Review on SainSmart 101 70 102 8 Channel Relay Module by Cindy Lloyd

Ideal device for automation projects with Arduino, Raspberry Pi,. Can use 3.3V but needs 5V to drive the relay more effectively. No documentation available. I had to do a bit of googling to find out what some of the pins mean and how much voltage each can handle. Essentially you can drive the transistors and "control" pins with 3.3V or 5V, but if you use 3.3V you need to apply 5V to the auxiliary pin (JDVCC) to fully/ activate effectively. The relays can then power 120V loads applied to them from an external power supply.