About resistors for beginners in electronics. Resistance to electric current Resistance 470 ohms
Ceramic wirewound cement resistors– fixed resistors, the nominal resistance, depending on the rating, is from 0.01 Ohm to 100 kOhm, power dissipation – 5W, 10W, 15W, 25W. Designed for use in DC or AC circuits, providing current limitation and voltage distribution.
Structurally, wirewound resistors are made in the form of a tubular ceramic base(pure alumina Al 2 O 3), used as a resistive element conductor wire(copper-nickel or chromium-nickel alloy) with high resistivity. The base with the winding is placed in cast rectangular body from soapstone ceramics and encapsulated with silica(silicon dioxide SiO 2).
The monolithic ceramic design of resistors has high fire resistance, moisture resistance and self-extinguishing properties.
Output of ceramic resistors– flexible axial wire type. Tinned copper is used as the terminal material. Installation is carried out using soldering using THT technology - the leads are mounted directly into the through holes of the printed circuit board.
Installation position- any, but you should remember about the resistive features, accompanied by heating of the resistor housing. Therefore, it is not recommended to place resistors close to the printed circuit board or temperature-sensitive elements.
The permissible resistance deviation of cement axial resistors is ±5%. A number of intermediate values of nominal resistances - E24 E24 - one of a series of fixed resistors, which is the result of standardization of the nominal resistances of resistors. 
. With alternating current, the maximum operating voltage is 1500V, at constant current – 1000V. The operating elevated temperature of the environment does not exceed +275°С, reduced – up to -55°С. The insulation resistance is at least 1000 MOhm.
When selecting the required denomination calculation it is recommended to carry out using flexible, with which you can determine the total parallel or series resistance of resistors, as well as the resistance of the resistors in the circuit.
The design features and characteristics of powerful resistors S5-35V, S5-36V, PEV, PEVR, RX24 and SQP are presented.
Apply high-power ceramic resistors in various industrial electronics, radio and television receivers, power supplies and control units, amplifiers, automotive electronics, and also as test loads or heating elements (for example, in outdoor video surveillance cameras).
More detailed characteristics of the presented powerful ceramic cement resistors, as well as a description of the markings, overall and installation dimensions are given below.
Guarantee period The performance of the powerful resistors supplied by our company is 2 years, which is supported by relevant quality documents.
The final price for high-power wirewound ceramic cement resistors depends on the quantity, delivery time and form of payment.
Conductors provide resistance to electric current; the greater the resistance, the less strength of the electric current through the conductor. The resistance of a conductor depends on the material of which it is composed, length, cross-section, and temperature. The longer the conductor, the greater the resistance; the shorter the conductor, the less resistance. The thinner the conductor, the greater the resistance; the thicker the conductor, the less resistance.
Resistance is indicated by the letter R, and the unit of resistance is written in letters Ohm. In practice, units of electrical resistance are also used: kiloohms ( kOhm) and megaohm ( MOhm).
1 kOhm = 1000 Ohm
1 Mohm = 1000000 Ohm
To find the resistance of a conductor in ohms, you need to divide the voltage at its ends in volts by the current in amperes:
Fixed resistors
A resistor is a passive element of an electrical circuit. Serves to reduce the current; during operation, the resistors heat up, because excess electrical energy is converted by the resistors into heat. On electrical circuit diagrams, resistors are displayed as a rectangle with two terminals or as a broken line (American standard), designated by the letter R with a serial number (R1, R2, etc.). The resistor value is indicated next to it.
The main parameter of a resistor is resistance. Resistor resistance is measured in ohms, kilo-ohms, mega-ohms. The rated power dissipation of the resistor (from 0.05 to 5 W) is indicated by special signs placed inside the symbol.
Resistor markings. According to GOST 2.702-75, resistances from 0 to 999 Ohms are indicated on the diagrams by a number without a unit of measurement (3.3; 47; 220; 750, etc.), from 1 to 999 kOhm - by a number with the letter k (47 k; 330 k; 910 k, etc.), over 1 megaohm - a number with the letter M (1 M; 4.7 M, etc.).
According to GOST 11076-69, units of resistance in the coded system are designated by the letters E or R (Ohm), K (kilo-ohm) and M (mega-ohm). So 33 Ohms are labeled 33E, 1 Ohm - 1R0, 47 Ohms - 47E, 10 kOhms - 10K, 47 kOhms - 47K, etc.
Resistances from 100 to 1000 Ohms and from 100 to 1000 kOhms are expressed in fractions of kilo-ohm and mega-ohm, respectively, and the corresponding unit of measurement is put in place of zero and comma: 150 Ohm = 0.15 kOhm = K150; 910 Ohm=0.91 kOhm=K91; 180 kOhm = 0.18 MOhm = M18; 680 kOhm=0.68 MOhm=M68, etc.
If the nominal resistance is expressed as an integer with a fraction, then the unit of measurement is placed in place of the decimal point: 3.3 Ohm - 3E3 or 3R3; 4.7 kOhm – 4K7; 3.3 MOhm – 3M3, etc.
SMD resistors and trimmers can be marked with three numbers, the first two indicate the resistance in ohms (mantissa), and the third - the number of subsequent zeros (exponent to base 10), and the letter R can be added to the marking to indicate the decimal point. Examples:
Marking 513 means 51 x 10 3 = 51000 ohms or 51 kohms
The R470 marking means 0.47 Ohm
There are still many markings with colored stripes, but resistor manufacturers currently do not adhere to a general standard, so it is more reliable to measure the resistance of resistors with a multimeter.
Variable resistors
Variable resistors are resistors whose resistance can be changed. Used as gain, volume, tone, etc. controls.
There are two schemes for including variable resistors in an electrical circuit. In one case, they are used to regulate the current in a circuit, and then the adjustable resistor is called a rheostat. In another case, they are used to regulate voltage, then the resistor is called a potentiometer.
Trimmer resistors
A type of variable resistors is tuning. The control unit for such resistors is adapted to control a screwdriver.
Connection of resistors
When resistors are connected in series, their resistances add up:
With a parallel connection, the total resistance is calculated using the formula:
When two identical resistors are connected in parallel, the total resistance will be equal to half the resistance of one of them.
In this way, you can obtain the required resistor values from the available ones.
Calculation of resistor value by color code:
specify the number of color bars and select the color of each of them (the color selection menu is located under each bar). The result will be displayed in the "RESULT" field
Calculation of color code for a given resistance value:
Enter a value in the "RESULT" field and indicate the required resistor accuracy. The marking stripes on the resistor image will be colored accordingly. The decoder selects the number of bands according to the following principle: priority is given to the 4-band marking of general-purpose resistors, and only if there are no general-purpose resistors with this rating, the 5-band marking of 1% or 0.5% resistors is displayed.
Purpose of the "REVERSE" button:
When you press this button, the color code of the resistor will be rebuilt in a mirror image from the original one. This way you can find out whether it is possible to read the color code in the opposite direction (from right to left). This calculator function is needed when it is difficult to understand which stripe comes first in the color coding of the resistor. Usually the first strip is either thicker than the others or located closer to the edge of the resistor. But in cases of 5 and 6 strip color markings of precision resistors, there may not be enough space to move the marking strips to one edge. And the thickness of the strips can differ very slightly... With 4-band markings of 5% and 10% general-purpose resistors, everything is simpler: the last strip, indicating accuracy, is golden or silver in color, and the first strip cannot have these colors.
Purpose of the "M+" button:
This button will save the current color marking in memory. Up to 9 resistor color codes are stored. In addition, all values selected from the color-coding example columns, from the table of values in standard rows, any values (correct or incorrect) entered in the "Result" field, and only correct values entered using the selection menu are automatically saved into the calculator's memory the colors of the stripes or the “+” and “-” buttons. The function is convenient when you need to determine the color marking of several resistors - you can always quickly return to the marking of any of the ones that have already been checked. Red in the list indicates values with erroneous and non-standard color markings (the value does not belong to the standard series, the color-coded tolerance on the resistor does not correspond to the tolerance of the standard series to which the value belongs, etc.).
"MC" button:- clearing all memory. To remove only one entry from the list, double-click on it.
Purpose of the "Fix" button:
When you click on this button (if there is an error in the resistor color code), one of the possible correct options will be offered.
Purpose of the "+" and "-" buttons:
When you click on them, the value in the corresponding strip will change one step up or down.
Purpose of the information field (under the "RESULT" field):
It displays messages indicating which standard series the entered value belongs to (with what tolerances resistors of this rating are produced by industry), as well as error messages. If the value is not standard, then either you made a mistake or the resistor manufacturer does not adhere to a generally accepted standard (which happens).
Examples of resistor color coding:
On the left are examples of color coding for 1% and on the right are examples of 5% resistors. Click on a value in the list, and the stripes on the resistor image will be repainted in the corresponding colors.
Resistor resistance- its main characteristic. The basic unit of electrical resistance is the ohm (Ω). In practice, derivative units are also used - kiloohm (kOhm), megaohm (MOhm), gigaohm (GOhm), which are related to the basic unit by the following relationships: 
1 kOhm = 1000 Ohm,
1 MOhm = 1000 kOhm,
1 GOhm = 1000 MOhm.
Resistors can be constant, that is, have a constant resistance, and variable, that is, those whose resistance during operation can be changed within certain limits. Resistors are produced with certain resistance values in a wide range from units of ohms to tens of megohms.
Fixed resistors
On circuit diagrams, next to the symbol of the resistor, the value of its resistance is indicated. Resistance less than a kilo-ohm is written as a number without units; resistances from one kilo-ohm and above, but less than one mega-ohm, are expressed in kilo-ohms and the letter “k” is placed next to the number; Resistances from one megaohm and above are written as a number, adding the letter “M” next to it. For example, 10 M (10 megohm), 5.1 K (5.1 kilo-ohm); 470 (470 Ohm); K68 (680 Ohm).
The resistance value is usually indicated on the surface of the resistors. To mark small-sized resistors, an alphanumeric code or a color code consisting of colored stripes is used.
When using an alphanumeric code, resistor resistances are designated by numbers indicating the unit of measurement. Usually denoted by letters: R - ohm, K - kiloohm, M - megaohm.
Deviation of resistor values
Due to imperfect resistor manufacturing technology, their resistance may differ from the specified (nominal) value. The industry produces resistors for a wide range of applications with a permissible resistance deviation of ±5%, ±10%, ±20%. Therefore, along with the nominal value, the limits of permissible deviations are indicated on the case and in the passport of the resistors. In this case, an entry of the form 12k ±5% means that the nominal value of the resistor is 12 kOhm. The actual value may differ from the nominal value, but not more than ±0.6 kOhm (±5% of 12 kOhm).
When color coding is used, the deviation of the resistor value is indicated by a separate stripe (see table at the bottom of the article).
In electronic measuring devices, high-precision resistors are used (so-called precision resistors).
Resistor power
The thermal energy released in the resistor when current flows is dissipated from its surface into the surrounding space. However, if the power released in the resistor is large, then the heat from its surface will not have time to be removed. The resistor will become excessively hot and may even burn out. Therefore, each resistor has a strictly defined maximum permissible value of power that it is capable of dissipating.
Resistor power usually recognized by their size (the larger the resistor, the greater its power) or by the designation on the cases.
Circuit diagrams usually indicate the power of the resistor used. The absence of an indication of the power of the resistor means that negligible power is released on it and any resistor with this resistance can be used.
Variable resistors
A variable resistor serves to smoothly regulate current and voltage.
Variable resistors are divided into adjustable and tuned. Resistors, with the help of which various adjustments are made by changing their resistance, are called variable resistors or potentiometers. Resistors whose resistance is changed only during the process of setting up (adjusting) the device are called tuning resistors.
Variable resistors have three terminals, one of which is connected to a movable contact sliding along the surface of the conductive layer. The adjusting resistor motor is moved by hand by turning the protruding knob, and the adjusting resistor is moved by a screwdriver inserted into the slot.
The resistance between any extreme terminal of the variable resistor and the moving contact depends on the position of the slider.
The type of marking in which paint in the form of colored rings or dots is applied to the resistor body is called a color code. Each color corresponds to a specific digital value. The color markings on the resistors are shifted to one of the terminals and can be read from left to right. If, due to the small size of the resistor, the color marking cannot be placed at one of the terminals, then the first sign is made in a strip twice as wide as the rest.
The color marking of foreign small-sized resistors, common in Russia, most often consists of four color rings. The resistance value is determined by the first three rings (two digits and a multiplier). The fourth ring contains information about the permissible resistance deviation from the nominal value in percent.
To avoid confusion between zero and the letter “O”, “Om” is often written with the letter “omega”:
The time to decipher the color code of resistors can be significantly reduced if you use a special
Resistors are the most common elements of electronic equipment. Previously, resistors were called resistances, but in accordance with the State Standard, electrical resistances, like circuit elements, are given the name “resistors”.
This was done in order to distinguish between “resistance” as a product (radio component) and “resistance” as its physical property, an electrical quantity. Resistors are characterized by electrical resistance.
The basic unit of electrical resistance according to the international system of units is Ohm. In practice, derivative units are also used - kiloohm (kOhm), megaohm (MOhm), gigaohm (GOhm), teraohm (TOm), which are related to the basic unit by the following relationships:
- 1 kOhm = 10^3 Ohm,
- 1 MOhm = 10^6 Ohm,
- 1 GOhm = 10^9 Ohm,
- 1 TOm = 10^І2 Ohm.
The following are distinguished: types of resistors: permanent And variables. Variables are also divided into adjusting and tuning. For fixed resistors, the resistance cannot be changed during operation.
Resistors, with the help of which various adjustments are made in electronic equipment by changing their resistance, are called variable resistors or potentiometers. Those resistors whose resistance is changed only during the process of setting up (adjusting) a radio-electronic device are called tuning.
Basic parameters of resistors
Resistors are characterized by the following basic parameters: nominal resistance value, permissible resistance deviation from the nominal value, nominal (permissible) power dissipation, maximum operating voltage, temperature coefficient of resistance, self-noise and voltage coefficient.
The nominal resistance value R is usually marked on the resistor body. The actual value of the resistor resistance may differ from the nominal value within the permissible deviation (tolerance determined as a percentage relative to the nominal resistance).
Resistor markings
On the resistor body, as a rule, its type, rated power, rated resistance, tolerance and date of manufacture are painted. To mark small-sized resistors, an alphanumeric code is used. The code consists of numbers indicating the nominal resistance, a letter indicating the unit of measurement, and a letter indicating the permissible resistance deviation. Examples of the letter code of units of measurement of the nominal resistance of the old and new standards applied to the resistor body are given in Table. 1.
If the nominal resistance is expressed as an integer, then the letter code is placed after this number. If the nominal resistance is a decimal fraction, then a letter is placed instead of a comma, separating the integer and fractional parts. In the case where the decimal fraction is less than one, the integer part (zero) is excluded.
When marking resistors, the tolerance code is placed after the coded designation of the nominal resistance. Letter tolerance codes are given in table. 2.
For example, the designation 4K7V (or 4K7M) corresponds to a nominal resistance of 4.7 kOhm with a permissible deviation of 20%. In table 1 and 2 show letter codes corresponding to both old and new standards, since both options are currently found. The rated power on small-sized resistors is not indicated, but is determined by the dimensions of the case.
Table 1. Designation of the nominal resistance value on resistor bodies.
| Full designation | Abbreviation on the body | |||||
| Designation | Notation examples | Unit designation | Notation examples | |||
| units of measurement | Old | New | Old | New | ||
| Ohm | Ohms | R | E | 13E 470E (K47) | ||
| kOhm | kiloohms | TO | TO | |||
| MOhm | megaohms | 470 MOhm | M | M | M47 | |
Table 2. Letter codes for resistance tolerances applied to resistor housings.
Resistor color code
The type of marking in which paint in the form of colored rings or dots is applied to the resistor body is called a color code (see Fig. 1). Each color corresponds to a specific digital value.
The color markings on the resistors are shifted to one of the terminals and can be read from left to right. If the marking cannot be placed at one of the terminals, then the first mark is made in a strip twice as wide as the others.
For resistors with a small tolerance value (0.1...10%), marking is done with five color rings. The first three rings correspond to the numerical value of the resistance in ohms, the fourth ring is the multiplier, and the fifth ring is the tolerance (Fig. 1).
Resistors with a tolerance value of 20% are marked with four colored rings and the tolerance value is not applied to them. The first three rings are the numerical value of the resistance in ohms, and the fourth ring is the multiplier. Sometimes resistors with a tolerance of 20% are marked with three colored rings.
In this case, the first two rings are the numerical value of the resistance in ohms, and the third ring is the multiplier. The insignificant zero in the third digit is not marked.
Due to the fact that foreign products occupy a significant place in the radio equipment market, we note that resistors from foreign companies are marked with both a digital and color code.
When marking digitally, the first two digits indicate the numerical value of the resistor in ohms, and the remaining ones represent the number of zeros. For example: 150 - 15 Ohm; 181 - 180 Ohm; 132 - 1.3 kOhm; 113-11 kOhm.
Color coding usually consists of four color rings. The resistance value represents the first three rings, two digits and a multiplier. The fourth ring contains information about the permissible resistance deviation from the nominal value in percent.
Determining the values of foreign resistors by color code is the same as for domestic ones. The color code tables for domestic and foreign resistors are the same.
Many companies, in addition to traditional markings, use their own in-house color and code markings. For example, SMD resistors are marked when a colon is placed instead of the number 8. So, the marking 1:23 means 182 kOhm, and 80R6 means 80.6 Ohm.
| Color of rings or dots | Nominal resistance, Ohm | Factor | Tolerance, % | TKS, %/GS | ||
| 1st digit | 2nd digit | 3rd digit | 4th digit | 5th digit | P | |
| Silver | - | - | - | 0601 | ±10 | - |
| Golden | - | - | - | 061 | ±5 | - |
| Black | - | 0 | - | 1 | - | - |
| Brown | 1 | 1 | 1 | 10 | ±1 | 100 |
| Red | 2 | 2 | 2 | 10^2 | ±2 | 50 |
| Orange | 3 | 3 | 3 | 10^3 | - | 15 |
| Yellow | 4 | 4 | 4 | 10^4 | - | 25 |
| Green | 5 | 5 | 5 | 10^5 | ±0.5 | - |
| Blue | 6 | 6 | 6 | 10^6 | ±0.25 | 10 |
| Violet | 7 | 7 | 7 | 10^7 | ±0.1 | 5 |
| Grey | 8 | 8 | 8 | 10^8 | ±0.05 | - |
| White | 9 | 9 | 9 | 10^9 | - | 1 |
Rice. 1. Color marking of domestic and foreign resistors in the form of rings or dots, depending on tolerance and TKE.
Literature: V.M. Pestrikov. Encyclopedia of amateur radio.