Relay Board

This board has optocouplers (LED/phototransistor pair) that isolate the relay coil circuitry from the signal input. The microprocessor likely couldn't drive the relay coils directly, at least not several at once, and the isolation gives you some additional isolation/protection. You need to supply power to the relay board as well as the signals for relay control. I don't have any experience with that particular board but someone else here may...
 
I use these instead of relays. http://www.ebay.com/...=item4168c2ca56Granted they are a bit larger but I feel more comfortable with them. Rumour has it that these are cheap imitations of Fotek and not the real thing. I haven't had any issues but never run something close to the max rating either. I've been using them for several years with no issues as of yet.
 
The relay board suggested by fwd03 looks to have very similar circuitry to the one in the original post. Either one should work ok but they both need a 5V supply (both positive and negative) in addition to the signals because they both have optoisolation. Solid state relays are a good way to go also.
 
Back
Top