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Types Of Relays And How To Use Them? SPDT, DPDT, and Solid-State Relay

What Are Relays?

Relays are a type of electrical switch that is used to control circuits and direct the flow of electricity. They are an important component in many different types of electrical and electronic systems and come in a wide range of sizes and designs to suit a variety of applications. In this blog, we will explore some of the different types of relays including the 4-channel relay modules, general-purpose Relay, SPDT, and more, and how they work.

What Are Different Types Of Relays?

Here is the list of various types of relays-

Electromagnetic Relay

One of the most common types of relays is the electromagnetic relay. This type of relay uses an electromagnet to operate a switching mechanism, allowing it to control a circuit by turning it on or off.

Delay Relay

Another type of relay is the time delay relay. As the name suggests, this type of relay is designed to delay the operation of a switch or circuit for a specific amount of time. This can be useful in a variety of applications, such as providing a delay before a motor starts, or allowing a circuit to warm up before it is switched on.

Solid State Relay

Solid state relays are another type of relay that uses electronic components instead of an electromagnet to operate a switch. These relays are often smaller and more reliable than electromagnetic relays and can handle higher switching frequencies.

Reed Relay

Reed relays are often used in applications where space is limited, such as instrumentation, test equipment, and telecommunications.

SPDT Relay

A SPDT Relay (Single Pole Double Throw Relay) is a type of electrical switch that has two switching positions. In the first position, the switch connects the input terminal to the first output terminal. In the second position, the switch connects the input terminal to the second output terminal.


DPDT relays or DPDT switches are commonly used in control systems, where they can be used to switch between multiple circuits or control multiple devices. For example, a DPDT relay could be used to control two motors by switching the power supply on or off for each motor independently.

Other types of relays include thermal relays, mercury-wetted relays, and contactor relays. Thermal relays use the heat generated by an electric current to operate a switch, while mercury-wetted relays use a small amount of mercury to create a low-resistance path for the current. Contactor relays, also known as motor starters, are used to control high-power electric motors.

How to Use Relay Modules?

Relays are typically used to control a circuit by turning it on or off using a low-power control signal. To use a relay, you first need to connect the relay to a power source and to the circuit that you want to control. The control signal is then applied to the relay, which activates the electromagnet or other switching mechanism, closing or opening the switch and turning the circuit on or off.

Here is a step-by-step guide on how to use a relay:

Identify the type of relay you are using and ensure that it is suitable for the intended application.

Connect the relay to a power source, following the manufacturer’s instructions. This may involve connecting the relay to a voltage source or to a current source, depending on the type of relay.

Connect the relay to the circuit that you want to control. This typically involves connecting the load, or the device that you want to control, to the switch or contacts on the relay.

Apply the control signal to the relay. This may involve sending a voltage or current to the control input on the relay or using a mechanical switch or other control mechanisms.

Monitor the operation of the relay and the circuit to ensure that it is functioning properly.


To sum it up, there are many different types of relays, each with its own specific purpose and function. From electromagnetic relays to solid-state relays and beyond, these versatile components play a crucial role in the operation of many different electrical and electronic systems. If you are looking for relays from top manufacturers like Ubintex, Campus component offers you the widest range of products ranging from sugar cube relays to T-type relays. All the above-discussed types of relays are also available to be purchased from Campus Component at the most affordable relay module prices.