Identification and detection of active resistance elements
Identification and detection of active resistance elements
Resistance is one of the most common and basic electronic components. Electric energy can be distributed to each component of the circuit to stabilize and regulate the current and voltage of the circuit by using the absorption of electrical energy by resistors.
In physics, resistance is used to indicate the size of the conductor's impediment to the current. The greater the resistance of a conductor, the greater the impediment of the conductor to the current. The resistance values of different conductors and resistors are also different from those of temperature.
There are many kinds of resistors. With the development of electronic technology, new resistors are increasing.
1. According to resistance characteristic
It can be divided into fixed resistors, adjustable resistors, special resistors (sensitive resistors).
2. According to manufacturing materials
It can be divided into carbon film resistors, metal film resistors, wire-wound resistors, non-inductive resistors, film resistors and so on.
By installation
It can be divided into plug-in resistors and chip resistors.
?Main parameters of resistor
1. Nominal value
The resistance rating on resistors is called the nominal value. The unit is Q, K and MQ. Nominal values are a series of national standards that are not calibrated by the manufacturer, but exist on resistors, not all resistors.
2. Admissible deviation
The actual resistance of the resistor is called allowable deviation, and the maximum permissible deviation is the nominal value. Deviation Code: J (SH 5%), K (SH 10%), I (+ 5%), II (See 10%).
Rated power
Rated power refers to the power consumed by the resistor at a given ambient temperature, assuming that ambient air does not circulate for a long time without damaging or basically changing the performance of the resistor. Common are W / 16, W / 8, W / 4, W / 2, 1W, 2W, 5W, 10W literacy, etc.
parameter
(1) direct labeling method
Direct annotation is to mark the main parameters of resistors directly on the outer surface of resistors.
Wireless assembly technology is mainly used in high-power resistors, as shown in Figures 1 to 1, more intuitive and easier to read.
(2) character number method
Character symbols are combinations of numbers and words. The number in front of the marker on the outer surface of the resistor represents the integer resistance L value of the resistor, and the number behind the literal symbol indicates the obstacle behind the decimal point; the unit is determined by the character symbol. It is mainly applied to high-power resistors, which is more intuitive and easy to read, as shown in Figure 1-2. 5W0.25JRJ720.252K7+ 20%
(3) color coded method
Color code is a method to mark the nominal resistance and allowable deviation on the surface of resistors with different color rings. It is mainly applied to small cylinder resistors, marked clearly, easy to read and numeric read.