Introducing Resistors and Types of Resistors

By | August 25, 2021

Resistors are electronic components that are used to limit / inhibit the amount of electricity flowing in an electronic circuit. Resistor is one of the components whose use is most often found in electronic circuits. Almost all electronic equipment use it. Basically a resistor is a passive component that has a certain resistance value or resistance whose value determines the amount of electric current generated.

Resistors are electronic components that function to limit and regulate the amount of electricity that will be used in other components in electronic circuits. Resistors are abbreviated with the letter “R”. The unit of resistance or resistance of a resistor is Ohm (Ω). As a tribute to the inventor, the term “OHM” is taken from the name of George Simonn Ohm, a German physicist who has discovered the electronic component of the resistor.

Resistor Symbol

The schematic symbol of the resistor is divided into two versions, namely the US version and the European version, although there are differences in the resistor symbol but you are free to choose. Although you are free to choose the resistor symbol you want to use, keep in mind that you should not mix or use the two symbols in one circuit.

Here’s the difference in the symbols

Material Resistance In Resistor

Resistors can be made of a number of different materials, the difference in resistance materials in the resistor will determine the quality of the resistor.

Here are some of the most common materials used in the manufacture of resistors

1. Carbon Composition

Having low to medium power, the tolerance and stability resulting from carbon composite resistors are relatively poor, while they also produce more noise than other types of resistors.

2. Carbon Film

It has low power, tolerance and stability is quite good, and does not produce a lot of noise.

3. Metal Film

It has low to medium power, tolerance and stability resulting from this type of resistor is very good, besides that there is almost no noise generated.

4. Wire Roll

It has high to very high power, the tolerance produced is very good and the stability is also good, besides that there is almost no noise produced.

Resistor Types

Based on the type and material used to make resistors, they are divided into wire resistors, charcoal resistors and metal oxide resistors.

While charcoal resistors and metal oxide resistors are based on a known arrangement of composition resistors and film resistors.

However, in general the types of resistors on the market are better known as fixed resistors and variable resistors.

1. Type of Fixed Resistor (Fixed Resistor)

Fixed resistor is a type of resistor whose value is written on the body of the resistor by using a color code or number. This resistor is widely used as a permanent resistor of electric current.


Fixed Resistor Symbol

Fixed resistors always have a number code or color code on their body.

For the type of fixed resistor, one of the characteristics that can be remembered is the value of its resistance which cannot change because in the manufacturing process a fixed value has been determined for the resistor.

Types of Fixed Resistors

A. Carbon Composition Resistor

The type of carbon composition resistor is made from a mixture of carbon or graphite with an insulating material that serves to wrap it.

Carbon composition resistor is a low type resistor because it has a low inductance so it is ideal for use in high frequencies.

But generally this type of resistor is quite annoying because it causes noise and is less stable when hot, but the carbon composition resistor is a type of resistor that is relatively cheap on the market and is generally used in an electrical circuit.

Composition resistors are generally given the “CR” prefix in their writing, for example CR10k and are available in packages E6 ( ± 20% tolerance), E12 ( ± 10% tolerance) and E24 ( ± 5% tolerance) with a power of 0.125 or 1/4 Watt to 5 Watts. Because it has a large enough tolerance value so it is less precise (accurate) in its use.

B. Film Resistor

Based on the material of manufacture, there are 3 types of film resistors, namely metal film resistors, carbon film resistors, and oxide film resistors. This type of film resistor is generally made by inserting a pure metal, such as nickel or an oxide film such as tin-oxide, into a ceramic rod.

• Carbon Film Resistor

Resistor Type This type of carbon film consists of a thin film of carbon deposited or wrapped in an insulator that is cut in a spiral. The resistance value depends on the proportion between the carbon and the insulator.

In principle, the larger the mixture of carbon materials contained in the resistor, the smaller the resistance value obtained.

The resistance values ​​of carbon film resistors commonly found in the market range from 1 to 10M with power values ​​ranging from 1/6 W to 5 W.

Due to their low sensitivity to temperature, carbon film resistors can perform well in temperatures ranging from -55°C to 155°C.

• Metal Film Resistor

Metal film type resistors have better temperature stability than carbon films, are less prone to noise and have better frequencies or are applied in radio frequencies.

Metal Film Resistor is a type of resistor that is coated with a thin metal film onto a ceramic substrate and cut in a spiral shape.

The resistance value is influenced by the length, width and thickness of the metal spiral. The oxide film resistors have better quality than metal film resistors.

Metal film resistors are generally written with the prefix “MFR” for example MFR100k and “CF” for carbon film resistors.

Metal film resistors are available in several packaging types such as E24 (±5% and ±2% tolerance), E96 (±1% tolerance) and E192 (±0.5%, ±0.25% & ±0.1% tolerance) with a power of 0.05 (1/ 20th) Watt to 1/2 Watt.

C. Wire Resistor

Another type of fixed resistor is a wire resistor, this type of resistor is made by wrapping a wire into a ceramic and then wrapping it with an insulating material.

The physical form of this resistor is quite varied and has a relatively large size.

Because this type of wire resistor generally has a relatively high resistance magnitude and is resistant to high temperatures, this resistor is only used in power circuits.

Wire resistors are generally written with the prefix “WH” or “W” for example (WH10 ) and are available in WH aluminum packaging (±1%, ±2%, ±5% & ±10% tolerance) or W covered with enamel (such as glass). ) has (±1%, ±2% & ±5% tolerance) with power from 1W to 300W or more.

2. Variable Resistor Type

The type of variable resistor or also called a variable resistor is a type of resistor whose resistance value can change and be adjusted as desired. As for the type of variable resistor is divided into 3 : Potentiometer, Rheostat and Trimpot.

A. Potensiometer

The potentiometer is the most commonly used type of variable resistor. Potentiometer is a type of Variable Resistor whose resistance value can vary by rotating its axis through a lever located on the potentiometer head.

The potentiometer resistance value is usually written on the potentiometer body in the form of a numeric code.

In general, the change in resistance in the potentiometer is divided into 2, namely linear and logarithmic. What is meant by linear change is the change in resistance value is directly proportional to the direction of rotation of the regulator.

Meanwhile, what is meant by a logarithmic change is a change in the resistance value based on a logarithmic calculation.

To distinguish linear and logarithmic potentiometers, it is enough to look at the letter code where the letter A indicates a linear potentiometer while the letter B indicates a logarithmic potentiometer.

B. Rheostat

Rheostat is a type of variable resistor that can operate at high voltages and currents. The rheostat is made of resistive wire coils and the resistance value setting is done by a sweeper that moves on the top of the Toroid.

C. Preset Resistor (Trimpot)

Preset Resistor or often also called Trimpot (Trimmer Potentiometer) is a type of Variable Resistor that functions like a potentiometer but has a smaller size and does not have a lever.

To adjust the resistance value, it takes a tool such as a small screwdriver to be able to rotate the axis.

The nature and physical of the trimpot are actually the same as the potentiometer, which differs the size of the trimpot is much smaller. The change in resistance value is also divided into 2, namely linear and logarithmic, where the letter A is linear and the letter B is logarithmic.

D. Thermistor (Thermal Resistor)

Thermistor is a type of resistor whose resistance value can change because it is affected by temperature (Temperature). Thermistor is an abbreviation of “Thermal Resistor”.

There are two types of thermistors, namely NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient) thermistors.

Thermistor Forms and Symbols:

 

E. LDR (Light Dependent Resistor)

LDR or Light Dependent Resistor is a type of resistor whose resistance value can change because it is influenced by the intensity of the light it receives.

LDR forms and symbols:

 

F. Varistor

Varistor is a type of resistor whose resistance value is affected by voltage. Varistor is the newest name for this component. Previously people called Varistor as VDR (Voltage dependent Resistance). This resistor is a bit unique, if it is measured using an ohm meter the “resistance” value is infinite ohms, even measured with a measuring limit of x10k though !! but this does not mean breaking up, it is. The characteristic of the varistor is that if the applied voltage exceeds the given working voltage, the VDR resistance will decrease drastically. Varistors are usually installed in parallel to the switching power supply, as protection from outside noise interference.

Varistors are usually installed in parallel with the PLN voltage input line on the TV power supply or Computer Power Supply, for example. How it works: When there is a transient voltage in the line, the voltage suddenly rises, reaches its specification limit, then it turns into a resistor with a small resistance and then immediately shorts the transient voltage, thus avoiding entering the power supply. When the transient voltage disappears or drops at the threshold voltage it becomes R which is infinite again.

Transient voltage, can be from a large power electric motor adjacent to the plug attached which we will secure with a Varistor. Or it could also come from a series of switching circuits that disconnect the coil/transformer coil at high speed.

G.Magnetic Field Dependent Resistance (MDFR)

MDFR is a type of resistor whose resistance value depends on changes in magnetic field flux. The greater the value of the magnetic field flux in the MDFR environment, the greater the resistance. This means that the MDFR resistance is directly proportional to the magnetic field flux. The use of MDFR is usually applied to metal detection sensors and electronic compasses.