By EECTECH | 15 July 2020 | 0 Comments
Basic introduction of power winding resistance and several kinds of resistance
Power wire-wound resistors are two-terminal electronic components that are made of resistive materials, have a certain structure, and can limit the flow of current in the circuit.
The resistance that cannot be changed is called a fixed resistor. Variable resistance is called potentiometer or variable resistor. The ideal resistor is linear, that is, the instantaneous current through the resistor is proportional to the applied instantaneous voltage. Some special resistors, such as thermistors, varistors and sensitive components, have a non-linear relationship between voltage and current. Resistors are the most widely used components in electronic circuits. They usually form different series according to power and resistance for circuit designers to choose. The resistor is mainly used to adjust and stabilize the current and voltage in the circuit, and can be used as a shunt and voltage divider, and can also be used as a circuit matching load.
According to the requirements of the circuit, it can also be used for the negative feedback or positive feedback of the amplifying circuit, voltage-current conversion, voltage or current protection components when the input is overloaded, and can be formed into an RC circuit for oscillation, filtering, bypass, differentiation, integration and time constant Components etc. Function Low-power carbon film resistors are usually made of carbon film encapsulated in a plastic case, while power wire-wound resistors are usually wire-wound resistors, which are made by winding a metal wire with a large resistivity on a ceramic core. .
If the resistance value of a resistor is close to zero ohms (for example, a large cross-section wire between two points), the resistor has no blocking effect on the current, and the loop connected with this resistor is short-circuited, and the current is infinite. If a resistor has infinite or very large resistance, the loop connected to the resistor in series can be regarded as an open circuit and the current is zero. The resistor commonly used in the industry lies between the two extreme cases. It has a certain resistance and can pass a certain current, but the current is not as large as in a short circuit. The current limiting function of the resistor is similar to that of a small diameter tube connected between two large diameter tubes to limit the flow of water.
Resistance, the English name resistance, is usually abbreviated as R. It is a basic property of a conductor and is related to the size, material, and temperature of the conductor. Ohm’s law says that I=V/R, then R=V/I. The basic unit of resistance is ohm, which is represented by the Greek letter "Ω". There is a definition: when a voltage of one volt is applied to a conductor, a current of one ampere is generated The corresponding resistance. The main function of the resistor is to block the flow of current. In fact, "resistance" refers to a property, and the resistance usually referred to in electronic products refers to a component such as a resistor.
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