Resistance and capacitance identification method - Database & Sql Blog Articles

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The nominal value and allowable deviation of resistors and capacitors are generally marked on the resistor body and the capacitor body. On the circuit diagram, only the nominal value is usually marked. The electrolytic capacitor is often increased in voltage withstand voltage, and the special purpose capacitor is marked with resistance. Also indicate the variety outside the pressure. Their marking methods are divided into the following four types.
1. Straight standard method: The direct standard method is to directly mark the nominal value of the resistor and capacitor with the digital and text symbols on the resistor body and the capacitor body, and the tolerance is expressed as a percentage. ±20% tolerance.
2. Text symbol method: The text symbol method is to combine the nominal value and the allowable deviation of the resistor and the capacitor with the digital and text symbols in a certain regular combination on the resistor body and the capacitor body.
Let me give you an example of several resistors: 6R2J means that the nominal value of the resistor is 6.2 ohms (Ω), the allowable deviation is ±5%; 3k6k means that the resistance value is 3.6 kohms (kΩ), the allowable deviation is 10%; 1M5 is Indicates a resistance value of 1.5 megohms (MΩ) with a tolerance of ±20%. Here are a few examples of capacitors: 2n2J means that the capacitor has a nominal value of 2.2 nanofarads (nF), or 2200 picofarads (pF), with an allowable deviation of ±5%; 47nk means that the capacitor has a capacity of 470 nanofarads (nF) or 0.47 microfarad (uF) with a tolerance of ±10%. In the circuit diagram, the ohmic symbol Ω of the resistor and the farad symbol F of the capacitance can often be omitted.
3, color standard method: ordinary resistor with four-color ring mark, precision resistor with five-color ring mark, the color ring close to the end of the resistor body is the first ring, the other end of the resistor body with more color is the last ring. The color scale method is also commonly used on capacitors. The user should memorize the order of the black, brown, red, orange, yellow, green, blue, purple, gray, and white color rings representing the numbers 0-9. The color scale method is introduced in various electronic introductory books and will not be described in detail here.
4. Digital notation: The method of using three digits to represent the nominal value of a component on a product and circuit diagram is called digital representation. Commonly found in imported electrical movements and joint venture products, such as pagers, mobile phone chip resistors almost invariably using digital notation. In the three digits, the first and second digits from left to right represent the first and second significant digits of the nominal value of the resistor, and the three digits of the cage are n with a magnification of 10^n (ie, after the first two digits) The number of 0), the unit is Ω. For example, a resistor labeled 222 has a resistance of 2200 Ω or 2.2 kΩ; a resistance of 105 is a resistance of 1 MΩ; and a resistance of 4R7 is 4.7 Ω. It should be noted that this marking method is distinguished from the traditional method: if the resistor marked with 220 has a resistance value of 22 Ω, only the resistor labeled 221 has a resistance of 220 Ω. The flag is a resistor of 0 or 000, which is actually a jumper with a resistance of 0 Ω.
At present, most of the wafer capacitors, ceramic capacitors and CBB capacitors on the electronic market are digitally represented, and the reading method is the same as that on the resistor.
In some imported movements, the sign method for fine-tuning the resistance of resistors uses two digits in addition to three digits. If the flag is 53 for 5kΩ, 14 and 54 are for 10kΩ and 50kΩ, respectively. Some precision chip resistors are also available in 4-digit representations, such as 1005 for 10MΩ.
Chip capacitors are generally unsigned and can be distinguished from the depth of the color based on experience. Light or white is pf (class), such as 100pF; dark, brown is DC, filter capacitor, is a nanofarad (nF) class capacitor.