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Fixed resistor and fuse selection
Mar 04, 2018

Fixed resistor and fuse selection


1. Selection of fixed resistors:

There are many types of fixed resistors, the choice of which material and structure of the resistor should be based on the specific requirements of the application circuit.

High-frequency circuits should be used distributed inductors and distributed small non-linear wound resistors, such as carbon film resistors, metal resistors and metal oxide film resistors, thin film resistors, thick film resistors, alloy resistors, anti-corrosion coating Resistors and so on. Low-noise resistors, such as metal film resistors, carbon film resistors and wirewound resistors, should be used in high-gain small-signal amplifier circuits. Noise-free synthetic carbon film resistors and organic solid resistors should not be used.

Wirewound resistors larger power, current noise, high temperature, but larger. Common wirewound resistors are commonly used in low-frequency circuits or as current-limiting resistors, voltage-dividing resistors, bleeder resistors or high-power tube bias resistors. High precision wire wound resistors are used for fixed attenuators, resistance boxes, computers and various sophisticated electronic equipment.

The resistance of the selected resistor should be close to a nominal value calculated in the application circuit and a standard series of resistors should be preferred. General circuit resistors allowable error of ± 5% ~ ± 10%. Resistors used in precision instruments and special circuits should be precision resistors. For precision resistors of less than 1%, such as 0.01%, 0.1%, 0.5% resistors of the order of magnitude should be used. The rated power of the selected resistor, in line with the requirements of the application circuit power capacity of the resistor, the general should not arbitrarily increase or decrease the power of the resistor. If the circuit requirements are power-type resistors, the rated power may be higher than the actual application of circuit power requirements of 1 to 2 times.

2. Fusing resistors of choice:

Fuses Resistors with protective functions. Selection should consider its dual performance, according to the specific requirements of the circuit to select the resistance and power and other parameters. It is necessary to ensure that it can quickly fuse when overloaded, but also to ensure that it can be long-term and stable work under normal conditions. Resistance is too large or too large power, can not play a protective role.

Three basic principles of resistor selection:

* Select a high level of standard resistor manufactured by a certification body certified production line.

* Select a manufacturer of resistors with functional advantages, quality advantages, efficiency advantages, cost-effectiveness advantages and service advantages.

* Select the manufacturer of the model catalog that meets the above requirements and order the resistor directly.