What Does A Resistor Do And Why Is It Important?

Whether you are fixing your air conditioning, connecting new LED lights, or wiring a relay, you are probably working with a resistor. Resistors can be found in almost every electrical circuit, but they are often built-in to other components. So what do these hidden resistors really do? And why are they so important to the electrical circuits you use every day?


What does a resistor do?

A resistor controls the flow of the electrical current within a circuit. Resistors are made from materials like copper or carbon, which make it difficult for the electrical charges to flow through a circuit. The most common type of resistor is a carbon resistor, which is a general purpose resistor, best suited for lower-powered circuits. Some other common resistor types include the film resistor and the wire-wound resistor. Resistors are essential to many electoral circuits, and they can be applied to a myriad of different applications.

Protect against voltage spikes. Resistors also protect components against voltage spikes. Components that are sensitive to a high electrical current, like LED lights, will be damaged if there is not a resistor to control the flow of the electrical current. In addition, fuses and circuit breakers can also be used to protect your electrical circuit against voltage spikes.   

Provide the proper voltage. Resistors ensure components receive the proper voltage by creating a voltage drop, and they can protect a component from voltage spikes. Each component in an electrical circuit, like a light or a switch, requires a specific voltage. If a component in your circuit requires less voltage than the rest of your circuit, a resistor will create a voltage drop to ensure the component does not receive too much voltage. The resistor will create a voltage drop by slowing down, or resisting, the electrons as they try to flow through the resistor. If a component receives too much voltage, it may be damaged or not function properly. When upgrading incandescent turn signals to LED, an LED load resistor is required for each light in order to ensure the turn signals work properly. The LED load resistor creates a voltage drop so the LED turn signals blink at a proper speed. If the LED load resistor was not installed, the LED turn signal would blink too rapidly, and would eventually be destroyed by the high voltage. Need to upgrade? Check out this post to learn how to make the switch to LEDs.


Common Resistor Applications

While resistors can be bought individually, they are often built-in to other electrical components, such as the LED load resistor, relays, and other 12V electrical products. In a relay, the resistor absorbs access voltage given off when the relay is activated. This will protect any other components in the circuit from voltage spikes. Relays allow for a high current flow circuit to be controlled by a low current flow circuit, and they are made to fit a variety of applications.

Some common relays include the relay with resistor, which will fit into a standard fuse box. This relay is ideal for full voltage applications such as fog horns, window lifters, air conditioners, and much more. While the relay is ideal for full voltage applications, the built-in resistor will protect any sensitive equipment against voltage spikes.

A potted relay is also ideal for full voltage applications, but it offers extra protection for marine applications and vehicles exposed to harsh conditions. The term “potted” means that the relay is sealed against dust and moisture, while the internal resistor protects against voltage spikes.

A mini 280 skirted relay with resistor is similar to the standard relay with resistor, but the skirted relay connects with the sealed OEM connector in the vehicle. This skirted relay also features Mini 280 style pins.

The ISO 280 Micro relay with resistor is a smaller version of the standard relay. The ISO 280 footprint will fit most common Mini (ATM) fuse boxes.




They may be small and often built-in to other components, but resistors are essential to almost every electrical circuit. These hidden resistors are essential because they control the flow of the electrical current to sensitive components, and they protect components from voltage spikes. So the next time you turn on your air conditioning or your new LED light, remember that a resistor is working to protect your component and ensure it is functioning properly.

If you would like learn more or have if you have questions about Del City’s products with built-in resistors, visit www.delcity.net or call 1.800.654.4757.







Posted in Relays & Power Distribution.