2 Channel Relay Module Relay Board Arduino Relay Module With Optocoupler allows a wide range of microcontrollers such as Arduino, AVR, PIC, ARM with digital outputs to control larger loads and devices like AC or DC Motors, electromagnets, solenoids, and incandescent light bulbs. 4–channel relay interface board, and each channel needs a 15-20mA driver current. It can be used to control various appliance
The positive (according to the relay voltage VCC: connect power supply)
GND: connect power negative
IN1: relay module (effective) high-level trigger signal trigger end
IN2: relay module (effective) high-level trigger signal trigger end
High-level trigger refers to using the anode voltage at the VCC connection way of a trigger and triggers the end when the trigger side has the positive voltage or to trigger voltage when the relay is off.
Low-level trigger refers to using the negative voltage at the GND connection way of a trigger and triggers the end when the trigger side has 0 v low voltage or voltage to can trigger, the relay is off.