Review on 💡 SainSmart 4-Channel Relay Module: Versatile Control for Your Electrical Devices by Keith Alvord

So far this product has been flawless in making a germination chamber which I use Arduino and DHT-22 sensors to periodically check the temperature and humidity of the volume and then the heater turn on. and/or a humidifier with a relay. However, I would like the documentation to be more accessible. I was hesitant to run the module with just the Arduino because I'm not very familiar with the reliability of the electrical isolation and they are all capable of powering both the optically isolated and the solenoid isolated part. (?) Where can I get the network relay power supply. After consulting the subreddit for r/askelectronics and r/arduino I was told that everything should be fine if there is a free wheeling diode to compensate for any voltage spikes when switching. There is documentation with a schematic showing a flyback diode, so I powered the entire module with an Arduino and it has worked great for a few months on the farm it is now being used on.