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How the Wrong Resistor Can Ruin a Project

10 Jul, 2019 | Quest Components

How the Wrong Resistor Can Ruin a Project

Resistors are special components made for the express purpose of creating a precise amount of resistance for insertion into a circuit. They are typically made of metal wire or carbon and engineered to maintain a consistent resistance throughout a wide range of environmental conditions.

Purpose of the Resistor

The resistor is an electronic component that resists current. When you add a resistor in tandem with a circuit, the current in the circuit decreases. Resistance is a normal property of all wires, with the exception of superconductors. By using resistors, you can design and control the voltage and currents that you need in a circuit.

Resistor Materials

Resistors can be found in a variety of different materials, with each type having its own characteristics and areas of use. You can read more about the various types of resistors here.

Wirewound (WW) Resistors
Wirewound resistors are made by winding resistance wires into a spiral around a non-conductive core. They are produced for high precision and power applications. The core is usually made of ceramic or fiberglass, while the resistance wire is made of nickel-chromium alloy and is not suitable for applications with frequencies higher than 50kHz. Low noise and stability with respect to temperature variations are standard characteristics of wirewound resistors.

Metal Film Resistors
Nichrome or tantalum nitride is typically used for metal film resistors. A combination of ceramic and metal materials typically make up the resistor. The resistance value is changed by cutting a spiral pattern in the film, much like carbon film with a laser or abrasive. Metal film resistors are usually less stable when exposed to extreme temperatures than wirewound resistors, but handle higher frequencies better.

Metal Oxide Film Resistors
Metal oxide resistors use metal oxides such as tin, making them slightly different from metal film resistors. These resistors are reliable, stable, and operate at higher temperatures than metal film resistors. Because of this, metal oxide film resistors are used in applications that require high endurance.

Foil Resistors
Foil resistors, originally developed in the 1960s, are still one of the most accurate and stable types of resistors that can be found today, and are used for applications with high precision requirements. A ceramic substrate that has a thin bulk metal foil cemented to it makes up the resistive element. Foil resistors feature a very low-temperature coefficient of resistance.

Power Dissipated by Resistor - What Can Go Wrong

When you pass a current through a resistor, some of the electrical energy is converted and dissipated as heat by the component. The power rating indicates how much power that resistor can safely dissipate when installed in a circuit. If you exceed the power rating of a resistor, it may get extremely hot. If you continue to increase the current, the power dissipated will also increase. The resistor will continue to increase in temperature--and may even burst into flames--before it finally fails.

Ohm’s Law

Developed by Georg Ohm, Ohm’s Law describes how voltage, current, and resistance are related. If you increase the voltage in a circuit, you get more current. On the other hand, if you increase the resistance in a circuit, you get less current. Voltage can be calculated by using the formula resistance times current, or (V=RI).

Resistors are the most basic and important passive elements of any circuit, and there must be at least one present in every unit. Resistors are used to limit and control the current to other components. For example, if too much current flows through an LED light, it is destroyed. Although resistors may seem trivial, they are absolutely critical to keep every circuit running in top condition.

Ready to Get Started?

Here at Quest Components, we are committed to providing you with the information you need to help your business continue to run smoothly. An ISO 9001:2015 Certified Company headquartered in Industry, CA, Quest Components specializes in passive and active board level components. We also provide a variety of services to OEMs (original equipment manufacturers) and CEMs (contract electronics manufacturers) across the globe. Contact Quest Components today at 626-333-5858 for all your electronic component needs!

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