Review on 🔌 Huayao 2pcs 4 Channel 5V Relay Module with Optocoupler for Arduino UNO R3 MEGA 2560 1280 DSP ARM PIC AVR STM32 Raspberry Pi by Chris Ostby

These relays are great. Simple and works exactly as you would expect. They are active at a low level, which confused me a bit. I just used #define RELAY_OFF HIGH and #define RELAY_ON LOW and then digitalWrite(RELAY1_PIN, RELAY_ON); turn it on this saves you the confusion of trying to remember that 0/LOW is on and 1/HIGH is off. They claim they can handle 10a at 125VAC. What I have to switch with them is only about 5 amps so I have a feeling they will work great. I bought another set that only has 2 as I don't need 4 for this project. But hey, you can't beat the price, right?