Review on ELEGOO Optocoupler Module for Arduino and Raspberry Pi - Channel-Enhanced for Optimal Performance by Dan Chunn

I just used it in a Raspberry PI project to control ceiling fans in the living room and bedroom. This module works very well when properly connected to the RPi. There is a lot of misinformation about this product and its counterparts. I measured the actual current draw based on my project and here are the facts: The current draw on a single 3.3V GPIO port to turn on the relay is only 0.47mA, not 16-20mA as in the specifications given. The maximum current draw for the RPi's GPIO port is 16mA, so there is enough current to drive these relays. The relays are driven by a 5V source and the GPIO only turns on the relay driver power. The main 5V power supply increase when a GPIO port is enabled is 53mA. I haven't measured it for 2 relays at the same time. The 53mA to turn on the relay comes entirely from a 5V power supply, in my case a 2.5A wall wart, connected to the microUSB header, so that current doesn't charge the RPi at all, only the wall wart. To connect the RPi to this module, connect the RPi's 5V pin to the JD VCC connector on the module and the RPi's GND pin to the GND pin on the module to the left of the JD VCC pin. Leave the middle VCC pin unused. Connect the 3.3V pin from the RPi to the VCC pin on the module's 10-pin header. I also connected another RPi GND pin to the GND pin on this header. Finally, connect the GPIO pins to each of the 8 inputs on this 10-pin header.