Aktronics 4 Channel 5V Relay Shield Module for Arduino R3 MEGA 2560 1280 DSP ARM PIC AVR STM32 Raspberry Pi (Pack of 5) Micro Controller Board Electronic Hobby Kit

5V 4-channel relay interface board each channel needs a 15-20mA driver current. It can be used to control various appliances and equipment with large current. It is equiped with high-current relays that work under AC250V 10A or DC30V 10A. It has a standard interface that can be controlled directly by microcontroller. Perfect used for domestic appliance, office machine, audio, equipment, automobile, etc. ?Remote control TV receiver, monitor display, Audio,Raspberry Pi equipment high rushing current use application? relay Principle When the signal port is at low level, the signal light will light up and the optocoupler 817c (it transforms electrical signals by light and can isolate input and output electrical signals) will conduct, and then the transistor will conduct, the relay coil will be electrified, and the normally open contact of the relay will be closed. When the signal port is at high level, the normally closed contact of the relay will be closed. So you can connect and disconnect the load by controlling the level of the control signal port.