A resistor is one of the most commonly used components in electronic circuits. Engineers use different types of resistors in the production of electronics.
However, the quality of these resistors varies. So, it’s essential to choose the right kind of resistor for each design to get excellent results.
This article discusses the different types of resistors available.
What is a Resistor?
A resistor is an electrical component that regulates the flow of electricity. It also sets a voltage for an active device, like a transistor, that needs it.
Resistors are found in much electronic equipment. As separate parts, practical resistors comprise various materials and shapes.
The resistance of a resistor determines how it works with electricity. Standard commercial resistors come in more than nine size orders, which is a lot.
Further, the resistance’s nominal value aligns with the manufacturing tolerance on the part.
Different Types of Resistors
Each resistor type comprises several materials and shapes. They all have unique characteristics and disadvantages.
Here are the different types of resistors.
Fixed Value Resistors
Fixed resistors are very common and have a specific value. Some fixed resistors come in axial-leaded and surface-mount packages. An ideal fixed resistor has the same resistance in all situations.
However, the resistance of practical resistors changes a little bit with temperature.
Further, a fixed resistor has two terminals, which we use to connect with the other parts.
Types of Fixed Value Resistors
Carbon Composition Resistor
A carbon composition resistor is a passive component that stops the flow of electricity at a certain level.
This fixed resistor used to be common, but now there are cheaper and more effective ones.
It comprises a cylindrical resistive element with metal end caps built into the end of the piece.
The cylindrical part of this fixed resistor consists of carbon powder and ceramic.
Wire Wound Resistor
This type of resistor is typically used in high-power applications. They were made by winding wire on a former with much higher resistance.
So, the metal wire serves as a resistive element to the electric current, limiting it.
The non-conductive substance is the metalcore. So, electric current cannot pass through it.
Metal Film Resistor
The resistor puts a thin film of conductive material atop an insulating core.
We can quickly get the desired resistance value of a metal film resistor by reducing the thickness of the layer.
We can also get it by cutting helical grooves of appropriate pitch along its length.
Carbon Film Resistor
Carbon film resistors are mostly used in electronic circuits. Compared to carbon composition resistors, they emit less noise.
Carbon film resistors work by applying a carbon film to a ceramic substrate. The carbon layer resists the electric current, but the ceramic substrate is an insulating medium.
Metal Glaze Resistor
The metal glazing resistor is one type of resistor that uses a mixture of glass powder and metal particles.
This resistor limits the flow of electric current to a specific level. However, metal glaze resistors have low Temperature Coefficient of Resistance (TCR).
TCR refers to how a material’s resistance changes as the temperature rises.
Metal Oxide Film Resistor
Metal oxide film resistors are almost identical to metal film resistors. The only variation is the type of material utilized to make the film.
Metal film resistors use nickel and chromium to create the film. In contrast, metal oxide film resistors use metal oxides such as tin oxide to make the film.
Foil Resistor
Foil resistors are the most precise and reliable parts for limiting the flow of electricity to a certain level.
Another name for these resistors is high precision, with a very low TCR. Further, it makes less noise than other types of resistors.
Variable Resistors
Variable resistors are resistors whose value may change by turning a shaft or a screwdriver in pre-set pots.
It is a variable resistor with three terminals. The wiper is the pin with the arrow in the middle, where the resistance changes.
There is a resistive semicircular bar or coil. When you wipe the contact, you change the length of the resistive element, which changes the resistance.
A slider taps onto the main resistor element, and a fixed resistor element makes up variable resistors.
So, a variable resistor is a potentiometer with only two instead of three wires that connect to it.
Types of Variable Resistors
Potentiometer
The potentiometer has three terminals, two of which are fixed, and one can change.
The potentiometer has two fixed terminals that link to both track ends. The third terminal connects to the slider, moving the slider or wiper up and down.
Moreover, the resistance of the potentiometer changes by sliding the slider along the resistive track.
Humistor
A humistor is a variable resistor whose resistance changes as the humidity of the air changes. A thermistor resistor is also called a Humidity-sensitive resistor.
The humistor’s resistance depends on the concentration of absorbed water molecules.
Also, the number of water molecules absorbed by the humistor increases as humidity rises.
Therefore, it makes the humistor more electrically conductive. As a result, the humistor’s resistance lowers.
However, when the humidity level drops, the number of water molecules absorbed by the humistor drops.
This makes the humistor becomes less electrically conductive. As a result, the humistor’s resistance increases.
Thermistor
Among the different types of resistors, a thermistor resistor changes its resistance value as the temperature changes.
In general, the resistance of most thermometers decreases as temperatures rise. They usually consist of semiconductor materials.
Thermistors can have resistance up to a few million ohms, and they can look for small temperature changes.
The reason is that any temperature change would make a big difference in the resistance value.
Rheostat
The rheostat’s structure is virtually identical to that of a potentiometer.
The rheostat has three terminals, like the potentiometer. However, we use two terminals in a rheostat to execute the function.
Also, an electric rheostat’s resistance depends on how long an electric current element moves.
Photoresistor
Two types of intrinsic and extrinsic photoresistors are made of the same materials.
Other names for photoresistors are light-dependent resistors, semiconductor photoresistors, and photoconductors.
The photoresistor’s resistance changes as more light energy enters it. So, its resistance changes as well.
However, photoresistor resistance decreases when the intensity of the light being put on it increases.
Magneto Resistor
A magneto resistor is a type of resistor that changes resistance when we apply a magnetic field to it.
In other words, when an external magnetic field gets to the magneto resistor, the flow of electric current through it varies.
Force-sensitive Resistor
A force-sensitive resistor is a material that alters its resistance in response to a force or pressure.
A conductive film is an example of a substance that resists force. Simply put, a force-sensitive resistor is a sensor that detects physical pressure.
