - symmetrical thyristor (semistor) Q - light emitting diode R - rectifier diode S - small signal diode T - avalanche diode V - varicap Z-zener diode |
Serial number:
10-9999 |
One or two letters:
device modifications |
Example: 2SB646, 2SC733
Phototransistors and photodiodes do not have markings for the third member. After marking, additional indices (N, M, S) can be applied, reflecting the requirements of special standards.
Marking of SMD diodes |
SMD diodes are manufactured in cylindrical cases, and in cases in the form of small parallelipipeds. Cylindrical SMD diodes are usually available in MiniMELF (SOD80 / DO213AA / LL34) or MELF (DO213AB / LL41) packages. Their standard sizes are set in the same way as for SMD inductors, SMD resistors and SMD capacitors.
For much more detail, see the guide to marking SMD diodes, the link is just above.
Color marking of domestic diodes |
| Type diode |
Case color or mark on body |
Label y anode (+) |
Label y cathode (-) |
Appearance |
| - |
Red ring |
- |  |
|
| - |
Orange or red + |
- |  |
|
| - |
yellow or red + |
- |  |
|
| - |
White or red + |
- |  |
|
| - |
Blue or red + |
- |  |
|
| - |
Green or red + |
- |  |
|
| - |
Two yellow rings |
- |  |
|
| - |
Two white rings |
- |  |
|
| - |
Two green rings |
- |  |
|
| - |
Two blue rings |
- |  |
|
| - |
Green dot |
- |  |
|
| - |
Blue dot |
- |  |
|
| - |
Yellow dot |
- |  |
|
| - |
Orange dot |
- |  |
|
|
Blue dot |
- |  |
||
|
Yellow dot |
- |  |
||
| - |
White point |
- |  |
|
|
The point is missing |
White or yellow |
- |  |
|
|
Green dot |
White or yellow |
- |  |
|
|
Red dot |
White or yellow |
- |  |
|
|
White or yellow |
White or yellow |
- |  |
|
|
Yellow dot |
Black, Green or |
- |  |
|
| - |
Black, Green or |
- |  |
|
|
White point |
Black, Green or |
- |  |
|
|
Black dot |
Black, Green or |
- |  |
|
|
Green dot |
Black, Green or |
- |  |
|
| - |
Blue dot |
- |  |
|
|
White point |
Blue dot |
- |  |
|
|
Black dot |
Blue dot |
- |  |
|
|
Green dot |
Blue dot |
- |  |
|
|
Beige dot |
Blue dot |
- |  |
|
|
Yellow dot |
Blue dot |
- |  |
|
| - | - |
Orange ring |
 |
|
| - | - |
Red ring |
 |
|
| - | - |
Green ring |
 |
|
| - | - |
Yellow ring |
 |
|
| - | - |
White ring |
 |
|
| - | - |
Blue ring |
 |
|
| - | - |
Purple ring |
 |
|
| - | - |
Orange ring |
 |
|
| - | - |
Red ring |
 |
|
| - | - |
Green ring |
 |
|
| - | - |
Yellow ring |
 |
|
| - | - |
White ring |
 |
|
Having a radio-electronic laboratory at home, you can make a variety of devices for electrical equipment or the devices themselves, which will allow you to significantly save on the purchase of equipment. An important element of many electrical circuits of devices is the zener diode.
Such an element (smd, smd) is a necessary part of many electrical circuits. Due to its wide range of applications, the zener diode has different markings. The markings applied to the body of such a diode provide detailed, but encrypted, information about this element. Our article today will help you understand what color markings are found on the housing (glass or not) of imported zener diodes.
What is this element of electrical circuits?
Before we begin to consider the question of what color markings exist for such elements, we need to understand what it is all about.
Volt-ampere characteristic of a zener diode
A zener diode is a semiconductor diode, which is designed to stabilize the DC voltage across the load in an electrical circuit. Most often, such a diode is used to stabilize voltage in various power supplies. This diode (smd) has a section with a reverse branch of the current-voltage characteristic, which is observed in the region of electrical breakdown.
Having such an area, the zener diode in a situation where the parameter of the current flowing through the diode changes from IST.MIN to IST.MAX, practically no changes in the voltage indicator are observed. This effect is used to stabilize voltage. In a situation where the RH load is connected in parallel to the SMD, then the diode voltage will remain constant, and within the specified limits of change in the current flowing through the zener diode.
Note! Zener diode (smd) is capable of stabilizing voltages above 3.3 V.
In addition to SMD, there are also zeners, which are turned on when switched on directly. They are used in situations where there is a need to stabilize the voltage in a certain range. A conventional diode can be used when it is necessary to stabilize the voltage in the range from 0.3 to 0.5 V. The region of their forward bias is observed when the voltage drops to 0.7 - 2v. Moreover, it practically does not depend on the current strength. In their work, stabistors use the direct branch of the current-voltage characteristic.
They should also be turned on when connected directly. Although this will not be the best solution, since a zener diode in such a situation will still be more effective.
Stabistors, like SMD, are often made from silicon.
Zener diodes are labeled according to their main characteristics. This marking looks like this:
- UST. This marking indicates the rated voltage for stabilization;
- ΔUST. Indicates the deviation of the voltage indicator of the rated stabilization voltage;
- IST. Indicates the current that flows through the diode at the rated stabilization voltage;
- IST.MIN - the minimum value of the current that flows through the zener diode. At this value, such an SMD diode will have a voltage in the range UST ± ΔUST;
- IST.MAX. Indicates the maximum permissible amount of current that can flow through the zener diode.
This marking is important when choosing an element for a specific electrical circuit.
Designations for the operation of an electrical circuit element
Schematic designation of a zener diode
Since the zener diode is a special diode, its designation is no different from them. Schematically, smd is designated as follows:
A zener diode, like a diode, has a cathode and anode part. Because of this, there is direct and reverse inclusion of this element.
Turning on the zener diode
At first glance, the inclusion of such a diode is incorrect, because it should be connected “the other way around”. In a situation where reverse voltage is applied to the SMD, the phenomenon of “breakdown” is observed. As a result, the voltage between its terminals remains unchanged. Therefore, it must be connected in series to a resistor in order to limit the current passing through it, which will ensure that the “excess” voltage from the rectifier drops.
Note! Each diode designed to stabilize voltage has its own “breakdown” (stabilization) voltage and also has its own operating current.
Due to the fact that each zener diode has such characteristics, it is possible to calculate the value of the resistor that will be connected in series with it. For imported zener diodes, their stabilization voltage is presented in the form of markings on the body (glass or not). The designation of such an smd diode always begins with BZY... or BZX..., and their breakdown (stabilization) voltage is marked V. For example, the designation 3V9 stands for 3.9 volts.
Note! The minimum voltage for stabilization of such elements is 2 V.
Operating principle of stabilization diodes
Despite the fact that the SMD is similar to a diode, it is essentially a different element of the electrical circuit. Of course, it can serve as a rectifier, but is usually used to stabilize the voltage. This element is capable of maintaining a constant voltage in a DC circuit. This principle of operation is used in power supply of various radio equipment.
Externally, SMD is very similar to a standard semiconductor. The similarity remains in the design features. But when designating such a radio element, unlike a diode, the letter G is placed on the diagram.
If you do not delve into mathematical calculations and physical phenomena, then the operating principle of smd will be quite clear.
Note! When turning on such an SMD diode, you must observe reverse polarity. This means that the connection is made with the anode to the minus.
Passing through this element, a small voltage in the circuit provokes a strong current. As the reverse voltage increases, the current also increases, only in this case its growth will be observed weakly. When you reach the mark, it can be anything. It all depends on the type of device. When the mark is reached, a “breakdown” occurs. After the “breakdown” has occurred, a large reverse current begins to flow through the smd. It is at this moment that the operation of this element begins until its permissible limit is exceeded.
How to distinguish a stabilization diode from a regular semiconductor
Very often people wonder how they can distinguish a zener diode from a standard semiconductor, because, as we found out earlier, both of these elements have almost identical symbols on the electrical circuit and can perform similar functions.
The easiest way to distinguish a stabilization semiconductor from a regular one is to use a multimeter attachment circuit. With its help, you can not only distinguish both elements from each other, but also identify the stabilization voltage, which is characteristic of a given SMD (if it, of course, does not exceed 35V).
The multimeter attachment circuit is a DC-DC converter, in which there is galvanic isolation between the input and output. This diagram looks like this:
Multimeter attachment circuit
In it, a generator with pulse-width modulation is implemented on a special microcircuit MC34063, and to create galvanic isolation between the measuring part of the circuit and the power source, the control voltage should be removed from the primary winding of the transformer. For this purpose there is a rectifier on VD2. In this case, the value for the output voltage or stabilization current is set by selecting resistor R3. A voltage of approximately 40V is released at capacitor C4.
In this case, the tested SMD VDX and the stabilizer for current A2 will form a parametric stabilizer. The multimeter, which is connected to terminals X1 and X2, will measure the voltage at this zener diode.
When connecting the cathode to the “-” and the anode to the “+” of the diode, as well as to the asymmetrical SMD of the multimeter, the latter will show a slight voltage. If you connect in reverse polarity (as in the diagram), then in a situation with a conventional semiconductor, the device will register a voltage of about 40V.
Note! For symmetrical SMD, the breakdown voltage will appear in the presence of any connection polarity.
Here the T1 transformer will be wound on a torus-shaped ferrite core with an outer diameter of 23 mm. Such winding 1 will contain 20 turns, and the second winding will contain 35 turns of PEV 0.43 wire. In this case, it is important to lay the turn to the turn when winding. It should be remembered that the primary winding goes on one part of the ring, and the second on the other.
When setting up the device, connect a resistor instead of smd VDX. This resistor should have a value of 10 kOhm. And resistance R3 must be selected in order to achieve a voltage of 40V on capacitor C4
This is how you can find out whether you have a zener diode or a regular diode.
Details about the color coding of the stabilizing diode
Any diode (zener diode, etc.) contains a special marking on its case, which reflects what material was used to manufacture each specific semiconductor. Such marking may look like this:
- letter or number;
- letter.
In addition, the marking reflects the electrical properties and purpose of the device. Usually a number is responsible for this. The letter, in turn, reflects the corresponding type of device. In addition, the marking contains the date of manufacture and the symbol of the product.
Integral type SMDs often contain full markings. In such a situation, there is a conditional code on the product body that indicates the type of microcircuit. An example of decoding the code markings for microcircuits applied to the housing is shown in the figure:
Example of microcircuit marking
In addition, there is also color coding. It exists in several versions, but the most commonly used is the Japanese marking (JIS-C-7012). The color coding is shown in the following table.
Zener diode color coding
- the first bar indicates the device type;
- the second is a semiconductor;
- third - what kind of device it is, and also what its conductivity is;
- fourth - development number;
- fifth - modification of the device.
It should be noted that the fourth and fifth stripes are not very important for choosing a product.
Conclusion
As you can see, there are many different markings and designations for a zener diode, which you need to remember when choosing it for a home laboratory and making various electrical devices with your own hands. If you are good at this issue, then this is the key to making the right choice.
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