They can be used to control devices such as lights, fans, motors, solenoids, etc. 5V relay has three high voltage terminals (NC, C, and NO) which connect to the device you want to control. The input voltage can be from any microcontroller or logic chip that outputs a digital signal. Like most other relays, the 5V relay module is an electrically operated, electromagnetic. The following are the major components present on a relay module; we will get into the details later in this article. 5V Relay, Transistor, Diode, LEDs, Resistors, Male Header pins, 3-pin screw-type terminal connector, etc. It consists of an electromagnet, an armature, a spring, and one or more sets of electrical contacts. This component is widely used in electronic.