ITEM NAME:20A 1 Road Relay Module w/Optical Coupling Isolation High Low Level Trigger Product Description Description: Feature: 1. This module is in line with international safety standards, the control area and the load area have isolation tank. 2. The use of pine music authentic relay. 3. With power supply and relay indicator, pull off bright, bright. 4. Signal input signal, the public side and often start will lead. 5. Can be used as a microcontroller development board module, can be used as a home appliance control. 6. Control the DC or AC signals, can control the 220V AC load. 7. There is a normally open and a normally closed contact. 8. Green terminal connected to the control line is more convenient. On the high level and the low level of the trigger instructions, do not understand the friend please look at: 1. High level trigger refers to the signal input terminal and the ground between the trigger mode, can be understood as the signal input and VCC cathode short-circuit trigger a way. 2. Low level trigger refers to the signal input terminal and the voltage between the ground for the OV trigger mode, can be understood as a signal input terminal and GND negative short-circuit trigger a way. Note: Please allow 1-3mm differs due to manual measurement. Due to the different display and different light, the picture may not show the actual color of the item. Thanks for your understanding. Included: 1 X 20A 1 Road Relay Module.The use of pine music authentic relay. Signal input signal, the public side and often start will lead. Due to the different display and different light, the picture may not show the actual color of the item.