Types of Resistance

Types of resistance are the most basic and widely used of all electronic components.

From very small surface mounted chip resistors to large wired power resistors, there are many different Types of Resistance that the electronics manufacturer can choose from.

The main task of a resistance within an electrical or electronic circuit is to "resist" to regulate or adjust the flow of electrons (current) using the type of conductive material they create.Resistors can also be connected in various series and parallel combinations to create resistance networks that can act as voltage reducers, voltage dividers or current limiters within a circuit.

types of resistance
resistance

Resistors are called "Passive Devices", that is, they do not contain any power supply or amplification, but only weaken or reduce the voltage or current signal that passes through them.This weakening causes electrical energy to disappear in the form of heat, as it resists the flow of electrons through the resistance.

Then a potential difference between the two terminals of a resistance is required for the current to flow.This potential difference balances the energy lost.When used in DC circuits, the potential difference, also known as resistance voltage drop, is measured between terminals as the circuit current passes through the resistance.

Most types of resistance are linear devices that produce voltage drop among themselves when an electric current passes through them because they comply with the Ohm Law, and produce different resistance values, different current or voltage values.This can be very useful in electronic circuits, as we can produce a voltage-to-current and current-to-voltage converter by controlling or reducing the current flow or the voltage produced between them.

There are thousands of different Types of Resistance and they are produced in various ways according to their specific characteristics and accuracy: suitable for certain application areas such as High Stability, High Voltage, High Current, etc., or used as general purpose resistors.

Some of the common features related to common resistances include; Temperature Coefficient, Voltage Coefficient, Noise, Frequency Response, Power, Temperature, Physical Size and Reliability .

In all Electrical and Electronic circuit diagrams, the most commonly used symbol for a fixed-value resistance is a "zigzag" type line given as resistance value Ohm, Ω. Resistors have constant resistance values of less than one ohm <1Ω ) ile="" on="" milyonlarca="" ohm'un="" ( ="">(10MΩ).</1Ω )>

Constant resistors have only one resistance value, for example 100Ω, but variable resistors(ponsiometers)can provide an infinite number of resistance values between zero and maximum values.

Standard Resistance Symbols

types of resistance

The symbol commonly used in schematic and electrical drawings for a Resistance can be a line of the type "zigzag" or a rectangular box.

All modern fixed-value resistors can be divided into four broad groups:

  • Carbon Composition Resistance – Made of carbon powder or graphite paste, it has low wattage values.
  • Film or Sermet Resistance – Made of conductive metal oxide paste, it has very low wattage values.
  • Wire-winded Resistance – Has metallic bodies for refrigeration installation, has very high wattage values.
  • Semiconductor Resistance – High frequency/precision surface mounting thin film technology is used.

A wide range of fixed and variable resistance types with different construction styles are available for each group, and each has its own characteristics, advantages and disadvantages over the others.Incorporating all types will make this section very large, so we will limit this content to the most widely used and easily available types of general purpose resistance.

Types of Resistance

Composite (Composite) Types of Resistance

Carbon Resistors

Carbon Resistors arethe most common type of composition resistance.Carbon resistances are inexpensive, general purpose resistance used in electrical and electronic circuits.

types of resistance
Carbon Resistance

Resistance elements are produced from a mixture of finely ground carbon powder or graphite (similar to a pen tip) and nonconductor ceramic (clay) powder, and all materials are compressed into one another in a small area.

The ratio of carbon dust to ceramics (conductive to ins isolated) determines the overall resistance value of the mixture, and the higher the carbon ratio, the lower the total resistance.The mixture is molded into a cylindrical shape before being covered with color-coded markings to indicate an external insulation material and resistance value, with metal wires or inserts attached to each end to ensure electrical connection as shown.

types of resistance
Carbon Resistance Structure

Carbon compound resistances are ideal for high frequency applications because they have low inducing. However, if the temperature is high, it starts to make noise in the signal or its accuracy may deteriorate. Carbon compound resistors are usually pre-attached with a "CR" notation (e.g. CR10kΩ) and are available in E6 (± 20% tolerance (accuracy) ), E12 (± 10% tolerance) and E24 (± 5% tolerance) packages.Rated from 0.250 or 1/4 Watt to 5 Watts.

Carbon compound resistance types are very inexpensive to make and are therefore widely used in electrical circuits.However, carbon-type resistors have very large tolerances due to production processes, so film-type resistors are used instead for more precise and high-value resistors.

Film Type Resistors

The general term Film Resistors consists of metal film, carbon film and metal oxide film resistance types, which are usually made by placing pure metals such as nickel or an oxide film such as tin oxide on an insulating ceramic rod.

Film Resistance
Film Resistance

The resistance value of the resistance is controlled by increasing the desired thickness of the accumulated film, which is called "thick film resistors" or "thin film resistors".

Once placed, a laser is used to cut a high-precision spiral spiral groove type pattern into this film.

This method of production allows much closer tolerance resistances (1% or less) compared to simpler types of carbon composition.The tolerance of a resistance is the difference between the preferred value (i.e. 100 ohm) and the actual generated value, that is, 103.6 ohm, and is expressed as a percentage, for example 5%, 10%, etc., and in our case the actual tolerance is 3.6%.Film-type resistors also achieve a much higher maximum omic value than other types and are available above 10MΩ (10 Million Ohm).

types of resistance
Film Resistance Structure

Metal Film Resistors have much better temperature stability and lower noise than their carbon equivalents and are often used for high frequency or radio frequency applications.Metal Oxide Resistors have a better high overcurrent capacity with a temperature much higher than equivalent metal film resistors.

Another type of film resistance, commonly known as Thick Film Resistance, is produced by releasing a much thicker conductive CERamic and METal paste called Cermet on an aluminum ceramic substrate.Sermet resistors have properties similar to metal film resistors and are often used to make small surface mounted chip type resistors, very resistant networks and high frequency resistors in a single package for PCBs.They have good temperature stability, low noise and good voltage values, but have low overcurrent properties.

A "MFR" notation (for example, MFR100kΩ) and a CF for Carbon Film types are added in front of Metal Film Resistors.Metal film resistors, E24 (± 5% and ± 2% tolerances), E96 (± 1% tolerance) and E192 (± 0.5%, ± 0.05 %, and ± 0.1% tolerances) packages with a power rating of 0.05 (1/) up to 1/2 Watt of a Watt.

Wirewound Resistance Types

Another type of resistance called Wirewound Resistance(metal resistance-stone resistance) is made by wrapping a thin metal alloy wire (Nikrom) or similar wire in an insulating ceramic constructor in the form of a spiral helix similar to the film resistance above.

types of resistance
Wirewound Resistance

Such resistors are usually only available at very low omic high sensitivity values (0.01Ω to 100kΩ), since the size of the wire and the number of rotations possible in the previous one make them ideal for use in measuring circuits and Wheatstone bridge type applications. .

In addition, they can process much higher electrical currents than other resistors with the same omic value with power ratings exceeding 300 Watts.These high-powered resistors are molded or pressed into an aluminum heatsucking body with fins attached to increase total surface areas to ensure heat loss and cooling.

These special types of resistance are called "Chassis Mounted Resistors" because they are designed to be physically installed in coolers or metal plates to further dissipate the generated heat.Mounting the resistance on a cooler further increases their current carrying abilities.

Another type of wired resistance is Power Wired Resistance.These are high temperature, high-power non-inductive types of resistance usually coated with glassy or glass epoxy enamators for use in resistance banks or DC motor/servo control and dynamic braking applications.They can even be used as low voltage area or cabin heaters.

The non-inductive resistance wire is wrapped around a ceramic or porcelain pipe covered with mica to prevent alloy wires from moving when hot.Wire-winded resistors are available in various resistance and power values, and a main use of power wire-winded resistance is in the electrical heating elements of an electric fire that converts the electric current flowing through it into heat, with each element dispersing up to 1000 Watts, (1kW) of energy.

Since the wire of standard wire-winded resistors is wrapped in a coil inside the resistance body, it acts like an inductor, causing them to have resistance as well as inductiveness.This affects the way resistance behaves in AC circuits, producing a phase shift at high frequencies, especially in larger-sized resistors.The length of the actual resistance path in resistance and at the ends contributes to the mass inducing with "visible" DC resistance, resulting in a general impedance path of Z Ohm.

Impedance ( Z ) is the combined effect of resistance ( R ) and inductee ( X ) measured in ohm and is given as Z 2 = R 2 + X 2 for a series of AC circuits.

When used in AC circuits, this inductive value changes with frequency (inductive reaccurrence, X L = 2ππL), and therefore the total value of resistance changes.Inductive reassurance increases with frequency, but in DC it is zero (zero frequency).In this case, wire-winded resistors should not be designed or used in AC or amplifier type circuits, where the frequency changes throughout the resistance.However, special non-inductive wire-winded resistors are also available.

types of resistance
Wirewound Resistance Structure

Wirewound resistance types, with a notation of "WH" or "W" (e.g.WH10Ω ) and available in WH aluminum coated package (± 1%, ±%2± 5% and ± 10% tolerance) or W glass. It is also available in easing packages with a power rating of 1W to 300W or more (±%1%, ±%2% and ± 5% tolerance).

Summarize

There are many different types of resistance, from low-cost, large-tolerant, general purpose carbon resistances to low-tolerance, high-cost, precision film resistors, as well as high-power, wire-winded ceramic resistors.A resistance regulates, blocks or adjusts the flow of the current along a certain path, or can apply a voltage drop in an electrical circuit.

The resistance value of a resistance, the ability to limit current flow, is measured in Ohms (Ω), ranging from an Ohm (Mega-Ohms) to millions of Ohms, each of which is less than an Ohm.Resistors can be of a constant value, for example: variable such as 100 Ohm, ( 100Ω ) or 0 to 100Ω.

Regardless of the feeding frequency at very high frequencies in DC circuits, a resistance will always have the same resistance value, and all resistors have one thing in common, the resistance values in Ohm in a circuit will be DAMA positive and will never be negative.

The uses and applications of resistance within an electrical or electronic circuit are very wide and varied with almost any electronic circuit designed using one or more types of resistance.Resistors are widely used for purposes such as current limitation, providing appropriate control voltages to semiconductor devices such as bipolar transistors, protecting LEDs or other semiconductor devices from overcurrent damage, as well as adjusting or limiting frequency response in an audio or filter circuit.

In digital circuits, different types of resistors can be used to control voltage at some point in a circuit by serially placing two resistors to pull up or down the voltage on the input pin of a digital logic chip, or to create a voltage divider network.

In the next tutorial on resistors, we will look at different ways to determine the resistance value of different types of constant resistors, the most common method of identification is the use of Color Codes and color bands around the body of resistance.