Should i use a relay

Secondly, relays can be positioned anywhere in the vehicle to provide efficient power transfer to the electrical accessory you are controlling.

Relays are perfect for controlling many circuits in a car like headlights, electric motors, heater etc. How to Understand the Electrical Specifications of a Relay Basic relays feature electrical ratings for both the coil and the internal switching contacts.

The coil voltage rating is the voltage required for the coil to operate correctly. The switching circuit of the relay also features a voltage and ampere rating. This is the maximum rating of the switch contacts and should NOT be exceeded. Double throw relays often have 2 x switch electrical specifications. One for the normally open terminal, the other for the normally closed terminal. Why are Protection Devices used in a Relay? Relays can produce a large voltage spike when they are switched off due to the coil de-energising.

Resistors are more durable than diodes, but not quite as efficient at eliminating voltage spikes. The difference between a 4 and 5 pin relay is that a 4 pin relay is used to control a single circuit, whereas a 5 pin relay switches power between two circuits.

There are 2 types of 4 pin relay available; normally open or normally closed. The coil develops a magnetic field, which closes the contacts. With the contacts closed, battery voltage is applied to the horn which is grounded. Used in this manner, the horn relay becomes a control of the high current necessary to blow the horn.

The control circuit may be wired with very thin wire because it will have low current flowing through it. The control unit may have only 0.

Why bother using a relay? I know that the relay coil completes the horn circuit using magnetism, and I know that the relay is necessary but I can't understand why. For me the relay is just a fancy way to close the path to the horn device. You really aren't understanding how a relay works or what it does. It states right in the quote that the control wire can only handle. The horn itself may require 24A or more. When the relay is activated, it can transfer the needed amperage to the horn through wiring which is designed to take the load.

There is only so much space within a steering wheel and column. In order to run wiring for everything which is controlled there, a relay is the way to go. If every item was to be controlled directly, you'd have to increase the thickness of every wire and thus the size of the steering column to house it.

Besides this, you should also consider the cost to run such wires. You'd have to extend wiring to these specific devices of the larger size, which all costs more. It would also make the vehicle heavier. Another thing to consider is the contact points in the horn button. To do so, you must first locate where the circuits enter and exit the relay, an area typically marked by pins.

After identifying this location, you can use the multimeter to measure the voltage at each point. Many types of relays exist, each bringing unique functions to a variety of applications. Some of the broader categories include:. Time-delay relays are useful in any situation that requires components to be powered for a set length of time, or when the component must power on or off after a specific delay.

These relays have time-delay functionality built in, making them desirable for a range of time-based applications. This category encompasses several types of time-delay relays, each with its specific uses.

Most time-delay relays can be sorted into one of two broad categories:. Other patterns of start and delay are possible with flashers, one-shot timers, or repeat cycles, and each of which allows for the component to be powered at different repeating intervals. This makes flashing indicator or warning lights possible and also enables certain types of timed cycles. Sequential relays can be used to power multiple components in turn, typically in a set order.

A common application for this type of relay involves powering multiple systems or sets of lights one after another, such as in runway lights or power supply sequencing. Relays have almost unlimited uses in automotive applications, and these applications encompass many of the relay types discussed. Many automotive relays allow manufacturers to implement advanced safety features and modern electrical conveniences.

To name just a few examples relays to power the following systems in standard cars or trucks:. Amperite offers a wide range of relays and other electronic components designed to help you save time, money, and energy. We also specialize in manufacturing custom products to address your individual concerns.

If you would like to learn more about our electronic applications and solutions, contact us today! Note: It is important that the new power feed to the driving lights is fused appropriately see our Knowledge Centr e fusing guide.

Tip: It is a good idea to use a separate relay for the left and right hand driving lights and have them switched independently from the left and right hand main beams. This way, if a relay on one side fails the driving light on the other side will still work.

Adding a buzzer that warns when you've left your headlights on. This circuit is designed to alert you that you've left your lights on by activating a buzzer when you open the driver's door. If the headlights are on and the driver's door is opened, the door switch will complete the coil circuit which will complete the high current circuit to the warning buzzer. A warning light could easily be added in parallel to, or used instead of, the buzzer.

Also connects in parallel to terminal This is a clever little circuit involving two relays and a momentary switch and is more a of a 'logic' circuit than one used to switch a high current with a low current. Once the ignition key is in the IGN position, you press and release the momentary switch and then turn the key to the START position and fire the engine as normal.

This has the effect of keeping the coil energised after the button is released note that whilst the button is pressed there is 0V between terminals 86 and Terminal 87 also sends power to the coil of Relay 2 which enables the starter motor solenoid connection, ready for when the key is turned to the START position. When the ignition is turned off the power to the coil of Relay 1 is cut which cuts the power to the coil in Relay 2 and breaks the starter motor solenoid circuit, so the engine cannot be started again without going through the above routine.

The momentary switch can be mounted out of sight and acts a simple starter inhibit security device. This supply also feeds the other side of the momentary switch. Need some hints, tips or guidance on 12V electrics? Visit our Knowledge Centre for a wealth of useful information. Watch our YouTube "how to" guides here. We accept telephone orders Call Relay Guide Overview What is a relay?

Why might I want to use a relay? There are several reasons why you might want or need to use a relay: Switching a high current circuit using a lower current circuit This is the most common reason and useful where an in-line switch or the existing circuit does not have the capacity to handle the current required.

Cost saving High current capacity wiring and switches cost more than lower current capacity versions, so by using relays the requirement for the more expensive components is minimised. Activating more than one circuit from a single input You can use a single input from one part of an electrical system e. All Rights Reserved. Company Reg no.