What is a resistor? Structure and role of resistors in electrical circuits

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A resistor is an electronic component found in most fields, such as cars, computers, phones, electronic circuits, etc. They play an important role in electronics, mechatronics, automation… So you already know “What is a resistor”? Let’s find out in the following article.

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What is a resistor?

A resistor (whose English name is resistor) is a type of passive electronic component with two connection points. They are responsible for blocking the current, reducing the current flowing in the circuit, adjusting the signal level, dividing the voltage, activating the electronic components to work, etc.

Resistor power is capable of converting large amounts of electrical energy into heat, which can be found in motor control units or power distribution systems. Resistors usually have a certain impedance value that is less affected by temperature and voltage during operation.

What is a resistor

What is the working principle of resistors?

Resistors work on the principle of Ohm’s law. This is a law of physics that states the dependence of amperage factors on voltage and resistor. The content of Ohm’s law states that when current flows through two points on a conductor, it is always proportional to the potential difference at those two points, at which the conductor has a constant resistor. There is a formula that describes this relationship as follows: V = IR

With:

V: voltage across the conductor (V)

I: current through the conductor (A)

R: resistor (Ω)

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What kind of resistors are there today?

Today, there are many types of resistors made in different ways for use in different fields. They have common properties such as voltage factor, noise, temperature, capacity, physical size, thermistor, etc. There are six common types of resistors:

Band resistor

Band resistors are also known as series resistors. They are a type of resistor created when a series of resistors of the same value need to be installed in parallel. First, they are manufactured separately and then soldered together. One leg can be with or without housing. In addition, this type of resistor is also made in the form of a microchip with DIP or SIP pins

What is a resistor

Film resistor

This type of resistor is made by crystallizing substances such as carbon, metal, metal oxide, and ceramic in the core. The coils and film thickness produced by the surface determine the resistor value. With a thickness of 1/20–1/2 W, its tolerance level is quite low.

Carbon Resistor

A carbon resistor is also known as a coal resistor. This is a resistor made by pressing a mixture of carbon powder and glue into a cylinder or rod with a ceramic or painted exterior. Currently, this is the most common and widely used resistor. The power level is usually quite small, only 1/8–2 W, and the tolerance level is large, so it is widely used in high-frequency areas. Carbon resistors are usually denoted CR, R6 (tolerance ±20%), E12 (tolerance ±10%) and E24 (tolerance ±5%). Power levels range from 0.25 W to 5 W.

What is a resistor

Winding resistor

This type of winding resistor uses a poorly conductive metal wire or similar wire wound around a spring-shaped insulating ceramic core. This resistor usually has a small value but can withstand large currents; the electrical power level is usually high in the range of 1–300 W, even up to thousands of W. The winding resistor is marked W or WH, with errors of 1–10%.

Membrane resistor or metal-ceramic resistor

The term film resistor is a general term for carbon film resistors, metal oxide film resistors, and metal film resistors. They are made by applying base metals or oxide films to insulating ceramic rods. Metal film resistors will be available in grades like E24 (tolerance ±5% and ±2%), E96 (tolerance ±1%) and E192 (tolerance ±0.5%, ±0.25% and ±0.1%) with power levels from 0.05 to 0.5W.

Surface resistor

The surface resistor is also known as a paste resistor. It is a resistor made by surface-gluing technology, also known as direct-on-PCB. This type of paste resistor is small, only about 0.6mm x 0.3mm.

Uses of resistors in electrical circuits

Here are some uses of resistors you can refer to:

Protect LEDs

The first application is the protection of LEDs. Because if you don’t connect the resistor, the LED will quickly fail. The main reason is that the rated current flowing through the LED is higher than the allowable rated current of the LED. So a direct connection between resistor and LED is commonly used. 

Electric limit

Another reason resistors are used in circuits is to limit current. To ensure the safety of the circuit, the resistor is usually connected in series with the transistor. As a result, it is possible to protect the circuit and prevent explosions.

Sound control

The next application of the resistor is to control the sound. Combinations of resistors and capacitors are often used to limit high frequencies in audio control circuits. The purpose of this circuit is to transmit high frequencies to the earth. Another name for this combination is a low-pass filter.

Applications in RC circuits

The resistor in the RC circuit is used to adjust the charge and discharge times when connected in series with the capacitor. When the switch is closed, the resistor limits the current flowing through the capacitor. This limits the charging rate from the mains to the capacitor.

What is a resistor

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Hopefully the information that we sent to you in today’s article has helped you understand “What is a resistor”. Although it is a small device, the benefits that it brings to people’s lives, industries, and fields are enormous. If you have a need for components, solder, solder paste, etc., contact Thetech for the most specific advice!

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